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| manufacturer = [[German Aerospace Center|DLR]]{{\}}[[Max Planck Institute for Solar System Research|MPS]]{{\}}[[CNES]]{{\}}[[Italian Space Agency|ASI]]
| manufacturer = [[German Aerospace Center|DLR]]{{\}}[[Max Planck Institute for Solar System Research|MPS]]{{\}}[[CNES]]{{\}}[[Italian Space Agency|ASI]]
| dry_mass = <!--spacecraft mass in orbit without fuel-->
| dry_mass = <!--spacecraft mass in orbit without fuel-->
| launch_mass = {{convert|100|kg|lb|abbr=on}}<ref name="nssdc">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-006C |title=Philae |publisher=[[National Space Science Data Center]] |access-date=18 November 2014}}</ref>
| launch_mass = {{convert|100|kg|lb|abbr=on}}<ref name="nssdc">{{Cite web |title=Philae |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-006C |url-status=live |archive-url=https://web.archive.org/web/20231205185354/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-006C |archive-date=5 December 2023 |access-date=18 November 2014 |publisher=[[National Space Science Data Center]] |id=2004-006C }}</ref>
| payload_mass = {{convert|21|kg|lb|abbr=on}}<ref name=nssdc />
| payload_mass = {{convert|21|kg|lb|abbr=on}}<ref name=nssdc />
| dimensions = {{convert|1|xx|1|xx|0.8|m|ft|abbr=on}}<ref name="nssdc" />
| dimensions = {{convert|1|xx|1|xx|0.8|m|ft|abbr=on}}<ref name="nssdc" />
| power = 32 watts at 3 [[Astronomical unit|AU]]<ref name="dlrPdf">{{cite web |url=http://www.dlr.de/dlr/Portaldata/1/Resources/documents/Philae_Lander_FactSheets.pdf |title=Philae lander fact sheet |publisher=[[German Aerospace Center]] |access-date=28 January 2014 }}</ref>
| power = 32 watts at 3 [[Astronomical unit|AU]]<ref name="dlrPdf">{{Cite web |title=Philae lander fact sheets |url=https://www.dlr.de/dlr/Portaldata/1/Resources/documents/Philae_Lander_FactSheets.pdf |url-status=live |archive-url=https://web.archive.org/web/20221122103836/https://www.dlr.de/dlr/Portaldata/1/Resources/documents/Philae_Lander_FactSheets.pdf |archive-date=22 November 2022 |access-date=28 January 2014 |publisher=[[German Aerospace Center]] }}</ref>


<!--Launch details-->
<!--Launch details-->
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|type = lander
|type = lander
|object = [[67P/Churyumov–Gerasimenko]]
|object = [[67P/Churyumov–Gerasimenko]]
|arrival_date = 12 November 2014, 17:32&nbsp;UTC<ref name="esathree20141114">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |title=Three Touchdowns For Rosetta's Lander |publisher=European Space Agency |date=14 November 2014 |access-date=15 November 2014}}</ref>
|arrival_date = 12 November 2014, 17:32&nbsp;UTC<ref name="esathree20141114">{{Cite press release |date=14 November 2014 |title=Three Touchdowns For Rosetta's Lander |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |url-status=live |archive-url=https://web.archive.org/web/20231018072901/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |archive-date=18 October 2023 |access-date=15 November 2014 |publisher=[[European Space Agency]] }}</ref>
|location = Abydos<ref name="Philaefound">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Philae_found |title=Philae found! |publisher=European Space Agency |date=5 September 2016 |access-date=5 September 2016}}</ref>
|location = Abydos<ref name="Philaefound">{{Cite press release |date=5 September 2016 |title=Philae found! |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Philae_found |url-status=live |archive-url=https://web.archive.org/web/20240116104049/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Philae_found |archive-date=16 January 2024 |access-date=5 September 2016 |publisher=[[European Space Agency]] }}</ref>
}}
}}


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|acronym8 =ROMAP |name8= Rosetta lander Magnetometer and Plasma monitor
|acronym8 =ROMAP |name8= Rosetta lander Magnetometer and Plasma monitor
|acronym9 =SD2 |name9=Sampling, Drilling and Distribution
|acronym9 =SD2 |name9=Sampling, Drilling and Distribution
|acronym10=SESAME |name10=Surface Electric Sounding and Acoustic Monitoring Experiment<ref>{{cite web |url=http://sci.esa.int/rosetta/31445-instruments/ |title=Lander Instruments |publisher=European Space Agency |access-date=3 March 2015}}</ref>
|acronym10=SESAME |name10=Surface Electric Sounding and Acoustic Monitoring Experiment<ref name="esa-ros-instruments">{{Cite web |title=Lander Instruments |url=https://sci.esa.int/web/rosetta/-/31445-instruments |url-status=live |archive-url=https://web.archive.org/web/20231225002314/https://sci.esa.int/web/rosetta/-/31445-instruments |archive-date=25 December 2023 |access-date=3 March 2015 |publisher=[[European Space Agency]] }}</ref>
|acronym11=CASSE |name11=Comet Acoustic Surface Sounding Experiment
|acronym11=CASSE |name11=Comet Acoustic Surface Sounding Experiment
|acronym12=DIM |name12=Dust Impact Monitor
|acronym12=DIM |name12=Dust Impact Monitor
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}}<!-- end infobox -->
}}<!-- end infobox -->


'''''Philae''''' ({{IPAc-en|'|f|aɪ|l|iː}}<ref>{{cite encyclopedia |url=http://dictionary.reference.com/browse/philae |title=philae |encyclopedia=Dictionary.com Unabridged |publisher=Random House |access-date=13 November 2014}}</ref> or {{IPAc-en|'|f|i:|l|eɪ}}<ref>{{cite news |url=http://www.cnn.com/2014/11/12/world/comet-landing-countdown/index.html |title=Space probe scores a 310-million-mile bull's-eye with comet landing |work=CNN |first=Ralph |last=Ellis |date=12 November 2014 |access-date=13 November 2014}}</ref>) was a [[robotic]] [[European Space Agency]] [[Lander (spacecraft)|lander]] that accompanied the [[Rosetta (spacecraft)|''Rosetta'']] [[spacecraft]]<ref name="NYT-20140805">{{cite news |url=https://www.nytimes.com/2014/08/06/science/space/rosetta-spacecraft-set-for-unprecedented-close-study-of-a-comet.html |title=Rosetta Spacecraft Set for Unprecedented Close Study of a Comet |work=[[The New York Times]] |first=Kenneth |last=Chang |date=5 August 2014 |access-date=5 August 2014}}</ref><ref name="NYT-20141123-ED">{{cite news |url=https://www.nytimes.com/2014/11/24/opinion/in-pursuit-of-an-oddly-shaped-comet.html |title=In Pursuit of an Oddly Shaped Comet |work=[[The New York Times]] |date=23 November 2014 |access-date=23 November 2014}}</ref> until it separated to land on [[comet]] [[67P/Churyumov–Gerasimenko]], ten years and eight months after departing Earth.<ref name="UlamecActa">{{cite journal |title=Rosetta Lander—Philae: Implications of an alternative mission |journal=Acta Astronautica |first1=S. |last1=Ulamec |first2=S. |last2=Espinasse |first3=B. |last3=Feuerbacher |first4=M. |last4=Hilchenbach |first5=D. |last5=Moura |first6=H. |last6=Rosenbauer |first7=H. |last7=Scheuerle |first8=R. |last8=Willnecker |display-authors=5 |volume=58 |issue=8 |pages=435–441 |date=April 2006 |doi=10.1016/j.actaastro.2005.12.009 |bibcode=2006AcAau..58..435U}}</ref><ref name="Biele2002">{{cite journal |title=The Experiments Onboard the ROSETTA Lander |journal=Earth, Moon, and Planets |first=Jens |last=Biele |volume=90 |issue=1–4 |pages=445–458 |year=2002 |doi=10.1023/A:1021523227314 |bibcode=2002EM&P...90..445B|s2cid=189900125 }}</ref><ref name="NASA-201401017">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2014-015 |title=Rosetta: To Chase a Comet |publisher=[[NASA]] |last1=Agle |first1=D. C. |last2=Cook |first2=Jia-Rui |last3=Brown |first3=Dwayne |last4=Bauer |first4=Markus |date=17 January 2014 |access-date=18 January 2014}}</ref> On 12 November 2014, ''Philae'' touched down on the comet, but it bounced when its anchoring harpoons failed to deploy and a thruster designed to hold the probe to the surface did not fire.<ref name="newsciprob20141113" /> After bouncing off the surface twice, ''Philae'' achieved the first-ever "soft" (nondestructive) landing on a [[comet nucleus]],<ref name="NASA-20141112-DCA">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2014-394 |title=Rosetta's 'Philae' Makes Historic First Landing on a Comet |publisher=NASA |last1=Agle |first1=D. C. |last2=Webster |first2=Guy |last3=Brown |first3=Dwayne |last4=Bauer |first4=Markus |date=12 November 2014 |access-date=13 November 2014}}</ref><ref name="NYT-20141112-KC">{{cite news |url=https://www.nytimes.com/2014/11/13/science/space/european-space-agencys-spacecraft-lands-on-comets-surface.html |title=European Space Agency's Spacecraft Lands on Comet's Surface |work=[[The New York Times]] |last=Chang |first=Kenneth |date=12 November 2014 |access-date=12 November 2014}}</ref><ref name="PhilaeInd1">{{cite news |url=https://www.independent.co.uk/news/science/philae-lander-bounced-twice-on-comet-and-may-still-not-be-stable-rosetta-mission-scientists-warn-9857551.html |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/philae-lander-bounced-twice-on-comet-and-may-still-not-be-stable-rosetta-mission-scientists-warn-9857551.html |archive-date=26 May 2022 |url-access=subscription |url-status=live |title=Philae lander 'bounced twice' on comet but is now stable, Rosetta mission scientists confirm |work=[[The Independent]] |last=Withnall |first=Adam |date=13 November 2014 |access-date=5 September 2016}}</ref> although the lander's final, uncontrolled touchdown left it in a non-optimal location and orientation.<ref name="PhilaeBBC1">{{cite news |url=https://www.bbc.com/news/science-environment-30034060 |title=Rosetta: Battery will limit life of Philae comet lander |work=BBC News |date=13 November 2014 |access-date=5 September 2016}}</ref>
'''''Philae''''' ({{IPAc-en|'|f|aɪ|l|iː}}<ref name="dict-com-philae">{{Cite encyclopedia |title=philae |encyclopedia=Dictionary.com Unabridged |publisher=Random House |url=https://www.dictionary.com/browse/philae |access-date=13 November 2014 |archive-url=https://web.archive.org/web/20231112155439/https://www.dictionary.com/browse/philae |archive-date=12 November 2023 |url-status=live }}</ref> or {{IPAc-en|'|f|i:|l|eɪ}}<ref name="cnn-20141112">{{Cite news |last=Gilbert |first=Dave |date=12 November 2014 |title=Space probe scores a 310-million-mile bull's-eye with comet landing |url=https://edition.cnn.com/2014/11/12/world/comet-landing-countdown/index.html |url-status=live |archive-url=https://web.archive.org/web/20240104233734/https://edition.cnn.com/2014/11/12/world/comet-landing-countdown/index.html |archive-date=4 January 2024 |access-date=13 November 2014 |work=[[CNN]] }}</ref>) was a [[robotic]] [[European Space Agency]] [[Lander (spacecraft)|lander]] that accompanied the [[Rosetta (spacecraft)|''Rosetta'']] [[spacecraft]]<ref name="NYT-20140805">{{Cite news |last=Chang |first=Kenneth |date=5 August 2014 |title=Rosetta Spacecraft Set for Unprecedented Close Study of a Comet |url=https://www.nytimes.com/2014/08/06/science/space/rosetta-spacecraft-set-for-unprecedented-close-study-of-a-comet.html |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20230807111121/https://www.nytimes.com/2014/08/06/science/space/rosetta-spacecraft-set-for-unprecedented-close-study-of-a-comet.html |archive-date=7 August 2023 |access-date=5 August 2014 |work=[[The New York Times]] }}</ref><ref name="NYT-20141123-ED">{{Cite news |date=23 November 2014 |title=Opinion: In Pursuit of an Oddly Shaped Comet |url=https://www.nytimes.com/2014/11/24/opinion/in-pursuit-of-an-oddly-shaped-comet.html |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20231112155439/https://www.nytimes.com/2014/11/24/opinion/in-pursuit-of-an-oddly-shaped-comet.html |archive-date=12 November 2023 |access-date=23 November 2014 |work=[[The New York Times]] }}</ref> until it separated to land on [[comet]] [[67P/Churyumov–Gerasimenko]], ten years and eight months after departing Earth.<ref name="UlamecActa">{{Cite journal |last1=Ulamec |first1=S. |last2=Espinasse |first2=S. |last3=Feuerbacher |first3=B. |last4=Hilchenbach |first4=M. |last5=Moura |first5=D. |last6=Rosenbauer |first6=H. |last7=Scheuerle |first7=H. |last8=Willnecker |first8=R. |display-authors=5 |date=April 2006 |title=Rosetta Lander—Philae: Implications of an alternative mission |journal=[[Acta Astronautica]] |volume=58 |issue=8 |pages=435–441 |bibcode=2006AcAau..58..435U |doi=10.1016/j.actaastro.2005.12.009 }}</ref><ref name="Biele2002">{{Cite journal |last=Biele |first=Jens |date=June 2002 |title=The Experiments Onboard the ROSETTA Lander |journal=Earth, Moon, and Planets |volume=90 |issue=1–4 |pages=445–458 |bibcode=2002EM&P...90..445B |doi=10.1023/A:1021523227314 |s2cid=189900125 }}</ref><ref name="NASA-201401017">{{Cite press release |last1=Agle |first1=D. C. |last2=Cook |first2=Jia-Rui |last3=Brown |first3=Dwayne |last4=Bauer |first4=Markus |date=17 January 2014 |title=Rosetta: To Chase a Comet |url=https://www.jpl.nasa.gov/news/rosetta-to-chase-a-comet |url-status=live |archive-url=https://web.archive.org/web/20231112083043/https://www.jpl.nasa.gov/news/rosetta-to-chase-a-comet |archive-date=12 November 2023 |access-date=18 January 2014 |publisher=[[NASA]] }}</ref> On 12 November 2014, ''Philae'' touched down on the comet, but it bounced when its anchoring harpoons failed to deploy and a thruster designed to hold the probe to the surface did not fire.<ref name="newsciprob20141113" /> After bouncing off the surface twice, ''Philae'' achieved the first-ever "soft" (nondestructive) landing on a [[comet nucleus]],<ref name="NASA-20141112-DCA">{{Cite press release |last1=Agle |first1=D. C. |last2=Webster |first2=Guy |last3=Brown |first3=Dwayne |last4=Bauer |first4=Markus |date=12 November 2014 |title=Rosetta's 'Philae' Makes Historic First Landing on a Comet |url=https://www.jpl.nasa.gov/news/rosettas-philae-makes-historic-first-landing-on-a-comet |url-status=live |archive-url=https://web.archive.org/web/20231216135840/https://www.jpl.nasa.gov/news/rosettas-philae-makes-historic-first-landing-on-a-comet |archive-date=16 December 2023 |access-date=13 November 2014 |publisher=[[NASA]] }}</ref><ref name="NYT-20141112-KC">{{Cite news |last=Chang |first=Kenneth |date=12 November 2014 |title=European Space Agency's Spacecraft Lands on Comet's Surface |url=https://www.nytimes.com/2014/11/13/science/space/european-space-agencys-spacecraft-lands-on-comets-surface.html |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20231112094834/https://www.nytimes.com/2014/11/13/science/space/european-space-agencys-spacecraft-lands-on-comets-surface.html |archive-date=12 November 2023 |access-date=12 November 2014 |work=[[The New York Times]] }}</ref><ref name="PhilaeInd1">{{cite news |url=https://www.independent.co.uk/news/science/philae-lander-bounced-twice-on-comet-and-may-still-not-be-stable-rosetta-mission-scientists-warn-9857551.html |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/philae-lander-bounced-twice-on-comet-and-may-still-not-be-stable-rosetta-mission-scientists-warn-9857551.html |archive-date=26 May 2022 |url-access=subscription |url-status=live |title=Philae lander 'bounced twice' on comet but is now stable, Rosetta mission scientists confirm |work=[[The Independent]] |last=Withnall |first=Adam |date=13 November 2014 |access-date=5 September 2016}}</ref> although the lander's final, uncontrolled touchdown left it in a non-optimal location and orientation.<ref name="PhilaeBBC1">{{Cite news |last=Amos |first=Jonathan |date=13 November 2014 |title=Rosetta: Battery will limit life of Philae comet lander |url=https://www.bbc.com/news/science-environment-30034060 |url-status=live |archive-url=https://web.archive.org/web/20240211141611/https://www.bbc.com/news/science-environment-30034060 |archive-date=11 February 2024 |access-date=5 September 2016 |work=[[BBC News]] }}</ref>


Despite the landing problems, the probe's instruments obtained the first images from a comet's surface.<ref name="esa20140116">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Europe_s_comet_chaser/ |title=Europe's Comet Chaser – Historic mission |publisher=European Space Agency |date=16 January 2014 |access-date=5 August 2014}}</ref> Several of the instruments on ''Philae'' made the first direct analysis of a comet, sending back data that would be analysed to determine the composition of the surface.<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Pioneering_Philae_completes_main_mission_before_hibernation |title=Pioneering Philae completes main mission before hibernation |publisher=European Space Agency |date=15 November 2014 |access-date=3 March 2015}}</ref> In October 2020, scientific journal ''[[Nature (journal)|Nature]]'' published an article revealing what ''Philae'' had discovered while it was operational on the surface of 67P/Churyumov–Gerasimenko.<ref name=reportsofdiscovery>{{cite journal|url=https://elib.dlr.de/137009/1/s41586-020-2834-3.pdf|title=The Philae lander reveals low-strength primitive ice inside cometary boulders|first1=Laurence|last1=O'Rourke|first2=Philip|last2=Heinisch|first3=Holger|last3=Sierks|journal=Nature|date=28 October 2020|volume=586|issue=7831|pages=697–701|doi=10.1038/s41586-020-2834-3|pmid=33116289|bibcode=2020Natur.586..697O|s2cid=226044338|accessdate=26 April 2021}}</ref>
Despite the landing problems, the probe's instruments obtained the first images from a comet's surface.<ref name="esa20140116">{{Cite news |date=16 January 2014 |title=Europe's comet chaser |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Europe_s_comet_chaser |url-status=live |archive-url=https://web.archive.org/web/20231218053956/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Europe_s_comet_chaser |archive-date=18 December 2023 |access-date=5 August 2014 |publisher=[[European Space Agency]] }}</ref> Several of the instruments on ''Philae'' made the first direct analysis of a comet, sending back data that would be analysed to determine the composition of the surface.<ref name="esa-20141115">{{Cite press release |date=15 November 2014 |title=Pioneering Philae completes main mission before hibernation |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Pioneering_Philae_completes_main_mission_before_hibernation |url-status=live |archive-url=https://web.archive.org/web/20240109021920/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Pioneering_Philae_completes_main_mission_before_hibernation |archive-date=9 January 2024 |access-date=3 March 2015 |publisher=[[European Space Agency]] }}</ref> In October 2020, scientific journal ''[[Nature (journal)|Nature]]'' published an article revealing what ''Philae'' had discovered while it was operational on the surface of 67P/Churyumov–Gerasimenko.<ref name="reportsofdiscovery">{{Cite journal |last1=O'Rourke |first1=Laurence |last2=Heinisch |first2=Philip |last3=Sierks |first3=Holger |date=28 October 2020 |title=The Philae lander reveals low-strength primitive ice inside cometary boulders |url=https://elib.dlr.de/137009/1/s41586-020-2834-3.pdf |url-status=live |journal=[[Nature (journal)|Nature]] |volume=586 |issue=7831 |pages=697–701 |bibcode=2020Natur.586..697O |doi=10.1038/s41586-020-2834-3 |pmid=33116289 |s2cid=226044338 |archive-url=https://web.archive.org/web/20231220065125/https://elib.dlr.de/137009/1/s41586-020-2834-3.pdf |archive-date=20 December 2023 |access-date=26 April 2021 }}</ref>


On 15 November 2014 ''Philae'' entered [[Safe mode (spacecraft)|safe mode]], or hibernation, after its batteries ran down due to reduced sunlight and an off-nominal spacecraft orientation at the crash site. Mission controllers hoped that additional sunlight on the solar panels might be sufficient to reboot the lander.<ref name="CNN-20141118">{{cite news |url=http://www.cnn.com/2014/11/14/world/comet-landing/ |title=On a comet 10 years away, Philae conks out, maybe for good |last1=Brumfield |first1=Ben |last2=Carter |first2=Chelsea J. |work=[[CNN]] |date=18 November 2014 |access-date=28 December 2014}}</ref> ''Philae'' communicated sporadically with ''Rosetta'' from 13 June to 9 July 2015,<ref name="NAT-20150614">{{cite journal |title=Philae comet lander wakes up and phones home |journal=[[Nature (journal)|Nature]] |first1=Celeste |last1=Biever |first2=Elizabeth |last2=Gibney |date=14 June 2015 |doi=10.1038/nature.2015.17756|s2cid=182262028 }}</ref><ref name="NYT-20140614">{{cite news |url=https://www.nytimes.com/aponline/2015/06/14/science/ap-eu-sci-comet-landing.html |title=Spacecraft That Landed on Comet Finally Wakes Up |work=[[The New York Times]] |agency=Associated Press |date=14 June 2015 |access-date=14 June 2015}}</ref><ref name="esablog20150720">{{cite web |url=http://blogs.esa.int/rosetta/2015/07/20/rosetta-and-philae-status-update/ |title=Rosetta and Philae status update |publisher=European Space Agency |first=Emily |last=Baldwin |date=20 July 2015 |access-date=11 August 2015}}</ref> but contact was then lost. The lander's location was known to within a few tens of metres but it could not be seen. Its location was finally identified in photographs taken by ''Rosetta'' on 2 September 2016 as the orbiter was sent on orbits closer to the comet. The now-silent ''Philae'' was lying on its side in a deep crack in the shadow of a cliff. Knowledge of its location would help in interpretation of the images it had sent.<ref name="Philaefound" /><ref name="NYT-20160905">{{cite news |url=https://www.nytimes.com/2016/09/06/science/philae-spacecraft-rosetta-comet.html |title=No Longer Missing: Rosetta's Philae Spacecraft Located on Comet |work=[[The New York Times]] |last=Victor |first=Daniel |date=5 September 2016 |access-date=5 September 2016}}</ref> On 30 September 2016, the ''Rosetta'' spacecraft ended its mission by crashing in the comet's Ma'at region.<ref name="space20160930">{{cite news |url=http://www.space.com/34254-rosetta-crash-lands-on-comet-mission-ends.html |title=Goodbye, Rosetta! Spacecraft Crash-Lands on Comet in Epic Mission Finale |work=Space.com |first=Megan |last=Gannon |date=30 September 2016 |access-date=1 October 2016}}</ref>
On 15 November 2014 ''Philae'' entered [[Safe mode (spacecraft)|safe mode]], or hibernation, after its batteries ran down due to reduced sunlight and an off-nominal spacecraft orientation at the crash site. Mission controllers hoped that additional sunlight on the solar panels might be sufficient to reboot the lander.<ref name="CNN-20141118">{{Cite news |last1=Brumfield |first1=Ben |last2=Carter |first2=Chelsea J. |date=18 November 2014 |title=On a comet 10 years away, Philae conks out, maybe for good |url=https://edition.cnn.com/2014/11/14/world/comet-landing/ |url-status=live |archive-url=https://web.archive.org/web/20230322100554/http://edition.cnn.com/2014/11/14/world/comet-landing/ |archive-date=22 March 2023 |access-date=28 December 2014 |work=[[CNN]] }}</ref> ''Philae'' communicated sporadically with ''Rosetta'' from 13 June to 9 July 2015,<ref name="NAT-20150614">{{Cite journal |last1=Biever |first1=Celeste |last2=Gibney |first2=Elizabeth |date=14 June 2015 |title=Philae comet lander wakes up and phones home |url=https://www.nature.com/articles/nature.2015.17756.pdf |url-status=live |journal=[[Nature (journal)|Nature]] |doi=10.1038/nature.2015.17756 |s2cid=182262028 |archive-url=https://web.archive.org/web/20240222121348/https://www.nature.com/articles/nature.2015.17756.pdf |archive-date=22 February 2024 |doi-access=free }}</ref><ref name="AP-20140614">{{Cite news |date=14 June 2015 |title=Comet lander Philae awakes from hibernation |url=https://www.latimes.com/science/sciencenow/la-comet-lander-philae-awakes-from-hibernation-20150614-story.html |url-status=live |archive-url=https://archive.ph/gfUpF |archive-date=22 February 2024 |access-date=14 June 2015 |work=[[Los Angeles Times]] |agency=[[Associated Press]] }}</ref><ref name="esablog20150720">{{Cite web |last=Baldwin |first=Emily |date=20 July 2015 |title=Rosetta and Philae status update |url=http://blogs.esa.int/rosetta/2015/07/20/rosetta-and-philae-status-update/ |url-status=live |archive-url=https://archive.ph/YwroM |archive-date=22 July 2015 |access-date=11 August 2015 |publisher=European Space Agency }}</ref> but contact was then lost. The lander's location was known to within a few tens of metres but it could not be seen. Its location was finally identified in photographs taken by ''Rosetta'' on 2 September 2016 as the orbiter was sent on orbits closer to the comet. The now-silent ''Philae'' was lying on its side in a deep crack in the shadow of a cliff. Knowledge of its location would help in interpretation of the images it had sent.<ref name="Philaefound" /><ref name="NYT-20160905">{{Cite news |last=Victor |first=Daniel |date=5 September 2016 |title=No Longer Missing: Rosetta's Philae Spacecraft Located on Comet |url=https://www.nytimes.com/2016/09/06/science/philae-spacecraft-rosetta-comet.html |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20231112094835/https://www.nytimes.com/2016/09/06/science/philae-spacecraft-rosetta-comet.html |archive-date=12 November 2023 |access-date=5 September 2016 |work=[[The New York Times]] }}</ref> On 30 September 2016, the ''Rosetta'' spacecraft ended its mission by crashing in the comet's Ma'at region.<ref name="space20160930">{{Cite news |last=Gannon |first=Megan |date=30 September 2016 |title=Goodbye, Rosetta! Spacecraft Crash-Lands on Comet in Epic Mission Finale |url=https://www.space.com/34254-rosetta-crash-lands-on-comet-mission-ends.html |url-status=live |archive-url=https://web.archive.org/web/20230609213804/https://www.space.com/34254-rosetta-crash-lands-on-comet-mission-ends.html |archive-date=9 June 2023 |access-date=1 October 2016 |work=[[Space.com]] }}</ref>


The lander is named after the [[Philae obelisk]], which bears a bilingual inscription and was used along with the [[Rosetta Stone]] to decipher [[Egyptian hieroglyphs]]. ''Philae'' was monitored and operated from [[German Aerospace Center|DLR's]] Lander Control Center in [[Cologne]], Germany.<ref>{{cite web |url=http://www.dlr.de/rb/en/desktopdefault.aspx/tabid-4539/ |title=Rosetta Lander Control Center |publisher=German Aerospace Center |access-date=20 March 2015}}</ref>
The lander is named after the [[Philae obelisk]], which bears a bilingual inscription and was used along with the [[Rosetta Stone]] to decipher [[Egyptian hieroglyphs]]. ''Philae'' was monitored and operated from [[German Aerospace Center|DLR's]] Lander Control Center in [[Cologne]], Germany.<ref name="dlr-rosettacenter">{{Cite web |title=Rosetta Lander Control Center |url=http://www.dlr.de/rb/en/desktopdefault.aspx/tabid-4539/ |url-status=live |archive-url=https://web.archive.org/web/20231112100354/https://www.dlr.de/rb/en/desktopdefault.aspx/tabid-4539/ |archive-date=12 November 2023 |access-date=20 March 2015 |publisher=[[German Aerospace Center]] }}</ref>


== Mission ==
== Mission ==
[[File:Landing on a Comet - The Rosetta Mission.webm|thumb|thumbtime=10|[[:File:Landing on a Comet - The Rosetta Mission.webm|Video report]] by the [[German Aerospace Center|German Aerospace Centre]] about ''Philae''{{'s}} landing mission. (10 min, English, in 1080p HD)]]
[[File:Landing on a Comet - The Rosetta Mission.webm|thumb|thumbtime=10|[[:File:Landing on a Comet - The Rosetta Mission.webm|Video report]] by the [[German Aerospace Center|German Aerospace Centre]] about ''Philae''{{'s}} landing mission. (10 min, English, in 1080p HD)]]
''Philae''{{'s}} mission was to land successfully on the surface of a comet, attach itself, and transmit data about the comet's composition. The ''Rosetta'' spacecraft and ''Philae'' lander were launched on an [[Ariane 5|Ariane 5G+]] rocket from [[French Guiana]] on 2 March 2004, 07:17 UTC, and travelled for 3,907 days (10.7 years) to Churyumov–Gerasimenko. Unlike the ''[[Deep Impact (spacecraft)|Deep Impact]]'' probe, which by design struck comet [[Tempel 1]]'s nucleus on 4 July 2005, ''Philae'' is not an impactor. Some of the instruments on the lander were used for the first time as autonomous systems during the Mars flyby on 25 February 2007. CIVA, one of the camera systems, returned some images while the ''Rosetta'' instruments were powered down, while ROMAP took measurements of the [[Magnetosphere of Mars|Martian magnetosphere]]. Most of the other instruments needed contact with the surface for analysis and stayed offline during the flyby. An optimistic estimate of mission length following touchdown was "four to five months".<ref name="techrep20140814">{{cite news |url=http://www.techrepublic.com/article/the-tech-behind-the-rosetta-comet-chaser-from-3d-printing-to-solar-power-to-complex-mapping/ |title=The tech behind the Rosetta comet chaser: From 3D printing to solar power to complex mapping |work=[[TechRepublic]] |first=Lyndsey |last=Gilpin |date=14 August 2014}}</ref>
''Philae''{{'s}} mission was to land successfully on the surface of a comet, attach itself, and transmit data about the comet's composition. The ''Rosetta'' spacecraft and ''Philae'' lander were launched on an [[Ariane 5|Ariane 5G+]] rocket from [[French Guiana]] on 2 March 2004, 07:17 UTC, and travelled for 3,907 days (10.7 years) to Churyumov–Gerasimenko. Unlike the ''[[Deep Impact (spacecraft)|Deep Impact]]'' probe, which by design struck comet [[Tempel 1]]'s nucleus on 4 July 2005, ''Philae'' is not an impactor. Some of the instruments on the lander were used for the first time as autonomous systems during the Mars flyby on 25 February 2007. CIVA, one of the camera systems, returned some images while the ''Rosetta'' instruments were powered down, while ROMAP took measurements of the [[Magnetosphere of Mars|Martian magnetosphere]]. Most of the other instruments needed contact with the surface for analysis and stayed offline during the flyby. An optimistic estimate of mission length following touchdown was "four to five months".<ref name="techrep20140814">{{Cite news |last=Gilpin |first=Lyndsey |date=14 August 2014 |title=The tech behind the Rosetta comet chaser: From 3D printing to solar power to complex mapping |url=http://www.techrepublic.com/article/the-tech-behind-the-rosetta-comet-chaser-from-3d-printing-to-solar-power-to-complex-mapping/ |url-status=dead |archive-url=https://web.archive.org/web/20140819184449/http://www.techrepublic.com/article/the-tech-behind-the-rosetta-comet-chaser-from-3d-printing-to-solar-power-to-complex-mapping/ |archive-date=19 August 2014 |work=[[TechRepublic]] }}</ref>


=== Scientific goals ===
=== Scientific goals ===
Line 84: Line 84:
== Landing and surface operations ==
== Landing and surface operations ==
[[File:Rosetta's Philae on Comet 67P Churyumov-Gerasimenko.jpg|thumb|Depiction of ''Philae'' on Churyumov-Gerasimenko]]
[[File:Rosetta's Philae on Comet 67P Churyumov-Gerasimenko.jpg|thumb|Depiction of ''Philae'' on Churyumov-Gerasimenko]]
''Philae'' remained attached to the ''Rosetta'' spacecraft after rendezvousing with Churyumov–Gerasimenko on 6 August 2014. On 15 September 2014, ESA announced "{{Nowrap|Site J}}" on the smaller lobe of the comet as the lander's destination.<ref name="esa20140915">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/J_marks_the_spot_for_Rosetta_s_lander |title='J' Marks the Spot for Rosetta's Lander |publisher=European Space Agency |first=Markus |last=Bauer |date=15 September 2014 |access-date=20 September 2014}}</ref> Following an ESA public contest in October 2014, {{Nowrap|Site J}} was renamed ''Agilkia'' in honour of [[Agilkia Island]].<ref name="space20141105">{{cite news |url=http://www.space.com/27662-rosetta-comet-landing-site-agilkia.html |title=Historic Comet Landing Site Has a New Name: Agilkia |work=Space.com |first=Miriam |last=Kramer |date=5 November 2014 |access-date=5 November 2014}}</ref>
''Philae'' remained attached to the ''Rosetta'' spacecraft after rendezvousing with Churyumov–Gerasimenko on 6 August 2014. On 15 September 2014, ESA announced "{{Nowrap|Site J}}" on the smaller lobe of the comet as the lander's destination.<ref name="esa20140915">{{Cite press release |last=Bauer |first=Markus |date=15 September 2014 |title='J' Marks the Spot for Rosetta's Lander |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/J_marks_the_spot_for_Rosetta_s_lander |url-status=live |archive-url=https://web.archive.org/web/20230615202531/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/J_marks_the_spot_for_Rosetta_s_lander |archive-date=15 June 2023 |access-date=20 September 2014 |publisher=[[European Space Agency]] }}</ref> Following an ESA public contest in October 2014, {{Nowrap|Site J}} was renamed ''Agilkia'' in honour of [[Agilkia Island]].<ref name="space20141105">{{Cite news |last=Kramer |first=Miriam |date=5 November 2014 |title=Historic Comet Landing Site Has a New Name: Agilkia |url=https://www.space.com/27662-rosetta-comet-landing-site-agilkia.html |url-status=live |archive-url=https://web.archive.org/web/20230321104239/https://www.space.com/27662-rosetta-comet-landing-site-agilkia.html |archive-date=21 March 2023 |access-date=5 November 2014 |work=[[Space.com]] }}</ref>


A series of four [[Go/no go|go/no-go checks]] were performed on 11–12 November 2014. One of the final tests before detachment from ''Rosetta'' showed that the lander's [[cold-gas thruster]] was not working correctly, but the "go" was given anyway, as it could not be repaired.<ref name=CS1 /><ref>{{cite web |url=http://blogs.esa.int/rosetta/2014/11/12/rosetta-and-philae-go-for-separation/ |title=Rosetta and Philae Go for separation |publisher=European Space Agency |first=Emily |last=Baldwin |date=12 November 2014 |access-date=12 November 2014}}</ref> ''Philae'' detached from ''Rosetta'' on 12 November 2014 at 08:35 UTC [[Spacecraft Event Time|SCET]].<ref name="esa20140926">{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_to_deploy_lander_on_12_November |title=Rosetta to Deploy Lander on 12 November |publisher=European Space Agency |date=26 September 2014 |access-date=4 October 2014}}</ref><ref name="NASA-20141106-JP">{{cite news |url=http://www.jpl.nasa.gov/news/news.php?release=2014-383 |title=Rosetta Races Toward Comet Touchdown |publisher=NASA |first=Jane |last=Platt |date=6 November 2014 |access-date=7 November 2014}}</ref>
A series of four [[Go/no go|go/no-go checks]] were performed on 11–12 November 2014. One of the final tests before detachment from ''Rosetta'' showed that the lander's [[cold-gas thruster]] was not working correctly, but the "go" was given anyway, as it could not be repaired.<ref name=CS1 /><ref name="esablog-20141112">{{Cite web |last=Baldwin |first=Emily |date=12 November 2014 |title=Rosetta and Philae Go for separation |url=https://blogs.esa.int/rosetta/2014/11/12/rosetta-and-philae-go-for-separation/ |url-status=live |archive-url=https://web.archive.org/web/20231112094844/https://blogs.esa.int/rosetta/2014/11/12/rosetta-and-philae-go-for-separation/ |archive-date=12 November 2023 |access-date=12 November 2014 |publisher=[[European Space Agency]] }}</ref> ''Philae'' detached from ''Rosetta'' on 12 November 2014 at 08:35 UTC [[Spacecraft Event Time|SCET]].<ref name="esa20140926">{{Cite press release |date=26 September 2014 |title=Rosetta to Deploy Lander on 12 November |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Rosetta_to_deploy_lander_on_12_November |url-status=live |archive-url=https://web.archive.org/web/20230501090227/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Rosetta_to_deploy_lander_on_12_November |archive-date=1 May 2023 |access-date=4 October 2014 |publisher=[[European Space Agency]] }}</ref><ref name="NASA-20141106-JP">{{Cite press release |last=Platt |first=Jane |date=6 November 2014 |title=Rosetta Races Toward Comet Touchdown |url=https://www.jpl.nasa.gov/news/rosetta-races-toward-comet-touchdown |url-status=live |archive-url=https://web.archive.org/web/20231112094851/https://www.jpl.nasa.gov/news/rosetta-races-toward-comet-touchdown |archive-date=12 November 2023 |access-date=7 November 2014 |publisher=[[NASA]] }}</ref>


=== Landing events ===
=== Landing events ===
[[File:Signal received from Rosetta (12055070794).jpg|thumb|left|''[[Rosetta (spacecraft)|Rosetta]]'' signal received at [[European Space Operations Centre|ESOC]] in Darmstadt, Germany (20 January 2014)]]
[[File:Signal received from Rosetta (12055070794).jpg|thumb|left|''[[Rosetta (spacecraft)|Rosetta]]'' signal received at [[European Space Operations Centre|ESOC]] in Darmstadt, Germany (20 January 2014)]]


''Philae''{{'s}} landing signal was received by Earth communication stations at 16:03&nbsp;UTC after a 28-minute delay.<ref name=nssdc /><ref>{{cite news |url=https://www.bbc.com/news/science-environment-30026398 |title=Probe makes historic comet landing |work=BBC News |date=12 November 2014 |access-date=12 November 2014}}</ref> Unknown to mission scientists at that time, the lander had bounced. It began performing scientific measurements while slowly moving away from the comet and coming back down, confusing the science team.<ref name="Lakdawalla2014-11-12">{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2014/11120821-philae-has-landed.html |title=Philae Has Landed! [Updated] |publisher=[[The Planetary Society]] |first=Emily |last=Lakdawalla |author-link=Emily Lakdawalla |date=12 November 2014 |access-date=13 November 2014}}</ref> Further analysis showed that it bounced twice.<ref name="NASA-20141113-DCA">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2014-396 |title=Rosetta's Comet Lander Landed Three Times |publisher=NASA |first1=D. C. |last1=Agle |first2=Dwayne |last2=Brown |first3=Markus |last3=Bauer |date=13 November 2014 |access-date=13 November 2014}}</ref><ref name="ESA-20141114">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |title=Three touchdowns for Rosetta's lander |publisher=European Space Agency |date=14 November 2014 |access-date=8 December 2014}}</ref>
''Philae''{{'s}} landing signal was received by Earth communication stations at 16:03&nbsp;UTC after a 28-minute delay.<ref name=nssdc /><ref name="bbc-20141112">{{Cite news |date=12 November 2014 |title=Probe makes historic comet landing |url=https://www.bbc.com/news/science-environment-30026398 |url-status=live |archive-url=https://web.archive.org/web/20240214121717/https://www.bbc.com/news/science-environment-30026398 |archive-date=14 February 2024 |access-date=12 November 2014 |work=[[BBC News]] }}</ref> Unknown to mission scientists at that time, the lander had bounced. It began performing scientific measurements while slowly moving away from the comet and coming back down, confusing the science team.<ref name="Lakdawalla2014-11-12">{{Cite web |last=Lakdawalla |first=Emily |author-link=Emily Lakdawalla |date=12 November 2014 |title=Philae Has Landed! [Updated] |url=https://www.planetary.org/articles/11120821-philae-has-landed |url-status=live |archive-url=https://web.archive.org/web/20231112094852/https://www.planetary.org/articles/11120821-philae-has-landed |archive-date=12 November 2023 |access-date=13 November 2014 |publisher=[[The Planetary Society]] }}</ref> Further analysis showed that it bounced twice.<ref name="NASA-20141113-DCA">{{Cite press release |last1=Agle |first1=D. C. |last2=Brown |first2=Dwayne |last3=Bauer |first3=Markus |date=13 November 2014 |title=Rosetta's Comet Lander Landed Three Times |url=https://www.jpl.nasa.gov/news/rosettas-comet-lander-landed-three-times |url-status=live |archive-url=https://web.archive.org/web/20231112155443/https://www.jpl.nasa.gov/news/rosettas-comet-lander-landed-three-times |archive-date=12 November 2023 |access-date=13 November 2014 |publisher=[[NASA]] }}</ref><ref name="ESA-20141114">{{Cite press release |date=14 November 2014 |title=Three touchdowns for Rosetta's lander |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |url-status=live |archive-url=https://web.archive.org/web/20231018072901/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander |archive-date=18 October 2023 |access-date=8 December 2014 |publisher=[[European Space Agency]] }}</ref>


''Philae''{{'s}} first contact with the comet occurred at 15:34:04&nbsp;UTC SCET.<ref name="esagraze20141128">{{cite web |url=http://blogs.esa.int/rosetta/2014/11/28/did-philae-graze-a-crater-rim-during-its-first-bounce/ |title=Did Philae graze a crater rim during its first bounce? |publisher=European Space Agency |first=Emily |last=Baldwin |date=28 November 2014 |access-date=8 December 2014}}</ref> The probe rebounded off the comet's surface at {{convert|38|cm/s|abbr=on}} and rose to an altitude of approximately {{convert|1|km|mi|abbr=on}}.<ref name="ESA-20141114" /> For perspective, had the lander exceeded about {{convert|44|cm/s|abbr=on}}, it would have escaped the comet's gravity.<ref name="spaceluck20141114">{{cite news |url=http://www.space.com/27769-philae-comet-landing-survival-luck.html |title=European Probe Survived Comet Landing with Luck and Great Design |work=Space.com |first=Mike |last=Wall |date=14 November 2014 |access-date=8 December 2014}}</ref> After detecting the touchdown, ''Philae''{{'s}} [[reaction wheel]] was automatically powered off, resulting in its momentum being transferred back into the lander. This caused the vehicle to begin rotating every 13 seconds.<ref name="esagraze20141128" /> During this first bounce, at 16:20&nbsp;UTC SCET, the lander is thought to have struck a surface [[prominence]], which slowed its rotation to once every 24 seconds and sent the craft tumbling.<ref name="esagraze20141128" /><ref name="unitoday20141202">{{cite news |url=http://www.universetoday.com/116927/philaes-wild-comet-landing-crater-grazing-spinning-and-landing-in-parts-unknown/ |title=Philae's Wild Comet Landing: Crater Grazing, Spinning And Landing In Parts Unknown |work=Universe Today |first=Elizabeth |last=Howell |date=2 December 2014 |access-date=8 December 2014}}</ref> ''Philae'' touched down a second time at 17:25:26&nbsp;UTC SCET and rebounded at {{convert|3|cm/s|abbr=on}}.<ref name="ESA-20141114" /><ref name="esagraze20141128" /> The lander came to a final stop on the surface at 17:31:17&nbsp;UTC SCET.<ref name="esagraze20141128" /> It sits in rough terrain, apparently in the shadow of a nearby cliff or crater wall, and is canted at an angle of around 30 degrees, but is otherwise undamaged.<ref name="skytel20141115">{{cite news |url=http://www.skyandtelescope.com/astronomy-news/philae-lander-success-11152014/ |title=Philae Wins Race to Return Comet Findings |work=[[Sky & Telescope]] |first=Kelly |last=Beatty |date=15 November 2014 |access-date=8 November 2014}}</ref> Its final location was determined initially by analysis of data from [[CONSERT]] in combination with the comet shape model based on images from the ''Rosetta'' orbiter,<ref name="esa-sitelocn">{{cite web |url=http://blogs.esa.int/rosetta/2014/11/21/homing-in-on-philaes-final-landing-site/ |title=Homing in on Philae's final landing site |publisher=European Space Agency |first=Emily |last=Baldwin |date=21 November 2014 |access-date=22 November 2014}}</ref> and later precisely by direct imaging from ''Rosetta''.<ref name="Philaefound" />
''Philae''{{'s}} first contact with the comet occurred at 15:34:04&nbsp;UTC SCET.<ref name="esagraze20141128">{{Cite web |last=Baldwin |first=Emily |date=28 November 2014 |title=Did Philae graze a crater rim during its first bounce? |url=https://blogs.esa.int/rosetta/2014/11/28/did-philae-graze-a-crater-rim-during-its-first-bounce/ |url-status=live |archive-url=https://web.archive.org/web/20230425215703/https://blogs.esa.int/rosetta/2014/11/28/did-philae-graze-a-crater-rim-during-its-first-bounce/ |archive-date=25 April 2023 |access-date=8 December 2014 |publisher=[[European Space Agency]] }}</ref> The probe rebounded off the comet's surface at {{convert|38|cm/s|abbr=on}} and rose to an altitude of approximately {{convert|1|km|mi|abbr=on}}.<ref name="ESA-20141114" /> For perspective, had the lander exceeded about {{convert|44|cm/s|abbr=on}}, it would have escaped the comet's gravity.<ref name="spaceluck20141114">{{Cite news |last=Wall |first=Mike |date=14 November 2014 |title=European Probe Survived Comet Landing with Luck and Great Design |url=https://www.space.com/27769-philae-comet-landing-survival-luck.html |url-status=live |archive-url=https://web.archive.org/web/20231201103153/https://www.space.com/27769-philae-comet-landing-survival-luck.html |archive-date=1 December 2023 |access-date=8 December 2014 |work=[[Space.com]] }}</ref> After detecting the touchdown, ''Philae''{{'s}} [[reaction wheel]] was automatically powered off, resulting in its momentum being transferred back into the lander. This caused the vehicle to begin rotating every 13 seconds.<ref name="esagraze20141128" /> During this first bounce, at 16:20&nbsp;UTC SCET, the lander is thought to have struck a surface [[prominence]], which slowed its rotation to once every 24 seconds and sent the craft tumbling.<ref name="esagraze20141128" /><ref name="unitoday20141202">{{Cite news |last=Howell |first=Elizabeth |date=2 December 2014 |title=Philae's Wild Comet Landing: Crater Grazing, Spinning And Landing In Parts Unknown |url=https://www.universetoday.com/116927/philaes-wild-comet-landing-crater-grazing-spinning-and-landing-in-parts-unknown/ |url-status=live |archive-url=https://web.archive.org/web/20231112155443/https://www.universetoday.com/116927/philaes-wild-comet-landing-crater-grazing-spinning-and-landing-in-parts-unknown/ |archive-date=12 November 2023 |access-date=8 December 2014 |work=Universe Today }}</ref> ''Philae'' touched down a second time at 17:25:26&nbsp;UTC SCET and rebounded at {{convert|3|cm/s|abbr=on}}.<ref name="ESA-20141114" /><ref name="esagraze20141128" /> The lander came to a final stop on the surface at 17:31:17&nbsp;UTC SCET.<ref name="esagraze20141128" /> It sits in rough terrain, apparently in the shadow of a nearby cliff or crater wall, and is canted at an angle of around 30 degrees, but is otherwise undamaged.<ref name="skytel20141115">{{Cite magazine |last=Beatty |first=J. Kelly |date=15 November 2014 |title=Philae Wins Race to Return Comet Findings |url=http://www.skyandtelescope.com/astronomy-news/philae-lander-success-11152014/ |url-status=live |archive-url=https://web.archive.org/web/20240222151546/https://skyandtelescope.org/astronomy-news/philae-lander-success-11152014/ |archive-date=22 February 2024 |access-date=8 November 2014 |magazine=[[Sky & Telescope]] }}</ref> Its final location was determined initially by analysis of data from [[CONSERT]] in combination with the comet shape model based on images from the ''Rosetta'' orbiter,<ref name="esa-sitelocn">{{Cite web |last=Baldwin |first=Emily |date=21 November 2014 |title=Homing in on Philae's final landing site |url=https://blogs.esa.int/rosetta/2014/11/21/homing-in-on-philaes-final-landing-site/ |url-status=live |archive-url=https://web.archive.org/web/20240222151733/https://blogs.esa.int/rosetta/2014/11/21/homing-in-on-philaes-final-landing-site/ |archive-date=22 February 2024 |access-date=22 November 2014 |publisher=[[European Space Agency]] }}</ref> and later precisely by direct imaging from ''Rosetta''.<ref name="Philaefound" />


An analysis of telemetry indicated that the initial impact was softer than expected,<ref name="indep20141112">{{cite news |url=https://www.independent.co.uk/news/science/rosetta-space-mission-philae-probe-lands-safely-on-comet-67p-9857162.html |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/rosetta-space-mission-philae-probe-lands-safely-on-comet-67p-9857162.html |archive-date=26 May 2022 |url-access=subscription |url-status=live |title=Rosetta space mission: Philae probe lands on Comet 67P |work=The Independent |first=Steve |last=Connor |date=12 November 2014 |access-date=11 August 2015}}</ref> that the harpoons had not deployed, and that the thruster had not fired.<ref name="cnnprob20141112">{{cite news |url=http://edition.cnn.com/2014/11/12/world/comet-landing-countdown/ |title=Philae touches down on the surface of a comet |work=CNN |first=Ralph |last=Ellis |date=12 November 2014 |access-date=12 November 2014}}</ref><ref name="newsciprob20141113">{{cite news |url=https://www.newscientist.com/article/dn26547-problems-hit-philae-after-historic-first-comet-landing.html |title=Problems hit Philae after historic first comet landing |work=[[New Scientist]] |first=Jacob |last=Aron |date=13 November 2014 |access-date=13 November 2014}}</ref> The harpoon propulsion system contained 0.3 grams of [[nitrocellulose]], which was shown by [[Copenhagen Suborbitals]] in 2013 to be unreliable in a vacuum.<ref name="ingenioren20141113">{{cite news |url=http://ing.dk/artikel/esa-skrev-til-danske-raketbyggere-om-eksplosiv-problem-paa-philae-172274 |title=ESA skrev til danske raketbyggere om eksplosiv-problem på Philae |trans-title=ESA wrote to Danish rocket builders about explosive problem on Philae|work=[[Ingeniøren]] |language=da |first=Thomas |last=Djursing |date=13 November 2014 |access-date=13 November 2014}}</ref>
An analysis of telemetry indicated that the initial impact was softer than expected,<ref name="indep20141112">{{cite news |url=https://www.independent.co.uk/news/science/rosetta-space-mission-philae-probe-lands-safely-on-comet-67p-9857162.html |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/rosetta-space-mission-philae-probe-lands-safely-on-comet-67p-9857162.html |archive-date=26 May 2022 |url-access=subscription |url-status=live |title=Rosetta space mission: Philae probe lands on Comet 67P |work=The Independent |first=Steve |last=Connor |date=12 November 2014 |access-date=11 August 2015}}</ref> that the harpoons had not deployed, and that the thruster had not fired.<ref name="cnnprob20141112">{{Cite news |last=Gilbert |first=Dave |date=12 November 2014 |title=Philae touches down on the surface of a comet |url=https://edition.cnn.com/2014/11/12/world/comet-landing-countdown |url-status=live |archive-url=https://web.archive.org/web/20231224043203/https://edition.cnn.com/2014/11/12/world/comet-landing-countdown/ |archive-date=24 December 2023 |access-date=12 November 2014 |work=[[CNN]] }}</ref><ref name="newsciprob20141113">{{Cite magazine |last=Aron |first=Jacob |date=13 November 2014 |title=Problems hit Philae after historic first comet landing |url=https://www.newscientist.com/article/dn26547-problems-hit-philae-after-historic-first-comet-landing/ |url-status=live |archive-url=https://web.archive.org/web/20230930102707/https://www.newscientist.com/article/dn26547-problems-hit-philae-after-historic-first-comet-landing/ |archive-date=30 September 2023 |access-date=13 November 2014 |magazine=[[New Scientist]] }}</ref> The harpoon propulsion system contained 0.3 grams of [[nitrocellulose]], which was shown by [[Copenhagen Suborbitals]] in 2013 to be unreliable in a vacuum.<ref name="ingenioren20141113">{{Cite news |last=Djursing |first=Thomas |date=13 November 2014 |title=ESA skrev til danske raketbyggere om eksplosiv-problem på Philae |trans-title=ESA wrote to Danish rocket builders about explosive problem on Philae |url=https://ing.dk/artikel/esa-skrev-til-danske-raketbyggere-om-eksplosiv-problem-paa-philae |url-status=live |archive-url=https://web.archive.org/web/20230426233818/https://ing.dk/artikel/esa-skrev-til-danske-raketbyggere-om-eksplosiv-problem-paa-philae |archive-date=26 April 2023 |access-date=13 November 2014 |work=[[Ingeniøren]] |language=da }}</ref>


=== Operations and communication loss ===
=== Operations and communication loss ===
[[File:ESA Rosetta NAVCAM Agilkia landing site on comet 67P 20141106 mosaic.jpg|thumb|300px|''Philae''{{'s}} intended landing site Agilkia (Site J)]]
[[File:ESA Rosetta NAVCAM Agilkia landing site on comet 67P 20141106 mosaic.jpg|thumb|300px|''Philae''{{'s}} intended landing site Agilkia (Site J)]]


The primary battery was designed to power the instruments for about 60 hours.<ref name="Amos2014-11-13">{{cite news |url=https://www.bbc.com/news/science-environment-30034060 |title=Rosetta: Battery will limit life of Philae comet lander |work=BBC News |first=Jonathan |last=Amos |date=13 November 2014 |access-date=14 November 2014}}</ref> ESA expected that a secondary rechargeable battery would be partially filled by the solar panels attached to the outside of the lander, but the limited sunlight (90 minutes per 12.4-hour comet day<ref name="Harwood2014.11.15" />) at the actual landing site was inadequate to maintain ''Philae''{{'s}} activities, at least in this phase of the comet's orbit.<ref name="Lakdawalla2014-11-13">{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2014/11131025-philae-status-a-day-later.html |title=Philae status, a day later |publisher=[[The Planetary Society]] |first=Emily |last=Lakdawalla |author-link=Emily Lakdawalla |date=13 November 2014 |access-date=14 November 2014}}</ref><ref name="Djursing2014-11-13">{{cite news |url=http://ing.dk/artikel/kometsonden-philae-staar-skaevt-under-en-klippe-og-faar-lidt-sollys-172277 |title=Kometsonden Philae står skævt under en klippe og får for lidt sollys |work=[[Ingeniøren]] |language=da |first=Thomas |last=Djursing |date=13 November 2014 |access-date=14 November 2014}}</ref>
The primary battery was designed to power the instruments for about 60 hours.<ref name="Amos2014-11-13">{{Cite news |last=Amos |first=Jonathan |date=13 November 2014 |title=Rosetta: Battery will limit life of Philae comet lander |url=https://www.bbc.com/news/science-environment-30034060 |url-status=live |archive-url=https://web.archive.org/web/20240211141611/https://www.bbc.com/news/science-environment-30034060 |archive-date=11 February 2024 |access-date=14 November 2014 |work=[[BBC News]] }}</ref> ESA expected that a secondary rechargeable battery would be partially filled by the solar panels attached to the outside of the lander, but the limited sunlight (90 minutes per 12.4-hour comet day<ref name="Harwood2014.11.15" />) at the actual landing site was inadequate to maintain ''Philae''{{'s}} activities, at least in this phase of the comet's orbit.<ref name="Lakdawalla2014-11-13">{{Cite web |last=Lakdawalla |first=Emily |author-link=Emily Lakdawalla |date=13 November 2014 |title=Philae status, a day later |url=https://www.planetary.org/articles/11131025-philae-status-a-day-later |url-status=live |archive-url=https://web.archive.org/web/20231112094838/https://www.planetary.org/articles/11131025-philae-status-a-day-later |archive-date=12 November 2023 |access-date=14 November 2014 |publisher=[[The Planetary Society]] }}</ref><ref name="Djursing2014-11-13">{{Cite news |last=Djursing |first=Thomas |date=13 November 2014 |title=Kometsonden Philae står skævt under en klippe og får for lidt sollys |trans-title=The comet probe Philae is tilted under a rock and receives too little sunlight |url=https://ing.dk/artikel/kometsonden-philae-staar-skaevt-under-en-klippe-og-faar-lidt-sollys |url-status=live |archive-url=https://web.archive.org/web/20231112100339/https://ing.dk/artikel/kometsonden-philae-staar-skaevt-under-en-klippe-og-faar-lidt-sollys |archive-date=12 November 2023 |access-date=14 November 2014 |work=[[Ingeniøren]] |language=da }}</ref>


On the morning of 14 November 2014, the battery charge was estimated to be only enough for continuing operations for the remainder of the day. After first obtaining data from instruments whose operation did not require mechanical movement, comprising about 80% of the planned initial science observations, both the MUPUS soil penetrator and the SD2 drill were commanded to deploy. Subsequently, MUPUS data<ref name="Lakdawalla2014-11-14">{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2014/11141330-philae-update-my-last-day-in-darmstadt.html |title=Philae update: My last day in Darmstadt, possibly Philae's last day of operations |publisher=[[The Planetary Society]] |first=Emily |last=Lakdawalla |author-link=Emily Lakdawalla |date=14 November 2014 |access-date=14 November 2014}}</ref> as well as COSAC and Ptolemy data were returned. A final set of CONSERT data was also downlinked towards the end of operations. During the evening's transmission session, ''Philae'' was raised by {{convert|4|cm}} and its body rotated 35 degrees to more favourably position the largest solar panel to capture the most sunlight in the future.<ref name="bbcnews20141115">{{cite news |url=https://www.bbc.com/news/science-environment-30058176 |title=Philae comet lander sends more data before losing power |work=BBC News |first=Jonathan |last=Amos |date=15 November 2014 |access-date=8 December 2014}}</ref><ref name="Lakdawalla2014-11-15">{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2014/20141115-now-philae-down-to-sleep.html |title=Now Philae down to sleep |publisher=[[The Planetary Society]] |first=Emily |last=Lakdawalla |author-link=Emily Lakdawalla |date=15 November 2014 |access-date=17 November 2014}}</ref> Shortly afterwards, electrical power dwindled rapidly and all instruments were forced to shut down. The downlink rate slowed to a trickle before coming to a stop.<ref name="Harwood2014.11.15">{{cite news |url=http://spaceflightnow.com/2014/11/15/loss-of-contact-with-philae/ |title=Loss of contact with Philae |work=Spaceflight Now |first=William |last=Harwood |date=15 November 2014 |access-date=15 November 2014}}</ref> Contact was lost on 15 November at 00:36&nbsp;UTC.<ref name="esa-asleep">{{cite web |url=http://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ |title=Our Lander's Asleep |first=Daniel |last=Scuka |publisher=[[European Space Agency]] |date=15 November 2014 |access-date=15 November 2014}}</ref>
On the morning of 14 November 2014, the battery charge was estimated to be only enough for continuing operations for the remainder of the day. After first obtaining data from instruments whose operation did not require mechanical movement, comprising about 80% of the planned initial science observations, both the MUPUS soil penetrator and the SD2 drill were commanded to deploy. Subsequently, MUPUS data<ref name="Lakdawalla2014-11-14">{{Cite web |last=Lakdawalla |first=Emily |author-link=Emily Lakdawalla |date=14 November 2014 |title=Philae update: My last day in Darmstadt, possibly Philae's last day of operations |url=https://www.planetary.org/articles/11141330-philae-update-my-last-day-in-darmstadt |url-status=live |archive-url=https://web.archive.org/web/20231112094953/https://www.planetary.org/articles/11141330-philae-update-my-last-day-in-darmstadt |archive-date=12 November 2023 |access-date=14 November 2014 |publisher=[[The Planetary Society]] }}</ref> as well as COSAC and Ptolemy data were returned. A final set of CONSERT data was also downlinked towards the end of operations. During the evening's transmission session, ''Philae'' was raised by {{convert|4|cm}} and its body rotated 35 degrees to more favourably position the largest solar panel to capture the most sunlight in the future.<ref name="bbcnews20141115">{{Cite news |last=Amos |first=Jonathan |date=15 November 2014 |title=Philae comet lander sends more data before losing power |url=https://www.bbc.com/news/science-environment-30058176 |url-status=live |archive-url=https://web.archive.org/web/20231120181130/https://www.bbc.com/news/science-environment-30058176 |archive-date=20 November 2023 |access-date=8 December 2014 |work=[[BBC News]] }}</ref><ref name="Lakdawalla2014-11-15">{{Cite web |last=Lakdawalla |first=Emily |author-link=Emily Lakdawalla |date=15 November 2014 |title=Now Philae down to sleep |url=https://www.planetary.org/articles/20141115-now-philae-down-to-sleep |url-status=live |archive-url=https://web.archive.org/web/20231203213414/https://www.planetary.org/articles/20141115-now-philae-down-to-sleep |archive-date=3 December 2023 |access-date=17 November 2014 |publisher=[[The Planetary Society]] }}</ref> Shortly afterwards, electrical power dwindled rapidly and all instruments were forced to shut down. The downlink rate slowed to a trickle before coming to a stop.<ref name="Harwood2014.11.15">{{Cite news |last=Harwood |first=William |date=15 November 2014 |title=Loss of contact with Philae |url=https://spaceflightnow.com/2014/11/15/loss-of-contact-with-philae/ |url-status=live |archive-url=https://web.archive.org/web/20230604032407/https://spaceflightnow.com/2014/11/15/loss-of-contact-with-philae/ |archive-date=4 June 2023 |access-date=15 November 2014 |work=Spaceflight Now }}</ref> Contact was lost on 15 November at 00:36&nbsp;UTC.<ref name="esa-asleep">{{Cite web |last=Scuka |first=Daniel |date=15 November 2014 |title=Our Lander's Asleep |url=https://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ |url-status=live |archive-url=https://web.archive.org/web/20231222112906/https://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ |archive-date=22 December 2023 |access-date=15 November 2014 |publisher=[[European Space Agency]] }}</ref>


The [[German Aerospace Center]]'s lander manager [[Stephan Ulamec]] stated:
The [[German Aerospace Center]]'s lander manager [[Stephan Ulamec]] stated:
Line 108: Line 108:


=== Instrument results ===
=== Instrument results ===
Data from the SESAME instrument determined that, rather than being "soft and fluffy" as expected, ''Philae''{{'s}} first touchdown site held a large amount of water ice under a layer of granular material about {{convert|25|cm|abbr=on}} deep.<ref name="space20150730">{{cite news |url=http://www.space.com/30100-comet-landing-discoveries-rosetta-philae-lander.html |title=Surprising Comet Discoveries by Rosetta's Philae Lander Unveiled |work=Space.com |last=Wall |first=Mike |date=30 July 2015 |access-date=31 July 2015}}</ref> It found that the mechanical strength of the ice was high and that cometary activity in that region was low. At the final landing site, the MUPUS instrument was unable to hammer very far into the comet's surface, despite power being gradually increased. This area was determined to have the consistency of solid ice<ref name="DLR_2014.11.17">{{cite web |url=http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-12176/year-all/#/gallery/17219 |title=Churyumov-Gerasimenko – hard ice and organic molecules |publisher=German Aerospace Center |date=17 November 2014 |access-date=18 November 2014}}</ref><ref name="timesindia20141118">{{cite news |url=http://timesofindia.indiatimes.com/home/science/Philae-reveals-presence-of-large-amount-of-water-ice-on-the-comet/articleshow/45195549.cms |title=Philae reveals presence of large amount of water ice on the comet |work=[[The Times of India]] |agency=Times News Network |first=Kounteya |last=Sinha |date=18 November 2014 |access-date=18 November 2014}}</ref> or [[pumice]].<ref name="eos20150731">{{cite journal |title=Comet Lander Makes a Hard Discovery |journal=[[Eos (magazine)|Eos]] |first=JoAnna |last=Wendel |volume=96 |date=31 July 2015 |doi=10.1029/2015EO033623|doi-access=free }}</ref>
Data from the SESAME instrument determined that, rather than being "soft and fluffy" as expected, ''Philae''{{'s}} first touchdown site held a large amount of water ice under a layer of granular material about {{convert|25|cm|abbr=on}} deep.<ref name="space20150730">{{Cite news |last=Wall |first=Mike |date=30 July 2015 |title=Surprising Comet Discoveries by Rosetta's Philae Lander Unveiled |url=http://www.space.com/30100-comet-landing-discoveries-rosetta-philae-lander.html |url-status=live |archive-url=https://web.archive.org/web/20231112100337/https://www.space.com/30100-comet-landing-discoveries-rosetta-philae-lander.html |archive-date=12 November 2023 |access-date=31 July 2015 |work=[[Space.com]] }}</ref> It found that the mechanical strength of the ice was high and that cometary activity in that region was low. At the final landing site, the MUPUS instrument was unable to hammer very far into the comet's surface, despite power being gradually increased. This area was determined to have the consistency of solid ice<ref name="DLR_2014.11.17">{{Cite web |date=17 November 2014 |title=Churyumov-Gerasimenko – hard ice and organic molecules |url=https://www.dlr.de/en/latest/news/2014/20141117_churyumov-gerasimenko-hard-ice-and-organic-molecules_12176/@@download/file |url-status=live |archive-url=https://web.archive.org/web/20240222153056/https://www.dlr.de/en/latest/news/2014/20141117_churyumov-gerasimenko-hard-ice-and-organic-molecules_12176/@@download/file |archive-date=22 February 2024 |access-date=18 November 2014 |publisher=[[German Aerospace Center]] |type=PDF }}</ref><ref name="timesindia20141118">{{Cite news |last=Sinha |first=Kounteya |date=18 November 2014 |title=Philae reveals presence of large amount of water ice on the comet |url=https://timesofindia.indiatimes.com/home/science/Philae-reveals-presence-of-large-amount-of-water-ice-on-the-comet/articleshow/45195549.cms |url-status=live |archive-url=https://web.archive.org/web/20231112100339/https://timesofindia.indiatimes.com/home/science/philae-reveals-presence-of-large-amount-of-water-ice-on-the-comet/articleshow/45195549.cms |archive-date=12 November 2023 |access-date=18 November 2014 |work=[[The Times of India]] |agency=Times News Network }}</ref> or [[pumice]].<ref name="eos20150731">{{Cite magazine |last=Wendel |first=JoAnna |date=31 July 2015 |title=Comet Lander Makes a Hard Discovery |url=https://eos.org/articles/comet-lander-makes-a-hard-discovery |url-status=live |archive-url=https://web.archive.org/web/20231027115440/https://eos.org/articles/comet-lander-makes-a-hard-discovery |archive-date=27 October 2023 |magazine=[[Eos (magazine)|Eos]] |publisher=[[American Geophysical Union]] |volume=96 |doi=10.1029/2015EO033623 |doi-access=free }}</ref>


In the atmosphere of the comet, the COSAC instrument detected the presence of molecules containing carbon and hydrogen. Soil elements could not be assessed, because the lander was unable to drill into the comet surface, likely due to hard ice.<ref name="guardian20141119">{{cite news |url=https://www.theguardian.com/science/2014/nov/18/philae-lander-comet-surface-detects-organic-molecules |title=Rosetta mission lander detects organic molecules on surface of comet |work=[[The Guardian]] |first=Richard |last=Gray |date=19 November 2014 |access-date=18 December 2014}}</ref> The SD2 drill went through the necessary steps to deliver a surface sample to the COSAC instrument,<ref name="DLR_2014.11.17" /> but nothing entered the COSAC ovens.<ref>{{cite web |url=https://twitter.com/erichand/status/534413817040867328 |title=COSAC PI: Drill tried to deliver sample. |work=Twitter.com |first=Eric |last=Hand |date=17 November 2014 |access-date=8 December 2014}}</ref>
In the atmosphere of the comet, the COSAC instrument detected the presence of molecules containing carbon and hydrogen. Soil elements could not be assessed, because the lander was unable to drill into the comet surface, likely due to hard ice.<ref name="guardian20141119">{{Cite news |last=Gray |first=Richard |date=19 November 2014 |title=Rosetta mission lander detects organic molecules on surface of comet |url=https://www.theguardian.com/science/2014/nov/18/philae-lander-comet-surface-detects-organic-molecules |url-status=live |archive-url=https://web.archive.org/web/20231112094834/https://www.theguardian.com/science/2014/nov/18/philae-lander-comet-surface-detects-organic-molecules |archive-date=12 November 2023 |access-date=18 December 2014 |work=[[The Guardian]] }}</ref> The SD2 drill went through the necessary steps to deliver a surface sample to the COSAC instrument,<ref name="DLR_2014.11.17" /> but nothing entered the COSAC ovens.<ref name="hand-20141117">{{Cite tweet |first=Eric |last=Hand |number=534413817040867328 |user=erichand |title=COSAC PI: Drill tried to deliver sample. Ovens heated up. But data show no actual delivery. "There’s nothing in it." #CometLanding |date=17 November 2014 |access-date=8 December 2014 |archive-url=https://web.archive.org/web/20150612090813/https://twitter.com/erichand/status/534413817040867328 |archive-date=12 June 2015 |url-status=live }}</ref>


Upon ''Philae''{{'s}} first touchdown on the comet's surface, COSAC measured material at the bottom of the vehicle, which was disturbed by the landing, while the Ptolemy instrument measured material at the top of the vehicle. Sixteen [[organic compound]]s were detected, four of which were seen for the first time on a comet, including [[acetamide]], [[acetone]], [[methyl isocyanate]] and [[propionaldehyde]].<ref name="wapo20150730">{{cite news |url=https://www.washingtonpost.com/world/philae-probe-finds-evidence-that-comets-can-be-cosmic-labs/2015/07/30/63a2fc0e-36e5-11e5-ab7b-6416d97c73c2_story.html |archive-url=https://web.archive.org/web/20181223235109/https://www.washingtonpost.com/world/philae-probe-finds-evidence-that-comets-can-be-cosmic-labs/2015/07/30/63a2fc0e-36e5-11e5-ab7b-6416d97c73c2_story.html |url-status=dead |archive-date=23 December 2018 |title=Philae probe finds evidence that comets can be cosmic labs |newspaper=The Washington Post |agency=Associated Press |first=Frank |last=Jordans |date=30 July 2015 |access-date=30 July 2015}}</ref><ref name="esa20150730">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Science_on_the_surface_of_a_comet |title=Science on the Surface of a Comet |publisher=European Space Agency |date=30 July 2015 |access-date=30 July 2015}}</ref><ref name="SCI-20150731">{{cite journal |last1=Bibring |first1=J.-P. |last2=Taylor |first2=M. G. G. T. |last3=Alexander |first3=C. |last4=Auster |first4=U. |last5=Biele |first5=J. |last6=Finzi |first6=A. Ercoli |last7=Goesmann |first7=F. |last8=Klingehoefer |first8=G. |last9=Kofman |first9=W. |last10=Mottola |first10=S. |last11=Seidenstiker |first11=K. J. |last12=Spohn |first12=T. |last13=Wright |first13=I. |display-authors=5 |title=Philae's First Days on the Comet |journal=[[Science (journal)|Science]] |volume=349 |issue=6247 |page=493 |date=31 July 2015 |doi=10.1126/science.aac5116 |pmid=26228139|bibcode=2015Sci...349..493B |doi-access=free |url=https://elib.dlr.de/97953/1/Science-2015-Bibring-493.pdf }}</ref>
Upon ''Philae''{{'s}} first touchdown on the comet's surface, COSAC measured material at the bottom of the vehicle, which was disturbed by the landing, while the Ptolemy instrument measured material at the top of the vehicle. Sixteen [[organic compound]]s were detected, four of which were seen for the first time on a comet, including [[acetamide]], [[acetone]], [[methyl isocyanate]] and [[propionaldehyde]].<ref name="ap-20150730">{{Cite news |last=Jordans |first=Frank |date=30 July 2015 |title=Philae probe finds evidence that comets can be cosmic labs |url=https://apnews.com/general-news-international-news-a8c32853d364494ca482c8e3dc00ced0 |url-status=live |archive-url=https://web.archive.org/web/20240222154017/https://apnews.com/general-news-international-news-a8c32853d364494ca482c8e3dc00ced0 |archive-date=22 February 2024 |access-date=30 July 2015 |work=[[Associated Press]] }}</ref><ref name="esa20150730">{{Cite press release |editor-last=Altobelli |editor-first=Nicolas |editor2-last=Bibring |editor2-first=Jean-Pierre |editor3-last=Ulamec |editor3-first=Stephan |date=30 July 2015 |title=Science on the Surface of a Comet |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Science_on_the_surface_of_a_comet |url-status=live |archive-url=https://web.archive.org/web/20240112110949/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Science_on_the_surface_of_a_comet |archive-date=12 January 2024 |access-date=30 July 2015 |publisher=[[European Space Agency]] }}</ref><ref name="SCI-20150731">{{Cite journal |last1=Bibring |first1=J.-P. |last2=Taylor |first2=M. G. G. T. |last3=Alexander |first3=C. |last4=Auster |first4=U. |last5=Biele |first5=J. |last6=Finzi |first6=A. Ercoli |last7=Goesmann |first7=F. |last8=Klingehoefer |first8=G. |last9=Kofman |first9=W. |last10=Mottola |first10=S. |last11=Seidenstiker |first11=K. J. |last12=Spohn |first12=T. |last13=Wright |first13=I. |display-authors=5 |date=31 July 2015 |title=Philae's First Days on the Comet |url=https://elib.dlr.de/97953/1/Science-2015-Bibring-493.pdf |url-status=live |journal=[[Science (journal)|Science]] |volume=349 |issue=6247 |page=493 |bibcode=2015Sci...349..493B |doi=10.1126/science.aac5116 |pmid=26228139 |archive-url=https://web.archive.org/web/20240113173750/https://elib.dlr.de/97953/1/Science-2015-Bibring-493.pdf |archive-date=13 January 2024 |doi-access=free }}</ref>


=== Reawakening and subsequent loss of communication ===
=== Reawakening and subsequent loss of communication ===
[[File:67P Churyumov-Gerasimenko - Rosetta (32755885495).png|thumb|right|[[67P/Churyumov–Gerasimenko|Comet Churyumov–Gerasimenko]] in March 2015 as imaged by ''Rosetta'' in true colour]]
[[File:67P Churyumov-Gerasimenko - Rosetta (32755885495).png|thumb|right|[[67P/Churyumov–Gerasimenko|Comet Churyumov–Gerasimenko]] in March 2015 as imaged by ''Rosetta'' in true colour]]
On 13 June 2015 at 20:28&nbsp;UTC, ground controllers received an 85-second transmission from ''Philae'', forwarded by ''Rosetta'', indicating that the lander was in good health and had sufficiently recharged its batteries to come out of [[Safe mode (spacecraft)|safe mode]].<ref name="NAT-20150614" /><ref name="esaphilae20150614">{{cite web |url=http://blogs.esa.int/rosetta/2015/06/14/rosettas-lander-philae-wakes-up-from-hibernation/ |title=Rosetta's lander Philae wakes up from hibernation |publisher=European Space Agency |first=Emily |last=Baldwin |date=14 June 2015 |access-date=14 June 2015}}</ref> ''Philae'' sent historical data indicating that although it had been operating earlier than 13 June 2015, it had been unable to contact ''Rosetta'' before that date.<ref name="NAT-20150614" /> The lander reported that it was operating with 24 watts of electrical power at {{convert|-35|C|F|abbr=on}}.<ref name="esaphilae20150614" />
On 13 June 2015 at 20:28&nbsp;UTC, ground controllers received an 85-second transmission from ''Philae'', forwarded by ''Rosetta'', indicating that the lander was in good health and had sufficiently recharged its batteries to come out of [[Safe mode (spacecraft)|safe mode]].<ref name="NAT-20150614" /><ref name="esaphilae20150614">{{Cite web |last=Baldwin |first=Emily |date=14 June 2015 |title=Rosetta's lander Philae wakes up from hibernation |url=https://blogs.esa.int/rosetta/2015/06/14/rosettas-lander-philae-wakes-up-from-hibernation/ |url-status=live |archive-url=https://web.archive.org/web/20240209213105/https://blogs.esa.int/rosetta/2015/06/14/rosettas-lander-philae-wakes-up-from-hibernation/ |archive-date=9 February 2024 |access-date=14 June 2015 |publisher=[[European Space Agency]] }}</ref> ''Philae'' sent historical data indicating that although it had been operating earlier than 13 June 2015, it had been unable to contact ''Rosetta'' before that date.<ref name="NAT-20150614" /> The lander reported that it was operating with 24 watts of electrical power at {{convert|-35|C|F|abbr=on}}.<ref name="esaphilae20150614" />


A new contact between ''Rosetta'' and ''Philae'' was confirmed on 19 June 2015.<ref name="esaphilae20150619">{{cite web |url=http://blogs.esa.int/rosetta/2015/06/19/rosetta-and-philae-in-contact-again/ |title=Rosetta and Philae in contact again |publisher=European Space Agency |first=Claudia |last=Mignone |date=19 June 2015 |access-date=20 June 2015}}</ref> The first signal was received on the ground from ''Rosetta'' at 13:37&nbsp;UTC, while a second signal was received at 13:54&nbsp;UTC. These contacts lasted about two minutes each and delivered additional status data.<ref name="esaphilae20150619" /> By 26 June 2015, there had been a total of seven intermittent contacts between the lander and orbiter.<ref name="transient contacts">{{cite news |url=http://blogs.esa.int/rosetta/2015/06/26/rosetta-and-philae-searching-for-a-good-signal/ |title=Rosetta and Philae: Searching for a good signal |publisher=European Space Agency |first=Emily |last=Baldwin |date=26 June 2015 |access-date=26 June 2015}}</ref> There were two opportunities for contact between the two spacecraft each Earth day, but their duration and quality depended on the orientation of the transmitting antenna on ''Philae'' and the location of ''Rosetta'' along its trajectory around the comet. Similarly, as the comet rotated, ''Philae'' was not always in sunlight and thus not always generating enough power via its solar panels to receive and transmit signals. ESA controllers continued to try to establish a stable contact duration of at least 50 minutes.<ref name="transient contacts" />
A new contact between ''Rosetta'' and ''Philae'' was confirmed on 19 June 2015.<ref name="esaphilae20150619">{{Cite web |last=Mignone |first=Claudia |date=19 June 2015 |title=Rosetta and Philae in contact again |url=https://blogs.esa.int/rosetta/2015/06/19/rosetta-and-philae-in-contact-again/ |url-status=live |archive-url=https://web.archive.org/web/20231112094847/https://blogs.esa.int/rosetta/2015/06/19/rosetta-and-philae-in-contact-again/ |archive-date=12 November 2023 |access-date=20 June 2015 |publisher=[[European Space Agency]] }}</ref> The first signal was received on the ground from ''Rosetta'' at 13:37&nbsp;UTC, while a second signal was received at 13:54&nbsp;UTC. These contacts lasted about two minutes each and delivered additional status data.<ref name="esaphilae20150619" /> By 26 June 2015, there had been a total of seven intermittent contacts between the lander and orbiter.<ref name="transient contacts">{{Cite news |last=Baldwin |first=Emily |date=26 June 2015 |title=Rosetta and Philae: Searching for a good signal |url=https://blogs.esa.int/rosetta/2015/06/26/rosetta-and-philae-searching-for-a-good-signal/ |url-status=live |archive-url=https://web.archive.org/web/20231120220619/https://blogs.esa.int/rosetta/2015/06/26/rosetta-and-philae-searching-for-a-good-signal/ |archive-date=20 November 2023 |access-date=26 June 2015 |publisher=[[European Space Agency]] }}</ref> There were two opportunities for contact between the two spacecraft each Earth day, but their duration and quality depended on the orientation of the transmitting antenna on ''Philae'' and the location of ''Rosetta'' along its trajectory around the comet. Similarly, as the comet rotated, ''Philae'' was not always in sunlight and thus not always generating enough power via its solar panels to receive and transmit signals. ESA controllers continued to try to establish a stable contact duration of at least 50 minutes.<ref name="transient contacts" />


Had ''Philae'' landed at the planned site of Agilkia in November 2014, its mission would probably have ended in March 2015 due to the higher temperatures of that location as solar heating increased.<ref name="planning2015">{{cite news |url=http://www.esa.int/Our_Activities/Operations/Philae_wake-up_triggers_intense_planning |title=Philae wake-up triggers intense planning |work=European Space Agency |date=15 June 2015 |access-date=16 June 2015}}</ref> {{As of|2015|06}}, ''Philae''{{'s}} key remaining experiment was to drill into the comet's surface to determine its chemical composition.<ref>{{cite news |url=https://www.bbc.com/news/science-environment-33206661 |title=Comet lander Philae renews contact |work=BBC News |last=Amos |first=Jonathan |date=19 June 2015 |access-date=19 June 2015}}</ref> Ground controllers sent commands to power up the [[CONSERT]] radar instrument on 5 July 2015, but received no immediate response from the lander. Confirmation was eventually received on 9 July, when the lander transmitted measurement data from the instrument.<ref name="DLR-20150710">{{cite news |url=http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-14156/ |title=New communication with Philae – commands executed successfully |publisher=Deutsches Zentrum für Luft- und Raumfahrt |date=10 July 2015 |access-date=11 July 2015}}</ref>
Had ''Philae'' landed at the planned site of Agilkia in November 2014, its mission would probably have ended in March 2015 due to the higher temperatures of that location as solar heating increased.<ref name="planning2015">{{Cite press release |date=15 June 2015 |title=Philae wake-up triggers intense planning |url=https://www.esa.int/Enabling_Support/Operations/Philae_wake-up_triggers_intense_planning |url-status=live |archive-url=https://web.archive.org/web/20240112110956/https://www.esa.int/Enabling_Support/Operations/Philae_wake-up_triggers_intense_planning |archive-date=12 January 2024 |access-date=16 June 2015 |publisher=[[European Space Agency]] }}</ref> {{As of|2015|06}}, ''Philae''{{'s}} key remaining experiment was to drill into the comet's surface to determine its chemical composition.<ref name="bbc-20150619">{{Cite news |last=Amos |first=Jonathan |date=19 June 2015 |title=Comet lander Philae renews contact |url=https://www.bbc.com/news/science-environment-33206661 |url-status=live |archive-url=https://web.archive.org/web/20231112094915/https://www.bbc.com/news/science-environment-33206661 |archive-date=12 November 2023 |access-date=19 June 2015 |work=[[BBC News]] }}</ref> Ground controllers sent commands to power up the [[CONSERT]] radar instrument on 5 July 2015, but received no immediate response from the lander. Confirmation was eventually received on 9 July, when the lander transmitted measurement data from the instrument.<ref name="DLR-20150710">{{Cite press release |date=10 July 2015 |title=New communication with Philae – commands executed successfully |url=https://www.dlr.de/en/latest/news/2015/20150710_new-communication-with-philae-commands-executed-successfully_14156 |url-status=live |archive-url=https://web.archive.org/web/20240222155032/https://www.dlr.de/en/latest/news/2015/20150710_new-communication-with-philae-commands-executed-successfully_14156 |archive-date=22 February 2024 |access-date=11 July 2015 |publisher=[[German Aerospace Center]] }}</ref>


Immediately after its reawakening, housekeeping data suggested that the lander's systems were healthy, and mission control uploaded commands for ''Rosetta'' to establish a new orbit and [[nadir]] so as to optimize communications, diagnostics, and enable new science investigations with ''Philae''.<ref name="planning2015" /><ref name="AP-20150615">{{cite news |url=http://apnews.excite.com/article/20150615/sci--comet_landing-edca488414.html |title=Europe's comet lander makes 2nd contact after waking up |work=Excite News |agency=Associated Press |first=Geir |last=Moulson |date=15 June 2015 |access-date=16 June 2015}}</ref><ref>{{cite news |url=https://www.bbc.com/news/science-environment-33163835 |title=Controllers wait on Philae link |work=BBC News |last=Amos |first=Jonathan |date=17 June 2015 |access-date=17 June 2015}}</ref> However, controllers had difficulties establishing a stable communications connection with the lander. The situation was not helped by the need to keep ''Rosetta'' at a greater and safer distance from the comet as it became more active.<ref>{{cite news |url=http://earthsky.org/space/rosetta-struggles-with-stable-philae-link |title=Rosetta team struggles with Philae link |work=Earthsky |date=29 June 2015 |access-date=30 June 2015}}</ref> The last communication was on 9 July 2015,<ref name="esablog20150720" /> and mission controllers were unable to instruct ''Philae'' to carry out new investigations.<ref name="sen20150814">{{cite news |url=http://sen.com/news/comet-s-fizzing-all-over-during-closest-approach-to-the-sun |title=Comet's fizzing all over during closest approach to the Sun |work=Space Exploration Network |first=Paul |last=Sutherland |date=14 August 2015}}</ref><ref>{{cite news |last=Sutherland |first=Paul |url=http://sen.com/news/rosetta-sends-software-patch-to-fix-philae |title=Rosetta sends software patch to fix Philae |work=Space Exploration Network |date=20 July 2015 |access-date=17 August 2015}}</ref> Subsequently, ''Philae'' failed to respond to further commands, and by January 2016, controllers acknowledged no further communications were likely.<ref name="newsci20160111">{{cite news |url=https://www.newscientist.com/article/dn28752-philae-lander-fails-to-respond-to-last-ditch-efforts-to-wake-it/ |title=Philae lander fails to respond to last-ditch efforts to wake it |work=New Scientist |first=Jacob |last=Aron |date=11 January 2016 |access-date=12 January 2016}}</ref>
Immediately after its reawakening, housekeeping data suggested that the lander's systems were healthy, and mission control uploaded commands for ''Rosetta'' to establish a new orbit and [[nadir]] so as to optimize communications, diagnostics, and enable new science investigations with ''Philae''.<ref name="planning2015" /><ref name="AP-20150615">{{Cite news |last=Moulson |first=Geir |date=15 June 2015 |title=Europe's comet lander makes 2nd contact after waking up |url=https://www.miamiherald.com/news/nation-world/world/article24398281.html |url-status=live |archive-url=https://web.archive.org/web/20240222155546/https://www.miamiherald.com/news/nation-world/world/article24398281.html |archive-date=22 February 2024 |access-date=16 June 2015 |work=[[Miami Herald]] |agency=[[Associated Press]] }}</ref><ref name="bbc-20150617">{{Cite news |last=Amos |first=Jonathan |date=17 June 2015 |title=Controllers wait on Philae link |url=https://www.bbc.com/news/science-environment-33163835 |url-status=live |archive-url=https://web.archive.org/web/20231112094838/https://www.bbc.com/news/science-environment-33163835 |archive-date=12 November 2023 |access-date=17 June 2015 |work=[[BBC News]] }}</ref> However, controllers had difficulties establishing a stable communications connection with the lander. The situation was not helped by the need to keep ''Rosetta'' at a greater and safer distance from the comet as it became more active.<ref name="earthsky-20150629">{{Cite news |date=29 June 2015 |title=Rosetta team struggles with Philae link |url=https://earthsky.org/space/rosetta-struggles-with-stable-philae-link/ |url-status=live |archive-url=https://web.archive.org/web/20231112094953/https://earthsky.org/space/rosetta-struggles-with-stable-philae-link/ |archive-date=12 November 2023 |access-date=30 June 2015 |work=Earthsky }}</ref> The last communication was on 9 July 2015,<ref name="esablog20150720" /> and mission controllers were unable to instruct ''Philae'' to carry out new investigations.<ref name="sen20150814">{{Cite news |last=Sutherland |first=Paul |date=14 August 2015 |title=Comet's fizzing all over during closest approach to the Sun |url=http://sen.com/news/comet-s-fizzing-all-over-during-closest-approach-to-the-sun |url-status=dead |archive-url=https://web.archive.org/web/20150822152511/http://sen.com/news/comet-s-fizzing-all-over-during-closest-approach-to-the-sun |archive-date=22 August 2015 |work=Space Exploration Network }}</ref><ref name="sen20150720">{{Cite news |last=Sutherland |first=Paul |date=20 July 2015 |title=Rosetta sends software patch to fix Philae |url=http://sen.com/news/rosetta-sends-software-patch-to-fix-philae |url-status=dead |archive-url=https://web.archive.org/web/20150822085720/http://sen.com/news/rosetta-sends-software-patch-to-fix-philae |archive-date=22 August 2015 |access-date=17 August 2015 |work=Space Exploration Network }}</ref> Subsequently, ''Philae'' failed to respond to further commands, and by January 2016, controllers acknowledged no further communications were likely.<ref name="newsci20160111">{{Cite magazine |last=Aron |first=Jacob |date=11 January 2016 |title=Philae lander fails to respond to last-ditch efforts to wake it |url=https://www.newscientist.com/article/dn28752-philae-lander-fails-to-respond-to-last-ditch-efforts-to-wake-it/ |url-status=live |archive-url=https://web.archive.org/web/20231112094853/https://www.newscientist.com/article/dn28752-philae-lander-fails-to-respond-to-last-ditch-efforts-to-wake-it/ |archive-date=12 November 2023 |access-date=12 January 2016 |magazine=[[New Scientist]] }}</ref>


On 27 July 2016, at 09:00&nbsp;[[UTC]], ESA switched off the Electrical Support System Processor Unit (ESS) onboard ''Rosetta'', making further communications with ''Philae'' impossible.<ref name="farewellphilae">{{cite web |url=http://blogs.esa.int/rosetta/2016/07/26/farewell-silent-philae/ |title=Farewell, silent Philae |publisher=European Space Agency |first=Claudia |last=Mignone |date=26 July 2016 |access-date=29 July 2016}}</ref><ref>{{cite news |url=http://www.nature.com/news/philae-comet-lander-goes-quiet-for-good-1.20338 |title=Philae comet lander goes quiet for good |journal=Nature |first=Elizabeth |last=Gibney |date=26 July 2016 |access-date=27 August 2016 |doi=10.1038/nature.2016.20338}}</ref>
On 27 July 2016, at 09:00&nbsp;[[UTC]], ESA switched off the Electrical Support System Processor Unit (ESS) onboard ''Rosetta'', making further communications with ''Philae'' impossible.<ref name="farewellphilae">{{Cite web |last=Mignone |first=Claudia |date=26 July 2016 |title=Farewell, silent Philae |url=https://blogs.esa.int/rosetta/2016/07/26/farewell-silent-philae/ |url-status=live |archive-url=https://web.archive.org/web/20161227033026/https://blogs.esa.int/rosetta/2016/07/26/farewell-silent-philae/ |archive-date=27 December 2016 |access-date=29 July 2016 |publisher=[[European Space Agency]] }}</ref><ref name="nature-20160726">{{Cite news |last=Gibney |first=Elizabeth |date=26 July 2016 |title=Philae comet lander goes quiet for good |url=https://www.nature.com/articles/nature.2016.20338.pdf |url-status=live |archive-url=https://web.archive.org/web/20221020185024/https://www.nature.com/articles/nature.2016.20338.pdf |archive-date=20 October 2022 |access-date=27 August 2016 |doi=10.1038/nature.2016.20338 |issn=1476-4687 |doi-access=free |journal=[[Nature (journal)|Nature]] }}</ref>


===Location===
===Location===
The lander was located on 2 September 2016 by the narrow-angle camera aboard ''Rosetta'' as it was slowly making its descent to the comet.<ref name="Philaefound" /> The search for the lander had been on-going during the ''Rosetta'' mission, using telemetry data and comparison of pictures taken before and after the lander's touchdown, looking for signs of the lander's specific reflectivity.<ref>{{cite web |url=http://blogs.esa.int/rosetta/2015/06/11/the-quest-to-find-philae-2/ |title=The quest to find Philae |publisher=European Space Agency |first=Emily |last=Baldwin |date=11 June 2015 |access-date=5 September 2016}}</ref>
The lander was located on 2 September 2016 by the narrow-angle camera aboard ''Rosetta'' as it was slowly making its descent to the comet.<ref name="Philaefound" /> The search for the lander had been on-going during the ''Rosetta'' mission, using telemetry data and comparison of pictures taken before and after the lander's touchdown, looking for signs of the lander's specific reflectivity.<ref name="esablog-20150611">{{Cite web |last=Baldwin |first=Emily |date=11 June 2015 |title=The quest to find Philae |url=https://blogs.esa.int/rosetta/2015/06/11/the-quest-to-find-philae-2/ |url-status=live |archive-url=https://web.archive.org/web/20240212031440/https://blogs.esa.int/rosetta/2015/06/11/the-quest-to-find-philae-2/ |archive-date=12 February 2024 |access-date=5 September 2016 |publisher=[[European Space Agency]] }}</ref>


The search area was narrowed down to the most promising candidate, which was confirmed by a picture taken at a distance of {{convert|2.7|km|mi|abbr=on}}, clearly showing the lander. The lander sits on its side wedged into a dark crevice of the comet, explaining the lack of electrical power and proper communication with the probe.<ref name="Philaefound" /> Knowing its exact location provides information needed to put ''Philae''{{'s}} two days of science into proper context.<ref name="Philaefound" />
The search area was narrowed down to the most promising candidate, which was confirmed by a picture taken at a distance of {{convert|2.7|km|mi|abbr=on}}, clearly showing the lander. The lander sits on its side wedged into a dark crevice of the comet, explaining the lack of electrical power and proper communication with the probe.<ref name="Philaefound" /> Knowing its exact location provides information needed to put ''Philae''{{'s}} two days of science into proper context.<ref name="Philaefound" />
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== Design ==
== Design ==
[[File:Rosetta and Philae (crop).jpg|thumb|left|''Rosetta'' and ''Philae'']]
[[File:Rosetta and Philae (crop).jpg|thumb|left|''Rosetta'' and ''Philae'']]
The lander was designed to deploy from the main spacecraft body and descend from an orbit of {{convert|22.5|km|0}} along a [[Projectile motion|ballistic trajectory]].<ref name="bbcnews20140926">{{cite news |url=https://www.bbc.com/news/science-environment-29380448 |title=Rosetta: Date fixed for historic comet landing attempt |work=BBC News |first=Jonathan |last=Amos |date=26 September 2014 |access-date=29 September 2014}}</ref> It would touch down on the comet's surface at a velocity of around {{convert|1|m/s|km/h mph}}.<ref name="bbcnews20140825">{{cite news |url=https://www.bbc.com/news/science-environment-28923010 |title=Rosetta mission: Potential comet landing sites chosen |work=BBC News |first=Jonathan |last=Amos |date=25 August 2014 |access-date=25 August 2014}}</ref> The legs were designed to dampen the initial impact to avoid bouncing as the comet's escape velocity is only around {{convert|1|m/s|km/h mph|abbr=on}},<ref name="mpg20140121">{{cite news |url=http://www.mpg.de/8323012/expedition_primeval_matter |title=Expedition to primeval matter |publisher=Max-Planck-Gesellschaft |first=Thorsten |last=Dambeck |date=21 January 2014 |access-date=19 September 2014}}</ref> and the impact energy was intended to drive ice screws into the surface.<ref>{{cite web |url=https://www.mps.mpg.de/3086295/Philae-Blog |title=About the Upcoming Philae Separation, Descent and Landing |publisher=[[Max Planck Institute for Solar System Research]] |first=Hermann |last=Böhnhardt |date=10 November 2014 |access-date=11 November 2014}}</ref> ''Philae'' was to then fire a [[harpoon]] into the surface at {{convert|70|m/s|km/h mph|abbr=on}} to anchor itself.<ref name="Biele2009">{{cite book |chapter-url=https://books.google.com/books?id=5YIPCbnTCeMC&pg=PA297 |chapter=The Strength of Cometary Surface Material: Relevance of Deep Impact Results for Philae Landing on a Comet |title=Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength |journal=Deep Impact as a World Observatory Event: Synergies in Space |publisher=Springer |series=ESO Astrophysics Symposia |first1=J. |last1=Biele |first2=S. |last2=Ulamec |first3=L. |last3=Richter |first4=E. |last4=Kührt |first5=J. |last5=Knollenberg |first6=D. |last6=Möhlmann |editor1-first=Hans Ulrich |editor1-last=Käufl |editor2-first=Christiaan |editor2-last=Sterken |page=297 |year=2009 |isbn=978-3-540-76958-3 |bibcode=2009diwo.conf..285B |doi=10.1007/978-3-540-76959-0_38}}</ref><ref name="Biele2013">{{cite conference |url=http://www.lpi.usra.edu/meetings/lpsc2013/pdf/1392.pdf |title=Preparing for Landing on a Comet – The Rosetta Lander Philae |conference=44th Lunar and Planetary Science Conference. 18–22 March 2013. The Woodlands, Texas. |first1=Jens |last1=Biele |first2=Stephan |last2=Ulamec |year=2013 |id=LPI Contribution No. 1719 |bibcode=2013LPI....44.1392B}}</ref> A thruster on top of ''Philae'' was to have fired to lessen the bounce upon impact and to reduce the recoil from harpoon firing.<ref name=CS1>{{cite news |url=http://www.csmonitor.com/Science/2014/1112/Will-Philae-successfully-land-on-comet-Thruster-trouble-heightens-drama |title=Will Philae successfully land on comet? Thruster trouble heightens drama |work=[[The Christian Science Monitor]] |first=Pete |last=Spotts |date=12 November 2014}}</ref> During the landing, the harpoons did not fire and the thruster failed to operate, leading to a multiple-contact landing.<ref name="cnnprob20141112" /><ref name="newsciprob20141113" />
The lander was designed to deploy from the main spacecraft body and descend from an orbit of {{convert|22.5|km|0}} along a [[Projectile motion|ballistic trajectory]].<ref name="bbcnews20140926">{{Cite news |last=Amos |first=Jonathan |date=26 September 2014 |title=Rosetta: Date fixed for historic comet landing attempt |url=https://www.bbc.com/news/science-environment-29380448 |url-status=live |archive-url=https://web.archive.org/web/20240120061628/https://www.bbc.com/news/science-environment-29380448 |archive-date=20 January 2024 |access-date=29 September 2014 |work=[[BBC News]] }}</ref> It would touch down on the comet's surface at a velocity of around {{convert|1|m/s|km/h mph}}.<ref name="bbcnews20140825">{{Cite news |last=Amos |first=Jonathan |date=25 August 2014 |title=Rosetta mission: Potential comet landing sites chosen |url=https://www.bbc.com/news/science-environment-28923010 |url-status=live |archive-url=https://web.archive.org/web/20231112094850/https://www.bbc.com/news/science-environment-28923010 |archive-date=12 November 2023 |access-date=25 August 2014 |work=[[BBC News]] }}</ref> The legs were designed to dampen the initial impact to avoid bouncing as the comet's escape velocity is only around {{convert|1|m/s|km/h mph|abbr=on}},<ref name="mpg20140120">{{Cite press release |last=Dambeck |first=Thorsten |date=20 January 2014 |title=Expedition to primeval matter |url=https://www.mpg.de/7769243/expedition-primeval_matter |url-status=live |archive-url=https://web.archive.org/web/20230604040223/https://www.mpg.de/7769243/expedition-primeval_matter |archive-date=4 June 2023 |access-date=19 September 2014 |publisher=[[Max Planck Society]] }}</ref> and the impact energy was intended to drive ice screws into the surface.<ref name="mpgblog-20141110">{{Cite web |last=Böhnhardt |first=Hermann |date=10 November 2014 |title=About the Upcoming Philae Separation, Descent and Landing |url=https://www.mps.mpg.de/en/rosetta/philae-blog |url-status=live |archive-url=https://web.archive.org/web/20231206104512/https://www.mps.mpg.de/en/rosetta/philae-blog |archive-date=6 December 2023 |access-date=11 November 2014 |publisher=[[Max Planck Institute for Solar System Research]] }}</ref> ''Philae'' was to then fire a [[harpoon]] into the surface at {{convert|70|m/s|km/h mph|abbr=on}} to anchor itself.<ref name="Biele2009">{{cite book |chapter-url=https://books.google.com/books?id=5YIPCbnTCeMC&pg=PA297 |chapter=The Strength of Cometary Surface Material: Relevance of Deep Impact Results for Philae Landing on a Comet |title=Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength |publisher=Springer |series=ESO Astrophysics Symposia |first1=J. |last1=Biele |first2=S. |last2=Ulamec |first3=L. |last3=Richter |first4=E. |last4=Kührt |first5=J. |last5=Knollenberg |first6=D. |last6=Möhlmann |editor1-first=Hans Ulrich |editor1-last=Käufl |editor2-first=Christiaan |editor2-last=Sterken |page=297 |year=2009 |isbn=978-3-540-76958-3 |bibcode=2009diwo.conf..285B |doi=10.1007/978-3-540-76959-0_38}}</ref><ref name="Biele2013">{{Cite conference |last1=Biele |first1=Jens |last2=Ulamec |first2=Stephan |date=March 2013 |title=Preparing for Landing on a Comet – The Rosetta Lander Philae |url=https://www.lpi.usra.edu/meetings/lpsc2013/pdf/1392.pdf |conference=44th Lunar and Planetary Science Conference |location=The Woodlands, Texas |publisher=[[Lunar and Planetary Institute]] |bibcode=2013LPI....44.1392B |id=LPI Contribution No. 1719 |archive-url=https://web.archive.org/web/20231209023314/https://www.lpi.usra.edu/meetings/lpsc2013/pdf/1392.pdf |archive-date=9 December 2023 |conference-url=https://www.lpi.usra.edu/meetings/lpsc2013/ |url-status=live }}</ref> A thruster on top of ''Philae'' was to have fired to lessen the bounce upon impact and to reduce the recoil from harpoon firing.<ref name="CS1">{{Cite news |last=Spotts |first=Pete |date=12 November 2014 |title=Will Philae successfully land on comet? Thruster trouble heightens drama |url=https://www.csmonitor.com/Science/2014/1112/Will-Philae-successfully-land-on-comet-Thruster-trouble-heightens-drama |url-status=live |archive-url=https://web.archive.org/web/20231112094835/https://www.csmonitor.com/Science/2014/1112/Will-Philae-successfully-land-on-comet-Thruster-trouble-heightens-drama |archive-date=12 November 2023 |work=[[The Christian Science Monitor]] }}</ref> During the landing, the harpoons did not fire and the thruster failed to operate, leading to a multiple-contact landing.<ref name="cnnprob20141112" /><ref name="newsciprob20141113" />


Communications with Earth used the ''Rosetta'' orbiter as a [[Broadcast relay station|relay station]] to reduce the electrical power needed. The mission duration on the surface was planned to be at least one week, but an extended mission lasting months was considered possible.{{citation needed|date=November 2020}}
Communications with Earth used the ''Rosetta'' orbiter as a [[Broadcast relay station|relay station]] to reduce the electrical power needed. The mission duration on the surface was planned to be at least one week, but an extended mission lasting months was considered possible.{{citation needed|date=November 2020}}
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The main structure of the lander is made from [[Carbon-fiber-reinforced polymer|carbon fiber]], shaped into a plate maintaining mechanical stability, a platform for the science instruments, and a [[hexagon]]al "sandwich" to connect all the parts. The total mass is about {{convert|100|kg|lb}}. Its exterior is covered with [[solar cell]]s for power generation.<ref name="Biele2002" />
The main structure of the lander is made from [[Carbon-fiber-reinforced polymer|carbon fiber]], shaped into a plate maintaining mechanical stability, a platform for the science instruments, and a [[hexagon]]al "sandwich" to connect all the parts. The total mass is about {{convert|100|kg|lb}}. Its exterior is covered with [[solar cell]]s for power generation.<ref name="Biele2002" />


The ''Rosetta'' mission was originally planned to rendezvous with the comet [[46P/Wirtanen]]. A failure in a previous [[Ariane 5]] launch vehicle closed the [[launch window]] to reach the comet with the same rocket.<ref name=esa-faq>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions |title=Why was 67P/Churyumov-Gerasimenko selected as the target comet instead of Wirtanen? |work=Rosetta's Frequently Asked Questions |publisher=European Space Agency |access-date=24 November 2014 |quote=The other options, including a launch to Wirtanen in 2004, would have required a more powerful launch vehicle, either an [[Ariane 5 ECA]] or a [[Proton (rocket family)|Proton]].}}</ref> It resulted in a change in target to the comet [[67P/Churyumov–Gerasimenko]].<ref name=esa-faq /> The larger mass of Churyumov–Gerasimenko and the resulting increased impact velocity required that the landing gear of the lander be strengthened.<ref name="esasci20141114">{{cite web |url=http://sci.esa.int/rosetta/54456-highlights-from-the-rosetta-mission-thus-far/ |title=Highlights from the Rosetta mission thus far |publisher=European Space Agency |date=14 November 2014 |access-date=6 July 2015}}</ref>
The ''Rosetta'' mission was originally planned to rendezvous with the comet [[46P/Wirtanen]]. A failure in a previous [[Ariane 5]] launch vehicle closed the [[launch window]] to reach the comet with the same rocket.<ref name="esa-faq">{{Cite web |title=Why was 67P/Churyumov-Gerasimenko selected as the target comet instead of Wirtanen? |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Frequently_asked_questions |url-status=live |archive-url=https://web.archive.org/web/20240217150512/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Frequently_asked_questions |archive-date=17 February 2024 |access-date=24 November 2014 |website=Rosetta's Frequently Asked Questions |publisher=[[European Space Agency]] |quote=The other options, including a launch to Wirtanen in 2004, would have required a more powerful launch vehicle, either an [[Ariane 5 ECA]] or a [[Proton (rocket family)|Proton]]. }}</ref> It resulted in a change in target to the comet [[67P/Churyumov–Gerasimenko]].<ref name=esa-faq /> The larger mass of Churyumov–Gerasimenko and the resulting increased impact velocity required that the landing gear of the lander be strengthened.<ref name="esasci20141114">{{Cite web |date=14 November 2014 |title=Highlights from the Rosetta mission thus far |url=https://sci.esa.int/web/rosetta/-/54456-highlights-from-the-rosetta-mission-thus-far |url-status=live |archive-url=https://web.archive.org/web/20231222185945/https://sci.esa.int/web/rosetta/-/54456-highlights-from-the-rosetta-mission-thus-far |archive-date=22 December 2023 |access-date=6 July 2015 |publisher=[[European Space Agency]] }}</ref>


{| class="wikitable" style="margin: 1em auto;"
{| class="wikitable" style="margin: 1em auto;"
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''Philae''{{'s}} power management was planned for two phases. In the first phase, the lander operated solely on battery power. In the second phase, it was to run on backup batteries recharged by solar cells.<ref name="techrep20140814" />
''Philae''{{'s}} power management was planned for two phases. In the first phase, the lander operated solely on battery power. In the second phase, it was to run on backup batteries recharged by solar cells.<ref name="techrep20140814" />


The power subsystem comprises two batteries: a non-rechargeable primary 1000 watt-hour battery to provide power for the first 60 hours and a secondary 140 watt-hour battery recharged by the solar panels to be used after the primary is exhausted. The solar panels cover {{convert|2.2|m2|sqft}} and were designed to deliver up to 32 watts at a distance of 3&nbsp;AU from the Sun.<ref>{{cite web |url=http://www.dlr.de/rd/Portaldata/28/Resources/dokumente/rx/Philae_Lander_FactSheets.pdf |title=Philae Lander Factsheets |publisher=DLR Public Relations |access-date=17 November 2014}}</ref>
The power subsystem comprises two batteries: a non-rechargeable primary 1000 watt-hour battery to provide power for the first 60 hours and a secondary 140 watt-hour battery recharged by the solar panels to be used after the primary is exhausted. The solar panels cover {{convert|2.2|m2|sqft}} and were designed to deliver up to 32 watts at a distance of 3&nbsp;AU from the Sun.<ref name="dlrPdf" />


=== Instruments ===
=== Instruments ===
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; [[APXS]]
; [[APXS]]
:The ''Alpha Particle X-ray Spectrometer'' detects alpha particles and X-rays, which provide information on the elemental composition of the comet's surface.<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/APXS |title=APXS |publisher=European Space Agency |access-date=26 August 2014}}</ref> The instrument is an improved version of the APXS on the [[Mars Pathfinder]].
:The ''Alpha Particle X-ray Spectrometer'' detects alpha particles and X-rays, which provide information on the elemental composition of the comet's surface.<ref name="esa-apxs">{{Cite web |title=APXS |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/APXS |url-status=live |archive-url=https://web.archive.org/web/20230811092159/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/APXS |archive-date=11 August 2023 |access-date=26 August 2014 |publisher=[[European Space Agency]] }}</ref> The instrument is an improved version of the APXS on the [[Mars Pathfinder]].


; CIVA
; CIVA
:The ''Comet Nucleus Infrared and Visible Analyser''<ref name=bibringetal>{{cite journal |last1=Bibring |first1=Jean-Pierre |last2=Lamy |first2=P |last3=Langevin |first3=Y |last4=Souufflot |first4=A |last5=Berthé |first5=J |last6=Borg |first6=J |last7=Poulet |first7=F |last8=Mottola |first8=S |title=CIVA |journal=Space Science Reviews |date=2007 |volume=138 |issue=1–4 |pages=397–412 |doi=10.1007/s11214-006-9135-5 |bibcode=2007SSRv..128..397B }}</ref> (sometimes given as ÇIVA<ref name=bieleulamec>{{cite journal |title=Capabilities of Philae, the Rosetta Lander |journal=Space Science Reviews |first1=J. |last1=Biele |first2=S. |last2=Ulamec |volume=138 |issue=1–4 |pages=275–289 |date=July 2008 |doi=10.1007/s11214-007-9278-z|bibcode=2008SSRv..138..275B |s2cid=120594802 }}</ref>) is a group of seven identical cameras used to take panoramic pictures of the surface plus a visible-light microscope and an infrared [[spectrometer]]. The panoramic cameras (CIVA-P) are arranged on the sides of the lander at 60° intervals: five mono imagers and two others making up a stereo imager. Each camera has a 1024×1024 pixel CCD detector.<ref name="nssdc-civa">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=2004-006C-01 |title=Comet nucleus Infrared and Visible Analyser (CIVA) |publisher=[[National Space Science Data Center]] |access-date=15 November 2014}}</ref> The microscope and spectrometer (CIVA-M) are mounted on the base of the lander, and are used to analyse the composition, texture and albedo (reflectivity) of samples collected from the surface.<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/CIVA |title=ÇIVA |publisher=European Space Agency |access-date=26 August 2014}}</ref>
:The ''Comet Nucleus Infrared and Visible Analyser''<ref name=bibringetal>{{cite journal |last1=Bibring |first1=Jean-Pierre |last2=Lamy |first2=P |last3=Langevin |first3=Y |last4=Souufflot |first4=A |last5=Berthé |first5=J |last6=Borg |first6=J |last7=Poulet |first7=F |last8=Mottola |first8=S |title=CIVA |journal=Space Science Reviews |date=2007 |volume=138 |issue=1–4 |pages=397–412 |doi=10.1007/s11214-006-9135-5 |bibcode=2007SSRv..128..397B }}</ref> (sometimes given as ÇIVA<ref name=bieleulamec>{{cite journal |title=Capabilities of Philae, the Rosetta Lander |journal=Space Science Reviews |first1=J. |last1=Biele |first2=S. |last2=Ulamec |volume=138 |issue=1–4 |pages=275–289 |date=July 2008 |doi=10.1007/s11214-007-9278-z|bibcode=2008SSRv..138..275B |s2cid=120594802 }}</ref>) is a group of seven identical cameras used to take panoramic pictures of the surface plus a visible-light microscope and an infrared [[spectrometer]]. The panoramic cameras (CIVA-P) are arranged on the sides of the lander at 60° intervals: five mono imagers and two others making up a stereo imager. Each camera has a 1024×1024 pixel CCD detector.<ref name="nssdc-civa">{{Cite web |title=Comet nucleus Infrared and Visible Analyser (CIVA) |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=2004-006C-01 |url-status=live |archive-url=https://web.archive.org/web/20231112094834/https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=2004-006C-01 |archive-date=12 November 2023 |access-date=15 November 2014 |publisher=[[National Space Science Data Center]] |id=2004-006C-01 }}</ref> The microscope and spectrometer (CIVA-M) are mounted on the base of the lander, and are used to analyse the composition, texture and albedo (reflectivity) of samples collected from the surface.<ref name="esa-civa">{{Cite web |title=ÇIVA |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/CIVA |url-status=live |archive-url=https://web.archive.org/web/20221023122558/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/CIVA |archive-date=23 October 2022 |access-date=26 August 2014 |publisher=[[European Space Agency]] }}</ref>


; [[CONSERT]]
; [[CONSERT]]
:The ''COmet Nucleus Sounding Experiment by Radiowave Transmission'' used electromagnetic wave propagation to determine the comet's internal structure. A [[radar]] on ''Rosetta'' transmitted a signal through the nucleus to be received by a detector on ''Philae''.<ref name="Kofman2007">{{cite journal |title=The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT): A Short Description of the Instrument and of the Commissioning Stages |journal=Space Science Reviews |first1=W. |last1=Kofman |first2=A. |last2=Herique |first3=J.-P. |last3=Goutail |first4=T. |last4=Hagfors |first5=I. P. |last5=Williams |first6=E. |last6=Nielsen |first7=J.-P. |last7=Barriot |first8=Y. |last8=Barbin |first9=C. |last9=Elachi |first10=P. |last10=Edenhofer |first11=A.-C. |last11=Levasseur-Regourd |first12=D. |last12=Plettemeier |first13=G. |last13=Picardi |first14=R. |last14=Seu |first15=V. |last15=Svedhem |display-authors=5 |volume=128 |issue=1–4 |pages=413–432 |date=February 2007 |doi=10.1007/s11214-006-9034-9 |bibcode=2007SSRv..128..413K|s2cid=122123636 }}</ref><ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/CONSERT2 |title=CONCERT |publisher=European Space Agency |access-date=26 August 2014}}</ref>
:The ''COmet Nucleus Sounding Experiment by Radiowave Transmission'' used electromagnetic wave propagation to determine the comet's internal structure. A [[radar]] on ''Rosetta'' transmitted a signal through the nucleus to be received by a detector on ''Philae''.<ref name="Kofman2007">{{cite journal |title=The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT): A Short Description of the Instrument and of the Commissioning Stages |journal=Space Science Reviews |first1=W. |last1=Kofman |first2=A. |last2=Herique |first3=J.-P. |last3=Goutail |first4=T. |last4=Hagfors |first5=I. P. |last5=Williams |first6=E. |last6=Nielsen |first7=J.-P. |last7=Barriot |first8=Y. |last8=Barbin |first9=C. |last9=Elachi |first10=P. |last10=Edenhofer |first11=A.-C. |last11=Levasseur-Regourd |first12=D. |last12=Plettemeier |first13=G. |last13=Picardi |first14=R. |last14=Seu |first15=V. |last15=Svedhem |display-authors=5 |volume=128 |issue=1–4 |pages=413–432 |date=February 2007 |doi=10.1007/s11214-006-9034-9 |bibcode=2007SSRv..128..413K|s2cid=122123636 }}</ref><ref name="esa-consert">{{Cite web |title=CONSERT |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/CONSERT2 |url-status=live |archive-url=https://web.archive.org/web/20240113191937/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/CONSERT2 |archive-date=13 January 2024 |access-date=26 August 2014 |publisher=[[European Space Agency]] }}</ref>


; COSAC
; COSAC
:The ''COmetary SAmpling and Composition'' instrument is a combined [[gas chromatograph]] and time-of-flight [[mass spectrometry|mass spectrometer]] to perform analysis of soil samples and determine the content of volatile components.<ref name="Gosmann2005">{{cite journal |title=COSAC Onboard Rosetta: A Bioastronomy Experiment for the Short-Period Comet 67P/Churyumov-Gerasimenko |journal=Astrobiology |first1=Fred |last1=Goesmann |first2=Helmut |last2=Rosenbauer |first3=Reinhard |last3=Roll |first4=Hermann |last4=Böhnhardt |volume=5 |issue=5 |pages=622–631 |date=October 2005 |doi=10.1089/ast.2005.5.622 |bibcode=2005AsBio...5..622G |pmid=16225435}}</ref><ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/COSAC |title=COSAC |publisher=European Space Agency |access-date=26 August 2014}}</ref>
:The ''COmetary SAmpling and Composition'' instrument is a combined [[gas chromatograph]] and time-of-flight [[mass spectrometry|mass spectrometer]] to perform analysis of soil samples and determine the content of volatile components.<ref name="Gosmann2005">{{cite journal |title=COSAC Onboard Rosetta: A Bioastronomy Experiment for the Short-Period Comet 67P/Churyumov-Gerasimenko |journal=Astrobiology |first1=Fred |last1=Goesmann |first2=Helmut |last2=Rosenbauer |first3=Reinhard |last3=Roll |first4=Hermann |last4=Böhnhardt |volume=5 |issue=5 |pages=622–631 |date=October 2005 |doi=10.1089/ast.2005.5.622 |bibcode=2005AsBio...5..622G |pmid=16225435}}</ref><ref name="esa-cosac">{{Cite web |title=COSAC |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/COSAC |url-status=live |archive-url=https://web.archive.org/web/20221024120351/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/COSAC |archive-date=24 October 2022 |access-date=26 August 2014 |publisher=[[European Space Agency]] }}</ref>


; MUPUS
; MUPUS
:The ''MUlti-PUrpose Sensors for Surface and Sub-Surface Science'' instrument measured the density, thermal and mechanical properties of the comet's surface.<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/MUPUS |title=MUPUS |publisher=European Space Agency |access-date=26 August 2014}}</ref>
:The ''MUlti-PUrpose Sensors for Surface and Sub-Surface Science'' instrument measured the density, thermal and mechanical properties of the comet's surface.<ref name="esa-mupus">{{Cite web |title=MUPUS |url=https://www.esa.int/Science_Exploration/Space_Science/Rosetta/MUPUS |url-status=live |archive-url=https://web.archive.org/web/20230818025511/https://www.esa.int/Science_Exploration/Space_Science/Rosetta/MUPUS |archive-date=18 August 2023 |access-date=26 August 2014 |publisher=[[European Space Agency]] }}</ref>


; Ptolemy
; Ptolemy
Line 257: Line 257:


;United Kingdom
;United Kingdom
:The [[Open University]] and the [[Rutherford Appleton Laboratory]] (RAL) developed PTOLEMY. RAL also constructed the blankets that kept the lander warm throughout its mission. [[Surrey Satellite Technology|Surrey Satellites Technology Ltd]]. (SSTL) constructed the [[reaction wheel|momentum wheel]] for the lander. It stabilised the module during the descent and landing phases.<ref name=dlrPdf /> Manufacturer [[e2v]] supplied the CIVA and Rolis camera systems used to film the descent and take images of samples, as well as three other camera systems.<ref>{{cite news |url=https://www.telegraph.co.uk/finance/newsbysector/industry/engineering/11221945/UK-space-industry-behind-Rosetta-comet-mission.html |title=UK space industry behind Rosetta comet mission |newspaper=The Telegraph |date=11 November 2014 |author=Alan Tovey}}</ref>
:The [[Open University]] and the [[Rutherford Appleton Laboratory]] (RAL) developed PTOLEMY. RAL also constructed the blankets that kept the lander warm throughout its mission. [[Surrey Satellite Technology|Surrey Satellites Technology Ltd]]. (SSTL) constructed the [[reaction wheel|momentum wheel]] for the lander. It stabilised the module during the descent and landing phases.<ref name="dlrPdf" /> Manufacturer [[e2v]] supplied the CIVA and Rolis camera systems used to film the descent and take images of samples, as well as three other camera systems.<ref>{{cite news |url=https://www.telegraph.co.uk/finance/newsbysector/industry/engineering/11221945/UK-space-industry-behind-Rosetta-comet-mission.html |title=UK space industry behind Rosetta comet mission |newspaper=The Telegraph |date=11 November 2014 |author=Alan Tovey}}</ref>
<!--ref for all modules-->
<!--ref for all modules-->



Revision as of 16:26, 22 February 2024

Philae
Illustration of Philae
Mission typeComet lander
OperatorEuropean Space Agency / DLR
COSPAR ID2004-006C Edit this at Wikidata
Websitewww.esa.int/rosetta
Mission durationPlanned: 1–6 weeks
Active: 12–14 November 2014
Hibernation: 15 November 2014 – 13 June 2015
Spacecraft properties
ManufacturerDLR / MPS / CNES / ASI
Launch mass100 kg (220 lb)[1]
Payload mass21 kg (46 lb)[1]
Dimensions1 × 1 × 0.8 m (3.3 × 3.3 × 2.6 ft)[1]
Power32 watts at 3 AU[2]
Start of mission
Launch date2 March 2004, 07:17 (2004-03-02UTC07:17) UTC
RocketAriane 5G+ V-158
Launch siteKourou ELA-3
ContractorArianespace
End of mission
Last contact9 July 2015, 18:07 (2015-07-09UTC18:08) UTC
67P/Churyumov–Gerasimenko lander
Landing date12 November 2014, 17:32 UTC[3]
Landing siteAbydos[4]

Philae (/ˈfl/[6] or /ˈfl/[7]) was a robotic European Space Agency lander that accompanied the Rosetta spacecraft[8][9] until it separated to land on comet 67P/Churyumov–Gerasimenko, ten years and eight months after departing Earth.[10][11][12] On 12 November 2014, Philae touched down on the comet, but it bounced when its anchoring harpoons failed to deploy and a thruster designed to hold the probe to the surface did not fire.[13] After bouncing off the surface twice, Philae achieved the first-ever "soft" (nondestructive) landing on a comet nucleus,[14][15][16] although the lander's final, uncontrolled touchdown left it in a non-optimal location and orientation.[17]

Despite the landing problems, the probe's instruments obtained the first images from a comet's surface.[18] Several of the instruments on Philae made the first direct analysis of a comet, sending back data that would be analysed to determine the composition of the surface.[19] In October 2020, scientific journal Nature published an article revealing what Philae had discovered while it was operational on the surface of 67P/Churyumov–Gerasimenko.[20]

On 15 November 2014 Philae entered safe mode, or hibernation, after its batteries ran down due to reduced sunlight and an off-nominal spacecraft orientation at the crash site. Mission controllers hoped that additional sunlight on the solar panels might be sufficient to reboot the lander.[21] Philae communicated sporadically with Rosetta from 13 June to 9 July 2015,[22][23][24] but contact was then lost. The lander's location was known to within a few tens of metres but it could not be seen. Its location was finally identified in photographs taken by Rosetta on 2 September 2016 as the orbiter was sent on orbits closer to the comet. The now-silent Philae was lying on its side in a deep crack in the shadow of a cliff. Knowledge of its location would help in interpretation of the images it had sent.[4][25] On 30 September 2016, the Rosetta spacecraft ended its mission by crashing in the comet's Ma'at region.[26]

The lander is named after the Philae obelisk, which bears a bilingual inscription and was used along with the Rosetta Stone to decipher Egyptian hieroglyphs. Philae was monitored and operated from DLR's Lander Control Center in Cologne, Germany.[27]

Mission

Video report by the German Aerospace Centre about Philae's landing mission. (10 min, English, in 1080p HD)

Philae's mission was to land successfully on the surface of a comet, attach itself, and transmit data about the comet's composition. The Rosetta spacecraft and Philae lander were launched on an Ariane 5G+ rocket from French Guiana on 2 March 2004, 07:17 UTC, and travelled for 3,907 days (10.7 years) to Churyumov–Gerasimenko. Unlike the Deep Impact probe, which by design struck comet Tempel 1's nucleus on 4 July 2005, Philae is not an impactor. Some of the instruments on the lander were used for the first time as autonomous systems during the Mars flyby on 25 February 2007. CIVA, one of the camera systems, returned some images while the Rosetta instruments were powered down, while ROMAP took measurements of the Martian magnetosphere. Most of the other instruments needed contact with the surface for analysis and stayed offline during the flyby. An optimistic estimate of mission length following touchdown was "four to five months".[28]

Scientific goals

The goals of the scientific mission have been summarised as follows:

"The scientific goals of its experiments focus on elemental, isotopic, molecular and mineralogical composition of the cometary material, the characterization of physical properties of the surface and subsurface material, the large-scale structure and the magnetic and plasma environment of the nucleus. In particular, surface and sub-surface samples will be acquired and sequentially analyzed by a suite of instruments. Measurements will be performed primarily during descent and along the first five days following touch-down. "[29]

Landing and surface operations

Depiction of Philae on Churyumov-Gerasimenko

Philae remained attached to the Rosetta spacecraft after rendezvousing with Churyumov–Gerasimenko on 6 August 2014. On 15 September 2014, ESA announced "Site J" on the smaller lobe of the comet as the lander's destination.[30] Following an ESA public contest in October 2014, Site J was renamed Agilkia in honour of Agilkia Island.[31]

A series of four go/no-go checks were performed on 11–12 November 2014. One of the final tests before detachment from Rosetta showed that the lander's cold-gas thruster was not working correctly, but the "go" was given anyway, as it could not be repaired.[32][33] Philae detached from Rosetta on 12 November 2014 at 08:35 UTC SCET.[34][35]

Landing events

Rosetta signal received at ESOC in Darmstadt, Germany (20 January 2014)

Philae's landing signal was received by Earth communication stations at 16:03 UTC after a 28-minute delay.[1][36] Unknown to mission scientists at that time, the lander had bounced. It began performing scientific measurements while slowly moving away from the comet and coming back down, confusing the science team.[37] Further analysis showed that it bounced twice.[38][39]

Philae's first contact with the comet occurred at 15:34:04 UTC SCET.[40] The probe rebounded off the comet's surface at 38 cm/s (15 in/s) and rose to an altitude of approximately 1 km (0.62 mi).[39] For perspective, had the lander exceeded about 44 cm/s (17 in/s), it would have escaped the comet's gravity.[41] After detecting the touchdown, Philae's reaction wheel was automatically powered off, resulting in its momentum being transferred back into the lander. This caused the vehicle to begin rotating every 13 seconds.[40] During this first bounce, at 16:20 UTC SCET, the lander is thought to have struck a surface prominence, which slowed its rotation to once every 24 seconds and sent the craft tumbling.[40][42] Philae touched down a second time at 17:25:26 UTC SCET and rebounded at 3 cm/s (1.2 in/s).[39][40] The lander came to a final stop on the surface at 17:31:17 UTC SCET.[40] It sits in rough terrain, apparently in the shadow of a nearby cliff or crater wall, and is canted at an angle of around 30 degrees, but is otherwise undamaged.[43] Its final location was determined initially by analysis of data from CONSERT in combination with the comet shape model based on images from the Rosetta orbiter,[44] and later precisely by direct imaging from Rosetta.[4]

An analysis of telemetry indicated that the initial impact was softer than expected,[45] that the harpoons had not deployed, and that the thruster had not fired.[46][13] The harpoon propulsion system contained 0.3 grams of nitrocellulose, which was shown by Copenhagen Suborbitals in 2013 to be unreliable in a vacuum.[47]

Operations and communication loss

Philae's intended landing site Agilkia (Site J)

The primary battery was designed to power the instruments for about 60 hours.[48] ESA expected that a secondary rechargeable battery would be partially filled by the solar panels attached to the outside of the lander, but the limited sunlight (90 minutes per 12.4-hour comet day[49]) at the actual landing site was inadequate to maintain Philae's activities, at least in this phase of the comet's orbit.[50][51]

On the morning of 14 November 2014, the battery charge was estimated to be only enough for continuing operations for the remainder of the day. After first obtaining data from instruments whose operation did not require mechanical movement, comprising about 80% of the planned initial science observations, both the MUPUS soil penetrator and the SD2 drill were commanded to deploy. Subsequently, MUPUS data[52] as well as COSAC and Ptolemy data were returned. A final set of CONSERT data was also downlinked towards the end of operations. During the evening's transmission session, Philae was raised by 4 centimetres (1.6 in) and its body rotated 35 degrees to more favourably position the largest solar panel to capture the most sunlight in the future.[53][54] Shortly afterwards, electrical power dwindled rapidly and all instruments were forced to shut down. The downlink rate slowed to a trickle before coming to a stop.[49] Contact was lost on 15 November at 00:36 UTC.[55]

The German Aerospace Center's lander manager Stephan Ulamec stated:

Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence ... This machine performed magnificently under tough conditions, and we can be fully proud of the incredible scientific success Philae has delivered.[55]

Instrument results

Data from the SESAME instrument determined that, rather than being "soft and fluffy" as expected, Philae's first touchdown site held a large amount of water ice under a layer of granular material about 25 cm (9.8 in) deep.[56] It found that the mechanical strength of the ice was high and that cometary activity in that region was low. At the final landing site, the MUPUS instrument was unable to hammer very far into the comet's surface, despite power being gradually increased. This area was determined to have the consistency of solid ice[57][58] or pumice.[59]

In the atmosphere of the comet, the COSAC instrument detected the presence of molecules containing carbon and hydrogen. Soil elements could not be assessed, because the lander was unable to drill into the comet surface, likely due to hard ice.[60] The SD2 drill went through the necessary steps to deliver a surface sample to the COSAC instrument,[57] but nothing entered the COSAC ovens.[61]

Upon Philae's first touchdown on the comet's surface, COSAC measured material at the bottom of the vehicle, which was disturbed by the landing, while the Ptolemy instrument measured material at the top of the vehicle. Sixteen organic compounds were detected, four of which were seen for the first time on a comet, including acetamide, acetone, methyl isocyanate and propionaldehyde.[62][63][64]

Reawakening and subsequent loss of communication

Comet Churyumov–Gerasimenko in March 2015 as imaged by Rosetta in true colour

On 13 June 2015 at 20:28 UTC, ground controllers received an 85-second transmission from Philae, forwarded by Rosetta, indicating that the lander was in good health and had sufficiently recharged its batteries to come out of safe mode.[22][65] Philae sent historical data indicating that although it had been operating earlier than 13 June 2015, it had been unable to contact Rosetta before that date.[22] The lander reported that it was operating with 24 watts of electrical power at −35 °C (−31 °F).[65]

A new contact between Rosetta and Philae was confirmed on 19 June 2015.[66] The first signal was received on the ground from Rosetta at 13:37 UTC, while a second signal was received at 13:54 UTC. These contacts lasted about two minutes each and delivered additional status data.[66] By 26 June 2015, there had been a total of seven intermittent contacts between the lander and orbiter.[67] There were two opportunities for contact between the two spacecraft each Earth day, but their duration and quality depended on the orientation of the transmitting antenna on Philae and the location of Rosetta along its trajectory around the comet. Similarly, as the comet rotated, Philae was not always in sunlight and thus not always generating enough power via its solar panels to receive and transmit signals. ESA controllers continued to try to establish a stable contact duration of at least 50 minutes.[67]

Had Philae landed at the planned site of Agilkia in November 2014, its mission would probably have ended in March 2015 due to the higher temperatures of that location as solar heating increased.[68] As of June 2015, Philae's key remaining experiment was to drill into the comet's surface to determine its chemical composition.[69] Ground controllers sent commands to power up the CONSERT radar instrument on 5 July 2015, but received no immediate response from the lander. Confirmation was eventually received on 9 July, when the lander transmitted measurement data from the instrument.[70]

Immediately after its reawakening, housekeeping data suggested that the lander's systems were healthy, and mission control uploaded commands for Rosetta to establish a new orbit and nadir so as to optimize communications, diagnostics, and enable new science investigations with Philae.[68][71][72] However, controllers had difficulties establishing a stable communications connection with the lander. The situation was not helped by the need to keep Rosetta at a greater and safer distance from the comet as it became more active.[73] The last communication was on 9 July 2015,[24] and mission controllers were unable to instruct Philae to carry out new investigations.[74][75] Subsequently, Philae failed to respond to further commands, and by January 2016, controllers acknowledged no further communications were likely.[76]

On 27 July 2016, at 09:00 UTC, ESA switched off the Electrical Support System Processor Unit (ESS) onboard Rosetta, making further communications with Philae impossible.[77][78]

Location

The lander was located on 2 September 2016 by the narrow-angle camera aboard Rosetta as it was slowly making its descent to the comet.[4] The search for the lander had been on-going during the Rosetta mission, using telemetry data and comparison of pictures taken before and after the lander's touchdown, looking for signs of the lander's specific reflectivity.[79]

The search area was narrowed down to the most promising candidate, which was confirmed by a picture taken at a distance of 2.7 km (1.7 mi), clearly showing the lander. The lander sits on its side wedged into a dark crevice of the comet, explaining the lack of electrical power and proper communication with the probe.[4] Knowing its exact location provides information needed to put Philae's two days of science into proper context.[4]

Design

Rosetta and Philae

The lander was designed to deploy from the main spacecraft body and descend from an orbit of 22.5 kilometres (14 mi) along a ballistic trajectory.[80] It would touch down on the comet's surface at a velocity of around 1 metre per second (3.6 km/h; 2.2 mph).[81] The legs were designed to dampen the initial impact to avoid bouncing as the comet's escape velocity is only around 1 m/s (3.6 km/h; 2.2 mph),[82] and the impact energy was intended to drive ice screws into the surface.[83] Philae was to then fire a harpoon into the surface at 70 m/s (250 km/h; 160 mph) to anchor itself.[84][85] A thruster on top of Philae was to have fired to lessen the bounce upon impact and to reduce the recoil from harpoon firing.[32] During the landing, the harpoons did not fire and the thruster failed to operate, leading to a multiple-contact landing.[46][13]

Communications with Earth used the Rosetta orbiter as a relay station to reduce the electrical power needed. The mission duration on the surface was planned to be at least one week, but an extended mission lasting months was considered possible.[citation needed]

The main structure of the lander is made from carbon fiber, shaped into a plate maintaining mechanical stability, a platform for the science instruments, and a hexagonal "sandwich" to connect all the parts. The total mass is about 100 kilograms (220 lb). Its exterior is covered with solar cells for power generation.[11]

The Rosetta mission was originally planned to rendezvous with the comet 46P/Wirtanen. A failure in a previous Ariane 5 launch vehicle closed the launch window to reach the comet with the same rocket.[86] It resulted in a change in target to the comet 67P/Churyumov–Gerasimenko.[86] The larger mass of Churyumov–Gerasimenko and the resulting increased impact velocity required that the landing gear of the lander be strengthened.[87]

Spacecraft component Mass[29]: 208 
Structure 18.0 kg 39.7 lb
Thermal control system 3.9 kg 8.6 lb
Power system 12.2 kg 27 lb
Active descent system 4.1 kg 9.0 lb
Reaction wheel 2.9 kg 6.4 lb
Landing gear 10.0 kg 22 lb
Anchoring system 1.4 kg 3.1 lb
Central data management system 2.9 kg 6.4 lb
Telecommunications system 2.4 kg 5.3 lb
Common electronics box 9.8 kg 22 lb
Mechanical support system, harness, balancing mass 3.6 kg 7.9 lb
Scientific payload 26.7 kg 59 lb
Sum 97.9 kg 216 lb

Power management

Philae's power management was planned for two phases. In the first phase, the lander operated solely on battery power. In the second phase, it was to run on backup batteries recharged by solar cells.[28]

The power subsystem comprises two batteries: a non-rechargeable primary 1000 watt-hour battery to provide power for the first 60 hours and a secondary 140 watt-hour battery recharged by the solar panels to be used after the primary is exhausted. The solar panels cover 2.2 square metres (24 sq ft) and were designed to deliver up to 32 watts at a distance of 3 AU from the Sun.[2]

Instruments

Philae's instruments

The science payload of the lander consists of ten instruments totalling 26.7 kilograms (59 lb), making up just over one quarter of the mass of the lander.[29]

APXS
The Alpha Particle X-ray Spectrometer detects alpha particles and X-rays, which provide information on the elemental composition of the comet's surface.[88] The instrument is an improved version of the APXS on the Mars Pathfinder.
CIVA
The Comet Nucleus Infrared and Visible Analyser[89] (sometimes given as ÇIVA[90]) is a group of seven identical cameras used to take panoramic pictures of the surface plus a visible-light microscope and an infrared spectrometer. The panoramic cameras (CIVA-P) are arranged on the sides of the lander at 60° intervals: five mono imagers and two others making up a stereo imager. Each camera has a 1024×1024 pixel CCD detector.[91] The microscope and spectrometer (CIVA-M) are mounted on the base of the lander, and are used to analyse the composition, texture and albedo (reflectivity) of samples collected from the surface.[92]
CONSERT
The COmet Nucleus Sounding Experiment by Radiowave Transmission used electromagnetic wave propagation to determine the comet's internal structure. A radar on Rosetta transmitted a signal through the nucleus to be received by a detector on Philae.[93][94]
COSAC
The COmetary SAmpling and Composition instrument is a combined gas chromatograph and time-of-flight mass spectrometer to perform analysis of soil samples and determine the content of volatile components.[95][96]
MUPUS
The MUlti-PUrpose Sensors for Surface and Sub-Surface Science instrument measured the density, thermal and mechanical properties of the comet's surface.[97]
Ptolemy
An instrument measuring stable isotope ratios of key volatiles on the comet's nucleus.[98][99] Parts of the instrument were manufactured by the Special Techniques Group at UKAEA.[100]
ROLIS
The Rosetta Lander Imaging System is a CCD camera used to obtain high-resolution images during descent and stereo panoramic images of areas sampled by other instruments.[101] The CCD detector consists of 1024×1024 pixels.[102]
ROMAP
The Rosetta Lander Magnetometer and Plasma Monitor is a magnetometer and plasma sensor to study the nucleus' magnetic field and its interactions with the solar wind.[103]
SD2
The Sampling, Drilling and Distribution system obtains soil samples from the comet and transfers them to the Ptolemy, COSAC, and CIVA instruments for in-situ analysis.[104] SD2 contains four primary subsystems: drill, ovens, carousel, and volume checker.[105][106] The drill system, made of steel and titanium, is capable of drilling to a depth of 230 mm (9.1 in), deploying a probe to collect samples, and delivering samples to the ovens.[107] There are a total of 26 platinum ovens to heat samples—10 medium temperature ovens at 180 °C (356 °F) and 16 high temperature ovens at 800 °C (1,470 °F)—and one oven to clear the drill bit for reuse.[108] The ovens are mounted on a rotating carousel that delivers the active oven to the appropriate instrument.[109] The electromechanical volume checker determines how much material was deposited into an oven, and may be used to evenly distribute material on CIVA's optical windows.[110] Development of SD2 was led by the Italian Space Agency with contributions by prime contractor Tecnospazio S.p.A. (now Selex ES S.p.A.) in charge of the system design and overall integration; the Italian company Tecnomare S.p.A., owned by Eni S.p.A., in charge of the design, development, and testing of the drilling/sampling tool and the volume checker; Media Lario; and Dallara.[106] The instrument's principal investigator is Amalia Ercoli-Finzi (Politecnico di Milano).[111]
SESAME
The Surface Electric Sounding and Acoustic Monitoring Experiments used three instruments to measure properties of the comet's outer layers. The Cometary Acoustic Sounding Surface Experiment (CASSE) measures the way in which sound travels through the surface. The Permittivity Probe (PP) investigates its electrical characteristics, and the Dust Impact Monitor (DIM) measures dust falling back to the surface.[112]

Analysis of comet

On 28 October 2020, it was reported that Philae had discovered, among other things, "low-strength primitive ice inside cometary boulders."[20] This also included primitive water ice from the comet's estimated formation 4.5 billion years prior.[20] This occurred primarily at the site of Philae's second touchdown onto the 67P/Churyumov–Gerasimenko, where the spacecraft successfully produced four distinct surface contacts on two adjoining cometary boulders.[20] Philae was also able to drill 0.25 metres into the comet's boulder ice.[20]

International contributions

Austria
The Austrian Space Research Institute developed the lander's anchor and two sensors within MUPUS, which are integrated into the anchor tips.[113]
Belgium
The Belgian Institute for Space Aeronomy (BIRA) cooperated with different partners to build one of the sensors (DFMS) of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument.[114][115] The Belgian Institute for Space Aeronomy (BIRA) and Royal Observatory of Belgium (ROB) provided information about the space weather conditions at Rosetta to support the landing of Philae. The main concern was solar proton events.[116]
Canada
Two Canadian companies played a role in the mission. SED Systems, located on the University of Saskatchewan campus in Saskatoon, built three ground stations that were used to communicate with the Rosetta spacecraft.[117] ADGA-RHEA Group of Ottawa provided MOIS (Manufacturing and Operating Information Systems) software which supported the procedures and command sequences operations software.[118]
Finland
The Finnish Meteorological Institute provided the memory of the Command, Data and Management System (CDMS) and the Permittivity Probe (PP).[119]
France
The French Space Agency, together with some scientific laboratories (IAS, SA, LPG, LISA) provided the system's overall engineering, radiocommunications, battery assembly, CONSERT, CIVA and the ground segment (overall engineering and development/operation of the Scientific Operation & Navigation Centre).[2]
Germany
The German Space Agency (DLR) has provided the structure, thermal subsystem, flywheel, the Active Descent System (procured by DLR but made in Switzerland),[120] ROLIS, downward-looking camera, SESAME, acoustic sounding and seismic instrument for Philae. It has also managed the project and did the level product assurance. The University of Münster built MUPUS (it was designed and built in Space Research Centre of Polish Academy of Sciences[121]) and the Braunschweig University of Technology the ROMAP instrument. The Max Planck Institute for Solar System Research made the payload engineering, eject mechanism, landing gear, anchoring harpoon, central computer, COSAC, APXS and other subsystems. The institute has led development and construction of COSAC and DIM, a part of SESAME, as well as contributed to the deveplopment and construction of ROMAP.[122]
Hungary
The Command and Data Management Subsystem (CDMS) designed in the Wigner Research Centre for Physics of the Hungarian Academy of Sciences jointly with the Space and Ground Facilities Ltd. (a spin-off company of the Wigner Research Centre for Physics).[123][124] The Power Subsystem (PSS) designed in the Department of Broadband Infocommunications and Electromagnetic Theory at Budapest University of Technology and Economics.[125] CDMS is the fault tolerant central computer of the lander, while PSS assures that the power coming from the batteries and solar arrays are properly handled, controls battery charging and manages the onboard power distribution.
Ireland
Captec Ltd., based in Malahide, provided the independent validation of mission critical software (independent software validation facility or SVF)[126] and developed the software for the communications interface between the orbiter and the lander. Captec also provided engineering support to the prime contractor for the launch activities at Kourou.[127][128] Space Technology Ireland Ltd. at Maynooth University has designed, constructed and tested the Electrical Support System Processor Unit (ESS) for the Rosetta mission. ESS stores, transmits and provides decoding for the command streams passing from the spacecraft to the lander and handles the data streams coming back from the scientific experiments on the lander to the spacecraft.[129]
Italy
The Italian Space Agency (ASI) developed the SD2 instrument and the photovoltaic assembly. Italian Alenia Space was involved in the assembly, integration and testing of the probe, as well as several mechanical and electrical ground support equipment. The company also built the probe's S-band and X-band digital transponder, used for communications with Earth.[130]
Netherlands
Moog Bradford (Heerle, The Netherlands) provided the Active Descent System, which guided and propelled the lander down to its landing zone. To accomplish the ADS, a strategic industrial team was formed with Bleuler-Baumer Mechanik in Switzerland.[120]
Poland
The Space Research Centre of the Polish Academy of Sciences built the Multi-Purpose Sensors for Surface and Subsurface Science (MUPUS).[121]
Spain
The GMV Spanish division has been responsible for the maintenance of the calculation tools to calculate the criteria of lighting and visibility necessary to decide the point of landing on the comet, as well as the possible trajectories of decline of the Philae module. Other important Spanish companies or educational institutions that have been contributed are as follows: INTA, Airbus Defence and Space Spanish division, other small companies also participated in subcontracted packages in structural mechanics and thermal control like AASpace (former Space Contact),[131] and the Universidad Politécnica de Madrid.[132]
Switzerland
The Swiss Centre for Electronics and Microtechnology developed CIVA.[133]
United Kingdom
The Open University and the Rutherford Appleton Laboratory (RAL) developed PTOLEMY. RAL also constructed the blankets that kept the lander warm throughout its mission. Surrey Satellites Technology Ltd. (SSTL) constructed the momentum wheel for the lander. It stabilised the module during the descent and landing phases.[2] Manufacturer e2v supplied the CIVA and Rolis camera systems used to film the descent and take images of samples, as well as three other camera systems.[134]

Media coverage

The landing was featured heavily in social media, with the lander having an official Twitter account portraying a personification of the spacecraft. The hashtag "#CometLanding" gained widespread traction. A Livestream of the control centres was set up, as were multiple official and unofficial events around the world to follow Philae's landing on Churyumov–Gerasimenko.[135][136] Various instruments on Philae were given their own Twitter accounts to announce news and science results.[137]

Vangelis composed the music for the trio of music videos released by ESA to celebrate the first-ever attempted soft landing on a comet by ESA's Rosetta mission.[138][139][140]

On 12 November 2014, the search engine Google featured a Google Doodle of Philae on its home page.[141] On 31 December 2014, Google featured Philae again as part of its New Year's Eve 2014 Doodle.[142]

Online comic author Randall Munroe wrote a live updating strip on his website xkcd on the day of the landing.[143][144]

See also

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