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{{short description|Efforts to study asteroids that might impact Earth}}
[[File:Potentially Hazardous Asteroids 2013.png|thumb|300px|Plot of orbits of known [[potentially hazardous asteroid]]s (size over {{convert|460|ft|m|disp=flip}} and passing within {{convert|4.7|e6mi|e6km|disp=flip}} of Earth's orbit) as of early 2013 ([[:File:PIA17041-Orbits-PotentiallyHazardousAsteroids-Early2013.jpg|alternative image]]).]]

The term '''Spaceguard''' loosely refers to a number of efforts to discover, [[Astronomical survey|catalogue]], and study [[near-Earth object]]s (NEO), especially those that may impact Earth ([[potentially hazardous objects]]).

Asteroids are discovered by [[telescope]]s which repeatedly [[Astronomical survey|survey large areas of sky]]. Efforts which concentrate on discovering NEOs are considered part of the "Spaceguard Survey," regardless of which organization they are affiliated with.

A number of organizations have also raised related discussions and proposals on [[asteroid-impact avoidance]].

== History ==
[[Arthur C. Clarke]] coined the term in his novel ''[[Rendezvous with Rama]]'' (1973) where "Project Spaceguard" was the name of an [[early warning system]] created following a fictional catastrophic [[Impact event|asteroid impact]].<ref name="paine">Michael Paine (2000-04-26), [http://www.space.com/news/japan_spacewatch_000426.html "Bigger Telescopes Seek Killer Asteroids"], ''[[Space.com]]'' (accessed on 2010-06-26)</ref> This name was later adopted by a number of real life efforts to discover and study near-[[Earth]] objects. The name was used for the Survey "with the permission and encouragement of Clarke."{{R|"Morrison"}} A 1992 [[United States Congress|US Congressional]] study produced a "Spaceguard Survey Report"<ref name="nasa">[[David Morrison (astrophysicist)|David Morrison]] (1992), "[http://impact.arc.nasa.gov/downloads/spacesurvey.pdf The Spaceguard Survey Report] {{webarchive|url=https://web.archive.org/web/20100108000136/http://impact.arc.nasa.gov/downloads/spacesurvey.pdf |date=2010-01-08 }}", ''[http://impact.arc.nasa.gov/gov_nasastudies.cfm NASA Studies] {{webarchive|url=https://web.archive.org/web/20100527151321/http://impact.arc.nasa.gov/gov_nasastudies.cfm |date=2010-05-27 }}'' at Asteroid and Comet Impact Hazards, [[NASA]] [[Ames Research Center]].</ref> which led to a mandate that [[NASA]] locate 90% of near-Earth [[asteroid]]s larger than 1&nbsp;km within 10 years.  This is often referred to as the "Spaceguard Goal."  A number of efforts which receive money through NASA are all considered to be working on the "Spaceguard Project."

The effect of the impact of [[Comet Shoemaker–Levy 9]] to Jupiter in July 1994 created a greater perception of importance to the detection of near Earth objects. As David Levy stated in an interview "The giggle factor disappeared after Shoemaker-Levy 9." He was referring to the contemporary attitude that [[extinction level event]]s were so improbable that those advocating for research for detection and possible deflection methods were only paranoid alarmists. The impact of one of its fragments created a giant dark spot on Jupiter over 12,000&nbsp;km across, and was estimated to have released an energy equivalent to 6 [[:wikt:teraton|teratons]] of TNT (600 times the world's nuclear arsenal). After the impact of Comet Shoemaker-Levy 9, asteroid detection programs all over the world received greater funding.<ref>{{Cite book|last=Levy|first=David H.|author-link=David H. Levy|url=https://books.google.com/books?id=-ePHSCLOMvwC&q=giggle&pg=PA169|title=Cosmic Discoveries: The Wonders of Astronomy|date=2010|publisher=Prometheus Books|isbn=978-1615925667|language=en|quote=In January 1993, [Levy] attended a meeting about hazards that could be caused from comets and asteroids. One of the biggest concerns that attending scientists had was what to do about the "giggle factor." Whenever anyone suggested that comets could post a hazard, the press responded with sarcasm. In those early days of 1993, it was difficult to make anyone take the threat seriously. [...] How could anyone know that at that meeting three of its participants<!--partipants[sic] in source--> would discover, within a few weeks, a comet that would spotlight the consequences of impacts very effectively?|page=[https://books.google.com/books?id=-ePHSCLOMvwC&q=giggle&pg=PA169 169]}}</ref>

The Working Group on Near-Earth Objects (WGNEO) of the [[International Astronomical Union]] held a workshop in 1995 entitled ''Beginning the Spaceguard Survey''<ref name="vulcano">[http://spaceguard.rm.iasf.cnr.it/SGF/Vulcano/INDEX.html Beginning the Spaceguard Survey] {{Webarchive|url=https://web.archive.org/web/20110722083645/http://spaceguard.rm.iasf.cnr.it/SGF/Vulcano/INDEX.html |date=2011-07-22 }}, Vulcano Workshop (1995), IAU Working Group on Near-Earth Objects. (accessed on 2010-06-26)</ref> which led to an international organization called the [[Spaceguard Foundation]]. Subsequently, there have been Spaceguard associations or foundations formed in countries around the world to support the ideas of discovering and studying near-Earth objects.  Generally, the Spaceguard organizations formed within individual countries are associated with the international foundation or with the NASA efforts only by name, common interests, and similar goals.

The initial Spaceguard Goal was achieved, although in slightly longer than 10 years.  An extension to the project gave NASA the mandate of reducing the minimum size at which more than 90% of near-Earth asteroids are known to 140 m.<ref>Harris, Alan. [http://www.nature.com/nature/journal/v453/n7199/full/4531178a.html  What Spaceguard did], ''[[Nature (journal)|Nature]]'', Vol. 453, pp. 1178–1179, June 26, 2008, {{doi|10.1038/4531178a}}; Published online 25 June 2008 {{subscription required}}.</ref>

== Observations ==

The [[2002 Eastern Mediterranean event]] and the [[Chelyabinsk meteor]] (Russia, February 2013) were not detected in advance by any Spaceguard effort. On October 6, 2008, the 4-meter [[2008 TC3|2008 TC<sub>3</sub>]] [[meteoroid]] was detected by the [[Catalina Sky Survey]] (CSS) 1.5 meter telescope at [[Mount Lemmon]], and monitored until it hit the Earth the next day.

New survey projects, such as the [[Asteroid Terrestrial-impact Last Alert System]] (ATLAS) program<ref>[http://www.fallingstar.com/ Asteroid Terrestrial-impact Last Alert System Project (ATLAS)], FallingStar.com website, last revised on March 29, 2013.</ref><ref>Tonry, John L. [https://arxiv.org/abs/1011.1028 An Early Warning System for Asteroid Impact] (thesis), Cornell University Library, submitted on November 3, 2010.</ref> operated by the [[University of Hawaii]], aim to greatly increase the number of small (down to approximately 10 m) impactors that are discovered before [[atmospheric entry]]—typically with days to weeks of warning, enabling evacuations of the affected areas and damage mitigation planning.  This is in contrast to other surveys which focus on finding much larger (greater than 100 m) objects years to decades before any potential impacts, at times when they could potentially still be deflected away from Earth.

Another short-term warning system is the NASA '''Scout''' program that came into operation in 2016.<ref>{{Cite web|url=https://www.universetoday.com/131737/nasas-new-asteroid-alert-system-gives-5-whole-days-warning/|title=NASA's New Asteroid Alert System Gives 5 Whole Days of Warning|first=Evan|last=Gough|date=November 2, 2016}}</ref><ref>[https://www.npr.org/sections/thetwo-way/2016/10/30/499751470/nasas-new-intruder-alert-system-spots-an-incoming-asteroid NASA's New 'Intruder Alert' System Spots An Incoming Asteroid]</ref><ref>{{Cite web|url=https://www.space.com/34149-asteroid-impact-warning-system-scout.html|title=Incoming! New Warning System Tracks Potentially Dangerous Asteroids|author1=Nola Taylor Tillman|date=September 23, 2016|website=Space.com}}</ref>

On October 19, 2017, one of the Survey telescopes, [[Pan-STARRS]] 1, discovered the first interstellar asteroid, [['Oumuamua]].{{R|"Morrison"}}<ref>{{cite web|title=ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before|url=https://www.eso.org/public/usa/news/eso1737/|website=European Southern Observatory|access-date=15 May 2018|archive-url=https://web.archive.org/web/20180515182033/https://www.eso.org/public/usa/news/eso1737/|archive-date=15 May 2018}}</ref>

The United Kingdom also hosts the self-styled Spaceguard Centre which conducts astrometric research (MPC code J26) and is open to the general public daily, but it is not affiliated with or supported by any public body.<ref>{{Cite web |title=The Spaceguard Centre &#124; The National Near Earth Objects Information Centre |url=https://spaceguardcentre.com/ |website=spaceguardcentre.com}}</ref>

== Issues ==
According to [[Michael A'Hearn|Dr. Michael F. A'Hearn]], a typical mission would take too long from approval to launch if there was an emergency:

{{cquote|REP. STEWART: ... are we technologically capable of launching something that could intercept [an asteroid]? ... DR. A'HEARN: No. If we had spacecraft plans on the books already, that would take a year ... I mean a typical small mission ... takes four years from approval to start to launch ...|author=[[Chris Stewart (politician)|Rep. Chris Stewart (R,UT)]] and [[Michael A'Hearn|Dr. Michael F. A'Hearn]], 10 April 2013|source=[[United States Congress]]<ref name="US-Congress-20130410">{{cite web |author=U.S.Congress |title=Threats From Space: a Review of U.S. Government Efforts to Track and mitigate Asteroids and Meteors (Part I and Part II) - Hearing Before the Committee on Science, Space, and Technology House of Representatives One Hundred Thirteenth Congress First Session |url=http://www.gpo.gov/fdsys/pkg/CHRG-113hhrg80552/pdf/CHRG-113hhrg80552.pdf |date=Spring 2013 |type=Hearings held 19 March 2013 and 10 April 2013 |page=147 |work=[[United States Congress]] |access-date=3 May 2014 }}</ref>}}
Lack of a master plan and dangers of false alarms have been pointed out by Stefan Lövgren.<ref>Stefan Lovgren (2004-03-08), "[https://web.archive.org/web/20040309084714/http://news.nationalgeographic.com/news/2004/03/0308_040308_asteroidimpact.html Asteroid False Alarm Shows Limits of Alert Systems], ''National Geographic News''. (accessed on 2010-06-26)</ref>

== See also ==

* [[The Spaceguard Foundation|Spaceguard Foundation]]
** [[Bisei Spaceguard Center]]
** [[Japan Spaceguard Association]]
* [[Asteroid-impact avoidance]] (includes list of survey projects)
* [[Asteroid impact prediction]]
* [[B612 Foundation]]
* [[NEOShield]]
* [[Planetary Defense Coordination Office]]
* [[Impact event]]
** [[Tunguska event]], 1908
* [[List of meteor air bursts]]
** [[Chelyabinsk meteor]], Russia, February 2013

==References==

{{reflist|refs=
<ref name="Morrison">{{cite journal|last1=Morrison|first1=David|author-link=David Morrison (astrophysicist)|title=Interstellar Visitor: The Strange Asteroid from a Faraway System|journal=Skeptical Inquirer|date=2018|volume=42|issue=2|pages=5–6}}</ref>
}}
<!--

 Neither of these links seem to work Sources on the web which contributed to this article:
* "Planetary Defense Systems" article by Kip Ingram [http://kipingram.com/index.php?p=219]
* http://www.space-frontier.org/PROJECTS/ASTEROIDS/aclarke_address_may26-98.html
* http://spaceguard.ias.rm.cnr.it/SGF/history.html -->

== Further reading ==

* Air Force 2025.  [https://web.archive.org/web/20060616060433/http://www.au.af.mil/au/2025/volume3/chap16/v3c16-2.htm Planetary Defense: Social, Economic, and Political Implications],  [[United States Air Force]], Air Force 2025 Final Report webpage, December 11, 1996.
* Daugherty, Laura and Emily Van Yuga. [http://www.oberlin.edu/faculty/bsimonso/group9.htm What Damage Have Impacts Done to Humans in Recorded History?] (Geol 117: Meteorite Impacts in Space and Time), Oberlin College Geology Department, [[Oberlin College]], May 11, 2001.
* Halliday, I., A.T. Blackwell, and A.A. Griffin.  "Meteorite Impacts on Humans and Buildings",  ''[[Nature (journal)|Nature]]'', pp.&nbsp;318–317.  [bib. of Yau et al.]
* Lapaz, L.  "Effects of Meteorites on the Earth",  ''Advances in Geophysics'', Vol. 4, pp.&nbsp;217–350.  [bib. of Yau et al.]
* Lewis, J.S. [https://books.google.com/books?id=-3NO2J95bBgC Rain of Iron and Ice: The Very Real Threat of Comet and Asteroid Bombardment], Reading, MA: Addison-Wesley Pub. Co., 1996;  Basic Books, 1997, {{ISBN|978-0201154948}}. [OBIS]
* Nield, Ted. [https://web.archive.org/web/20090108211256/http://www.geolsoc.org.uk/gsl/geoscientist/page4463.html Don't wrong the meteorite: Ted Nield thinks it's time to reassess our attitude to cosmic impacts. Meteorites are our friends], Geoscientist Online, [[Geological Society of London|The Geological Society]], October 2008.
* Norton, O.R.  "''Rocks from Space''".  Missoula Montana: Mountain Press Publishing Company, 1998.  [course textbook].
* Paine, M.P. [http://mpainesyd.com/idisk/Public/rocks_from_space/japan_spaceguard.pdf Bigger Telescopes Seek Killer Asteroids] Archive from Space.com April 2000.
* Reimold, W. U. and R. L. Gibson, Anton Pelser, Mauritz Naudé, Kevin Balkwill. [https://books.google.com/books?id=fwcIAQAAMAAJ Meteorite impact!: the danger from space and South Africa's mega-impact the Vredefort structure], Chris van Rensburg, 2005, {{ISBN|978-1919908625}}.
* "Special Report: Death and Property Damage Due to Meteor Destruction", UFO Research: Cincinnati!,  November, 1998.
* Swindel, G.W. Jr., and W.B. Jones. ''Meteoritics'', Vol. 1, pp.&nbsp;125–132.  [bib. of Lapaz 1958].
* Webb, S.K.  [https://web.archive.org/web/20030308060603/http://www.pairlist.net/pipermail/meteorite-list/2000-December/000203.html A Novel Measure of Meteorite Flux]",  [meteorite-list] How Many Meteorites Fall?,  November 30, 2000.
* Worthey, G. [https://web.archive.org/web/20001020135536/http://astro.sau.edu/~astro/html/im-meteor/strikes.html Meteor Near Misses and Strikes],  St. Ambrose University Astronomy, 11 October 1999.
* Yau, K., Weissman, P., & Yeomans, D. [http://articles.adsabs.harvard.edu/full/1994Metic..29..864Y Meteorite Falls In China And Some Related Human Casualty Events], ''[[Meteoritics]]'', 1994, Vol. 29, No. 6, pp.&nbsp;864–871, {{ISSN|0026-1114}}, bibliographic code: 1994Metic..29..864Y.

== External links ==
* [http://spaceguard.iaps.inaf.it/ Spaceguard Central Node] {{Webarchive|url=https://web.archive.org/web/20191129045216/http://spaceguard.iaps.inaf.it/ |date=2019-11-29 }}
* [https://web.archive.org/web/19990508161132/http://neo.jpl.nasa.gov/ NASA's Near-Earth Office Program]
* [https://archive.today/20130104190333/http://www.spaceref.com/news/viewnews.html?id=196 NEO News: Spaceguard Survey of Near Earth Asteroids]  David Morrison Tuesday, August 1, 2000 (Discovery statistics by 2000)
* [https://archive.today/20130104190333/http://www.spaceref.com/news/viewnews.html?id=196 Progress in the Spaceguard Survey] Saturday, February 9, 2002 (Status report by 2002)
* [http://www.spaceguarduk.com/ UK Spaceguard Centre]
* [https://sites.google.com/site/planetarydefensefoundation/ Planetary Defense Foundation]
* [http://users.tpg.com.au/horsts/spacegd.html Australian Spaceguard news and links]
* [https://web.archive.org/web/20141011223401/http://spaceguard.iasf-roma.inaf.it/SSystem/lists/plist.html Priority List]

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