Space capsule: Difference between revisions

{{Short description|Type of spacecraft}}

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==History==

The capsule was originally designed for use both as a camera platform for the Soviet Union's first spy satellite program, [[Zenit spy satellite|Zenit]] and as a crewed spacecraft. This [[dual-use]] design was crucial in gaining [[Communist Party of the Soviet Union|Communist Party]] support for the program. The design used a spherical reentry module, with a biconic descent module containing [[Spacecraft attitude control|attitude control]] thrusters, on-orbit consumables, and the retro rocket for orbit termination. The basic design has remained in use for some 40 years, gradually adapted for a range of other uncrewed [[satellite]]s.

 

 

 

===Voskhod===

The Vostok design was modified to permit carrying multi-cosmonaut crews, and flown as two flights of the [[Voskhod programme]]. The cylindrical interior cabin was replaced with a wider, rectangular cabin which could hold either three cosmonauts seated abreast (Voskhod 1), or two cosmonauts with an inflatable airlock in between them, to permit [[extravehicular activity]] (Voskhod 2). A backup solid-fuel retro rocket was added to the top of the descent module. Vostok's ejection seat was removed to save space (thus there was no provision for crew escape in the event of a launch or landing emergency). The complete Voskhod spacecraft weighed {{convert|5682|kg|lb}}.

 

 

The lack of ejection seats meant that the Voskhod crew would return to Earth inside their spacecraft unlike the Vostok cosmonauts who ejected and parachuted down separately. Because of this, a new landing system was developed, which added a small solid-fuel rocket to the parachute lines. It fired as the descent module neared touchdown, providing a softer landing.

[[File:Mercury Spacecraft.png|thumb|right|Mercury capsule internal diagram]]

{{Main|Project Mercury#Spacecraft}}

 

The spacecraft was cone shaped, with a neck at the narrow end.{{sfn|Catchpole|2001|p=131}} It had a convex base, which carried a heat shield (Item '''2''' in the diagram below){{sfn|Catchpole|2001|pp=134–136}} consisting of an aluminum [[honeycomb structure|honeycomb]] covered with multiple layers of [[fiberglass]].{{sfn|Alexander & al.|1966|pp=140, 143}} Strapped to it was a retropack ('''1'''){{sfn|Catchpole|2001|pp=132–134}} consisting of three rockets deployed to brake the spacecraft during reentry.{{sfn|Catchpole|2001|p=132}} Between these were three minor rockets for separating the spacecraft from the launch vehicle at orbital insertion.{{sfn|Alexander & al.|1966|p=188}} The straps that held the package could be severed when it was no longer needed.{{sfn|Catchpole|2001|p=134}} Next to the heat shield was the pressurized crew compartment ('''3''').{{sfn|Catchpole|2001|pp=136–144}} Inside, an astronaut would be strapped to a form-fitting seat with instruments in front of him and with his back to the heat shield.{{sfn|Catchpole|2001|pp=136–137}} Underneath the seat was the environmental control system supplying oxygen and heat,{{sfn|Catchpole|2001|p=138}} scrubbing the air of CO₂, vapor and odors, and (on orbital flights) collecting urine.{{sfn|Catchpole|2001|p=139}}{{refn|group=n|On the first suborbital flight there was no urine collection whereas on the other, the astronaut had a reservoir added to the space suit{{sfn|Alexander & al.|1966|p=368}}}} The recovery compartment ('''4'''){{sfn|Catchpole|2001|pp=144–145}} at the narrow end of the spacecraft contained three parachutes: a drogue to stabilize free fall and two main chutes, a primary and reserve.{{sfn|Catchpole|2001|p=144}} Between the heat shield and inner wall of the crew compartment was a landing skirt, deployed by letting down the heat shield before landing.{{sfn|Catchpole|2001|p=135}} On top of the recovery compartment was the [[Antenna (radio)|antenna]] section ('''5'''){{sfn|Catchpole|2001|pp=145–148}} containing both antennas for communication and scanners for guiding spacecraft orientation.{{sfn|Catchpole|2001|p=147}} Attached was a flap used to ensure the spacecraft was faced heat shield first during reentry.{{sfn|Alexander & al.|1966|p=199}} A launch escape system ('''6''') was mounted to the narrow end of the spacecraft{{sfn|Catchpole|2001|pp=179–181}} containing three small solid-fueled rockets which could be fired briefly in a launch failure to separate the capsule safely from its booster. It would deploy the capsule's parachute for a landing nearby at sea.{{sfn|Catchpole|2001|p=179}} (See also [[#Mission profile|Mission profile]] for details.)

 

 

The US launched its first Mercury astronaut [[Alan Shepard]] on a [[Mercury-Redstone 3|suborbital flight]] almost a month after the first crewed orbital spaceflight. The Soviets were able to launch a second Vostok on a one-day flight on August 6, before the US finally orbited the first American, [[John Glenn]], on February 20, 1962. The United States launched a total of two crewed suborbital Mercury capsules and four crewed orbital capsules, with the longest flight, [[Mercury-Atlas 9]], making 22 orbits and lasting 32 and one-half hours.

{{Main|Project Gemini#Spacecraft}}

[[File:Gemini1.png|thumb|right|Gemini capsule internal diagram, with equipment adapter]]

[[File:Gemini 12 spacecraft at the Adler Planetarium.jpg|thumb|The [[Gemini 12]] capsule from the 1966 10th and final mission of [[Project Gemini]], flown by [[Jim Lovell]] and [[Buzz Aldrin]] (exhibited at Chicago's [[Adler Planetarium]])]]

Gemini's emergency [[launch escape system]] did not use an escape tower powered by a [[solid-fuel rocket]], but instead used aircraft-style [[ejection seat]]s. The tower was heavy and complicated, and NASA engineers reasoned that they could do away with it as the Titan II's [[hypergolic propellant]]s would burn immediately on contact. A Titan II booster explosion had a smaller blast effect and flame than on the cryogenically fueled Atlas and Saturn. [[Ejection seat]]s were sufficient to separate the astronauts from a malfunctioning launch vehicle. At higher altitudes, where the ejection seats could not be used, the astronauts would return to Earth inside the spacecraft, which would separate from the launch vehicle.{{sfnp|Dryden|1964|page=364}}

The main proponent of using ejection seats was Chamberlin, who had never liked the Mercury escape tower and wished to use a simpler alternative that would also reduce weight. He reviewed several films of Atlas and Titan II ICBM failures, which he used to estimate the approximate size of a fireball produced by an exploding launch vehicle and from this he gauged that the Titan II would produce a much smaller explosion, thus the spacecraft could get away with ejection seats.

 

 

The Gemini ejection system was never tested with the Gemini cabin pressurized with pure oxygen, as it was prior to launch. In January 1967, the fatal [[Apollo 1]] fire demonstrated that pressurizing a spacecraft with pure oxygen created an extremely dangerous fire hazard.<ref>{{cite magazine |last=Betancourt |first=Mark |date=October–November 2018 |title=Abort! |url=https://www.airspacemag.com/space/abort-180970364/ |magazine=[[Air & Space/Smithsonian]] |page=39 |volume=33 |issue=5 |access-date=March 16, 2019}}</ref> In a 1997 oral history, astronaut [[Thomas P. Stafford]] commented on the [[Gemini 6]] launch abort in December 1965, when he and command pilot [[Wally Schirra]] nearly ejected from the spacecraft:

 

 

 

===Apollo===

The Apollo spacecraft was first conceived in 1960 as a three-man craft to follow Project Mercury, to accomplish several types of mission: ferrying astronauts to an Earth-orbiting [[space station]], [[circumlunar trajectory|circumlunar]] flight, or a [[Moon landing]]. NASA solicited [[Apollo spacecraft feasibility study|feasibility study designs]] from several companies in 1960 and 1961, while Faget and the [[Space Task Group]] worked on their own design using a conical/blunt-body capsule (Command Module) supported by a cylindrical Service Module providing electrical power and propulsion. NASA reviewed the entrants' designs in May 1961, but when President [[John F. Kennedy]] proposed a national effort to land a man on the Moon during the 1960s, NASA decided to reject the feasibility studies and proceed with Faget's design, focused on the lunar landing mission. The contract to build Apollo was awarded to [[North American Aviation]].

 

 

Early on, the direct ascent mission profile was replaced with [[lunar orbit rendezvous]], augmenting the CSM with the [[Apollo Lunar Module|Lunar Excursion Module]] (LM) to ferry two astronauts to the lunar surface. This reduced the net spacecraft mass, allowing the mission to be launched with a single [[Saturn V]]. Since significant development work had started on the design, it was decided to continue with the existing design as Block I, while a Block II version capable of rendezvous with the LEM would be developed in parallel. Besides addition of a docking tunnel and probe, Block II would employ equipment improvements based on lessons learned from the Block I design. Block I would be used for uncrewed test flights and a limited number of Earth orbit crewed flights. Though the service propulsion engine was now bigger than required, its design was not changed since significant development was already in progress; however, the propellant tanks were downsized slightly to reflect the modified fuel requirement. Based on astronaut preference, the Block II CM would replace the two-piece [[plug door]] hatch cover, chosen to avoid an accidental hatch opening such as had happened on [[Gus Grissom]]'s [[Mercury-Redstone 4]] flight, with a one-piece, outward-opening hatch to make egress easier at the end of the mission.

He employed a small, lightweight bell-shaped reentry capsule, with an orbital crew module attached to its nose, containing the bulk of the mission living space. The service module would use two panels of electric [[solar cell]]s for power generation, and contained a propulsion system engine. The [[Soyuz 7K-OK|7K-OK model]] designed for Earth orbit used a {{convert|2810|kg|lb|adj=on}} reentry module measuring {{convert|2.17|m|ft|sp=us}} in diameter by {{convert|2.24|m|ft|sp=us}} long, with an interior volume of {{convert|4.00|m3|ft3|sp=us}}. The {{convert|1100|kg|lb|adj=on}} spheroidal orbital module measured {{convert|2.25|m|ft|sp=us}} in diameter by {{convert|3.45|m|ft|sp=us}} long with a docking probe, with an interior volume of {{convert|5.00|m3|ft3|sp=us}}. The total spacecraft mass was {{convert|6560|kg|lb}}.

 

 

The Russians continued to develop and fly the Soyuz to this day.

[[File:Post S-7 Shenzhou spacecraft.png|thumb|right|Diagram of the post-Shenzhou 7 spacecraft]]

{{Main|Shenzhou (spacecraft)}}

 

===Dragon 2===

{{Main|New Shepard}}

 

 

==Developmental crewed capsule designs==

 

===China===

 

===Iran===