Editing Space capsule (section)

===Mercury===
[[File:Mercury Spacecraft.png|thumb|right|Mercury capsule internal diagram]]
{{Main|Project Mercury#Spacecraft}}
The Mercury program was the United States' first crewed space program. It ran from 1958 through 1963, with the goal of putting a human in orbit around the Earth and returning him safely. The program used a small capsule attached to a booster rocket to achieve orbit. The development of the Mercury capsule began in earnest after NASA selected the McDonnell Aircraft Corporation as its contractor in 1959.<ref name="Baker1981">{{Cite web |title=The History of Manned Space Flight|author=David Baker|url=https://catalog.library.vanderbilt.edu/discovery/fulldisplay/alma991005815469703276/01VAN_INST:vanui |access-date=2023-03-08 |website=catalog.library.vanderbilt.edu |language=en|date=1981}}</ref> The Mercury spacecraft's principal designer was [[Maxime Faget]], who started research for human spaceflight during the time of the NACA.<ref>{{cite book|last=Catchpole|first=John|title=Project Mercury - NASA's First Manned Space Programme|date=2001|publisher=Springer Praxis|location=Chichester, UK|isbn=1-85233-406-1|url-access=registration|url=https://archive.org/details/projectmercuryna0000catc|page = 150}}</ref> It was {{convert|10.8|ft}} long and {{convert|6.0|ft}} wide; with the launch escape system added, the overall length was {{convert|25.9|ft}}.{{sfn|Catchpole|2001|p=131}} With {{convert|100|ft3|m3}} of habitable volume, the capsule was just large enough for a single crew member.<ref>{{cite book|title=This New Ocean: a History of Project Mercury|page = 47 |last1= Alexander |first1= C. C.|last2=Grimwood|first2=J. M.|last3=Swenson|first3=L. S.| date=1966| publisher=NASA| url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670005605_1967005605.pdf |isbn=1934941875|location=US|ref={{sfnRef|Alexander & al.|1966}}}}</ref> Inside were 120 controls: 55 electrical switches, 30 [[Fuse (electrical)|fuses]] and 35 mechanical levers.{{sfn|Alexander & al.|1966|p=245}} The heaviest spacecraft, Mercury-Atlas 9, weighed {{convert|3000|lb}} fully loaded.{{sfn|Alexander & al.|1966|p=490}} Its outer skin was made of [[René 41]], a nickel alloy able to withstand high temperatures.{{sfn|Catchpole|2001|p=136}}

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 CO<sub>2</sub>, 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 Mercury spacecraft did not have an on-board computer, instead relying on all computation for reentry to be calculated by computers on the ground, with their results (retrofire times and firing attitude) then transmitted to the spacecraft by radio while in flight.<ref name="NASAComp1">{{cite web|author1=NASA|author-link1=NASA|title=Computers in Spaceflight: The NASA Experience – Chapter One: The Gemini Digital Computer: First Machine in Orbit|url=https://history.nasa.gov/computers/ch1-1.html|website=NASA History|date=March 1988 |publisher=NASA|access-date=15 September 2016}}</ref><ref name="DanCompSpace">{{cite web|last1=Rutter|first1=Daniel|title=Computers in space|url=http://www.dansdata.com/spacecomp.htm|website=Dan's Data|access-date=15 September 2016|date=28 October 2004}}</ref> All computer systems used in the Mercury space program were housed in [[NASA]] facilities on [[Earth]].<ref name="NASAComp1" /> The computer systems were [[IBM 701]] computers.<ref name="IBMArchSpace">{{cite web|title=Space flight chronology|url=http://www-03.ibm.com/ibm/history/exhibits/space/space_chronology.html|archive-url=https://web.archive.org/web/20050119055349/http://www-03.ibm.com/ibm/history/exhibits/space/space_chronology.html|url-status=dead|archive-date=January 19, 2005|website=IBM Archives|date=23 January 2003|publisher=IBM|access-date=15 September 2016}}</ref><ref name="IBM701">{{cite web|title=IBM 701 – A notable first: The IBM 701|url=http://www-03.ibm.com/ibm/history/exhibits/701/701_intro.html|archive-url=https://web.archive.org/web/20041228004544/http://www-03.ibm.com/ibm/history/exhibits/701/701_intro.html|url-status=dead|archive-date=December 28, 2004|website=IBM Archives|date=23 January 2003|publisher=IBM|access-date=15 September 2016}}</ref>

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.