Editing Project Mercury (section)

==Launch vehicles==
[[File:Mercury-launch-vehicles.png|thumb|upright=1.4|Launch vehicles: 1. Mercury-Atlas (orbital flights). 2. Mercury-Redstone (suborbital flights). 3. Little Joe (uncrewed tests)]]

===Launch escape system testing===
A {{convert|55|ft|m|adj=mid|-long}} launch vehicle called [[Little Joe (rocket)|Little Joe]] was used for uncrewed tests of the launch escape system, using a Mercury capsule with an escape tower mounted on it.{{sfn|Catchpole|2001|p=197}}{{sfn|Alexander & al.|1966|p=638}} Its main purpose was to test the system at [[max q]], when aerodynamic forces against the spacecraft peaked, making separation of the launch vehicle and spacecraft most difficult.{{sfn|Catchpole|2001|p=223}} It was also the point at which the astronaut was subjected to the heaviest vibrations.{{sfn|Catchpole|2001|p=284}} The Little Joe rocket used [[solid-fuel rocket|solid-fuel]] propellant and was originally designed in 1958 by NACA for suborbital crewed flights, but was redesigned for Project Mercury to simulate an Atlas-D launch.{{sfn|Catchpole|2001|p=196}} It was produced by [[North American Aviation]].{{sfn|Catchpole|2001|p=197}} It was not able to change direction; instead its flight depended on the angle from which it was launched.{{sfn|Catchpole|2001|p=198}} Its maximum altitude was {{convert|100|mi|abbr=on}} fully loaded.{{sfn|Alexander & al.|1966|p=125}} A [[Mercury-Scout 1|Scout launch vehicle]] was used for a single flight intended to evaluate the tracking network; however, it failed and was [[Range safety|destroyed from the ground]] shortly after launch.{{sfn|Alexander & al.|1966|pp=392–397}}

===Suborbital flight===
{{Multiple image |total_width=365px
|image1=Chimpanzee Ham in Biopack Couch - cropped.jpg|caption=
|image2=Mercury-Atlas 5 Enos with handler (cropped).jpg |caption2=
|footer=Space pioneers [[Ham (chimpanzee)|Ham]] (left), who became the first [[great ape]] in space during his [[Mercury-Redstone 2|January 31, 1961, mission]], and [[Enos (chimpanzee)|Enos]], the only chimpanzee and third primate to orbit the Earth ([[Mercury-Atlas 5|November 29, 1961]]), were research subjects in the Project Mercury program.}}
The [[Mercury-Redstone Launch Vehicle]] was an {{convert|83|ft|m|adj=mid|-tall}} (with capsule and escape system) single-stage launch vehicle used for suborbital ([[ballistic missile|ballistic]]) flights.{{sfn|Catchpole|2001|p=206}} It had a liquid-fueled engine that burned alcohol and liquid oxygen producing about {{convert|75,000|lbf|kN}} of thrust, which was not enough for orbital missions.{{sfn|Catchpole|2001|p=206}} It was a descendant of the German [[V-2 (rocket)|V-2]],{{sfn|Alexander & al.|1966|p=21}} and developed for the [[U.S. Army]] during the early 1950s. It was modified for Project Mercury by removing the warhead and adding a collar for supporting the spacecraft together with material for damping vibrations during launch.{{sfn|Catchpole|2001|p=207}} Its rocket motor was produced by [[North American Aviation]] and its direction could be altered during flight by its fins. They worked in two ways: by directing the air around them, or by directing the thrust by their inner parts (or both at the same time).{{sfn|Alexander & al.|1966|p=21}} Both the Atlas-D and Redstone launch vehicles contained an automatic abort sensing system which allowed them to abort a launch by firing the launch escape system if something went wrong.{{sfn|Catchpole|2001|pp=209, 214}} The [[Mercury-Jupiter|Jupiter]] rocket, also developed by [[Wernher von Braun]]'s team at the Redstone Arsenal in Huntsville, was considered as well for intermediate Mercury suborbital flights at a higher speed and altitude than Redstone, but this plan was dropped when it turned out that man-rating Jupiter for the Mercury program would actually cost more than flying an Atlas due to economics of scale.{{sfn|Alexander & al.|1966|p=151}}{{sfn|Grimwood|1963|p=69}} Jupiter's only use other than as a missile system was for the short-lived [[Juno II]] launch vehicle, and keeping a full staff of technical personnel around solely to fly a few Mercury capsules would result in excessively high costs.{{citation needed|date=January 2017}}

===Orbital flight===
Orbital missions required use of the [[Atlas LV-3B]], a man-rated version of the [[SM-65D Atlas|Atlas D]] which was originally developed as the [[United States]]' first operational [[intercontinental ballistic missile|intercontinental ballistic missile (ICBM)]]{{sfn|Catchpole|2001|p=211}} by [[Convair]] for the Air Force during the mid-1950s.{{sfn|Alexander & al.|1966|p=22}} The Atlas was a "one-and-one-half-stage" rocket fueled by [[kerosene]] and liquid [[oxygen]] (LOX).{{sfn|Catchpole|2001|p=211}} The rocket by itself stood {{convert|67|ft}} high; total height of the Atlas-Mercury space vehicle at launch was {{convert|95|ft}}.{{sfn|Catchpole|2001|p=212}}

The Atlas first stage was a booster skirt with two engines burning liquid fuel.{{sfn|Catchpole|2001|pp=225, 250}}{{refn|group=n|At the time, the word "booster" was sometimes used for the first stage of the launch stack. Later, "booster" came to refer to additional single-stage rockets attached to the sides of the main launch vehicle, as on the Space Shuttle.}} This, together with the larger sustainer second stage, gave it sufficient power to launch a Mercury spacecraft into orbit.{{sfn|Catchpole|2001|p=211}} Both stages fired from lift-off with the thrust from the second stage sustainer engine passing through an opening in the first stage. After separation from the first stage, the sustainer stage continued alone. The sustainer also steered the rocket by thrusters guided by gyroscopes.{{sfn|Catchpole|2001|pp=458–459}} Smaller vernier rockets were added on its sides for precise control of maneuvers.{{sfn|Catchpole|2001|p=211}}

===Gallery===
<gallery mode="packed">
Little Joe 5B capsule mating.jpg|Little Joe assembling at Wallops Island
Mercury-Redstone 4 booster erectionWB.jpg|Erection of Redstone at [[Cape Canaveral Air Force Station Launch Complex 5|Launch Complex 5]]
Unloading Atlas Launch Vehicle - GPN-2003-00041.jpg|Unloading Atlas at Cape Canaveral
Launch Complex 14-MA-9.jpg|Atlas - with spacecraft mounted - on launch pad at Launch Complex 14
</gallery>
{{clear}}