page_title: Space capsule
section_title: Mercury
hierarchical_section_title: Space capsule / History / Mercury
context_page_description: A space capsule is an often-crewed spacecraft that uses a blunt-body reentry capsule to reenter the Earth's atmosphere without wings. Capsules are distinguished from satellites primarily by the ability to survive reentry and return a payload to the Earth's surface from orbit. Capsule-based crewed spacecraft such as Soyuz or Orion are often supported by a service or adapter module, and sometimes augmented with an extra module for extended space operations. Capsules make up the majority of crewed spacecraft designs, although one crewed spaceplane, the Space Shuttle, has flown in orbit.
  Current examples of crewed space capsules include Soyuz, Shenzhou, Orion, Starliner, and Dragon 2. Examples of new crew capsules currently in development include Orel and Gaganyaan. Historic examples of crewed capsules include Vostok, Mercury, Voskhod, Gemini, and Apollo. A crewed space capsule must be able to sustain life in an often demanding thermal and radiation environment in the vacuum of space. It may be expendable or reusable.
context_section_description: The Mercury spacecraft's principal designer was Maxime Faget, who started research for human spaceflight during the time of the NACA. It was 10.8 feet (3.3 m) long and 6.0 feet (1.8 m) wide; with the launch escape system added, the overall length was 25.9 feet (7.9 m). With 100 cubic feet (2.8 m³) of habitable volume, the capsule was just large enough for a single crew member. Inside were 120 controls: 55 electrical switches, 30 fuses and 35 mechanical levers. The heaviest spacecraft, Mercury-Atlas 9, weighed 3,000 pounds (1,400 kg) fully loaded. Its outer skin was made of René 41, a nickel alloy able to withstand high temperatures.
  The spacecraft was cone shaped, with a neck at the narrow end. It had a convex base, which carried a heat shield (Item 2 in the diagram below) consisting of an aluminum honeycomb covered with multiple layers of fiberglass. Strapped to it was a retropack (1) consisting of three rockets deployed to brake the spacecraft during reentry. Between these were three minor rockets for separating the spacecraft from the launch vehicle at orbital insertion. The straps that held the package could be severed when it was no longer needed. Next to the heat shield was the pressurized crew compartment (3). 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. Underneath the seat was the environmental control system supplying oxygen and heat, scrubbing the air of CO₂, vapor and odors, and (on orbital flights) collecting urine. The recovery compartment (4) at the narrow end of the spacecraft contained three parachutes: a drogue to stabilize free fall and two main chutes, a primary and reserve. Between the heat shield and inner wall of the crew compartment was a landing skirt, deployed by letting down the heat shield before landing. On top of the recovery compartment was the antenna section (5) containing both antennas for communication and scanners for guiding spacecraft orientation. Attached was a flap used to ensure the spacecraft was faced heat shield first during reentry. A launch escape system (6) was mounted to the narrow end of the spacecraft 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. (See also 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. All computer systems used in the Mercury space program were housed in NASA facilities on Earth. The computer systems were IBM 701 computers.
  The US launched its first Mercury astronaut Alan Shepard on a 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.
caption: Mercury capsule internal diagram
exif: {}