Mercury Capsule Retrorocket Test in the Altitude Wind Tunnel
A mechanic at the National Aeronautics and Space Administration (NASA) Lewis Research Center prepares the inverted base of a Mercury capsule for a test of its posigrade retrorockets inside the Altitude Wind Tunnel. In October 1959 NASA’s Space Task Group allocated several Project Mercury assignments to Lewis. The Altitude Wind Tunnel was modified to test the Atlas separation system, study the escape tower rocket plume, train astronauts to bring a spinning capsule under control, and calibrate the capsule’s retrorockets. The turning vanes, makeup air pipes, and cooling coils were removed from the wide western end of the tunnel to create a 51-foot diameter test chamber. The Mercury capsule had a six-rocket retro-package affixed to the bottom of the capsule. Three of these were posigrade rockets used to separate the capsule from the booster and three were retrograde rockets used to slow the capsule for reentry into the earth’s atmosphere. Performance of the retrorockets was vital since there was no backup system. Qualification tests of the retrorockets began in April 1960 on a retrograde thrust stand inside the southwest corner of the Altitude Wind Tunnel. These studies showed that a previous issue concerning the delayed ignition of the propellant had been resolved. Follow-up test runs verified reliability of the igniter’s attachment to the propellant. In addition, the capsule’s retrorockets were calibrated so they would not alter the capsule’s attitude when fired.
The Space Race began with a shock to the American public when the Soviet satellite Sputnik was launched in 1957. United states created NASA accelerate U.S. space exploration efforts and launched the Explorer 1 satellite in 1958. The Soviet Union was first again when it puts the first human, cosmonaut Yuri Gagarin, into a single orbit on April 12, 1961. Shortly after this, on May 5, the U.S. launched Alan Shepard, on a suborbital flight and reached its orbital goal on February 20, 1962, when John Glenn made three orbits around the Earth in the Mercury capsule. The Mercury space capsule was a pressurized cabin produced by McDonnell Aircraft and carried supplies of water, food, and oxygen for about one day. Mercury was launched on a top of modified Atlas D ballistic missiles. The capsule was fitted with a launch escape rocket to carry it safely away from the launch vehicle in case of a failure. Small retrorockets were used to bring the spacecraft out of its orbit, after which an ablative heat shield protected it from the heat of atmospheric reentry. Finally, a parachute slowed the craft for a water landing. Both astronaut and capsule were recovered by helicopters deployed from a U.S. Navy ship. The Mercury project missions were followed by millions on radio and TV around the world. Its success laid the groundwork for Project Gemini, which carried two astronauts in each capsule and perfected space docking maneuvers essential for manned lunar landings in the Apollo program announced just a few weeks after the first manned Mercury launch.