Alan Shepard

May 5, 1961
First Man U.S. man in Space
Launch Complex 5
Alan Shepard

Mercury-Redstone 3 was a U.S. Mercury program manned space mission launched on May 5, 1961 using a Redstone rocket, from Launch Complex 5 (LC-5) at Cape Canaveral, Florida. The Mercury capsule was named Freedom 7 and it performed a suborbital flight, piloted by astronaut Alan Shepard—the first American in space. The flight lasted less than 16 minutes and attained an altitude of just over 187 km.



Unlike the earlier Soviet Vostok 1 flight, Shepard did not orbit the earth but simply went up and down which requires a less powerful rocket and simpler guidance. He did however become the first astronaut to return to Earth with his ship, while the Russian cosmonaut parachuted away from his during landing. Soviet Premier Nikita Khruschev criticized Freedom 7 as a mere 'flea hop' compared to the recent flight of Vostok 1 and its passenger Yuri Gagarin.





In the early morning of May 5, 1961, Alan Shepard donned his pressure suit with the assistance of technician Joe W. Schmitt. A transfer van carried him to the launch pad, and he ascended the gantry at 10:15 UTC. At 10:21 UTC he entered Freedom 7, and the gantry crew helped attach the harness and hose connections. He would spend the next four hours in the capsule waiting for the launch.



At 9:34 AM EST (14:34 UTC), there were 45 million Americans watching and listening live to their televisions, when at about two seconds after liftoff Alan Shepard reported, "Ahh, Roger; lift-off and the clock is started... Yes, sir, reading you loud and clear. This is Freedom 7. The fuel is go; 1.2 g [12 m/s²]; cabin at 14 psi [97 kPa]; oxygen is go... Freedom 7 is still go!" He was riding on Redstone MRLV-7 and in Mercury spacecraft # 7. In all subsequent Mercury flights, the number 7 was appended to the astronaut-chosen spacecraft/mission name and call sign, in honor of the fact that there were 7 original Mercury astronauts.



At T+16 seconds (where T is the time of launch) the Pitch Program started and the Redstone began a 2 deg/s pitch over, from 90 to 45 degrees. At about T+40 seconds, the Pitch Program was complete. Max-Q was reached at 1 minute 24 seconds into the flight when Freedom 7 experienced a maximum dynamic pressure of 580 lbf/ft² (2.8 kPa). During ascent the cabin pressure sealed off at 5.5 lbf/in² (38 kPa) of pure oxygen. At 2 minutes into the flight, Shepard experienced 6 g (59 m/s²) of acceleration.

Launch of the Mercury-Redstone 3 spacecraft on May 5, 1961, 9:34 a.m. EST, with Alan Shepard onboard.



The Redstone's engine shut down on schedule at 2 minutes 21.8 seconds. Outside the spacecraft, its shingle temperature reached 220 °F (104 °C). Inside, the cabin was 91 °F (33 °C) The temperature inside Shepard's pressure suit was 75 °F (24 °C). Escape Tower separation, occurred 2 minutes and 22.2 seconds after launch. This is 1 second earlier than nominal, and there was some indication from the recovered escape tower that the jettison rockets had been fired manually. Shepard said he did not remember pulling the manual "JETT TOWER" override ring.



Three Posigrade Rockets with 370 lbf (1.6 kN) thrust each, fired for 1 second and separated the spacecraft from the Redstone booster at a rate of 15 ft/s (4.6 m/s) at 2 minutes 32.3 seconds after launch. At 3 minutes the automatic attitude control system (AACS) rotated the spacecraft 180 degrees, to a heatshield-forward position. The spacecraft remained in this position for the remainder of the flight. The spacecraft had almost reached apogee in its ballistic flight.
Shepard took manual control of the spacecraft attitude, one axis at a time, from the automatic attitude control system. The first thing he did was position the spacecraft to its retrofire attitude of 34 degrees pitch (nose of spacecraft pitched down 34 degrees). He then tested manual control of yaw and roll. When he took control of all three axes, he found that the spacecraft response was about the same as that of the Mercury simulator.



He then made observations outside the spacecraft, using the two porthole windows and the periscope. He saw the outlines of the west coast of Florida and the Gulf of Mexico. Lake Okeechobee, in central Florida, was also visible, but he could not see any city. Andros Island and the Bahamas were also observed in the periscope.



The retrorockets were fired at about T+5 minutes and 15 seconds into the flight, shortly after the spacecraft reached an apogee of 116.5 miles (187 km). The three 1000 lbf (4.4 kN) thrust retrograde rockets ripple-fired to provide a 510 ft/s (155 m/s) delta-V in the opposite direction of travel. Each retrorocket fired for a total of 10 seconds. They were fired 5 seconds apart so they overlap in burning (Retro #1 fired at 5:14.1; Retro #2 fired at 5:18.8 and Retro #3 fired at 5:23.6 MET). The retrorocket firing could be easily heard, but the noise was not as loud as the sound of the jet trainers he had flown. The periscope was retracted at T+5 minutes and 45 seconds and the retropack was jettisoned at about T+6 minutes and 13.6 seconds. After retrofire the nose of the spacecraft was pitched up to a 14 degree from Earth-vertical attitude for reentry. This happened at about T+6 minutes and 20 seconds.


During the descent, Shepard tried to look out the awkwardly placed porthole windows to observe the stars. He could see nothing, not even the horizon. At about T+7 minutes and 48.2 seconds, the 0.05 g (0.5 m/s²) light came on, an indication that the acceleration buildup was about to start. The Automatic Stabilization & Control System (ASCS) detected the beginning of reentry and initiated a 10 deg/s roll. This maneuver makes the spacecraft more stable during reentry. During reentry a peak of 11.6 g (114 m/s²) was reached.


At 21,000 ft (6.4 km) about T+9 minutes and 38.1 seconds after launch, the drogue parachute came out, at 15,000 ft (4.6 km) a snorkel valve opened to equalize cabin pressure with the outside air. At 10,000 ft (3 km), about T+10 minutes and 14.8 seconds into the flight, the antenna canister at the top of the spacecraft jettisoned as planned, pulling out the main parachute. About 5 seconds later, the beryllium heatshield dropped down four feet (1.2 m), extending the landing bag under the spacecraft. Freedom 7 was descending under the parachute at 35 ft/s (11 m/s).


Splashdown occurred at T+15 minutes and 22.0 seconds. Water impact was comparable to landing a jet aircraft on an aircraft carrier. Freedom 7 tilted over on the right side, about 60 degrees from an upright position. Shepard checked the spacecraft interior for leaks, but found none. Slowly, Freedom 7 came to an upright position, taking about a minute to do so.