Mercury-Redstone 3
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Mercury-Redstone 3 was a U.S. Mercury program human crewed space mission launched on May 5, 1961 using a Redstone rocket, from Launch Complex 5 (LC-5) at Cape Canaveral, Florida. The Mercury spacecraft was named Freedom 7 which performed a suborbital flight piloted by astronaut Alan Shepard, who became the first American in space as a result of this mission. The flight lasted less than 16 minutes and attained an altitude of just over 187 kilometres (116 mi).
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 safely return to Earth inside his vehicle. In the Vostok 1 mission, the Soviet cosmonaut parachuted out of his vehicle prior to landing. Soviet Premier Nikita Khruschev criticized Freedom 7 as a mere 'flea hop' compared to the recent flight of Vostok 1 and its pilot Yuri Gagarin.
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Crew
Backup crew
Mission parameters
- Mass: 1,295 kg (2,850 lb) (apogee)
- Maximum Altitude: 187.42 km (116.46 mi)
- Range: 487.26 km (302.77 mi)
- Launch Vehicle: Redstone rocket
Mission highlights
The Freedom 7 spacecraft had been delivered to Cape Canaveral on December 9, 1960. Freedom 7 was spacecraft # 7, and it had been given special attention at the factory since it was selected for the first manned suborbital flight in October, 1960. It had originally been expected to be ready for launch almost immediately. However, 21 weeks of unplanned preparation would be needed before it could be launched on its mission. Reaction control system rework was responsible for postponement of the launch until at least March 6, 1961. Damaged and corroded peroxide lines that needed replacement forced a further delay of eight days. The simulated mission test needed to be rerun and structural and equipment defects corrected. The MR-3 mission was finally ready to be launched on May 2, 1961.
Three astronauts had been chosen as finalists to fly the MR-3 mission in January, 1961, and on February 22, 1961 their names were announced to the public. The three were Alan Shepard, Gus Grissom and John Glenn. The public was not told who would actually fly the mission until after a May 2, 1961 launch attempt was cancelled due to weather. It was then revealed that Shepard had been suited up and waiting for 3 hours in Hangar "S" at Cape Canaveral for the launch. The May 2 launch was cancelled 2 hours and 20 minutes before launch, due to weather conditions.
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 spacecraft 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 pounds per square inch (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 2.9 kilopascals (0.42 psi). During ascent the cabin pressure sealed off at 38 kilopascals (5.5 psi) of pure oxygen. At 2 minutes into the flight, Shepard experienced 6 g (59 m/s²) of acceleration.
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 400 pounds-force (1,800 N) thrust each, fired for 1 second and separated the spacecraft from the Redstone booster at a rate of 15 feet per second (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 (187.5 km). The three 1,000 pounds-force (4,400 N) thrust retrograde rockets ripple-fired to provide a 510 ft/s (160 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 (3.0 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 4 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.
A recovery helicopter that had been watching Freedom 7 for five minutes of its descent now came overhead and hooked a cable to the top of the spacecraft. The helicopter crew was in radio communications with Shepard. The astronaut indicated he would release the spacecraft hatch when it had cleared the water. The helicopter pulled the spacecraft a couple of feet (about 1 m) higher in the water and Shepard released the hatch. A sling was lowered to the astronaut and he was lifted into the helicopter. Both Shepard and the Freedom 7 were then flown to the deck of the nearby recovery carrier, the USS Lake Champlain. They were on board the carrier 11 minutes after landing in the water. The astronaut and spacecraft came through the flight in fine shape.
The flight lasted 15 minutes 28 seconds, and the spacecraft traveled 302 miles (486 km) from its launch point, ascending to 116.5 miles (187.5 km). Freedom 7 landed at these coordinates: 27°14′N 75°53′W / 27.23°N 75.88°W. It reached a speed of 5,180 mph (8,340 km/h). During the launch phase, Shepard experienced 6.3 g (62 m/s²) and during reentry 11.6 g (114 m/s²).
Following the flight the spacecraft was examined by engineers and found to be in excellent shape; so much so that they decided it could have been safely used again in another launch. The Freedom 7 is now on display in the lobby of the Armel-Leftwich Visitor Center, at the U.S. Naval Academy, Annapolis, MD. It was placed there after Shepard's death in 1998.
Depiction in popular culture
In June 1961, Laurie Records issued a 45 rpm single featuring William Allen and Orchestra entitled "Space Flight Freedom 7." It consisted of recreations of the tower to astronaut communications spoken over an instrumental backing. The Mercury-Redstone 3 mission was dramatized in the HBO miniseries From the Earth to the Moon episode "Can We Do This?" (starring Ted Levine as Alan Shepard), as well as in Tom Wolfe's book The Right Stuff, and Philip Kaufman's movie The Right Stuff based on the book.
Flight events
References
- ^ "Chapter 11: Sub-orbital Flights, Section 1" (HTML). This New Ocean: A History of Project Mercury. NASA. 1964. http://www.hq.nasa.gov/office/pao/History/SP-4201/ch11-1.htm. Retrieved 2009-05-06.
- ^ "NASA Project Mercury Mission MR-3" (HTML). NASA, Kennedy Space Center. 2000-08-25. http://science.ksc.nasa.gov/history/mercury/mr-3/mr-3.html. Retrieved 2009-05-05.
External links
- This New Ocean: A History of Project Mercury - NASA SP-4201
- Project Mercury - Results of the First U.S. Manned Suborbital Space Flight - NASA - 1961
- NASA NSSDC Master Catalog
- Postlaunch Report for Mercury-Redstone No. 3 (NASA)
- NASA 40th anniversary of the Mercury 7 — Alan B. Shepard, Jr.
- NASA Mercury MR3 press kit - Apr 26, 1961
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