Mercury-Atlas 6

Mercury-Atlas 6 (MA-6) was the first crewed American orbital spaceflight, which took place on February 20, 1962. Piloted by astronaut John Glenn and operated by NASA as part of Project Mercury, it was the fifth human spaceflight, preceded by Soviet orbital flights Vostok 1 and 2 and American sub-orbital flights Mercury-Redstone 3 and 4.

The Mercury spacecraft, named Friendship 7, was carried to orbit by an Atlas LV-3B launch vehicle lifting off from Launch Complex 14 at Cape Canaveral, Florida. After three orbits, the spacecraft re-entered the Earth's atmosphere, splashed down in the North Atlantic Ocean, and was safely taken aboard . The total mission flight time was 4 hours 55 minutes and 23 seconds.

Preparation

After the successful completion of the Mercury-Atlas 5 flight that carried Enos, a chimpanzee, in late November 1961, a press conference was held in early December. Reporters asked NASA's Robert Gilruth who would be the first U.S. astronaut in orbit, piloting MA-6. He then announced the team members for the next two Mercury missions. John H. Glenn was selected as prime pilot for the first mission (MA-6), with M. Scott Carpenter as his backup. Donald K. Slayton and Walter M. Schirra were pilot and backup, respectively, for the second mission, Mercury-Atlas 7.

The MA-6 launch vehicle, Atlas #109-D, arrived at Cape Canaveral the evening of November 30, 1961. NASA had wanted to launch MA-6 in 1961 (hoping to orbit an astronaut in the same calendar year as the Soviets did), but by early December it was apparent that the mission hardware would not be ready for launch until early 1962.

Mercury spacecraft #13 began taking form on McDonnell's St. Louis, Missouri assembly line in May 1960. It was chosen for the MA-6 mission in October 1960 and delivered to Cape Canaveral on August 27, 1961. Mercury spacecraft #13 and Atlas #109-D were stacked on the pad at Launch Complex 14 on January 2, 1962.

As the effects of orbital space flight on humans were unknown except to the Soviets, who were keeping whatever knowledge they had a secret, Glenn was prepared with an onboard medical kit consisting of morphine for pain relief, mephentermine sulfate to treat any shock symptoms, benzylamine hydrochloride to counter motion sickness and racemic amphetamine sulfate, a stimulant. A survival kit was also placed on board to assist Glenn while waiting for recovery after splashdown, including desalter kits, dye marker, distress signal, signal mirrors, signal whistle, first aid kits, shark chaser, a PK-2 raft, survival rations, matches, and a radio transceiver.

Prior to MA-6, there had been a reluctance on the part of NASA to permit the use of cameras by astronauts as it was feared these might prove an unnecessary distraction. Glenn, however, was successful in persuading NASA that he should be allowed to take one on the mission, and a Minolta Hi-Matic 35mm film camera (which he purchased himself at a local drug store) duly made the trip into orbit. This was modified to be used with pressure suit gloves, although changing the film in a weightless environment proved a difficult operation and during the flight Glenn knocked a film canister which then floated away, ending up behind the instrument panel.

Naming

Glenn dubbed his capsule "Friendship 7", the seven in honor of the seven original astronauts selected for Mercury, a tradition inadvertently started by prior Mercury pilot, Alan Shepard, who incorporated the seven in "Freedom 7" as his spacecraft was factory model no. 7. The other astronauts liked the symbolism, and so each appended 7 to their spacecraft names as well.

The spacecraft's name was developed democratically, with Glenn, his wife, Annie, and their children all participating in the process, consulting dictionaries and a thesaurus for possibilities.

<blockquote>"We played around with Liberty, Independence, a lot of them. The more I thought about it, the more I leaned toward the name Friendship. Flying around the world, over all those countries, that was the message I wanted to convey. In the end, that was the name the kids liked best, too. I was real proud of them." John Glenn

thumb|Launch of Friendship 7

At 14:47 UTC, after two hours and 17 minutes of holds and three hours and 44 minutes after Glenn entered Friendship 7, engineer T. J. O'Malley pressed the button in the blockhouse launching the spacecraft. O'Malley said, "the good Lord ride all the way," and then capsule communicator Scott Carpenter uttered the famous phrase "Godspeed, John Glenn." Due to a glitch in Glenn's radio, he did not hear the Carpenter phrase during launch. At liftoff Glenn's pulse rate climbed to 110 beats per minute.

Thirty seconds after liftoff, the General Electric-Burroughs designed guidance system locked onto a radio transponder in the booster to guide the vehicle to orbit. As the Atlas and Friendship 7 passed through max Q Glenn reported, "Have some vibration area coming up here now." After max Q the flight smoothed out. At two minutes and 14 seconds after launch, the booster engines cut off and dropped away. Then at two minutes and twenty-four seconds, the escape tower was jettisoned, right on schedule.

thumb|left|Lift-off of Friendship 7 on February 20, 1962.

After the tower was jettisoned, the Atlas and spacecraft pitched over still further, giving Glenn his first view of the horizon. He described the view as "a beautiful sight, looking eastward across the Atlantic". Vibration increased as the last of the fuel supply was used up. Booster performance had been nearly flawless through the entire powered flight. At sustainer engine cut-off, it was found that the Atlas had accelerated the capsule to a speed only below nominal. At 14:52 UTC, Friendship 7 was in orbit. Glenn received word that the Atlas had boosted the MA-6 into a trajectory that would stay up for at least seven orbits. Meanwhile, computers at the Goddard Space Flight Center in Maryland indicated that the MA-6 orbital parameters appeared good enough for almost 100 orbits.

First orbit

thumb|View of Mission Control (called "Mercury Control" at the time) during the Mercury-Atlas 6 mission

When the posigrade rockets fired and separated the capsule from the booster, the five-second rate-damping operation started two and a half seconds late. This caused a substantial roll error as the capsule began its turnaround. The automatic attitude control system took 38 seconds to place Friendship 7 into its proper orbital attitude. The turnaround maneuver used of fuel from a total supply of : for automatic and for manual control system. The spacecraft then settled into orbital flight with a velocity of . noticed that "Segment 51", a sensor providing data on the spacecraft landing system, was giving a strange reading. According to the reading, the heat shield and landing bag were no longer locked in position. If this were the case, the heat shield was only being held against the spacecraft by the straps of the retro package. Mercury Control ordered all tracking sites to monitor "Segment 51" closely and advise Glenn that the landing-bag deploy switch should be in the "off" position.

Glenn was not immediately aware of the problem, but he became suspicious when site after site asked him to make sure that the landing-bag deploy switch was off. Meanwhile, Friendship 7 was crossing the Atlantic for the second time. Glenn was busy manually keeping the spacecraft attitude correct and also trying to accomplish as many of the flight plan tasks as he could.

Crossing over the Canary Islands, Glenn observed that the "fireflies" outside the spacecraft had no connection with gas from the reaction control jets. His suit temperature felt too warm, but he did not take time to adjust it. The Kano, Nigeria and Zanzibar sites suddenly noticed a 12 percent drop in the spacecraft secondary oxygen supply.

During his second pass over the Indian Ocean, Glenn found that the Indian Ocean tracking ship was in heavy weather. The tracking station had planned to release balloons for a pilot observation experiment, but instead the ship fired star-shell parachute flares as Friendship 7 passed overhead. Glenn was able to observe the flashes of lightning from storms in the area but was unable to see the flares.

The temperature in Glenn's spacesuit was too warm. It had been since he passed over the Canary Islands, earlier in the second orbit. As he crossed the Indian Ocean, he tried to adjust the suit temperature. As he approached Woomera, Australia, a signal light came on warning him of excess cabin humidity. For the rest of the flight, Glenn had to carefully balance suit cooling against the cabin humidity.

While he was still over Australia, another warning light came on, indicating that the fuel supply for the automatic control system was down to 62%. Mercury Control recommended that Glenn let the spacecraft attitude drift to conserve fuel.

There were no more problems for Friendship 7 during the remainder of the second orbit. Glenn continued to manually control the spacecraft attitude, not allowing it to drift too far out of alignment. In doing so, he consumed more fuel than a functioning automatic system would have used. Fuel consumption was from the automatic tank and from the manual tank during the second orbit. This amounted to almost 30% of the total fuel supply.

Third orbit

On the third orbit of Friendship 7, the Indian Ocean tracking ship did not attempt to launch any objects for pilot observation experiments, as the cloud coverage was still too thick. When the spacecraft came across Australia for the third time, Glenn joked with Cooper at the Muchea Tracking Station. Glenn asked Cooper to notify General Shoup, Commandant of the Marine Corps, that three orbits should meet the minimum monthly requirement of four hours' flying time. He also asked to be certified as eligible for his regular flight pay.

Reentry

During Glenn's orbits, Mercury Control had been monitoring the problem with "Segment 51". The Hawaiian tracking station asked Glenn to toggle the landing bag deploy switch into the automatic position. If a light came on, reentry should take place while retaining the retro pack. Given the earlier questions about the landing bag switch, Glenn realized the controllers must have found a possible problem with a loose heat shield. The test was run but no light appeared. Glenn also reported there were no bumping noises during spacecraft maneuvers. overruling Flight Director Chris Kraft. Walter Schirra, the California communicator at Point Arguello, relayed the instructions to Glenn: the retro pack should be retained until the spacecraft was over the Texas tracking station. After the mission was over, the "Segment 51" warning light problem was later determined to be a faulty sensor switch, meaning that the heat shield and landing bag were in fact secure during reentry.

"The Fourth Orbit"

After the return of Friendship 7, NASA announced on April 19, 1962, that the spacecraft would be lent to the United States Information Agency for a world tour. The tour included more than 20 stops, becoming known as the "Fourth orbit of Friendship 7".

Timeline and parameters

Launch

{| class="wikitable"

! Attempt

! Planned (UTC)

! Result

! Turnaround

! Reason

! Decision point

! Notes

| 1

| 27 Jan 1962, 12:00:00 am

| scrubbed

| weather

| T-minus 29 minutes

| Weather conditions

In popular culture

thumb|NASA documentary with Glenn about Friendship 7, 2012

Philip Kaufman's 1983 film The Right Stuff includes a dramatization of the Friendship 7 mission in which Ed Harris plays Glenn. The sequence depicts the spacecraft's three orbits and Glenn's responses to what he saw, sometimes quoted verbatim, as well as the concerns over the heat shield during reentry. The mysterious "fireflies" are also shown, but their true explanation is not revealed; instead they are depicted as magical protection summoned by Aboriginal Australians at the Muchea Tracking Station.

The 2016 film Hidden Figures features the Friendship 7 mission in the climax of the movie, focusing on Katherine Johnson's calculations of the landing.

Notes

References

External links

Mercury-Atlas 6 Radio Transcripts on spacelog.org
NASA Mercury MA6 press kit - Jan 21, 1962
Results of the first U.S. crewed orbital space flight - Feb 20, 1962 (Friendship 7) NASA report - (PDF format)