Mercury-Atlas 6
Mercury-Atlas 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, 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, 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. In addition, due to the lessons learnt from the previous two manned flights, MA-6 was the first American spaceflight to include a dedicated urine collection device.
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 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.
"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
Flight
Delays
The launch date was first announced as January 16, 1962, then postponed to January 20 because of problems with the Atlas rocket fuel tanks. A faulty yaw gyro was detected by the Spin Motor Rotation Detection System and replaced on January 13. The launch then slipped day by day to January 27 due to unfavorable winter weather. On that day, Glenn was on board Mercury 6 and ready to launch, when, at T−29 minutes, the flight director called off the launch because of thick clouds that would have made it impossible to photograph or film the launch vehicle after the first 20 seconds of the mission. The large crowd of reporters gathered at Cape Canaveral for the launch went home, disappointed. Mission Director Walter Williams felt a sense of relief at the bad weather, as there was still a general sense that the spacecraft and booster were not ready to fly yet.NASA informed the anxious public that the mission would take time to get ready since crewed launches required a high degree of preparation and safety standards. The launch was postponed until February 1, but when technicians began to fuel the Atlas on January 30, they discovered a fuel leak had soaked an internal insulation blanket between the RP-1 and LOX tanks. This caused a two-week delay while necessary repairs were made. On February 14, the launch was again postponed due to weather, which started to break on February 18, and it appeared that February 20 would be a favorable day to attempt a launch.
The Flight Safety Review Board then met a few days before the launch to overview the twelve Atlas flights since Mercury-Atlas 5 last November. Four failures had occurred in this time. Atlas 5F and Ranger 3 had guidance failures that were of no concern for Mercury as it used a different model of guidance system and Atlas 6F and Samos 5 had random quality defects unlikely to be an issue on the more tightly supervised Mercury program.
Launch
Glenn boarded the Friendship 7 spacecraft at 11:03 UTC on February 20 following an hour-and-a-half delay to replace a faulty component in the Atlas's guidance system. The hatch was bolted in place at 12:10 UTC. Most of the 70 hatch bolts had been secured, when one was discovered to be broken. This caused a 42-minute delay while all the bolts were removed, the defective bolt was replaced and the hatch was re-bolted in place. The count was resumed at 11:25 UTC, and the gantry was rolled back at 13:20 UTC. At 13:58 UTC the count was held for 25 minutes while a liquid oxygen propellant valve was repaired.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.
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
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.Friendship 7 began its first orbit with all systems go. It crossed the Atlantic and passed over the Canary Islands. Controllers there reported all capsule systems in perfect working order. Looking at the African coastline, and later the interior over Kano, Nigeria, Glenn told the tracking station team that he could see a dust storm. Kano flight communicators replied that the winds had been quite heavy for the past week.
Over Kano, Glenn took control of the spacecraft and started a major yaw adjustment. He allowed the spacecraft to continue the yaw maneuver until it was facing into its flight path. Glenn noticed that the attitude indicators disagreed with what he observed was the true spacecraft attitude. Even with the incorrect instrument readouts, he was pleased to be facing forward instead of backward on his orbital path.
Over the Indian Ocean, Glenn observed his first sunset from orbit. He described the moment of twilight as "beautiful". The sky in space was very black, he said, with a thin band of blue along the horizon. He said the sun set fast, but not as quickly as he had expected. For five or six minutes there was a slow reduction in light intensity. Brilliant orange and blue layers spread out 45 to 60 degrees on either side of the sun, tapering gradually toward the horizon. Clouds prevented him from seeing a mortar flare fired by the Indian Ocean tracking ship as part of a pilot observation experiment.
Continuing his journey on the night side of Earth, nearing the Australian coastline, Glenn made star, weather, and landmark observations. He looked for but failed to see the dim light phenomenon known as the zodiacal light; his eyes had insufficient time to adapt to the darkness.
The spacecraft came into radio range of Muchea, Australia. At the Mercury Tracking Station there, Gordon Cooper was the capsule communicator. Glenn reported that he felt fine and had no problems. He saw a very bright light and what appeared to be the outline of a city. Cooper said that he probably was looking at the lights of Perth and its satellite town of Rockingham. This turned out to be correct; many people in Perth turned on their lights so as to be visible to Glenn as he passed over. "That sure was a short day," he excitedly told Cooper. "That was about the shortest day I've ever run into."
The spacecraft moved across Australia and across the Pacific to Canton Island. Glenn experienced a short 45 minute night and prepared the periscope for viewing his first sunrise from orbit. As the sun rose over the island, he saw thousands of "little specks, brilliant specks, floating around outside the capsule"; he momentarily felt that the spacecraft was tumbling or that he was looking into a star field. A quick hard look out of the spacecraft window corrected the illusion and Glenn was sure that the "fireflies", as he called them, were streaming past his spacecraft from ahead. They seemed to flow by slowly but did not seem to be coming from any part of the spacecraft, and they disappeared as Friendship 7 moved into brighter sunlight. It was later determined that they were probably small ice crystals venting from onboard spacecraft systems.
"I am in a big mass of some very small particles, they're brilliantly lit up like they're luminescent. I never saw anything like it. They round a little: they're coming by the capsule and they look like little stars. A whole shower of them coming by. They swirl around the capsule and go in front of the window and they're all brilliantly lighted." Glenn started banging the capsule wall and watched the "fireflies" come off, just as Alan Shepard did.
File:Mercury-Atlas 6 Earth photo.jpg|thumb|250px|left|Photo taken by Glenn during his flight
As the spacecraft crossed the Kauai, Hawaii tracking station, Glenn noticed a lot of interference on the HF radio band. As he crossed the Pacific coast of North America, the tracking station at Guaymas, Mexico, informed Mercury Control in Florida that a yaw thruster was causing attitude control problems. Glenn later recalled, this problem "was to stick with me for the rest of the flight".
Glenn noticed the control problem when the automatic stabilization and control system allowed the spacecraft to drift about a degree and a half per second to the right. Glenn switched control to manual-proportional control mode and moved Friendship 7 back to the proper attitude. He tried different control modes to see which used the least fuel to maintain altitude. The manual fly-by-wire combination used the least fuel. After about twenty minutes, the yaw thruster began working again and Glenn switched back to the automatic control system. It worked for a short time and then began having problems again, this time with the opposite yaw thruster. He then switched back to the manual fly-by-wire system and flew the spacecraft in that mode for the remainder of the flight.