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 inability of launch crews to film the failed
Mercury-Atlas 1 launch 16 months earlier had proven the importance of flying only in clear skies). 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. 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 . 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. Glenn was now preparing for reentry. Retaining the retro package meant he would have to retract the periscope manually. He would also have to activate the 0.05-g sequence by pushing the override switch.
Friendship 7 neared the California coast. It had been four hours and 33 minutes since launch. The spacecraft was maneuvered into retrofire attitude and the first retrorocket fired. "Roger. Retros are firing. ... Are they ever. It feels like I'm going back toward Hawaii", Glenn radioed. The second and then the third retros fired at five-second intervals. The spacecraft attitude was steady during retrofire. Six minutes after retrofire, Glenn maneuvered the spacecraft into a 14-degree nose up pitch attitude for reentry.
Friendship 7 lost altitude in its reentry glide over the continental United States, and headed toward splashdown in the Atlantic. The Texas tracking station told Glenn to retain the retro pack until the accelerometer read 1.5
g (14.7 m/s2). Glenn reported as he crossed Cape Canaveral that he had been controlling the spacecraft manually and would use the fly-by-wire mode as a backup. Mercury Control then gave him the 0.05
g (0.49 m/s2) mark, and he pressed the override button. About the same time, Glenn heard noises that sounded like "small things brushing against the capsule". "This is Friendship 7 – a real fireball outside," he radioed Mercury Control. A strap from the retro package broke partially loose and hung over the spacecraft window as it was consumed in the reentry plasma stream. The spacecraft control system was working well but the manual fuel supply was down to 15 percent. The peak of reentry deceleration was still to come. Glenn switched to fly-by-wire and the automatic tank supply. This combination had more available fuel. The spacecraft now experienced peak reentry heating. Glenn later reported, "I thought the retro pack had jettisoned and saw chunks coming off and flying by the window." He feared the chunks were pieces of his heat shield that might be disintegrating. The chunks were pieces of the retro package breaking up in the reentry fireball. After passing the peak
g region,
Friendship 7 began oscillating severely. The astronaut could not control the ship manually. The spacecraft was oscillating past 10 degrees on both sides of the vertical zero-degree point. "I felt like a falling leaf," Glenn later said. He activated the auxiliary damping system, which helped to stabilize the large yaw and roll rates. Fuel in the automatic tanks was getting low. Glenn wondered if the spacecraft would retain stability until it was low enough to deploy the
drogue parachute. The automatic fuel supply ran out at 1 minute and 51 seconds, and manual fuel ran out at 51 seconds, before drogue chute deployment. The oscillations resumed. At , Glenn decided to deploy the drogue chute manually to regain attitude stability. Just before he reached the switch, the drogue chute opened automatically at instead of the programmed . The spacecraft regained stability and Glenn reported, "everything was in good shape." At the periscope opened and was available for the astronaut to use. Glenn tried to look out the overhead window instead, but it was coated with so much smoke and film that he could see very little. The spacecraft continued to descend on the drogue chute. The antenna section jettisoned and the main chute deployed and opened to its full diameter. Mercury Control reminded Glenn to manually deploy the landing bag. He toggled the switch and the green light confirmation came on. A "clunk" could be heard as the heat shield and landing bag dropped into place, below the capsule.
Splashdown The spacecraft splashed down in the North Atlantic about northwest of
Puerto Rico and near , short of the planned landing zone. Retrofire calculations had not taken into account spacecraft mass loss due to use of onboard consumables. , a destroyer code-named "Steelhead", had spotted the spacecraft when it was descending on its parachute. The destroyer was about away when it radioed Glenn that it would reach him shortly.
Noa came alongside
Friendship 7 seventeen minutes later. One crewman cleared the spacecraft antenna and another crewman attached a line to hoist
Friendship 7 aboard. After being pulled from the water, the spacecraft bumped against the side of the destroyer. Once
Friendship 7 was on deck, Glenn intended to leave the capsule through the upper hatch, but it was too hot in the spacecraft and Glenn decided to blow the side hatch instead. He told the ship's crew to stand clear and hit the hatch detonator plunger with the back of his hand. The detonator plunger recoiled, and slightly cut the astronaut's knuckles through his glove. With a loud bang, the hatch was off.
Harry Beal, the first U.S. Navy Seal, pulled Glenn out of
Friendship 7. A smiling Glenn got out of
Friendship 7 and stood on the deck of
Noa. His first words were, "It was hot in there." The astronaut and spacecraft came through the mission in good shape. ==Publicity==