Gemini 5
Gemini 5
was a 1965 crewed spaceflight in NASA's Project Gemini. It was the third crewed Gemini flight, the eleventh crewed American spaceflight, and the nineteenth human spaceflight of all time. It was also the first time an American crewed space mission held the world record for duration, set on August 26, 1965, by breaking the Soviet Union's previous record set by Vostok 5 in 1963.
Crew
Backup crew
Support crew
- Edwin E. "Buzz" Aldrin
- Virgil I. "Gus" Grissom
- James A. McDivitt
Mission parameters
- Mass:
- Perigee:
- Apogee:
- Inclination: 32.61°
- Period: 89.59 min
- REP sub-satellite:
Objectives
Gemini 5 doubled the U.S space-flight record of the Gemini 4 mission to eight days, the length of time it would take to fly to the Moon, land and return. This was possible due to new fuel cells that generated enough electricity to power longer missions, a pivotal innovation for future Apollo flights, instead of the chemical batteries used on previous crewed spacecraft. Cooper and Conrad were to have made a practice space rendezvous with a "pod" deployed from the spacecraft, but problems with the electrical supply forced a switch to a simpler "phantom rendezvous," whereby the Gemini craft maneuvered to a predetermined position in space. Command Pilot and Mercury veteran Gordon Cooper was the first person to fly two Earth orbital missions. He and Conrad took high-resolution photographs for the United States Department of Defense, but problems with the fuel cells and maneuvering system forced the cancellation of several other experiments. The astronauts found themselves marking time in orbit, and Conrad later lamented that he had not brought along a book. On-board medical tests, however, continued to show the feasibility of longer flights.| Gemini 5 | REP |
| REP | Rendezvous Evaluation Pod |
| NSSDC ID: | 1965-068C |
| Mass | |
| Launch date | August 21, 1965 |
| Release time | 16:07:15 UTC |
| Perigee | |
| Apogee | |
| Period | 89.59 min |
| Inclination | 32.61° |
| Reentered | August 27, 1965 |
Conrad, who had a reputation for frequently having a punchline on hand, called the mission "Eight days in a garbage can."
Flight
The launch went perfectly except for a few seconds of Pogo oscillation. This was measured at +0.38 g during first stage flight, exceeding the permitted +0.25 g for a total of about 13 seconds. Conrad and Cooper found their vision and speech momentarily impaired by the strong vibrations. The cause was traced to improper gas levels in an oxidizer standpipe, and severe oscillations did not affect any subsequent Gemini flights. The initial orbit wasFilm of the launch revealed a series of unexplained light flashes in the first stage exhaust plume, but telemetry data failed to indicate anything that could have caused them. Subsequent review of previous Gemini launches as well as film of Titan II ICBM tests also showed the presence of these light flashes. This phenomenon was thought to be caused by duct tape securing desiccant bags to the turbine exhaust pipe.
The top half of the Titan II's first stage, comprising the nitrogen tetroxide tank and its surrounding fuselage, was found floating on the surface of the Atlantic Ocean and retrieved; it is now on display at the US Space and Rocket Center in Huntsville, Alabama.
The first major event on the mission was the ejection of the Rendezvous Evaluation Pod at 2 hours and 13 minutes into the flight. The radar showed that the pod was moving a relative speed of two meters per second. While out of radio contact with the ground, the crew found that the pressure in one fuel cell had dropped from 4 hours and 22 minutes into the flight. This was still above the minimum but Cooper decided to shut the fuel cells down. With only battery power, they would be unable to rendezvous with the REP, and it could also mean a premature end to the mission. The cause of this mishap was believed to be a short circuit in the oxygen tank heater that tripped a breaker.
Tests on the ground found that it was possible for the fuel cell to work, even with low oxygen pressure. However, with the fuel cells off, they would only be able to stay in orbit for a day and still have enough battery power for reentry.
It was decided to turn the fuel cells back on and test them by using equipment that required more and more power. These showed that the fuel cells were stable and the crew could continue the mission.
In the meantime, Buzz Aldrin had been working out an alternative rendezvous test. He had a doctorate in orbital mechanics and worked out a scheme where the crew could rendezvous with a given point in space.
The crew became cold as they drifted. Even with the coolant pipes in the suits turned off and the airflow on low, they still shivered. Stars slowly drifting by the windows also proved disorienting, so the crew put covers on the windows.
As with Gemini 4, the crew had difficulty sleeping in alternate rest periods. They still had little rest when they decided to take their sleep periods together.
The phantom rendezvous came on the third day. It went perfectly, even though it was the first precision maneuver on a spaceflight. They tried four maneuvers—apogee adjust, phase adjust, plane change, and coelliptical maneuver—using the orbit attitude and maneuvering system.
The next day, flight controllers discovered another problem with the fuel cells: they were producing waste water not suitable for drinking, as it was too acidic, in 20% higher quantity than expected. The cells discharged into a storage tank on board used for both potable and non-potable water, separated by a bladder wall. However, as the astronauts would be draining the potable water for drinking, it was soon determined that there would still be room left over at the end of the mission. In general, the fuel cells were successful at producing cool drinking water, but the astronauts reported that it had a high quantity of gas bubbles in it.
On the fifth day, a major problem occurred when one of the OAMS thruster blocks malfunctioned repeatedly. The exact reason for these problems was unclear and a variety of possible causes were suggested. This meant the cancellation of all experiments requiring the use of the thrusters and the crew were not able to get them operating again.
Seventeen experiments were planned, with one cancelled, as it involved photography of the REP. Experiment D-1 involved the crew photographing celestial objects, and D-6 was a ground photography experiment. Experiments D-4/D-7 involved making brightness measurements of celestial and terrestrial backgrounds and of rocket plumes. Experiments S-8/D-13 investigated whether the crew's eyesight changed during the mission.
All of the medical experiments from Gemini 4 were performed, as well as experiment M-1 into the performance of the heart. This involved Conrad wearing inflatable leg cuffs. Experiment M-9 also investigated whether the astronauts' ability to measure horizontally changed.
The astronauts did not experience much of an appetite during the mission and averaged about 1000 calories a day, well below the intended 2700 calorie per day food intake. They reported dandruff to be a persistent problem to the point where their loose skin flakes would settle on the Gemini's instrument panel and partially obscure some instrument readouts. This condition was believed to be due to very low ambient humidity in the cabin causing the astronauts' skin to become dry and flaky. Postflight medical examinations showed some loss of red blood cells and plasma. Conrad's circulatory system returned to normal values within two days after the mission while Cooper took over four days.
S-1 involved Cooper taking the first photographs of the zodiacal light and the gegenschein from orbit. There was also syntopic photography of Earth. One photograph of the Zagros Mountains revealed greater detail than the official geologic map of Iran. Experiment S-7, the Cloud-Top Spectrometer revealed that the height of clouds could be determined from orbit.
Retrofire was initiated over Hawaii at 190 hours, 27 minutes, and 43 seconds into the mission. The astronauts controlled the reentry, creating drag and lift by rotating the capsule. Due to a computing error, the crew landed 80 miles short of the planned landing point in the Atlantic Ocean. Although the computer had worked perfectly, a programmer had entered the rate of the Earth's rotation as 360° per 24 hours instead of 360.98° See Sidereal day.
The Gemini 5 mission was supported by the following U.S. Department of Defense resources: 10,265 personnel, 114 aircraft and 19 ships. Recovery was by the aircraft carrier.