The launch went perfectly except for a few seconds of Pogo oscillation (axial vibration of the rocket).
This was measured at +0.38 g (3.7 m/s²) during first stage flight, exceeding the permitted +0.25 g (2.5 m/s²) 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 was 101 × 216 miles (163 × 349 kilometers).

Film 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 (REP) 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 850 to 65 pounds per square inch (5,860 to 450 kPa) 4 hours and 22 minutes into the flight.
This was still above the 22.2 psi (153 kPa) 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 (OAMS).

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 (comprising thrusters 5, 6, 7, and 8) malfunctioned repea
The launch went perfectly except for a few seconds of Pogo oscillation (axial vibration of the rocket). This was measured at +0.38 g (3.7 m/s²) during first stage flight, exceeding the permitted +0.25 g (2.5 m/s²) 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 was 101 × 216 miles (163 × 349 kilometers).
Film 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 (REP) 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 850 to 65 pounds per square inch (5,860 to 450 kPa) 4 hours and 22 minutes into the flight. This was still above the 22.2 psi (153 kPa) 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 (OAMS).
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 (comprising thrusters 5, 6, 7, and 8) malfunctioned repea
Gemini 5