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Gemini 8

Last Revised 7 June 2011

Gemini VIII with USAF Pararescue personnel on USS Leonard F. Mason

(NASA caption) The Gemini 8 crew stands on the deck of the recovery vessel, the U.S.S. Leonard F. Mason, with three U.S. Air Force pararescue men. Left to right (standing) are Astronaut Neil A. Armstrong, command pilot; A/2C Glenn M. Moore; Astronaut David R. Scott, pilot; kneeling, left to right are A/1C Eldridge M. Neal; and S/Sgt Larry D. Huyett.

Mission Commander: Neil Armstrong

Pilot: Dave Scott

Mission Plan: Perform second manned revdezvous with an unmanned target vehicle and perform the first docking between two vehicles in earth orbit. Perform extended EVA activities.

Agena target vehicle launch: 09:00:03 US Eastern Standard Time, 16 March 1966. Gemini VII launch: 10:41:02 USEST. 16 March 1966.

Rendezvous completed: 5 hours 58 minutes Ground Elapsed Time

The following is from the Gemini 8 Mission Report (19 Mb, document courtesy Bob Andrepont and David Harland):

After station keeping for about 36 minutes, docking with the Gemini Agena Target Vehicle was accomplished. The final docking maneuver was begun when a distance of about 2 feet separated the two vehicles. A relative velocity of about three-fourths of a foot per second was achieved at the moment of contact. The nose of the spacecraft moved into the docking adapter very smoothly and the docking and rigidizing sequence took place very quickly and with no difficulty. The docking sequence was completed at 6:33:22 ground elapsed time, with the two vehicles rigidized together.

For a period of 27 minutes after docking, the stability and control of the docked vehicles was excellent. At approximately 7:00:30 ground elapsed time, the crew noted that the spacecraft-Gemini Agena Target Vehicle combination was developing unexpected roll and yaw rates. The command pilot was able to reduce these rates to essentially zero; however, after he released the hand comtroller, the rates began to increase again and the crew found it difficult to effectively control the rates without excessive use of spacecraft Orbital Attitude and Maneuver System propellants. In an effort to isolate the problem and stop the excessive fuel consumption, the crew initiated the sequence to undock the spacecraft from the Gemini Agena Target Vehicle. After undocking, the spacecraft rates in roll and yaw began to increase, indicating a spacecraft problem which the crew attempted to isolate by initiating malfunction-analysis procedures. When the rates reached approximately 300 degrees per second, the crew completely deactivated the Orbital Attitude and Maneuver System and activated both rings of the Reentry Control System in the direct-direct mode. After ascertaining that spacecraft rates could be reduced using the Reentry Control System, one ring of the system was turned off to save fuel for reentry and the spacecraft rates were reduced to zero using the other ring. The crew continued the malfunction analysis and isolated the problem area to the No. 8 thruster (yaw left-roll left) in the Orbital Attitude and Maneuver System. The circuitry to this thruster had failed to an "on" condition.

The dry words of the Mission report do not convey the fact that, at roll/yaw rates of up to 300 degrees per second, Neil and Dave were in serious trouble. In his book, Two Sides of the Moon, Dave tells us, "This spinning roll was going on far too long. The chances of recovering from such a high rate of spin in space were very remote. Both Neil and I were beginning to feel dizzy." They soon decided that only option they had was to shut down the maneuvering system they used in orbit and activate the separate system designed for use during re-entry. Once they did so, they were able to gain control of the vehicle and stop the tumbling. Mission rules dictated that, having activated the Reentry Control system, they prepare for a prompt return to Earth.

During the emergency, they had a few minutes, via tracking ship Coastal Sentry Quebec (CSQ), stationed in the South China Sea, to let Houston know they were in trouble. Twenty minutes later, through the Hawaiian tracking station, they let Houston know they had regained control. Houston decided that they would have to land in a secondary recovery zone east of Okinawa. On their next pass over CSQ, they received data to be entered in their computer for the reentry. Then, over Hawaii, they were told that two recovery aircraft had left from US bases in Japan and that the destroyer USS Leonard F. Mason was on its way to the recovery zone. Half an orbit later, over central Africa, they fired the retro rockets . The foillowing is from the Pilot's Report, section 7 in the Mission Report:

Postlanding communications consisted of one period of radio communication with the rescue aircraft approximately 30 minutes after landing. Shortly thereafter, the crew observed the pararescuemen descend into the water; however, flotation-collar attachment took an unusually long time because of the heavy sea state. The crew completed their postflight checks without difficulty but were quite uncomfortable due to the sea condition. Subsequent to attachment of the flotation collar, the hatches were opened and the crew became more comfortable as they awaited pickup by the destroyer, the U.S.S. Leonard F. Mason. Approximately 3 hours after landing, the U.S.S. Mason came along side and attached a line to the spacecraft. The crew egressed from the left hatch with some difficulty due to the fairly severe bobbing caused by swells of 12 to 15 feet. The main parachute, which had been attached to the spacecraft, was lost during this operation.
Neil's biographer, James R. Hansen, tells us that the "Gemini VIII Mission Evaluation Team 'positively ruled out' pilot error as a factor in the emergency"and that Robert Gilruth, then Directror of the Manned Spacecraft Center, "commented, 'In fact, the crew demonstrated remarkable piloting skill in overcoming this very serious and bringing the spacecraft to a safe landing." Dave Scott tells us that, every year on March 16th, he and Neil mark the occasion with a private telephone call.

See, also, the Gemini VIII Technical Debriefing (3 Mb)

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