The Gemini 8 Flight Journal

Previous Index Next
Part 15: Docking Journal Home Page Part 17: After the tumble

Gemini 8

Part 16: The tumble

Corrected Transcript and Commentary Copyright © 2025 by Tracy L. Scott and W. David Woods. All rights reserved.
Last updated 2025-09-09
There seem to be some difficulty with this line. This is Gemini Control, Houston, excuse the mechanical delay. The Gemini 8 crew should be about beginning a yaw maneuver with the Agena. They will use the Agena thrusters yawing at about as much as 180 degrees at the rate of about a degree and a half per second. They then will check the Agena gyros and perform additional yaw maneuvers before going into a series of bending mode tests, which will call for an Agena yaw thrusters as well as spacecraft thrusters. And also, during this period as we approach the Coastal Bentry Quebec, they are to perform a fuel cell purge and a little later, they will again exercise the secondary propulsion system when they're back over the Rose Knot Victor. We have some tape conversation for you from the Tananarive station. In this conversation, there are questions about the receipt of some commands that went up to the Agena. According to the Flight Director, the commands were transmitted from the Hawaii station, earlier, and again from the Rose Knot Victor. We got a valid indication that they have been received, then as the spacecraft computer looked at the commands and there seemed to be disagreement on exactly what commands were in. We suspect right now, that the programming may be a bit off in the computer for this particular case. Want to underscore it there, there appears to be no problem with the computer, they certainly worked very well coming into the rendezvous. But in this particular area of the program, there may have been improper loading some disagreement with the actual commands that went up for the Agena system. Here now is the Tananarieve conversation.
As PAO replays the tape recording of the air-ground communications via Tananarive, the Gemini-Agena stack coasts towards the Coastal Sentry Quebec tracking ship. While out of communication, one of the thrusters at the rear of the Gemini spacecraft begins to fire intermittently. Its unbalanced thrust rotates the ship in a combination of roll and yaw. Neil counters the rotation using the OAMS system but it soon begins to build up again. Earlier in the mission, the crew were told that if the attitude control system on the Agena were to start playing up, they should shut it down, which Dave does by sending a 400 command to the vehicle. This seems ineffective. Believing that the problem is likely with the Agena, Neil elects to undock in the hope that he will therefore be able to stabilise the Gemini. However, once they come off the Agena, the tumbling gets worse. By the time they get into radio range of Coastal Sentry Quebec, the spacecraft's rotation rates are becoming intolerable.
Communications via Coastal Sentry Quebec
007:17:12 CSQ CC: Gemini VIII, CSQ CapCom. Comm Check. How do you read?
007:17:15 Scott: We have serious problems here. We're - we're tumbling end over end up here. We're disengaged from the Agena.
007:17:22 CSQ CC: Okay. We got your Spacecraft Free indication here.
007:17:26 Scott: Say again.
007:17:28 CSQ CC: We're showing your Spacecraft Free.
007:17:31 CSQ CC: What seems to be the problem?
007:17:35 Armstrong: We're rolling up and we can't turn anything off.
007:17:39 Armstrong: Continuously increasing in a left roll.
007:17:45 CSQ CC: Roger.
007:18:22 CSQ CC: Gemini VIII, CSQ.
007:18:25 Armstrong: Stand by.
007:18:33 Scott: We have a violent left roll here at the present time and we can't turn the RCS's off, and we can't fire it, and we certainly have a roll. [Garble] stuck hand control.
007:18:45 CSQ CC: Roger.
Transcription break.
007:20:05 Scott: Okay. We're regaining control of the spacecraft slowly, in RCS Direct.
007:20:11 CSQ CC: Roger. Copy.
007:21:12 Armstrong: We're pulsing the RCS pretty slowly here so we don't control roll right. We're trying to kill our roll rate.
007:21:19 CSQ CC: Okay. Fine. Keep at it.
Transcription break.
007:22:35 CSQ CC: VIII, CSQ. How much RCS have you used and are you just on one ring?
007:22:41 Armstrong: That's right. We are on one ring, trying to save the other ring. We started with two rings, but now we are on one ring.
007:22:48 CSQ CC: Roger. What about RCS usage?
007:22:51 Armstrong: Now okay. We're down to 1,700 pounds right now on RCS B.
007:22:57 CSQ CC: Roger.
007:22:58 Armstrong: We now have about - have about 2,350 on A.
007:23:01 CSQ CC: Okay. Copy.
007:23:35 CSQ CC: VIII, CSQ. How are you doing?
007:23:39 Armstrong: We're working on it.
007:23:40 CSQ CC: Okay. Relax. Everything's okay.
007:23:51 Armstrong: The spacecraft-Agena combination took off. Yaw and roll, and we had ACS, Off, and affirmative 7 hours.
007:24:01 CSQ CC: Roger. Understand. Can you see the Agena now?
007:24:04 Armstrong: [Garble] up. We turned the spacecraft system on, tried to stabilize, and in so doing we may have burned out our lower left thrusters.
007:24:13 CSQ CC: Okay. I copy. Can you - do you have visual sighting of the Agena right now?
007:24:17 Scott: No. We haven't seen the Agena since we undocked a little while ago.
007:24:21 CSQ CC: Okay.
007:24:34 Scott: The [garble]...
007:24:38 Scott: ...[garble] ACS was shut off and a Map was achieved.
007:24:42 CSQ CC: Roger.
Very long transcription break.
This is Gemini Control, Houston. We've encountered some trouble in the flight. Neil Armstrong has backed off from the Agena. He reported this trouble occurred at approximately 7 hours into the flight. We were advised of it some 5 to 6 minutes ago over the Coastal Sentry Quebec. The present situation is, he's using the rate one of his RCS rings to maintain attitude and we are watching the situation very carefully. This is Gemini Control, Houston.
This is Gemini Control, Houston again. Apparently the last transmission was not received by all stations, so we repeat. Trouble has developed in the flight of Gemini 8. While docked with the Agena, the configuration apparently got in a maneuver which Neil Armstrong did not like. He elected to undock and back off from the Agena. It is also our understanding that his maneuvering system, his onboard maneuvering system, that is his big thrusters on the adapter are inoperative. He is using one of two rings in his Reentry Control System to maintain his attitude during flight. It is possible that the flight may be terminated early. This trouble developed, according to Armstrong, at 7 hours into the flight. It was passed on to us some 10 minutes ago while the spacecraft was over the Coastal Sentry Quebec. We presently read 7 hours, 34 minutes into the flight and we are standing by. This is Gemini Control, Houston.
Previous Index Next
Part 15: Docking Journal Home Page Part 17: After the tumble