The Gemini 8 Flight Journal
Gemini 8
Part 11: Terminal Phase Initiation
Corrected Transcript and Commentary Copyright © 2025 by Tracy L. Scott and W. David Woods. All rights reserved.
Last updated 2025-09-03
Houston Flight: Guaymas, Flight.
004:41:30 Scott: Guaymas, Gemini VIII. Go ahead with the TPI.
004:41:33 Lovell: Roger. GET B: 05:13:13; GTNSR, 012538; Delta-V, 32.6; forward, 32.0; up, 1.7; left, 5.7; RB, 32.5; Delta RB, 131; azimuth 27.4; elevation 0.
004:42:10 Scott: Roger, Guaymas. Real smooth. Stand by. I'll get it back to you.
004:43:16 Scott: Guaymas, Gemini VIII.
004:43:19 Lovell: This is Houston CapCom. Go ahead, VIII.
004:43:21 Scott: Okay. TPI coming back at you. You ready?
004:43:24 Lovell: All set to go.
004:43:26 Scott: 05:13:13; 012538, 32.6, 32.0 forward, 1.7 up, 5.7 left, 32.5, 131, 27.4 on the elevation, and 0 on the azimuth. How's that?
004:43:50 Lovell: The other way around, VIII. The azimuth is 27.4 and 0 on the elevation.
004:43:55 Scott: That's what I thought you said. Okay.
004:43:58 Lovell: Otherwise, sounds good.
004:44:04 Lovell: We'll check that, VIII. That doesn't sound right.
004:44:13 Lovell: Roger. 27.4 on the elevation.
004:44:17 Armstrong: [Garble]. Advise at 76 miles we've got what appears to be the Agena, and also we have a visual on another object which, this time, 56 minutes, is approximately 12 degrees above the Agena and appears to be in plane with it. It's possible it could be a planet.
Houston Flight: RKV, Houston Flight.
RKV CC: Houston Flight, RKV CapCom.
Houston Flight: Roger, on that Terminal Phase backup solution, we should have reversed the elevation and the azimuth. Just check with him, will you? Elevation is 27.4 up, azimuth zero.
RKV CC: Would you read the el[evation] please, again?
Houston Flight: Roger. Elevation 27.4 up.
RKV CC: Roger, I copy 27.4 degrees up.
Houston Flight: Azimuth, zero.
RKV CC: Affirmative.
004:44:47 Scott: Got a scanner?
004:44:50 Armstrong: Oh, listen, Dave, I've got to align.
004:44:53 Scott: Yes. You're l0 degrees right now.
004:44:57 Armstrong: Yes. I've got to align right now. Better quit...
004:45:02 Scott: Houston. Gemini VIII with a point.
004:45:11 Scott: Houston, Gemini VIII.
004:45:16 Armstrong: Boy, we didn't stay with them very long, did we?
004:45:23 Armstrong: TPI is at 13:13. Right?
004:45:26 Armstrong: Does that mean that it's only 16 minutes from now?
004:45:31 Scott: No, no! That's - 05:13:13; 5 hours, 13 minutes and 13 seconds.
004:45:35 Armstrong: Yes. Okay. That's on this watch, which is about a half an hour from now.
004:45:40 Scott: That's better.
004:45:45 Armstrong: I want to read 84 now. Stay awake, Kid.
004:46:30 Scott: 289 degrees. That doesn't look very good. Went back up. Okay. Attitude Control, Plat; pitch down to 0, 0, 0; align for 10 minutes.
004:46:51 Armstrong: Okay. I went to Pulse because I want to get a little better alignment on the Platform. I'm going to hold it right on.
004:46:57 Scott: They gave us 32 feet per second - we've got an Out-Of-Plane that's pretty healthy.
004:47:02 Scott: 5.7 degrees left.
004:47:04 Scott: 32-feet-per-second forward; 1.7 up. So that doesn't look too bad.
004:47:33 Armstrong: Okay. We have a good solid visual on the Agena at 56 miles. I'm taking a second look at it with the sextant.
This is Gemini Control, Houston; 4 hours, 48 minutes into the flight. In the course of that conversation you heard Neil Armstrong say that he had acquired visually the Agena. He gave the range as 76 miles and he had that acquisition at 4 hours, 40 minutes into the flight. This is Gemini Control, Houston.
004:55:23 Scott: Loud and clear.
004:55:30 Armstrong: I can get an angle of this for you.
004:55:35 Armstrong: You have a terrible horizon. Better look at it and see.
004:55:40 Scott: That-a-boy!
004:55:41 Armstrong: The only way to fly.
004:55:46 Armstrong: [Garble] there's nothing there to look at. Doesn't hurt to try. Unable to get a horizon there.
004:58:51 RKV CC: Gemini VIII, RKV CapCom.
004:58:56 RKV CC: Roger. We'd like to confirm on this TPI that you did copy correctly with the elevation at 27.4 up and azimuth as 0 degrees.
004:59:10 Armstrong: Roger. We understand that. Thank you.
004:59:14 RKV CC: We also show on the ground that the L-Band Coder is not locked.
Houston Flight: 'Not on' is the terminology.
004:59:25 Armstrong: Understand that it's not locked. Is that correct?
004:59:31 RKV CC: Roger. That's what we're showing on the ground. How are your readings going?
004:59:34 Armstrong: We have [garble] it's on.
004:59:37 RKV CC: Roger. Understand.
RKV CC: L-band coder is on, Flight. It's just the coder lock light that shows it's not on.
Houston Flight: Forget it.
004:59:58 Scott: RKV, got a data point. You ready?
005:00:02 Scott: Number 41: 14.9, 49.78, 138, 58.7, 142.
005:00:18 RKV CC: Also be advised that your TPI and TPF may be approximately 9 minutes late.
Houston Flight: RKV, Houston Flight.
RKV CC: Go ahead, Flight.
Houston Flight: Forget the rest of it.
RKV CC: Rog, Flight. We're showing that the L-band is On, however, we're showing that the L-band coder is not locked and I think there may be some kind of instrumentation problem with this, because he says he's getting good data points and everything.
Houston Flight: We're talking about Encoder On which prevents us from sending commands.
RKV CC: Oh, Encoder, yes, that's off.
Houston Flight: Okay.
RKV CC: Sorry, I misunderstood.
Houston Flight: Great.
005:01:28 Scott: RKV, RKV. Gemini VIII with a data point.
005:01:32 RKV CC: Roger. Go ahead.
005:01:33 Scott: 42: 15.5, 47.74, 137, 45.2.
005:01:46 RKV CC: Roger. And would you confirm that your Encoder is On?
005:01:53 Scott: It's on now.
005:01:54 RKV CC: Roger. Thank you.
RKV CC: Flight, RKV, S-band case temp - hotel 049 is sitting at 118 degrees [Fahrenheit, 48°C].
Houston Flight: Okay, that's fine.
RKV CC: By the way, we had visual sighting...
Houston Flight: Very good.
005:02:18 Armstrong: Going into darkness at - let's see - 05:02. We lost a visual on the Agena and I had the ACQ light right away. Range was 45 miles. It's very hard to see, but it looks like a sixth-magnitude star, I'd say.
005:03:04 Scott: 23-30 seconds to a readout.
005:03:36 Scott: Gemini VIII with another point.
005:03:38 RKV CC: Roger. Go ahead.
005:03:39 Scott: Number 43: 17.2, 45.5, 138, 34.3, 102.
005:03:54 Armstrong: [Garble.]
Houston Flight: RKV, Flight.
RKV CC: Go ahead, Flight.
Houston Flight: Agena contingency dock please?
RKV CC: Roger, Delta.
Houston Flight: Yes, we have some old Air Force types here.
RKV CC: Okay. Say, Sorry about that mix up on the encoder.
Houston Flight: That's okay.
RKV CC: Flight, both vehicles are looking very good at LOS here.
Houston Flight: Roger.
This is Gemini Control, Houston. We're 5 hours, 8 minutes into the flight. And in about 2 to 3 minutes, we estimate the pilots will begin their Terminal Phase Initiation. The magic number here is not so much time as the angle. When they achieve an angle from their target vehicle of 27.4 degrees, they will begin their Terminal Phase Initiation and some 32 to 33 minutes should be very much in the proximity of the target vehicle. We have some tape from the recently concluded pass over the Rose Knot Victor, parked off the southeast coast of South America and here's how that conversation went.
005:11:52 Armstrong: Close Loop. Giving us 26 forward.
005:11:54 Armstrong: 7 left, 6 up.
005:11:55 Scott: Okay. Attitude Control, Rate Command. Maneuver Controller, On.
005:12:02 Armstrong: Okay. Did you get...
005:12:04 Scott: 15 seconds till we read out.
005:12:05 Scott: 10, - 5, 4, 3, 2, 1...
005:12:57 Armstrong: Oh, boy!
005:13:11 Scott: Are you sure you had the right angles?
005:13:14 Armstrong: Well, the radar needles were wandering around some, Dave. I can't really be sure. I was - as best I could - in the middle of the oscillation.
005:13:28 Scott: I get an horrendous 20 - 25-feet-per-second down, Neil.
005:13:42 Armstrong: I just can't see any possible reason for that.
005:13:47 Scott: What does the chart look like?
005:13:48 Armstrong: A plot. We're up above it.
005:13:57 Scott: Yes, but I mean does it look like...
005:13:59 Armstrong: I can't talk to you. I've got to figure this. I'm sorry, old Buddy. I really have to look at this.
005:14:04 Armstrong: 25-feet-per-second forward. Boy, oh boy! Look at it!
005:14:16 Scott: Look at the plot. To have 25 down we've got to have a tremendous ellipticity.
005:14:35 Armstrong: I have to start counting.
005:14:37 Scott: We're steady right above the line all the way.
005:14:39 Armstrong: Okay. We're going to go with the Closed Loop.
005:14:40 Scott: What've you got?
005:14:42 Armstrong: 25 forward, 8 left, 3 up, and I'm going to Rate Command.
005:14:49 Armstrong: Ready to back me on the clock?
005:14:52 Scott: Yes. Any time.
005:14:54 Armstrong: 3, 2, 1, burn.
005:14:59 Scott: Did you burn at 26:10?
005:15:00 Armstrong: No. That - that's right. I got it. It was about 30 - 34 - 36, as a matter of fact.
005:15:25 Scott: Okay. There's 30 seconds.
005:15:35 Scott: Okay. Agena is in center of reticle. Attitude Control, Pulse. Set your ET to 3 minutes and stand by.
005:15:42 Armstrong: Okay. I've got it circled.
005:15:46 Armstrong: Okay. Get the Controller Off. Okay. Now again.
005:15:53 Scott: Okay. I need a readout at 1 minute, which is in 20 seconds from now.
005:15:57 Armstrong: Okay.
005:15:59 Scott: Don't hit the Computer switch.
005:16:02 Armstrong: Right.
005:16:06 Scott: 10 seconds. 5, 4, 3, 2, 1...
005:16:47 Scott: Start - set your clock for 3 minutes. Can't you do that?
005:16:48 Armstrong: It gets - it's running 2 - 3 minutes now.
005:16:53 Scott: Set it at 3 minutes. I'll start you out.
005:16:54 Armstrong: Okay. [Garble].
005:17:04 Scott: 10 seconds going up to 2 minutes.
005:17:13 Armstrong: Is it 2 minutes?
005:17:21 Armstrong: Okay. Now we're going to want to send Spiral Antennas to the Agena.
005:17:33 Armstrong: At 5.
005:18:21 Scott: About 3 minutes.
005:18:23 Armstrong: No, I'm sorry. I've just got too much to do over here to catch up with you.
005:18:34 Lovell: Gemini VIII, this is Houston. You need not answer. We're standing by for information.
005:18:45 Armstrong: Gemini VIII has burned TPI on Closed Loop.
005:18:59 Scott: 15 seconds to a readout and then 4 minutes.
005:19:01 Armstrong: Okay.
005:19:11 Scott: 4, 3, 2, 1...
This is Gemini Control, Houston at 5 hours, 19 minutes into the flight. We can assume, although we have not heard from the spacecraft since the Rose Knot Victor that their Terminal Phase Initiate maneuver is completed. Jim Lovell is attempting to reach them now. They are over in the Tananarive area off the east coast of South Africa. This would place them some 25 to 26 miles below and behind the Agena as they begin to sweep gently up to 161 miles, orbital altitude of the Agena. This is Gemini Control standing by.
