Spacelog Apollo 13

Okay. For attitude control coordinates, we're recommending manual control VERB 76 and watch your middle gimbal angle. Your DAP load that you have now looks good.

Aquarius, our decision for the time is to leave the IMU powered up, power down the LGC, and power down other nonessential items. We'll be coming up with a more precise checklist as soon as we can get it. Over.

Okay. The decision is to keep the platform, power down the computer, and we'll be standing by for further word on the powerdown, Jack.

Roger.

And, Aquarius, for your information, we now have 136-mile perigee. Confirmed by Doppler.

Okay. 136-mile perigee now. That's very nice.

Oh, wait a minute, Jack. Did you say pericynthion or perigee?

I meant pericynthion.

And, Houston, we pulled out your UPDATA LINK circuit breaker, so if you want to update it for anything, let us know and we'll put it back in.

Aquarius, AFT OMNI, please.

Houston, do you read Apollo 13?

This is Houston. Go ahead. Reading you weakly.

Okay, Jack. We don't want to bug you, but you ought to be thinking—or what your thoughts are concerning what the next burn will be. I got to figure out a watch schedule and the sleep schedule and just how we can meet the next maneuver.

Roger. We're getting you a flight plan update. We're still computing on your next burn, and we're getting ready to give you a procedure for powerdown.

Aquarius, one idea on managing the OMNI antennas. It might make it easier on everybody if we disabled the UPLINK SQUELCH and managed the antennas by switching when we hear the noise. Over.

Okay, Aquarius. Here's what we're going to do. We'd like you to point the LM X-axis either north or south. That's the positive X-axis. It appears to us that it would be closer to orient the LM plus X-axis toward the south. Do that with the LGC powered up using the TTCA. After that, we propose to power down the LGC to save some power. However, this means that we lose the use of the TTCA, and we'll have to control the spacecraft with the hand controller in the DIRECT mode. Request your—your position on these two items.

Aquarius, Houston. How do you read?

Okay, Jack. Understand. You want us to point the LM X—plus X-axis to the south using the TTCAs with the LGC powered up. Then, by powering down the LGC, we'll lose a TTCA. I wasn't too successful in controlling the spacecraft in attitude only, but I might be able to keep it out of gimbal lock.

That's affirmative, Jim. We'd keep your ball powered up and go to DIRECT on the hand controller. And maintain attitude in a DIRECT position.

Okay. Understand; and do you want some sort of a PTC mode, Jack?

Affirmative. We'll take whatever PTC mode you can set up, Jim.

Okay. And since you know our approximate attitude, how about just getting me something to find you on the DSKY for a southerly plus X-direction.

Roger. Stand by 1.

And one other question, Houston. When you say power down the DSKY or the LGC, do you mean going into 06 or multiple circuit breaker?

Stand by on powering down the DSKY, Jim. We'll give you the procedure for that. The procedure that we —

Okay.

— the procedure that we have is listed in several places. It's in the Contingency checklist under “Power down” on page 1, second paragraph.

And we'll give you that word when we want you to do that. That's LGC only, not to power down the IMU. But we'd like to have you hold off on that until we send you the word. Over.

And, Aquarius, while we're working on this, we have a proposed flight plan update for your working and resting cycles. And—You ready to copy?

Okay. Do you want me to write this in the flight plan, per se, Jack?

You can probably write it on a piece of scratch paper. This is pretty easy.

Okay. Go ahead. We got a lot of scratch paper.

Okay, Jack. As I read that, the LMP is to go to sleep at 63:00 for about 6 hours. During that period, the CDR and CMP should try to get a bite to eat. I'm to awake at 69 hours. CDR and CMP sleep at 70 hours, and they are to awake at 76 hours. And we should plan on doing our P51, P52 at 76 hours or 76:30. At 78:30, we're going to load a P30 and aline AGS to PGNS. Second maneuver is to take place at 79:25:26.5 for ignition time. Then we're all to eat at 81 to 82 hours.

Okay. With a minor modification, your P51, P52 will be about 77 hours, and that's the period of darkness. And the commander and the CMP ought to eat around 68 to 69 hours, and you should eat between 69 to 70 hours just after you get up. We have left an hour in there where everybody is awake together to talk things over. Go ahead.

Okay. I'll eat after I wake up between 69 and 70.

All right we have additional —

— and I've got the correction to P —

Go ahead, Fred.

Yes. We got the word the P51, P52 is going to be done around 77 hours, while we're in darkness.

That's affirmative. And we have a work-rest cycle laid out for further on, which we can relay to you later.

Okay.

Okay. And, Houston, you have advice on what attitude you want me to go to.

Okay. That'll be the next bit of information. I'll get that for you, Jim.

Okay.

And, Aquarius, just to get you thinking in that direction, we've run a fairly thorough analysis, and we've found out that it's going to be cheaper to keep the LGC and the DSKY up and turn the inverter and the ball off. It's going to save us 1 amp and also some water, so it looks like what we're going to do. And we'll have to monitor the middle gimbal angle. And we'll get the procedure on that, and it'll also be an easier control mode where we'll be able to use the TTCA through the—through the DAP.