Spacelog Apollo 13

Okay, Houston. We're starting PTC. We're disabling quads A and B now.

Roger, Apollo 13. Houston copies.

Apollo 13, Houston. Over.

Go ahead.

Jim, we'd like to verify that the high gain is secured, that the S-BAND antenna is on OMNI, and OMNI B should be the right antenna. Over.

Okay. You want the high gain secured and you want the OMNI on OMNI Charlie, huh? Or Baker?

That's affirm. And this'll be maintained in the PTC.

Okay.

Houston, Apollo 13.

Roger. Go ahead.

Stand by for another Earth weather picture. I'll give you a mark.

Okay. Standing by, Jim.

3, 2, 1 -

MARK.

Houston copies.

Apollo 13, Houston.

Go ahead, Houston.

Houston here. Your rates look very stable. It looks like your rates are damped out completely here. As far as we can see, it would be alright to start the PTC.

Hello, Houston. This is 13. How do you read?

Hello, 13; Houston. Loud and clear. 13, Houston is reading loud and clear. How do you read?

Okay. And do you have any estimate, Vance, on how long we'll be charging battery B?

Stand by 1, Fred.

Apollo 13, Houston.

Go ahead.

We'll be charging for 4-1/2 to 5 hours yet, Jim.

Apollo 13, Houston.

Go ahead.

Fred, recommend that, when your window comes around facing the Earth again, that you catch another one of those pictures, and at the same time, you should probably start PTC again. We might have sent a confusing bit of info up to you. The “disable two quads” only applies to an early step in the procedure. We didn't mean that for the latter part of the procedure where we have the statement “enable all jets.” Over.

Houston, Apollo 13.

Apollo 13, Houston. Go ahead.

Vance, Fred said that you had some more information about PTC and a different way of establishing it or something, huh?

Roger. Referring to the procedure on G/8-2, if you have that open, I'll tell you what we had to give you.

Okay. Stand by and I'll get it out.

Okay.

Okay. Go ahead, Van.

Okay. On checklist G/8-2 under step 5, there's a statement, “disable all jets on two adjacent quads,” and that's what we were referring to when we called up saying “disable quads A and B.” So that's all fine; however, going down now to step 7 where it says “enable all jets,” we hoped that you didn't think we meant leave A and B disabled there. In that case, it's as written. All jets should be enabled. Over.

Okay. Our checklist has “all jets” scratched out, and it says “enable couples on all axes.” So what we'll do is—we'll reestablish this thing and come down to that step 7, and we'll enable all jets. That means enable quads A and B. Is that right?

That's affirm. You'll have A, B, C, and D enabled for step 7.

Okay, real fine. I'll start on it now.

Jim, Houston here. Two items: first of all, your PTC is looking very good and it should carry you through the night; second point, have a procedure to give you, if you're ready to copy. We'd like to set three bits in the computer, and I'll explain why.

Go ahead, Vance, we're ready to copy.

Okay. The procedure is as follows: VERB 25, NOUN 07, ENTER; 1331, ENTER; 7, ENTER; and ENTER. Explanation as follows. During the P23s, there was one time when VERB 37 was entered into the computer at about 16 seconds after the OPTICS ZERO switch was flicked to ZERO. This is a very uncommon anomaly in that, if you do this during—0.4-second interval at around 16 seconds after you zero the optics, some OPT-mode bits are reset; and this would mean that, if you had a OCDU fail, it wouldn't be indicated; so all this procedure is doing is setting these three bits back again where they should be.

Okay, Vance, and I guess I'll try to be slower on that VERB 37.

Yes. Actually slower or faster, either one, I guess. Well, yes, slower. It's a very unusual thing to have that happen.