ATSP Launch Abort.........Alternative Mission

[Big RI Joe]

It's been awhile...........Let's say that during the S-4B burn, the J-2 powering the second stage of the Saturn 1B launcher shutdown late enough in the burn for Apollo to achieve orbit with the service module engine. The Docking Module for the flight was located in the S 4-B launch adapter, so no docking could take place with the Soyuz. Apart from a rendezvous, what possible mission could be accomplished?

[Bob B.]

I tend to believe that if an abort to orbit occurred as you describe, the remainder of the mission would probably be cancelled.  They would probably plan a reentry and recovery as soon as practicable.

[LunarOrbit]

Yeah, that's what I was thinking, Bob. What more could they do besides take some pictures of the Earth and then come home?

[Ottawan]

I'm thinking they would have stayed up and performed a minimum mission. Assuming the orbit was stable enough to achieve rendezvous with Soyuz 19 that is. They could still have done the solar eclipse moves for each other and just do advanced rendezvous maneuvers. . . . . Besides,Deke waited 15 years for this flight so I doubt he would have supported coming down early!!!!

[Big RI Joe]

The reason that I ask is because over in one of the usenet space history forums, someone claimed that there was a point during the S-4-B burn where if shutdown occurred, the +Y thrusters on the Apollo Service module would fire long enough to get the second stage and the Apollo CSM into some type of orbit where the DM could be extracted and the docking mission continued. Sounds pretty far fetched to me.

[Bob B.]

The reason that I ask is because over in one of the usenet space history forums, someone claimed that there was a point during the S-4-B burn where if shutdown occurred, the +Y thrusters on the Apollo Service module would fire long enough to get the second stage and the Apollo CSM into some type of orbit where the DM could be extracted and the docking mission continued. Sounds pretty far fetched to me.

That might be possible if the S-IVB shutdown maybe a second early.  The total impulse of the entire SM RCS is less than the S-IVB delivers in just four seconds.  In other words, if the S-IVB shutdown four seconds early, you could run the RCS propellant dry and still come up short of the intended orbit.

[ijuin]

I thought there was crossfeed between the SPS fuel supply and the RCS fuel supply in the Service Module?

[Bob B.]

I thought there was crossfeed between the SPS fuel supply and the RCS fuel supply in the Service Module?

I don't know, maybe there was.  I think a crossfeed existing in the LM but I haven't researched it in the SM.  Of course, the SM would have to fire its RCS for 500 seconds in impart the same impulse as just one second of firing the S-IVB.  I don't think the orbit could be too bad or else there might not be time to recover.

Using the RCS to trim the velocity was a normal procedure on any mission.  The S-IVB isn't precise enough to get it just right, so the velocity has to be fine tuned with a trim maneuver.  So, yes, if the vehicle came up a little short on velocity the RCS was used to make a correction.  Typically these corrections are small, though surely a larger correction could be done if necessary, but there has to be a limit to how big.  I don't know what that limit is.