Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ncar!unmvax!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!rice!titan!phil From: phil@titan.rice.edu (William LeFebvre) Newsgroups: sci.space.shuttle Subject: Re: Launch Retry Turnaround Message-ID: <2320@kalliope.rice.edu> Date: 14 Dec 88 19:47:03 GMT References: <629@ablnc.ATT.COM> Sender: usenet@rice.edu Reply-To: phil@Rice.edu (William LeFebvre) Organization: Rice University, Houston Lines: 36 In article <629@ablnc.ATT.COM> rcpilz@ablnc.ATT.COM (Robert C. Pilz) writes: >As everyone knows, the Dec 1 launch was scrubbed. What is the quickest >turnaround to launch again? What has to be done? I believe the amount >of turnaround time increases if they get closer to zero in a launch >sequence and then have to scrub the launch. This is my understanding of what I have been told. After two days, the fuel tanks have to be "retanked". I assume that means they have to be purged and refilled. That takes about two days. So, if the second attempt at launching Atlantis had not been successful, they would not have been able to try the following day (I have heard contradictory information from the media along the lines of "they may have to try again tomorrow", but I trust my sources more than the media). During prelaunch, once the APUs (Auxiliary Power Units) are started, there is a limited amount of time which they can stay on before a launch. By limited I mean on the order of a few minutes. The last chance hold is at T-31 seconds. The autosequencer forces a hold at that point if it percieves that something is no go. Since the APUs are already going at that point (I believe they are started at T-5 minutes....by hand), the hold at T-31 secs can only last for a few minutes. If they hold too long, they have to scrub the launch and repower the APUs (apparently a non-trivial task). Of course, once the SRBs start, there's no stopping! :-) There are likely other restrictions. The dream *IS* alive, | William LeFebvre ESPECIALLY at NASA. | Department of Computer Science | Rice University | P.S.: if Steve Ryan ever posts anything intelligent, please let me know. I won't see it on account of my kill file :-) And to think that he shares the same last name with one of the greatest baseball pitchers that ever lived. Sigh.