Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!euclid.jpl.nasa.gov!pjs From: pjs@euclid.jpl.nasa.gov (Peter Scott) Newsgroups: sci.space.shuttle Subject: Re: Shuttle Status for 04/22/91 (Forwarded) Message-ID: <1991Apr24.163541.21584@elroy.jpl.nasa.gov> Date: 24 Apr 91 16:35:41 GMT References: <1991Apr22.234907.29805@news.arc.nasa.gov> <1991Apr23.133522.21767@zoo.toronto.edu> Sender: news@elroy.jpl.nasa.gov (Usenet) Reply-To: pjs@euclid.jpl.nasa.gov Organization: Jet Propulsion Laboratory, NASA/Caltech Lines: 25 Nntp-Posting-Host: euclid.jpl.nasa.gov In article , mvk@aix01.aix.rpi.edu (Michael V. Kent) writes: > In article <1991Apr23.133522.21767@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > >In article rose@beowulf.ucsd.edu (Dan Rose) writes: > >>This may be a naive question, but . . . Why do they have these planned > >>countdown holds? > > > >Well, the reason for having pauses in the sequence is to give some slack > >in case minor problems develop (which does happen with some frequency). > >However, it is basically a NASA quirk that the clock stops during these > >planned pauses. They could just as easily be figured into the official > >clock time. > > Not to correct the famous Henry Spencer :) but I believe the holds are there > on purpose. The reason is that it is psychologically easier to extend a > planned hold than to stop the countdown in progress. I believe that there is also a second clock running during the countdown that has holds figured into it, and therefore does not stop. I heard them mentioning it during a launch sequence once, but I forget what it was called. -- This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@euclid.jpl.nasa.gov)