Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!usc!ucsd!ucbvax!SCFVM.GSFC.NASA.GOV!ZMLEB From: ZMLEB@SCFVM.GSFC.NASA.GOV (Lee Brotzman) Newsgroups: comp.lang.forth Subject: Re: Forth and Astronomy Message-ID: <9012132221.AA13218@ucbvax.Berkeley.EDU> Date: 13 Dec 90 22:13:35 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 46 > >Didn't I hear news reports that all the trouble this Space Shuttle > >flight has been having have been due to "problems" and "fragility" with > >the software? If so, that's *HARDLY* good publicity for forth... > --- > That would indeed be extremely _BAD_ publicity. Forth was invloved in > this mission. I refer you to John Hayes rather detailed report of two > days ago for specifics. I will also have to defer to John Hayes or > perhaps Marty Fraeman for an accounting if the mission snafus were > contributed to and/or caused by Forth based programs. From the reports > I read and John's net message I am thinking Forth is not the culprit, > but lacking specifics I am obviously guilty of speculation, and it may > be wishful speculation. > Gary gars@glsrk The first computer problem Astro encountered was with the Instrument Pointing System, the gizmo that moves the telescopes into the right position. As far as I know, this device is not controlled by Forth software. The was primarily mechanical. The IPS has three star trackers, all of which must agree that the pointing is correct. The vibration from launch screwed up the alignment of the star trackers and several software patches were required to make up for the physical problem of have cross-eyed trackers. Also, I think the sensors were too sensitive and too many stars were showing up in the field of view, another patch had to be applied for that. The IPS finally started working just a few hours before they had to button up for the ride home. The second and third problems were with the two Data Display Units (DDU) which are basically just terminals. I don't believe that these use Forth software either, although perhaps they do. I'm not sure what happened to the first DDU, but the second overheated and gave off an alarming smokey smell. It seems that there was a buildup of lint fouling up the electronics. After cleaning all the lint they could, the smell persisted and the second DDU had to be shut down. Forth IS used within the telescopes themselves, for controlling the movement of filter wheels, motion compensation devices, etc. The telescopes, as far as I know, all worked pretty well. The problems arose in getting them pointed and then sending them commands. What I just said isn't gospel, but I tried to follow the mission as closely as I could. One of the payload specialists, Ron Parise, and I had collaborated on a Forth kernel for the Commodore 64 about six years ago, and I still run into him now and again here at Goddard. It's neat being able to say you know an astronaut! -- Lee Brotzman (FIGI-L Moderator) -- BITNET: ZMLEB@SCFVM Internet: zmleb@scfvm.gsfc.nasa.gov -- "Between an idea and implementation, is software." -- Curse from Hubble -- Space Telescope engineer.