Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Wed, 11 Jul 1990 02:31:10 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 11 Jul 1990 02:30:39 -0400 (EDT) Subject: SPACE Digest V12 #47 SPACE Digest Volume 12 : Issue 47 Today's Topics: Re: SPACE Digest V12 #40 Hubble Space Telescope Update - 07/06/90 Re: grim tidings for the future Old Space Digest Re: grim tidings for the future Re: HST down and out Re: HST down and out Re: Inaccurate quotes (was: Re: More on NASA 91 Appropriation Vote) Re: grim tidings for the future Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- From: AZM@CU.NIH.GOV Date: Tue, 10 Jul 90 11:04:42 EDT Subject: Re: SPACE Digest V12 #40 > >In article <3660@calvin.cs.mcgill.ca> msdos@calvin.cs.mcgill.ca (Mark > SOKOLOWSKI) writes: > >> ... It's simply that by 1993, the technology > >>of ground-based telescopes and their effective power will literally make > >>the HST absolete, even if it can by then have the perfomances we expect > >>from it _NOW!!!_. I remember having read an article in a european science > >>magazine (I think it was Science & Vie from France) that proved quite > >>clearly that the small HST's aperture (2.4m) isn't quite capable of > >>matching the power gathering abilities of the most recent ground-based > >>projects (like some 10m scopes in Chile, a few 6-15m in aperture scopes > >>linked for interferometry in some other places etc...). > > I don't have the original version of the above message, just this extract. > I'm sorry if lack of context has caused me to misinterpret anything.... > > There is more to consider than light gathering power. Besides the fact > that a ground based scope can't see IR or UV, the HST will surpass (or > would have surpassed) ground based scopes in resolution. For some kinds > of objects, even the uncorrected HST will be capable of good resolution. > The following quote discussing the 10m Keck scope is from the July S&T > (before knowledge of the HST optics problem, of course). > > "Keck and HST will actually reach the same stellar magnitude > in visible light, 28 or so," comments [Keck project scientist, > Jerry] Nelson. "HST does it by better resolution. Keck will do > it, in spite of poorer seeing on the ground, because it collects > so much more light. For resolution of small bright objects HST > wins hands down, of course. But in the spectroscopy of faint > extended objects, like very remote galaxies, Keck will just > _swamp_ HST." [S&T's emphasis] > > HST will not be obsolete in '93. > If the above, regarding Keck, is true, then why in the name of god did they ever waste $1.5 billion on the Hubble Toy Telescope? Why would they want to risk that much money, and the guffaws and screams of a public up to its eyesockets in too-high taxes when the thing failed (as it has), when the same capabilities will very shortly be available on the ground. This little revelation makes the whole kettle of stinking fish stink even worse. What WAS the real reason for sending that thing up there? D.V. AZM@NIHCU ------------------------------ Date: 10 Jul 90 16:12:10 GMT From: swrinde!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Hubble Space Telescope Update - 07/06/90 Hubble Space Telescope Update July 6, 1990 The biggest event with the Hubble Space Telescope (HST) in the past week was a spacecraft safing event (specifically, a software sunpoint with the +V3 axis toward the sun) that occurred at 2:25 PM EDT on July 5. All the Scientific Instruments (SI) and spacecraft subsystems are fine, recovery is underway. The cause of the event was human error: a series of 6 Fixed Head Star Tracker (FHST) updates failed (cause under investigation) resulting in a small 100 arc second attitude error, a real-time slew was requested to correct the pointing, somehow, in PASS/OPS, the final attitude of an earlier slew entered the system as the final position of the short real-time slew, checks of the maneuver failed to uncover the error (due in part to the fact that there is no easy way to check either the slew length or end point), as a result a request for a 90 DEGREE slew was sent to the spacecraft, the slew was executed and upon completion of the slew the spacecraft onboard computers noted that the sun was not normal to the solar panels, concluded that the ground controllers did not know what they were doing and safed itself. Recovery is underway, the telescope is in a Health & Safety load until 1 AM EDT July 7. Not surprisingly, steps are being taken to prevent this type of error from occurring in the future. A day before this safing event there was a SI safing: The Faint Object Spectrograph (FOS) safed because of a microprocessor reset. The data on this safing event is under investigation. Efforts to get Faint Object Camera (FOC) images in support of the focus analysis have failed completely due to a combination of human error and Fine Guidance Sensor (FGS) acquisition failure. Before their safing event FOS successfully brought up full high voltage on the Blue detector with no anomalies or surprises. Because of the safing event a number of scheduled SI testing never executed. This weekend the telescope will recover from the safing event and begin more Bootstrap focus measurements. Nothing new regarding the Pointing Control Subsystem (PCS) day/night terminator instability fix. It is obvious that the FHST's are still a major problem. The effort to understand how best to operate these star trackers is in progress, and it is expected that this problem will not totally disappear until a few more pointings are done. A few FGS failures are still ocurring for currently unknown reasons, investigations of these are underway. A major effort is now underway to document and analyze all FHST and FGS failures. One good note on recent PCS activities: the software that fixes the South Atlantic Anomaly (SAA) induced "bit flips" in the FGS's seems to be working quite well. A major new activity here has been the attempt to get FOC images in support of the focus study. Unfortunately, this effort has yet to produce anything very useful. The initial FOC field contained stars that, due to human error, had magnitudes that were too faint (by 3-4 magnitudes) to give good image quality. These exposures also suffered from failed FGS fine lock acquisitions. A second field was chosen, this time containing stars of the appropriate brightness, but FGS acquisitions again failed and no useful data was obtained. The HST safing event halted any further attempts. The Bootstrap Science Mission Specifications (SMS) that have been running this week obtained a number of wavefront sensor measurements (WFS) (WFS1 is still giving good data and WFS2 and 3 are still giving bad data), some additional Wide Field Planetary Camera (WFPC) images have also been obtained. In summary, there has been little new data obtained in orbit and little new in the analyses of the existing images. The first opportunity at new information on the HST image quality will probably be in the middle of next week. The FOC tried three times to take images this week but, while they did get a few stars in their first image none of the data was usable due to the very low count rate. There were two problems: due to human error the stellar brightness was overestimated and the stars were too faint by 3-4 magnitudes, in addition failed guide star acquisitions kept the "take data" flag off during all or part of the exposures. Analysis of the one image that showed stars yielded a pointing error of ~4 arc seconds, similar in magnitude to an earlier image, but in a different direction. This, too, is under study. A third set of the FOC images on a brighter star failed because of a failed acquisition. FOS successfully turned on their High Voltage (HV) on the Blue side. All went very well, dark count was as expected, no anomalies, no surprises. Then on July 4 the instrument safed itself. Analysis of the data showed that the safing event was triggered by a microprocessor reset. There is no history of this in the FOS, the last reset event occurring in thermal vacuum tests. The data is under study at this time. At this time, the FOS team does not feel that the reset is not indicative of any fundamental failure. Blue side Coarse Y-Base measurement and SAA noise measurements were not run because of the safing. It will probably be a week before the FOS gets back in the SMS's. The Goddard High Resolution Spectograph (GHRS) has been doing a series of HV electronic dark count tests skirting the SAA. All went well. These tests were also cut short by the HST safing. The High Speed Photometer (HSP) proposals were also hit by the safing. One more Photomultiplier Tube (PMT) test gave the same (expected) results. WFPC is awaiting recovery from safemode. A few images were taken this week in support of the focus testing. The next run of WFPC diagnostic images are scheduled for July 9. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 10 Jul 90 17:26:34 GMT From: usc!cs.utexas.edu!ut-emx!grads@ucsd.edu (Feulner ... Matt Feulner) Subject: Re: grim tidings for the future Speaking of grim tidings - Not too long ago (~month) I heard a news report that said the USSR was claiming that a bunch of shuttle flights in the next 10 years will completely destroy the ozone layer. I realize "a bunch" is a little ambiguous. The number I remember (which is almost certainly not right) is 300. Any comments, or anyone have more information? Matthew Feulner ------------------------------ Date: 10-JUL-90 14:45:00 EDT From: Steven R. Heleski Subject: Old Space Digest I am requesting some help on a FTP site which contains some old copies of Space Digest. The FTP is 128.2.209.58. I can get to the directory but I can not list the files in the directory. Could someone direct me to the person in charge of this FTP Site. Sorry to have to post this problem here, But I have no else to contact. Steven Heleski STEVEN@LTUVAX.BITNET ------------------------------ Date: 10 Jul 90 03:13:27 GMT From: eagle!news@ucbvax.Berkeley.EDU (Teddy Fabian) Subject: Re: grim tidings for the future In article <37486@ucbvax.BERKELEY.EDU> gwh@OCF.Berkeley.EDU (George William Herbert) writes: >In article <7315@timbuk.cray.com> gbt@sequoia.cray.com (Greg Titus) writes: >> >>Doesn't matter what they call it. They're all experimental. >>By the time the entire shuttle program is ended, the SMEs will >>still not have been run for as much aggregate time as the >>engines on a Boeing 747 on a *single* New York to Tokyo round >>trip. Experience with the things NASA flies was, is and will >>remain for a long time very limited compared with what we know >>about more mundane objects. > >While I agree in general, your example is in error... The engines run >8 minutes each in a flight, or 24 engine-minutes. With the testing that is >run outside of flights, there are about three times as many off-flight engine >hours as on-flight, or about 96 engine-minutes (1.5 engine-hours) per flight. >This totals to about fifty flight hours so far, and with fifty to a hundred >shuttle flights ahead, another seventy five to one hundred fifty hours of >operation. > >Now, while a 747 has four engines, i doubt that it takes 25 hours to fly >from New York to Tokyo... > >-george You're failing to see something though George.. How many 747s with four engines are flying at any one time?? maybe fifty??? or a hundred and fifty?? or more?? if you add up all the time built up by the running of EVERY jet engine, including all the hours each engine is tested, I think you'll find that there is considerable more data collected and available on them than there is on the shuttle main engines... - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Thanks, * * Ted Fabian NASA Lewis Research Center * * Cleveland, Ohio * * * * phone: 216-433-6307 FTS 297-6307 | disclaimer: * * email: tpfabian@nasamail.nasa.gov | my opinions * * tfabian@earth.lerc.nasa.gov | are my own * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- ---------------------------------------------------- Thanks, Ted Fabian NASA Lewis Research Center tpfabian@nasamail.nasa.gov *my opinions tfabian@mars.lerc.nasa.gov *are my own.. -- ---------------------------------------------------- Thanks, Ted Fabian NASA Lewis Research Center tpfabian@nasamail.nasa.gov *my opinions tfabian@mars.lerc.nasa.gov *are my own.. ------------------------------ Date: 10 Jul 90 19:14:06 GMT From: skipper!bowers@ames.arc.nasa.gov (Al Bowers) Subject: Re: HST down and out In article <1990Jul9.171321.1034@uoft02.utoledo.edu> fax0112@uoft02.utoledo.edu writes: >In article <7924@ncar.ucar.edu>, steve@groucho.ucar.edu (Steve Emmerson) writes: >> The military routinely >> does this for its spysats. >> >> Steve Emmerson >I keep hearing this comparison for HST. I wonder if this is valid >(I am not an expert in this field)... >bright earth rather than a faint distant object. I know it is classified >but I wonder how HST requirements compare to the keyhole sats. The equation for angular resolution as a function of aperature is fairly simple. Why not calculate it and figure it out? Assume a typical resolution, from photos in Jane's All the World's Aircraft I would guess a license plate is about right. Assume a pretty standard 100 mile orbit. Assume your optics are diffraction limited. I think HST still comes out as the largest optical system orbited yet, by a couple of factors, though not an order of magnitude. Another opinion... -- Albion H. Bowers bowers@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!bowers ------------------------------ Date: 10 Jul 90 15:08:38 GMT From: mtndew!friedl@uunet.uu.net (Stephen J. Friedl) Subject: Re: HST down and out > Second, Hubble is designed to work in a micro-gravity environment, > which means that it cannot be tested as a complete unit on the ground > - gravity would distort all of the optics to make the test completely > meaningless. I've been wondering something. From published reports, the mirror is about two microns off, and to my non-astronomer mind this seems like a pretty tiny number. Is this larger or smaller than the difference in the mirror between the 0g and the 1g environments? Steve -- Stephen J. Friedl, KA8CMY / Software Consultant / Tustin, CA / 3B2-kind-of-guy +1 714 544 6561 / friedl@mtndew.Tustin.CA.US / {uunet,attmail}!mtndew!friedl Berkeley UNIX is for people who don't have real work to do ------------------------------ Date: 10 Jul 90 23:25:23 GMT From: zaphod.mps.ohio-state.edu!samsung!umich!umeecs!itivax!vax3.iti.org!aws@tut.cis.ohio-state.edu (Allen W. Sherzer) Subject: Re: Inaccurate quotes (was: Re: More on NASA 91 Appropriation Vote) In article web@garnet.berkeley.edu (William Baxter) writes: >>I stand by the quote. It was an offhand remark and I'm not suprised he >>doesn't remember. It stuck with me because it wasn't the sort of thing >>I expected to hear from him. > >Allen thought that this was unrepresentative of Andy's views, and that's >why it stuck with him. At the tim yes. Later when he asked for active e support of SEI in his NSS campaign literature, I concluded that my memory of the conversation was correct. However, it is clear Andy does not feel this way. Let me therefore publicly apologize for any misunderstanding. All I can say is that Andy prides himself on working for the things he supports and vigerously works against the things he opposes. I assumed that since he is working on SEI and makes a special point of asking in his NSS campaign literature for support that he thought it was a good idea. It is clear that I misunderstood and that dispite his work and campaign statements he does not support it. Again, I apologize for any misunderstanding. Allen | | In War: Resolution | | Allen W. Sherzer | In Defeat: Defiance | | aws@iti.org | In Victory: Magnanimity | | | In Peace: Good Will | ------------------------------ Date: 10 Jul 90 06:30:20 GMT From: uoft02.utoledo.edu!fax0112@tut.cis.ohio-state.edu Subject: Re: grim tidings for the future In article <7928@ncar.ucar.edu>, dlb@hao.hao.ucar.edu (Derek Buzasi) writes: > >>> >> > >>And another thing, HST has not failed!!!!!!!! I am tired of hearing >>this. We have every reason to beleive in the end most if not all >>of the science will be done. > > Tell me -- do you regard everything that doesn't perform to within even > 10% of specifications to be a potential future success. Would you buy > a car that got 3 miles to the gallon and had a maximum speed of 8 miles > per hour based on the promise that eventually it would achieve 30 mpg > and 80 mph -- after three years or so in the repair shop! > >> I think your 10% is grossly off the mark. NASA official estimate 50% of the projects will me accomplished as currentl configured and I suspect that in the end much more than 50% will be done. But even if NASA is over confident at this point 10% sounds way too low. I have not heard any of the HST observers quibble with NASA's projection. Robert Dempsey Ritter Observatory ------------------------------ End of SPACE Digest V12 #47 *******************