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 ; Tue, 3 Jul 1990 01:29:09 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 3 Jul 1990 01:28:36 -0400 (EDT) Subject: SPACE Digest V12 #3 SPACE Digest Volume 12 : Issue 3 Today's Topics: Telescope mirror testing Re: RE Hubble Space Telescope Update - 06/28/90 Re: Reflections on Hubble and NASA Hubble Space Telescope Update - 07/02/90 grim tidings for the future Re: Hubble Space Telescope Update - 06/28/90 Re: Hubble Space Telescope Update - 06/28/90 Perkin-Elmer and the Hubble (none) Re: Meaning of Palo Alto 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 ---------------------------------------------------------------------- Date: 3 Jul 90 05:21:02 GMT From: uoft02.utoledo.edu!fax0112@tut.cis.ohio-state.edu Subject: Telescope mirror testing Here is some info I thought I would pass along. In Astronomical Optics by Daniel Schroeder he discusses in very excellent detail telescopes, abberation and testing. Yes testing. (We keep hearing from certain groups that it was obvious that they should have done this or that. While they were sitting around criticizing I was trying ti understand more of what is going on.) Anyway, he mentions that one of the best tests of a mirror is using the Twyman-Green interferometer, which is a modified Michelson interferometer. Picture a standard Mich. int. Here the movable mirror is replaced with a positve lense, called a null lense, and the test mirror. The lens and mirror are placed so that their optical axes coincide, with the focal point of the lens coincident with the center of curvature of the mirror. The other change si to use a laser plus beam expander as the light source, with the pinhole in the beam expander placed at the focal point of the input collimator lens. The beamsplitter divides the amplitudes of the incident plaen wavefront, which, after refelction in the two arms of the interferometer, returns to the beamsplitter. A portion fo the two beams is recombined at the beamsplitter and directed toward the output lens and detector (D). A good picture etc can be found in Malacara (1978) Optical Shop Testing (Wiley:New York). Note: "It should be evident from this discussion that the test using the T-G interferometer is one of the null lens and mirror combination, not the mirror itself." The lense must be independently tested. This is what was done with HST. Other interesting articles are Wetherell and Rimmer Appl Opt 11, 2817 (1972) and "Instrument Handbooks" 1985 STscI. Doesn't really add much but I thought others might find this of interest. Besides, as Ron Baalke has pointed out they are not exactly sure where the trouble is. Speculation at this point is just that. Robert Dempsey Ritter Observatory lens ------------------------------ Date: 2 Jul 90 13:55:50 GMT From: xanth!xanth.cs.odu.edu!paterra@ames.arc.nasa.gov (Frank C. Paterra) Subject: Re: RE Hubble Space Telescope Update - 06/28/90 I remember reading a few years ago that some university in the midwest determined that since all the R&D for hubble was already paid for, it would be relatively cheap to build a clone. Except for the fact that they are missing the TDRS and ground station support, they could have their very own *Great Observatory*. If this is true (Seems reasonable), why doesn't NASA take their lead and start building the replacement? Of course you have to convince everyone that they are to build a clone and not a new design. Rambling thoughts ... Frank Paterra paterra@cs.odu.edu -- Frank Paterra paterra@cs.odu.edu ------------------------------ Date: 2 Jul 90 15:20:55 GMT From: uoft02.utoledo.edu!fax0112@tut.cis.ohio-state.edu Subject: Re: Reflections on Hubble and NASA In article , ron@mlfarm.uucp (Ronald Florence) writes: > fax0112@uoft02.utoledo.edu writes: > > > Lets draw a lesson from Hubble himself. He first studied law and > > passed the bar. He then enlisted and became an officer. Later > > he turned Yerkes, 'a moribund institution', into a major research center > > and made many famous discoveries. Pretty good for such a humble > > start in the wrong direction. > > The comparison between Hubble and NASA is valid, though in a slightly > different way. Hubble's autobiography shouldn't be trusted any more > than his British accent, which was pure affectation. Yerkes was > hardly a "moribund" institution before Hubble's arrival. Under Hales > it was probably the premier institution for astronomical research in > the United States. Hubble dismissed the work of Shapley and his other > predecessors at Mount Wilson as "of no significance", which is > remarkably like the NASA press releases which described the Hubble > Space Telescope as the most important event in astronomy since > Galileo. > -- > I did not draw from his autobiography. If you wish you might like to read the Mercury Jan/Feb issue where this was the description given by Donald Osterbrock, Ronald Brashear and Joel Gwinn. By 1904 Hale had gone to California taking all the top notch astronomers with him. Frost inherited the directorship but just carried on. E.E Barnard was one of the others - a very good observer but no real scientific background. The others were obscure astronomers. By the time Hubble got there it was a "moribund institution". Robert Dempsey Ritter Observatory ------------------------------ Date: 2 Jul 90 23:17:29 GMT From: usc!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Hubble Space Telescope Update - 07/02/90 Hubble Space Telescope Update July 2, 1990 The telescope has been slowly returned to nominal roll without major thermal problems. There has been a modest amount of activity in orbit, most of it dealing with the Scientific Instruments (SI) rather than the focus. Bootstrap activities continued as before with good Wavefront Sensor (WFS1) measurements and bad WFS2 & 3 data. The first attempt at using the Faint Object Camera (FOC) to assist in characterizing the focus was not successful -- possible pointing errors and a "take data" flag problem gave null results. However, Wide Field Planetary Camera (WFPC) pictures were successfully taken. All the SI related events went quite well with no anomalies or unexpected events. The Faint Object Spectograph (FOS) is in the process of turning on their Blue Side High Voltage (HV) (successfully, so far), the FOC worked well, despite not seeing stars, in its first focus support effort. The Goddard High Resolution Spectrograph (GHRS) was gathering HV dark count near the South Atlantic Anomaly (SAA), The High Speed Photometer (HSP) was testing the Photomultiplier Tube (PMT) detector, WFPC and the Fine Guidance Sensors (FGS) continue to operate smoothly. Nothing new regarding the Pointing Control Subsystem (PCS) day/night terminator instability fix. There is high confidence that most of the disturbance should be removed with the new flight software. Expected time of completion is early August (maybe late July). The fix is expected to bring HST stability to pre-launch expectations. As for the rest of the PCS system, it is clear that there are still problems with the Fixed Head Star Trackers (FHST) but the problems do appear to be getting less frequent and understood quicker than before. The FHST's do appear to be the weakest link in the PCS, but there is a growing understanding of how their operation can be made more reliable. This problem is not expected to totally disappear until we get a few more pointings under our belt (a month or two). Flight operations has begun to load the software to fix the "bit flips" in the FGS's caused by the SAA. This should remove the cause of some of the FGS acquisition failures. A few FGS failures are still ocurring for currently unknown reasons, investigations are underway. In orbit activities are centered on setting up the new focus star, epsilon Sco, for Wavefront Sensor (WFS) measurements. In the past there have been lot of problems getting good data off WFS2 & 3 (they do not see any modulation of the signal in these two sensors). The failure has been attributed to a variety of causes, most recently an apparent inability to properly center the star in the WFS aperture. There have been a few more pictures but nothing really new regarding the image quality. Most of the ground effort is directed at assessing the impact on existing science programs, what can be done (if anything) to improve the existing focus, and once a focus is established what should be done to better characterize the focus. FOC is taking images in support of focus efforts. Their first attempt was a failure, not because of anything within the FOC but because of a possible pointing error and a command management problem that kept the "take data" flag off during one of the FOC images (take data flag off = closed shutter). FOS is in the process of turning on HV on the Blue side, so far (2 steps) all is good. Coarse Y-Base measurement went well. Blue side HV finishes on July 4. GHRS is doing a series of HV electronic dark count tests skirting the SAA. All so far is going well. Counts are lower than expected but the analysis of the data has just begun. HSP is awaiting further testing of the PMT detector. Ground hardware tests seem to show that the cause of the problem is a minor "instability" in one of the electronic components that should vanish with the application of higher voltage. The prediction is that no problems will exist when normal operation voltage is reached. WFPC is in full operate mode. Next images are scheduled for tomorrow. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ From: bwebber@NMSU.Edu Date: Mon, 2 Jul 90 21:20:23 MDT Subject: grim tidings for the future News flash: shuttle fleet grounded due to design error on h2 pump system News flash: Hubble useless (almost) due to lack of testing on ground What does all this mean? It means that if we aren't careful, some group of budget cutting myopics will seize this as a chance to lay waste to the entire U.S. space effort for the rest of the decade. Sound like overreaction? Could be, but I didn't think the Challenger disaster would stop the program more than a year, but I was wrong then, too. Korac MacArthur (not bwebber) ------------------------------ Date: 1 Jul 90 23:19:37 GMT From: amdahl!JUTS!ked01@sun.com (Kim DeVaughn) Subject: Re: Hubble Space Telescope Update - 06/28/90 In article <1990Jul1.001404.4618@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: > In article <1990Jun30.060205.20398@zorch.SF-Bay.ORG> phil@zorch.SF-Bay.ORG (Phil Gustafson) writes: > >...Various unnamed spokesmen say that the facility could not have > >verified the the HST was within spec, but could have detected the > >gross aberration currently present. > > In other words, it could not have checked the telescope for the sort of > tiny errors that were likely possibilities, but could have checked for > gross errors that nobody had any reason to expect. At a substantial cost. > What are the odds that Congress, if carefully given all the facts, would > have authorized funding for this? I usually agree with most everything you say Henry, but I have to differ on this issue. When developing anything as sophisticated and unique as the HST, one *must* count on good ol' Murphy lurking around *every* corner. And plan accordingly. The same can be said of any project where you are breaking new ground. Here, where we R&D very large mainframe machines, I and about 60 other Engineers devote ourselves to ensuring that our machines are designed correctly. Possibily another 300 or more folks are involved in other forms of testing (chip test, test equipment development, RAS testing, performance testing, etc). That is a *significant* percentage of the development budget! And believe me, we find all sorts of errors ... including the really gross ones. And even so, we still manage to miss a few. But believe me, I would never consider shipping a machine where we'd thoroughly tested both the CPU complex and the I/O complex independently, but had never tested them hooked together. No way! Why should the HST be viewed any differently? The sign above my desk reads, "What you simulate, is what you get". Words to live by. /kim -- UUCP: kim@uts.amdahl.com or: {sun,decwrl,hplabs,pyramid,uunet,oliveb,ames}!amdahl!kim DDD: 408-746-8462 USPS: Amdahl Corp. M/S 249, 1250 E. Arques Av, Sunnyvale, CA 94086 BIX: kdevaughn GEnie: K.DEVAUGHN CIS: 76535,25 ------------------------------ Date: 2 Jul 90 20:48:13 GMT From: mojo!SYSMGR%KING.ENG.UMD.EDU@mimsy.umd.edu (Doug Mohney) Subject: Re: Hubble Space Telescope Update - 06/28/90 In article <1990Jun30.060205.20398@zorch.SF-Bay.ORG>, phil@zorch.SF-Bay.ORG (Phil Gustafson) writes: >>Nice idea, but it's not quite that simple. You have intrinsic problems >>testing a flexible mirror in a gravity well when it's supposed to be >>operational in space. I.E. it wouldn't have looked right even if we >>DID test it down here. > >This morning's New York Times says that the spooks offered their >spy-telescope test facility to NASA, but the latter turned the offer >down. Various unnamed spokesmen say that the facility could not have >verified the the HST was within spec, but could have detected the >gross aberration currently present. > The 7/1 Washington Post said the same thing. >I don't see much difference between testing a telescope designed to >point down and one designed to point up -- the spooks seem to have >space telescope testing under control. I'm just surprised that they >loosened up enough to deal with NASA. The Post went on to say that the Hubble was a very complicated relative of the KH-9 spy satellite, with tighter focusing specifications. Since Perkin- Elmer (now a Hughes subs...) did work on both KH-9 and Hubble, NASA felt fairly confident that the job would be done without incident. ------------------------------ Date: 2 Jul 90 13:01:15 GMT From: fernwood!portal!cup.portal.com!fleming@uunet.uu.net (Stephen R Fleming) Subject: Perkin-Elmer and the Hubble I'm confused. I've been following the discussion on the Hubble, and most of the fingers seem to be pointing at Perkin-Elmer for screwing up the optics. But I remember reading a lengthy article last year (Discover? Scientific American? I don't remember where...) which gave a well-written account of the mirror-polishing process at Perkin-Elmer in Connecticut. In the article, a major focus (pardon the pun) was how wonderful the QA was and how P-E significantly -exceeded- NASA's specs for the primary mirror. So... was the article a puff piece planted by Perkin-Elmer's PR group? Or did they do a great job of building to the wrong spec? Or is it some other mirror we're talking about? +------------------------+---------------------------------------+ | Stephen Fleming | In ten years, computers will just be | | fleming@cup.portal.com | bumps in cables. --Gordon Bell | | CI$: 76354,3176 +---------------------------------------| | BIX: srfleming | My employers may disagree vehemently. | +------------------------+---------------------------------------+ ------------------------------ Date: 3 Jul 90 02:30:00 GMT From: leah!rpi!rpitsmts!forumexp@bingvaxu.cc.binghamton.edu (Commander Krugannal) Subject: (none) Subject: Someone asked about the AST being built here at RPI. I haven't heard a thing about it in a few years, but if I get the chance, I'll check it out. Greg_d._Moore@mts.rpi.edu ------------------------------ Date: 2 Jul 90 18:04:09 GMT From: mcsun!inesc!unl!unl!ray@uunet.uu.net (Vitor Duarte & Sergio Duarte) Subject: Re: Meaning of Palo Alto In article <2280@l.cc.purdue.edu>, cik@l.cc.purdue.edu (Herman Rubin) writes: >> > It stands for "tall trees", ..... >> This is incorrect, it is "tall tree." It refers to a single tall pine/ >> I do not know if that tree is still standing. >this is incorrect. the conventional derivation, which you have used: >(palo from the root "pale" - modern "paling" for tree-like thingy; > alto from the same root which begets "altitude") >is frowned on by the residents, who prefer "old horse". >followups to rec.pedant. now back to your published programme. I don't know if there was a tree or not over there, but a direct translation of Palo Alto is: Tall stick of wood. - Alto means Tall in spanish ( and portuguese by the way) - Palo is a stick a wooden one. Therefore the people of Palo Alto should be called WoodenSticks :-) -- +--------------------------------------------+ Dept. de Informatica Faculdade de Ciencias e Tecnologia Universidade Nova de Lisboa ray@fctunl.rccn.pt ; ray@unl.uucp ------------------------------ End of SPACE Digest V12 #3 *******************