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 ; Fri, 29 Jun 1990 02:14:40 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 29 Jun 1990 02:14:10 -0400 (EDT) Subject: SPACE Digest V11 #580 SPACE Digest Volume 11 : Issue 580 Today's Topics: Re: Full Funding for NASA Re: Anyone Know What MOL Is/Was? Re: Is there a backup HST mirror ??? Re: The Scout, Pershing II's and ICBM's Re: ESA-brief summary of activity Re: Pegasus What Spherical Aberration is Re: 10 psi overpressure Re: Is there a backup HST mirror ??? ESA Bulletin no. 62 F-117 at Oshkosh Current status of HOTOL? US on Mars 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: Wed, 27 Jun 90 00:31:28 EDT From: kfl@quake.LCS.MIT.EDU (Keith F. Lynch) To: eagle!news@ucbvax.berkeley.edu Subject: Re: Full Funding for NASA Cc: kfl@quake.LCS.MIT.EDU, space+@andrew.cmu.edu > I've heard several stories that state that private industry _wants_ > NASA to do the basic research and initial testing, then turn the > technology over to them for commercial development. Of course! Who wouldn't like to have their R&D done for them, at taxpayer expense? Let them do their own R&D. I'll decide for myself where and how to invest or spend my money, thank you. ...Keith ------------------------------ Date: 27 Jun 90 14:21:33 GMT From: usc!cs.utexas.edu!titan!heskett@ucsd.edu (Donald Heskett) Subject: Re: Anyone Know What MOL Is/Was? It was to have been a small military space station, originally intended to be serviced by the DynaSoar spaceplane. Launcher was, I think, the Titan-II. Later, in the waning days of the project, as it was fighting for its life, the transfer craft was changed to a variant of the Gemini capsule. The project died because it could not prove it would perform a mission whose value was commensurate with its cost. If I remember correctly, Robert Macnamara (spelling?), Mr. Cost-Effectiveness, was the executioner. ------------------------------ Date: 27 Jun 90 17:36:56 GMT From: zephyr.ens.tek.com!tektronix!percy!3cpu!brycen@uunet.uu.net (Bryce Nordgren) Subject: Re: Is there a backup HST mirror ??? In article <31170@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >Now that the HST is safely in orbit, what happens to the backup mirror >(assuming there was one)? Will it be auctioned as scrap? Providing that one does actually exist, it may be sent up to fix the "spherical aberration" mentioned in another article. ;) ---Brycen PS - I'm a new user and have never posted to this net before. I tried to find and view the "nettiquette" document, but the system said we didn't have the newsgroup that it was in. Could someone please mail it to me? I've really enjoyed the discussion in here, and would like to participate, but don't want to step on any toes. Your help is much appreciated. ------------------------------ Date: 28 Jun 90 16:12:47 GMT From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: The Scout, Pershing II's and ICBM's In article <00938D33.A8EFC200@KING.ENG.UMD.EDU> sysmgr@KING.ENG.UMD.EDU (Doug Mohney) writes: >... You would have to buy them as surplus(?). One or two >of the Titan(s) retired in the early '80s might have been refuburished to >launch a payload, but I'm not real sure about this. They are all in storage, and contracts are out to refurbish an initial batch as launchers. I don't think they've launched the first one yet. Doug is correct that you would have to buy them. They belong to the USAF. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John Osterhout | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 27 Jun 90 15:32:53 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: ESA-brief summary of activity In article <5866@videovax.tv.tek.com> dmc@videovax.tv.tek.com (Donald M. Craig) writes: >writes: "Beginning on >19 February, a series of telecommands was transmitted to Giotto via the Madrid >tracking station, using a 70m antenna and a 100000 W transmitter, many thousand >times the power of a TV broadcasting station." >Reaching for my trusty Television and Cable Factbook... >That's 3 million watts, 5 million watts, and 4 million watts. Perhaps the >100000 W number was a typo? Almost certainly they are talking about *effective* power, i.e. what the TV station would have to radiate to put the same signal into the receiver at the same distance. The tight beam from that 70m dish is equivalent to a very large increase in output power. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John Osterhout | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 27 Jun 90 15:30:41 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Pegasus In article <3168@td2cad.intel.com> jreece@yoyodyne.intel.com (john reece) writes: >How about using a C-5, or C-17, and building a bigger rocket with a larger >payload? Either one can carry twice the payload of a B-52... Not externally they can't. You can launch very big rockets from a heavy transport -- a Minuteman was experimentally launched from a C-5, by pushing it out the rear, deploying a parachute to stabilize it, and firing the first stage a few seconds later -- but not ones with *wings*, because they won't fit. Pegasus is not a particularly small object except by launcher standards; I'm not sure its wingspan is small enough to go in a C-5, and I am fairly sure that nothing much larger would fit. Also, there are no civil C-5s or C-17s, and OSC/H is a civilian firm, not another appendage of the military-industrial complex. Pegasus can be dropped from a Tristar or 747, and in fact OSC/H plans to acquire or lease such an aircraft before too long. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John Osterhout | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 28 Jun 90 02:52:00 GMT From: uvaarpa!murdoch!news@mcnc.org (Greg S. Hennessy) Subject: What Spherical Aberration is Once more with feeling. Since HST is apparently suffering from Spherical aberration, and seeing how lousy the news reports were tonight, I thought I would give the readers a brief summary of what spherical aberration is. An "aberration" is a manner in which an image is degraded. There are five principal aberrations: coma, spherical aberration, astigmatism, chromatic aberration, and field curvature. It is impossible to get rid of all of these at the same time, but you try to get them to acceptable limits. To explain spherical aberration, I will make use of the principle of reprocitity, which means that instead of light coming into the telescope, I will use light going out of a telescope. If you have a point source of light, and want to have a curved surface to change the radially expanding rays into plane parallel rays, it is easy to calculate that the proper shape for the mirror is a parabola. However, if the mirror is a spherical mirror, the rays are not parallel after being reflected. This means that parallel rays coming into the mirror (as from a distant star) are not reflected into a point, but into a fuzzy area. Parabolas do not suffer spherical aberration. Spherical mirrors do. (Actually all non spherical mirrors suffer from spherical aberration. Don't ask why it is named such.) There are many different designs of telescopes. One of the most common is the Cassegrain, which has a paraboloidal primary, and a hyperbolic secondary (the shapes are generally conic sections). If you look at a picture of HST you may think that its optics are Cassegrain, but the optics are actually a Ritchey-Chretien design. The advantage of the Ritchey-Chretien is that the field of view is much larger than a Cassegrain, which is important for HST since it has to have several instruments collecting light at the same time. The Ritchey-Chretien has a more relaxed primary than a parabola (i.e. closer to a sphere) by a few wavelengths. This introduces spherical aberration, but cuts down on coma by quite a bit. The secondary mirror is modified such that it will eliminate the spherical aberration from the primary. A RC telescope does suffer from astigmatism and field curvature. For earth based instruments, these effects are much reduced if you are on axis, and for mechanical reasons most instruments are mounted on axis. The HST has the WF/PC on axis, while all the other instruments are off axis. Each of these instruments are designed to compensate for astigmatism and field curvature. So far I have been factual. I will now begin speculation. It seems that the secondary mirror of HST was not designed in the proper shape. Simply moving it around (as they can do) will not solve the problem. Replacing the primary mirror will not fix the problem, since it is not the cause. Replacing the secondary should fix it, except this is impossible. The instruments were designed to be replaced, but the secondary was not, and they won't bring HST back to earth. The people who built the mirrors and assembled it apparently made the mirrors to the specs they were given, but it appears the specs were incorrect. New instruments CAN be designed to correct for the spherical aberration, but it will be a few years before this can happen. The instruments were planned to be replaced anyway in a few years, this gives us more reason to. It is presently unclear how much science will be lost, although I heard a quote that the Wide Field camera is useless for scientific work. I hope this helps. -- -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w ------------------------------ Date: 28 Jun 90 16:09:46 GMT From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: 10 psi overpressure In article <00938D2F.9299D1C0@KING.ENG.UMD.EDU> sysmgr@KING.ENG.UMD.EDU (Doug Mohney) writes: >>>I seem to recall that the charges went in by the SSMEs ... >>References, please? ... >This was a post-Rogers, post-Challenger launch. Other than that, I'll have >to dig through AvWeek to find the reference. I've been reading AW&ST cover to cover since well before Challenger, and summarizing it to the net since Challenger, and I recall nothing like that. I also class this as a very unlikely change for several reasons (not least of which is that destroying the ET makes a destruct charge on the SSMEs totally redundant, since they can't do anything without fuel). I'm afraid I'm not going to believe it without at least an exact reference. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John Osterhout | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 28 Jun 90 17:53:11 GMT From: mephisto!prism!gs26@handies.ucar.edu (Glenn R. Stone) Subject: Re: Is there a backup HST mirror ??? In article <1990Jun28.162225.5140@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >There is talk of a mission in 1991 -- one had been pencilled in as a >contingency in case something went badly wrong [....] If >a replacement WFPC with aberration compensation can be built in haste, >that might perhaps be done. I saw a blurb on CNN Headline News this morning that that was the current plan, i.e. attempt to finish the WFPC in time for the 1991 launch. Pity the poor people who have to try to schedule shuttle missions nowadays; what with the Columbia problem and now this, their scheduling boards doubtless look like a cross between scrambled eggs and spaghetti. life goes on. -- Glenn R. Stone gs26@prism.gatech.edu "Go, baby, go!" -- Walter Cronkite, July, 1969 ------------------------------ Date: Wed, 27 Jun 90 10:39:15 SET From: LMASSONN%ESOC.BITNET@vma.cc.cmu.edu Comment: CROSSNET mail via MAILER@CMUCCVMA Comment: File BULL62 TEXT A Subject: ESA Bulletin no. 62 Subject: ESA Bulletin no. 62 (May 1990) Here is an overview of the contents of ESA bulletin no. 62. Articles: ERS-1: A Contribution to Global Environmental Monitoring in the 1990's Description of the ERS-1 mission, the experiments on-board, the spacecraft operations and the envisaged results Focus Earth: Two Landsat images of Greenland and Brittany La promotion de l'utilisation de Columbus/Foerderung der Columbus- Nutzung French/German article about promotion and marketing concepts for the European space station part and the free-flying laboratory External Servicing of Spacecraft - The Hermes Capability Description of external servicing concepts, featuring descriptions of the Hermes robotic arm ("HERA") and the design of the EVA suits for the European astronauts (500 hPa pressure suits to reduce prebreathing times, combination of hard torso and soft limbs) ESA's Advanced Relay and Technology Mission The Artemis spacecraft (planned launch date 1994), featuring advanced communication concepts (optical communications between geostationary satellites and from Artemis to the low-orbit French SPOT-4 satellite, a large inflatable antenna with adjustable spot beams, an ion-propulsion system for stationkeeping. Supernova Remnants and the Exosat Satellite Featuring Exosat X-ray observations of Supernovas. My favourite quotation: "Unless you happen to be in the immediate vicinity, supernovae are a good thing" The Exosat Database System Description of the post-operational activities around the Exosat database The Consultative Committee for Space Data Systems Setting up international standards Mechanical Coolers: An Option for Space Cryogenic Cooling Applications Development of cooling systems based on Stirling cycle and Joule-Thompson cycle machines EFSY - The Backbone of ESA's Financial-Control System Managing ESA's finances In Brief ESA-USSR Cooperative Agreement J-M Luton (former CNES director) appointed new ESA Director General Hipparcos survives Solar eclipse Giotto reactivated Hubble Space Telescope launched Dan Quayle visits ESA Headquarters Ariane V36 Board of Inquiry Establishment of European Astronaut Centre in Cologne (Germany) Meteosat-4 tests completed (after noise problems in M-4 detector) Other News: Hermes Development: Mach 3 Ejection seats selected Hermes airframe material now aluminium instead of carbon composites New orbit injection scheme does not longer require an Hermes propulsion module Ariane 5: 1st test firing of P230 solid booster with 15 tonnes of propellant 1st Vulcain engine (Ariane 5 main engine) 80% integrated The ESA Bulletin can be ordered from ESA Publications Division ESTEC Postbus 299 200 AG Noordwijk The Netherlands Regards, Lutz Massonne ------------------------------ Date: Wed, 27 Jun 90 12:47:34 EST From: WHITEMAN%IPFWVM.BITNET@vma.cc.cmu.edu Subject: F-117 at Oshkosh Just a BTW the F-117 is scheduled to do a fly-by at the EAA convention in Oshkosh between 27 July and 2 August. EAA is trying to talk USAF into a several day display. Source - Sport Aviation, June 1990, page 5. ------------------------------ Date: 27 Jun 90 21:32:58 GMT From: swrinde!zaphod.mps.ohio-state.edu!uwm.edu!ogicse!milton!unicorn!n8035388@ucsd.edu (Worth Henry A) Subject: Current status of HOTOL? Does anyone know what the current status is of the HOTOL launcher? The last I heard, nearly two years ago, an attempt was being made to form a private consortium (led, if memory serves, by a real estate holding firm?), as the British government had cut all support. ------------------------------ Date: 28 Jun 90 20:28:58 GMT From: fed!m1rlr01@uunet.uu.net (Rich Rauscher) Subject: US on Mars Does there exist any U.S. Plans for a manned trip to Mars? I remember hearing Quayle say something about it, and I haven't been keeping up with this newsgroup. Thanks, Rich Rauscher ____ _ ____ Rich Rauscher, Unix Systems Programmer | __ | | | | __ | Federal Reserve Board of Governors, Washington, D.C. | | | | | | rauscher@madness.rutgers.edu | | \\ | |_ | | \\ rauscher@zodiac.bitnet ------------------------------ End of SPACE Digest V11 #580 *******************