Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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 ; Thu, 21 Feb 91 01:25:21 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 21 Feb 91 01:25:13 -0500 (EST) Subject: SPACE Digest V13 #178 SPACE Digest Volume 13 : Issue 178 Today's Topics: Terraforming, sun shield NASA Headline News for 02/13/91 (Forwarded) Re: Magellan heating Re: Magellan heating Pioneer Venus Update #2 - 02/18/91 Re: Cost of Living in a New Frontier Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 19 Feb 91 06:47:16 GMT From: sdd.hp.com!caen!kuhub.cc.ukans.edu!2fmzmumble@hplabs.hpl.hp.com Subject: Terraforming, sun shield Question (doozie!): I am a senior CS undergrad who has had some physics but my imagination is going way beyond my ability to compute, and I'm a'thinkin' maybe somebody thinks this is an interesting problem, too: Problem: Terraform Venus. Method: Orbit a large shield in front of the sun to cut incident visible sunlight by 50%. Assume: Manufacturing and transportation available for as much thin mylar (silvered?) as needed. Minimize mylar used by varying distance b/w shield and Venus. My real issue: how does the fact that light bends around edges affect this optimum distance? Is the apparent diameter of the sun at that distance relevant? Would solar wind just blow this thing away or would heavy particles just punch right through? Could the wind or light be used for stationkeeping? If the surface were silvered, can anyone think of a good use for the reflected light (esp. if surface was even slightly concave)? For those out there who know about mylar, is it easy to produce and does it break down (hydrocarbon chain, right) in strong sunlight? Another idea is instead of opaque, how about circular (would just be lines, really, at that diameter) diffraction grating that focused on a single point and then having a very, very polished mirror do some reflecting? Interstellar communications? Flashbulb for photos of astronomical objects (or energy source for laser that does same)? The diffraction idea cuts down on the mass of the object since much of it would be full of (small) holes. "Holey sun-shields, Batman!" Any ideeeeaaars? ------------------------------------------------------------------------------ "Remember, If you smoke after sex, | Kevin J. Rice: you're doing it too fast." | 2FMZMUMBLE@UKANVAX "If Avg. lifespan = 72 yrs., and | 2FMZMUMLBE@KUHUB.CC.UKANS.EDU Avg. intercourse = 5 to 7 mins., | 2014 27th Terr. #5 Lawrence KS 66046 and Avg. min. rest after = 15 mins., | (913) 749-1519 then tot. poss. int/lifespan=1,893,456"| "Ain't science wonderful?" ------------------------------------------------------------------------------ ------------------------------ Date: 19 Feb 91 04:18:26 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 02/13/91 (Forwarded) Headline News Internal Communications Branch (P-2) NASA Headquarters Wednesday, February 13, 1991 Audio Service: 202 / 755-1788 This is NASA Headline News for Wednesday, February 13, 1991 Activity at the Kennedy Space Center is proceeding well with regard to preparations of Discovery for its rollout to Launch Pad 39-A early Friday morning. The orbiter will be powered up today for the Shuttle Interface Test, which verifies connections between the various vehicle elements and the launch platform. The terminal countdown demonstration test is scheduled for next Tuesday and Wednesday, Feb. 19 and 20. Work on Atlantis is also proceeding smoothly towards that orbiter's planned April launch for the deployment of the Gamma Ray Observatory. Orbital maneuvering system pod installation and testing continue, and should be complete by week's end. Technicians are installing work platforms about Columbia, as post-mission processing on that orbiter begins in earnest, now that it is in the Orbiter Processing Facility. The Astro-1 and Broad Band X-ray Telescope payloads should be removed by this weekend. * * * * * * * * * * * * * * * * Administrator Richard Truly yesterday announced a nationwide search for a senior official to direct agency activities to send people to the Moon and to explore Mars. Adm. Truly said NASA is seeking "an outstanding individual, with talent and vision" for the newly created position of Associate Administrator for Exploration. The vacancy announcement for the position will be issued today and will be open through March 6. The announcement is for a career appointment in NASA's Senior Executive Service. Initial duties for the individual selected will be to formulate "well thought-out" options to meet the challenges of a return to the Moon and exploration of Mars. * * * * * * * * * * * * * * * * The NASA Advisory Council, in a letter sent to Vice President Quayle, has praised Adm. Truly and his management team "for taking quick, decisive and promising action" to implement the Report of the Advisory Committee on the Future of the U.S. Space Program. The NASA Advisory Council members are appointed by NASA for one-year terms . The Council reviews NASA policies, programs and strategies, and provides advice directly to the NASA Administrator. * * * * * * * * * * * * * * * * The Combined Release and Radiation Effects Satellite has another series of release opportunities beginning tonight and ending early tomorrow. The window for this release opens at 11:30 pm tonight and closes at 3:30 am tomorrow. Tonight's opportunity is for a barium release. Should it occur, and local weather conditions permit, the release will be visible along the East Coast in a southwesterly direction about halfway up the sky. Southwestern residents will have a southeasterly view at the same apparent elevation. Here's the broadcast schedule for Public Affairs events on NASA Select TV. All times are Eastern. **indicates a live program. Wednesday, 2/13/91 1:15 pm **Magellan-at-Venus report live from the Jet Propulsion Laboratory. 1:30 pm Black History Month program. 2:30 pm Von Braun Forum, taped highlights. 3:30 pm Reaching for Tomorrow program. 4:00 pm **Discovery Lecture Series: "Miracles by Design," live from the University of Alabama at Huntsville. See description below. 5:00 pm Premier show of PBS Infinite Voyager series featuring Dr. Olson's work. The program, entitled "Miracles by Design," will be transmitted at the conclusion of the Discovery Lecture. Thursday, 2/14/91 11:30 am NASA Update will be transmitted. 12:00 pm NASA programs will be transmitted. Discovery Lecture Series This program will feature Dr. Gregory Olson, a professor of material science and engineering at Northwestern University. Dr. Olson will report on test results of a new stainless steel alloy designed by computer thermodynamics. The alloy was designed for NASA to enhance the performance of critical ball bearings in the Space Shuttle Main Engines. This program will also be broadcast live on the PBS Elementary and Secondary Service satellite to 350 PBS stations, will be carried by the PBS Adult Learning Satellite Service, and will also be broadcast overseas by the USIS WorldNet Service to 200 U.S. embassies in 125 countries. The premier screening of the Public Broadcast Service's Infinite Voyager series will follow the conclusion of the Discovery Lecture. The first Infinite Voyager show features the work of Dr. Olson, and will be shown on the PBS network at 8:00 pm tonight. All events and times may change without notice. This report is filed daily, Monday through Friday, at 12:00 pm, EST. It is a service of Internal Communications Branch at NASA Headquarters. Contact: CREDMOND on NASAmail or at 202/453-8425. NASA Select TV: Satcom F2R, Transponder 13, C-Band, 72 degrees West Longitude, Audio 6.8, Frequency 3960 MHz. ------------------------------ Date: 20 Feb 91 02:04:13 GMT From: elroy.jpl.nasa.gov!jato!mars!baalke@decwrl.dec.com (Ron Baalke) Subject: Re: Magellan heating In article <1991Feb19.222809.24866@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > >I don't know the details of the battery choice for Magellan, but in general, >spacecraft hardware is chosen to meet expected conditions plus a suitable >safety margin. The problem is not that Magellan's batteries are warm, but >that they are substantially warmer than expected. Magellan's insulating >blankets are not performing nearly as well as they should, for unknown >reasons. The main concern is that if the safety margin are exceeded, the spacecraft will go into a safemode, and the electronics aboard the spacecraft can suffer damage to the excessive heat. Incidently, Magellan uses mirrors to reflect the sunlight. These mirrors are not working as expected because dust or corrosion is suspected to have reduced their effectiveness. Also, the current orientation of the spacecraft is such that one side is always in the sunlight, whereas in the past it was often shaded by Venus or by its large High Gain Antenna. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter, ___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind? /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind. |_____|/ |_|/ |_____|/ | It doesn't matter. ------------------------------ Date: 19 Feb 91 22:28:09 GMT From: bonnie.concordia.ca!news-server.csri.toronto.edu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: Magellan heating In article <9102132244.AA28756@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >It's difficult for an outsider to understand why the designers of a mission >to be conducted significantly closer to the sun than is Earth's orbit should >choose batteries for which an approach to room temperature is a matter of >concern... I don't know the details of the battery choice for Magellan, but in general, spacecraft hardware is chosen to meet expected conditions plus a suitable safety margin. The problem is not that Magellan's batteries are warm, but that they are substantially warmer than expected. Magellan's insulating blankets are not performing nearly as well as they should, for unknown reasons. -- "Read the OSI protocol specifications? | Henry Spencer @ U of Toronto Zoology I can't even *lift* them!" | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 18 Feb 91 17:56:12 GMT From: mintaka!snorkelwacker.mit.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@bloom-beacon.mit.edu (Ron Baalke) Subject: Pioneer Venus Update #2 - 02/18/91 PIONEER VENUS STATUS REPORT February 18, 1991 Note: In a prior posting, I said "the Pioneer Spacecraft was over", when I meant to say "the Pioneer Spacecraft emergency was over". Sorry for any confusion. On the afternoon of February 14, the Pioneer Venus spacecraft experienced an Under Voltage Trip which turned off all non-essential loads, including the antenna despin electronics; and the downlink went silent. A spacecraft emergency was declared, and a large number of receiver reverse commands at 300KW were sent in a drift through mode to the backup (bad) receiver. On February 15, during a Goldstone 70 meter track, the spacecraft was reaquired, and is being returned to normal configuration at this time. Project analysis is that during the eclipse the battery sank to an unprecedented low, setting flags to open the three power busses. As is normal during eclipses, the low voltage protection circuitry had been disabled prior to entering the eclipse. Upon exit from the eclipse, telemetry showed an adequate power level, as expected. When the low voltage protection circuitry was commanded back on, as was routinely done on all past eclipses, the flags (latched relays) of the low power level during the eclipse were acted upon by the control logic. In retrospect, the relays should have been commanded to reset prior to commanding the protection circuitry back on. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter, ___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind? /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind. |_____|/ |_|/ |_____|/ | It doesn't matter. ------------------------------ Date: 19 Feb 91 06:30:02 GMT From: snorkelwacker.mit.edu!usc!zaphod.mps.ohio-state.edu!rpi!mvk@bloom-beacon.mit.edu (Michael V. Kent) Subject: Re: Cost of Living in a New Frontier In article <21159@crg5.UUCP> szabo@crg5.UUCP (Nick Szabo) writes: [allignment of units deleted] >The total cost of Fred is projected at $30 billion. ($30e9+historical >NASA overuns)/$5.5e12 ~= 1% or 1/4% per person. Two orders of magnitude >difference in %GNP/crew costs. Adjusting for the number of taxpayers >(20 million vs. 220 million) that gives us three orders of magnitude >difference. First of all, $30G Freedom total cost / $5.5T 1 year USA GNP / 4 men = 0.14% of 1 year's GNP / man over 30 year lifetime. 0.14% / (1/500 %) = 68. That is, Freedom is 68 times more expensive to our society than the caravels were to ancienct Portugal. Not even 2 orders of magnitude, certainly not 3. I don't know if we want to factor in population when comparing GNP-based numbers. If we do, it would go in Freedom's favor, since Freedom's cost is spread over 250 million people while Portugals caravels were spread only over 20 million (is that really right? -- 20 million?) So the cost of Freedom to the typical American is about 5.5 times that of the caravel to the ancient native of Portugal. > >> 1) Freedom has been in the design stage for only about three years. > >Huh? Fred was announced in 1983, and much design work was carried on >even before that during the 70's and 80's. Space station design work was >also done on the USAF MOL in the 60's and Skylab in the 70's. Fred has >been shuffling paper for so long people have forgotten when it started. :-( According the the Augusting report (the only official reference I have handy) the official Freedom design phase is 3 years old. The conceptual design phase stretched five years beyond that. The detailed design and development phase marks the beginning of serious work on a project. American companies are already working on conceptual design of Martian space depots. Certainly you're not going to claim they are DESIGNING them, are you? By that line of reasoning, Portugal spent 3 millenia designing its caravels since Atlantic- based voyages were mulled over since ancient Greece. > >>That is not out of line with other major aerospace >>projects, even those that do no leave the atmosphere. > >The subject was the cost of living in new frontiers, not the cost >of other aerospace projects. But on the latter point, $3.7 billion >is near the all-time high -- up there with Apollo adjusted >for inflation -- on pre-prototype design costs for civilian aerospace >projects. I assume you mean Apollo design costs -- or do you mean Apollo program costs? According to the Augistine report, Apollo cost $94.07 billion in 1990 dollars. Or, put another way, Freedom will provide 30 years of on-orbit science and engineering for 1/3 the cost of 4 weeks of lunar rock-collecting. > >Also, it is ridiculous to spend the same amount of R&D on something >that will serve millions of customers (a modern airplane) who >will pay those costs, and something that will serve only a few >dozen who won't. You seem to think that we taxpayers are spending all our money to put 4 astrnauts in orbit to have a good time. We're not. We're putting them up there to do scientific research, and our lives will be vastly improved for doing it. Using the same reasoning, how do you feel about jet fighters? Do you feel we taxpayers are spending millions so fighter-pilots can have a good time buzzing around in their jets? We're spending that money for the liberty our defense gives us. In the same manner we're spending money on Freedom for the scientific knowledge that it will give us. Michael Kent mvk@itsgw.rpi.edu ------------------------------ End of SPACE Digest V13 #178 *******************