Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from holmes.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Mon, 22 May 89 03:16:57 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 22 May 89 03:16:47 -0400 (EDT) Subject: SPACE Digest V9 #451 SPACE Digest Volume 9 : Issue 451 Today's Topics: Re: Long Duration Exposure Facility Re: Long Duration Exposure Facility Magellan Status for 05/19/89 (Forwarded) nasa sites Re: Alien viruses Re: Sun's invisible partner NEMESIS New space shuttle name Re: The late NEMESIS Theory Re: Magellan Status for 05/19/89 (Forwarded) Re: New Orbiter Name Announced Re: Sun's invisible partner NEMESIS Re: Magellan & SRB exhaust Magellan Advisory (Forwarded) ---------------------------------------------------------------------- Date: 19 May 89 15:04:05 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!kcarroll@purdue.edu (Kieran A. Carroll) Subject: Re: Long Duration Exposure Facility ZMLEB@SCFVM.GSFC.NASA.GOV (Lee Brotzman) writes: >mnetor!utzoo!henry@uunet.uu.net (Henry Spencer) writes: >>...NASA is terrified of the public-relations impact of another Skylab, >>and considers it quite urgent that LDEF not be allowed to reenter. > >If NASA is so "terrified" of allowing a light-weight, sure-to-burn, satellite >like LDEF to reenter, then why is the Solar Maximum Mission (SMM) being allowed >to reenter? Although public relations may be part of it, I think that the >main reason to get LDEF is simply that it is useful to do so. The materials >that were placed on it are pretty much useless now since they have had a >*really* long exposure (maybe not). That doesn't mean the thing shouldn't be >brought back, looked over and possibly loaded up and re-launched. > According to one of the recent issues of AWST, the SDI Organization is keen on seeing LDEF retrieved. While most of the experiments (including one from here at the U of T) were designed for a one-year mission, and so will likely return poor results after an additional four years in space, the SDIO is interested in the effects of the space environment on the spacecraft's >>bus<<. SDI would result in a large number of satellites being orbited, and left dormant for years at a time; they are interested in finding out how typical satellite components stand up to years of time in space. Also, they apparently plan to do tests on some LDEF components, to determine how well they would stand up to attack after being in space for a long time (ie. does the hardness of a laser battle station deteriorate with time?). A chilling note: the article states that, due to recent unexpectedly- high levels of solar activity, LDEF's projected re-entry time is now sooner than it was -- sometime in December 1989. The SDIO wants NASA to mount a mission prior to December to do the retrieval; administrator Truly says that it likely won't fly until mid-december, but that that's all right, because the re-entry probably won't occur until >late< December. The sticking point in the negotiations is that NASA only wants to fly one mission between Galileo and Ulysses (I think that's the pair they mentioned); the one flight is a DoD payload that's been delayed for quite awhile now. To retrieve LDEF before re-entry, it looks like DoD will have their payload bumped again (by NASA and SDIO), or else NASA will have to fly a mission that they don't think they have time to prepare for (shades of early 1986). -- Kieran A. Carroll @ U of Toronto Aerospace Institute uunet!attcan!utzoo!kcarroll kcarroll@zoo.toronto.edu ------------------------------ Date: 19 May 89 15:48:35 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@purdue.edu (Henry Spencer) Subject: Re: Long Duration Exposure Facility In article ZMLEB@SCFVM.GSFC.NASA.GOV (Lee Brotzman) writes: >>... NASA is terrified of the public-relations impact of another Skylab, >>and considers it quite urgent that LDEF not be allowed to reenter. > >If NASA is so "terrified" of allowing a light-weight, sure-to-burn, satellite >like LDEF to reenter, then why is the Solar Maximum Mission (SMM) being allowed >to reenter? ... Because Solar Max is much smaller. It's "just another satellite"; they reenter all the time. LDEF is one of the biggest things launched since Skylab. Remember, we are talking about public perceptions, and fears thereof, not actual dangers. -- Subversion, n: a superset | Henry Spencer at U of Toronto Zoology of a subset. --J.J. Horning | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 19 May 89 18:33:11 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Magellan Status for 05/19/89 (Forwarded) MAGELLAN STATUS May 19, 1989 Daily momentum wheel desaturations continue as scheduled, twice daily, 00:45 a.m. and 12:45 p.m. PDT, project said today. The daily star calibration also was performed without difficulty. Both stars were detected and a full attitude update was obtained. The temperatures of Rocket Engine Modules 3 and 4 continue to slowly cool as the celestial geometry gradually changes. They are running a steady 56-58 C (132.8-136.4 F) except during wheel desaturations when they warm up into the 60s C (140-156 F), still considerably below the design limit of 83 C (181.4 F). The Command Data System breadboard began working again in the System Verification Lab and the test of Cruise)2 computer command sequence, which holds the upcoming Trajectory Correction Maneuver, is going well and nearing completion. Project will be prepared to upload the sequence Saturday. A meeting today was scheduled to address solution options to the three current problems: 1) Rocket Engine Module temperatures; 2) star rejects during star calibrations; and 3) desaturation frequency. SPACECRAFT Distance From Earth (mi) 2,220,474 Velocity Geocentric 5,905 mph Heliocentric 59,970 mph Round Trip Light Time 12.2 sec ------------------------------ Date: 19 May 89 23:26:59 GMT From: asuvax!enuxha!kluksdah@noao.edu (Norman C. Kluksdahl) Subject: nasa sites (Apologies for the use of the bandwidth--once again, the infamous evil e-mail system prevents direct response) Joni Guldenpfennig, I got your note, and tried to forward the info four different paths. None of them worked. Sorry. Can you get me a better path? N. Kluksdahl kluksdah@enuxha.eas.asu.edu ------------------------------ Date: Fri, 19 May 89 11:03:53 EDT From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Alien viruses >From: Robert Nelson >I noticed that someone commented on waht would happen if we had contact >with ETs, and if we could get a virus from them or perhaps something >from -us- could affect them. I turn your interest to the book/movie >_The_Andromeda_Strain_. It depicts a scenerio that has a meteor landing >and there is a virus of sorts on it, actually I think that it is some >form of bacteria, which breaks down carbon compounds like plastics... >any comments? I don't think Crichton's story matches any plausible real-life scenario. In the book/movie, an alien microorganism finds its way to Earth, and begins to enthusiastically wipe out 99+% of the population in affected areas. Suddenly, every one of the teeming trillions of organisms just happens to mutate into harmless form (!) Another writer in this class is D.F. Jones (the Colossus series), who has written novels filled with numbers that are off by dozens of orders of magnitude. Some science fiction writers *are* very careful with numbers (though they can still mess up on the sociology, etc.) Robert Heinlein reported that in the process of writing a novel, he had spent several days working on a set of calculations, just so a single paragraph describing orbital maneuvers would be accurate. John Roberts roberts@cmr.icst.nbs.gov ------------------------------ Date: 19 May 89 10:56:37 GMT From: bunny!krs0@husc6.harvard.edu (Rod Stephens) Subject: Re: Sun's invisible partner NEMESIS Read the book "NEMESIS". It's quite readable. As I read it the theory is not dead. The author predicts that Nemesis (if it exists) would be some sort of red dwarf (I think) that would be visible from the earth but would be hard to tell apart from a bigger more distant star. He implies there is some hope of locating it soon since imaging systems are just about sensitive to record and analyze stuff of this brightness now. Rod Stephens GTE Laboratories ------------------------------ Date: Fri, 19 May 89 12:04:48 PDT From: Peter Scott Subject: New space shuttle name ginosko!infinet!ulowell!hawk!rlevasse@uunet.uu.net (Roger Levasseur) writes: >Captain James Cook who explored the Pacific Ocean in the late 1770's, >and charted Alaska and Hawaii sailed in ships named HMS Resolution >and HMS Endeavour. If the shuttle is named after it, it would certainly >be silly to use another spelling. If they named if after this particular ship, agreed. AW&ST uses the name "Endeavor" several times in the current issue with no allusion to any alternate spelling, however, so it'll be interesting to see what actually winds up on the side. Peter Scott (pjs@grouch.jpl.nasa.gov) ------------------------------ Date: 19 May 89 14:19:44 GMT From: sun-barr!cs.utexas.edu!ut-emx!ethan@decwrl.dec.com (Ethan Tecumseh Vishniac) Subject: Re: The late NEMESIS Theory In article <1568@cfa.cfa.harvard.EDU>, wyatt@cfatst.HARVARD.EDU (Bill Wyatt) writes: > > Several things would have to be verified for the entire NEMESIS theory > to be accepted. A short list, off the top of my head: > > ...list mostly deleted .. > 5) The iridium layer(s) must be of extraterrestrial origin. The original claim was that the K-T boundary had to be. One comment that I see periodically is that the same irridium anomaly that shows up in meteorite abundances is also present (perhaps to a lesser degree) in the mantle. It follows that extensive volcanism *might* have a similar effect. Any geologists following this? > 6) There must be an Ir or other tracer layer at every extinction boundary. Although there have been some claims along these lines, I believe that the K-T boundary is the only well accepted instance. Given the claimed periodicity and the existence of at least one more drastic (although earlier) extinction this seems somewhat damning. One point which I haven't seen treated much is the question of whether it is even necessary to explain the (debatable) periodicity using astronomy. Mass extinctions appear to follow from some combination of climate and biology. Dropping rocks on everything (or comets) is simply a crude way to ensure this. However, climate and ecology are coupled, extremely complicated nonlinear systems. One might add geological processes, including continental drift, to the list as the source of episodes of intense volcanism, disruption of ecological systems due to the creation of land bridges, and changes in climatic patterns. It is my understanding that such systems frequently show oscillations on somewhat unpredictable time scales that may appear, at first glance, crudely periodic. To take an extreme example, suppose mass extinctions are due entirely to episodes of volcanism and the K-T boundary is either a coincidence ( comet(s) happened to hit close to such an episode) or simply reflective of an unusually deep upwelling of mantle material during this episode. Then one really needs to explain an approximate periodicity in certain kinds of flow patterns in the Earth's core. I don't think this would strike anyone as particularly outrageous. -- I'm not afraid of dying Ethan Vishniac, Dept of Astronomy, Univ. of Texas I just don't want to be {charm,ut-sally,emx,noao}!utastro!ethan there when it happens. (arpanet) ethan@astro.AS.UTEXAS.EDU - Woody Allen (bitnet) ethan%astro.as.utexas.edu@CUNYVM.CUNY.EDU These must be my opinions. Who else would bother? ------------------------------ Date: 19 May 89 19:15:24 GMT From: cdaf@iuvax.cs.indiana.edu (Charles Daffinger) Subject: Re: Magellan Status for 05/19/89 (Forwarded) In article <25609@ames.arc.nasa.gov> yee@trident.arc.nasa.gov (Peter E. Yee) writes: > > MAGELLAN STATUS > May 19, 1989 > > > Daily momentum wheel desaturations continue as scheduled, twice >daily, 00:45 a.m. and 12:45 p.m. PDT, project said today. The daily What are these momentum wheel desaturations? -charles -- Charles Daffinger >Take me to the river, Drop me in the water< (812) 339-7354 cdaf@iuvax.cs.indiana.edu {pur-ee,rutgers,pyramid,ames}!iuvax!cdaf Home of the Whitewater mailing list: whitewater-request@iuvax.cs.indiana.edu ------------------------------ Date: 18 May 89 14:05:39 GMT From: asuvax!anasaz!scott@noao.edu (Scott Gibson) Subject: Re: New Orbiter Name Announced In article <13000@ut-emx.UUCP> bonin@ut-emx.UUCP (Marc Bonin) writes: > >Enterprise : Obvious ! >Discovery: the ship from 20001 ^^^^^ ^^^^^ AAAAAHHHHHHHHH! You mean this is really 19989?? I knew I was feeling sort of run down.......( ;-) ) Scott ------------------------------ Date: 19 May 89 09:00:00 GMT From: well!pokey@apple.com (Jef Poskanzer) Subject: Re: Sun's invisible partner NEMESIS In the referenced message, henry@utzoo.uucp (Henry Spencer) wrote: }Last I heard, this idea was no longer taken seriously by most people. It }appears unlikely that Nemesis's orbit would be stable against perturbations }by other stars over billions of years. It doesn't have to be stable for billions of years, just for the few hundred million that we can see in the fossil record. This specious objection comes straight from a Nature editorial, by the way. Read "The Nemesis Affair: A Story of the Death of Dinosaurs and the Ways of Science", by David M. Raup, 1986. Read "Nemesis: The Death Star", by Richard Muller, 1988. Then decide. --- Jef Jef Poskanzer jef@helios.ee.lbl.gov ...well!pokey "Back off, man - I'm a scientist!" ------------------------------ Date: 19 May 89 16:05:44 GMT From: dinl!holroyd@handies.ucar.edu (kevin w. holroyd) Subject: Re: Magellan & SRB exhaust In article <394@illusion.UUCP> marcus@illusion.UUCP (Marcus Hall) writes: > stuff deleted >Are the windows considered more critical than the bottom tiles? I guess they stuff deleted Only when it comes time to land and you can't see outside. -- ******************************************************************************* Kevin W. Holroyd * CFI Aspen Flying Club * Got tired of last .signature file Denver CO. * ******************************************************************************* ------------------------------ Date: 19 May 89 23:40:16 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Magellan Advisory (Forwarded) JET PROPULSION LABORATORY News Advisory May 19, 1989 Editors: The Magellan spacecraft, on a 15)month journey to Venus, will perform a trajectory correction Sunday at 7 p.m. PDT. The maneuver will increase the spacecraft's velocity 2.9 meters per second, or about 6.6 miles per hour. It also will slightly alter the course of the spacecraft's trajectory. Friday, Magellan was moving at 59,970 miles per hour, relative to the sun. Magellan, launched from the shuttle Atlantis May 4, is to map up to 90 percent of the surface of Venus with imaging radar. It is to be placed in Venus orbit Aug. 10, 1990. Seventeen days prior to orbit insertion, Magellan will perform a second Trajectory Correction Maneuver. ------------------------------ End of SPACE Digest V9 #451 *******************