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 ; Thu, 13 Dec 1990 01:41:19 -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, 13 Dec 1990 01:40:45 -0500 (EST) Subject: SPACE Digest V12 #645 SPACE Digest Volume 12 : Issue 645 Today's Topics: Re: atmospheric pressure on Mars Re: Good Bye (Quite possibly my last posting from this site) BBXRT Status for 12/06/90 [1430 CST] (Forwarded) Dr. Scott Madry lecture Re: Photon engine Re: MAJOR SOLAR FLARE ALERT Re: * SpaceNews 03-Dec-90 * Astro-1 Status for 12/05/90 [2130 CST] (Forwarded) Re: Payload Specialist Selection Re: Another Russian first 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: 6 Dec 90 08:04:25 GMT From: eru!hagbard!sunic!mcsun!unido!fauern!forwiss.uni-passau.de!nntpserver!himsolt@bloom-beacon.mit.edu (Michael Himsolt) Subject: Re: atmospheric pressure on Mars The avarage athmospheric pressure on Mars is 4.9 mbar, the maximal pressure is thought to be ~10 mbar (in very deep regions like Hellas). The maximum pressure recorded by Viking (2) was ~8 mbar. There has been a discussion on the net about exposing human bodies to the vacuum - in '2001' there is such a scene (I did not see 'Total Recall'). If my memory serves me right, the body does *not* blow up or explodes, simply because the forces are much too weak. In the 50's and early 60's, some people believed the atmospheric pressure on Mars to be ~100 mbar. I am not shure whether a human could live in such an environment even with a respirator. -- Michael -- Michael Himsolt, Universitaet Passau, Postfach 2540, D-8390 Passau, GERMANY himsolt@fmi.uni-passau.de graphed@fmi.uni-passau.de ------------------------------ Date: 6 Dec 90 20:43:18 GMT From: spotted.rice.edu!jsd@rice.edu (Shawn Joel Dube) Subject: Re: Good Bye (Quite possibly my last posting from this site) In article <1990Dec6.051731.23161@rice.edu>, jsd@boreal.rice.edu (Shawn Joel Dube) writes: |> In article <114321@philabs.Philips.Com>, rfc@briar.Philips.Com (Robert Casey) writes: |> |> I'm afraid that this may be my last posting. Philips is having layoffs, and I |> |> might get canned..... |> |> |> This brings up a question. How many people subscribe to this |> newsgroup??? I'm curious to know. |> |> Just EMail a small letter and I'll post a total count in about a week. |> Sorry I ask!!!! It's well over 70 so......Please, no more mail :-) -- rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr r ___ _ "...but then there was the r r /__ | \ possibility that they were r r ___/hawn |__\ube LaRouche democrats which, of r r jsd@owlnet.rice.edu course, were better off dead." r rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr ------------------------------ Date: 6 Dec 90 23:29:40 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: BBXRT Status for 12/06/90 [1430 CST] (Forwarded) BBXRT Status Report #05 2:30 p.m. CST Dec. 6, 1990 Spacelab Mission Operations Control Marshall Space Flight Center, Huntsville, AL Controlling BBXRT and its Two Axis Pointing System (TAPS) from the ground at Goddard Space Flight Center in Greenbelt, MD, has allowed BBXRT team members the opportunity to do science observations despite today's shut down on the Dedicated Display Unit (DDU). During the next 12 hours while flight controllers, mission management and science teams work to troubleshoot the DDU problem, BBXRT team members at Marshall Space Flight Center and at GSFC will use this period to further test the alignment of the instrument and to look at several high priority targets, said Dr. Peter Serlemitsos of GSFC, principal investigator. Observations today include NGC 4051, a Seyfert galaxy, and Q 1821, a quasar. This afternoon, BBXRT also plans to observe Supernova 1987A. BBXRT was not part of the originally selected Astro payload. It was added to the mission after the appearance of Supernova 1987A in February 1987. ------------------------------ Date: 7 Dec 90 00:37:09 GMT From: window!mcconley@princeton.edu (Marc Wayne Mcconley) Subject: Dr. Scott Madry lecture Dr. SCOTT MADRY to speak at Princeton University Princeton, NJ - Dr. SCOTT MADRY, Associate Director of Cook College Remote Sensing Center at Rutgers University, will give a public lecture at Princeton University on the evening on Tuesday, December 11. He will discuss NASA's Mission to Planet Earth and the International Space University (ISU). Madry will serve as Chair of the Satellite Applications Department at the International Space University to be held in Moscow this summer. ISU offers graduate-level programs encompassing space-related fields from architecture and engineering to life sciences and business. In 1989 he was a Senior Project Manager at the Institute for Technology Development, Space Remote Sensing Center, at NASA Stennis Space Center. Madry has also conducted field research in the U.S. and Europe related to the applications of satellite remote sensing data for environmental and ecological analysis. His talk is sponsored by the Princeton Planetary Society, Princeton's space-interest organization and a chapter of the National Space Society. The event will begin at 7:30 pm in the Auditorium of McCormick Hall (the Art and Archaeology Building) on the Princeton University campus. Admission is free; parking is available. For more information, contact PPS President Audrey Robinson at (609) 258-7947. -- Marc W. McConley Vice President, Princeton Planetary Society Reply-To: mcconley@phoenix.Princeton.EDU || (609) 258-7674 ------------------------------ Date: Wed, 5 Dec 90 20:32:56 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Photon engine >From roberts Fri Nov 30 21:01:57 1990 >Subject: Re: Photon engine >Some other interesting general formulae to compare photon drives and matter >reaction mass drives: >Drive momentum xfer / energy >----- ---------------------- >photon 1 / c >matter 2 / v >which illustrates that a matter drive will always give more than twice as >much thrust per joule than a photon drive (since v < c). Also, a matter drive >uses energy more efficiently when exhaust velocity is lower, which means that >it is always in your best interest to use as much reaction mass as you have >available. Pushing against a large celestial body (i.e. linear launcher) is >particularly efficient. Note that the force of a photon drive depends only >on the power radiated - wavelength is irrelevant. Oops! As Steve Willner pointed out, this is a non-relativistic calculation for matter. Poking around with the numbers a little, I get: kinetic energy = rest mass * c^2 * ((1 - L) / L), momentum = rest mass * v / L where L = sqrt(1 - v^2 / c^2) Drive momentum xfer (impulse) / energy ----- -------------------------------- photon 1 / c matter v / (c^2 * (1 - sqrt(1 - v^2 / c^2))) which is about (2 / v) for (v << c), but which approaches (1 / c) as v approaches c. Thus, if exhaust velocity is very close to the speed of light, it doesn't matter whether you think of the exhaust as matter or energy, since the result is much the same. In either case, energy efficiency is much less than for the use of slower matter as reaction mass. For instance, a hydrogen- oxygen rocket engine with a specific impulse of 450 has (impulse / energy) or (thrust / power) of about 4.54E-4, meaning that it is nearly 140000 times as energy-efficient as a photon drive, which is why it is able to launch against earth's gravity with so little power and such a small total energy consumption compared to what a pure photon drive would require. Note: for the formula given above, you need plenty of digits of accuracy - I used 30. Also, for the photon purists, I believe that with the right material for a reflector, a "spotlight" would almost always be better than a laser. The coherence and monochromatic output of a laser don't get you anything, except perhaps in terms of the physical characteristics of the reflector. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 6 Dec 90 23:03:58 GMT From: uhccux!munnari.oz.au!metro!cluster!ultima!dcorbett@ames.arc.nasa.gov (Dan Corbett) Subject: Re: MAJOR SOLAR FLARE ALERT std_oler@HG.ULeth.CA (Cary Oler) writes: > Flare probabilities for the next 72 hours (ending 07 December) follow: > Flare Probability > Type 24hr 48hr 72hr > -------------- ---- ---- ---- > Class M Flare 60% 60% 60% > Class X Flare 20% 20% 20% > Proton Flare 05% 05% 10% Sorry if this has been discussed before, but could you give a brief explanation of what each of these types of flares are? ------------------------------------------------------------------------------ Dan Corbett University of Technology, Sydney Sydney, New South Wales, Australia ------------------------------------------------------------------------------ ------------------------------ Date: 6 Dec 90 17:36:28 GMT From: sdd.hp.com!wuarchive!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: * SpaceNews 03-Dec-90 * In article <1990Dec6.121859.836@qualcomm.com> antonio@drzeus.qualcomm.com (Franklin Antonio) writes: >... How can this billions of years stability stuff be science >if you can't test the result of the theory? Meet me in two billion years >for pizza. If it turned out that the solar system WAS stable, i'll buy you >a beer. Seen in Usenet newsgroup sci.space.celmech.history, 6 Dec 2000001990: The adjudicating committee appointed last year has regretfully announced that the Two Billion Year Bet has had to be called off. The pizza was good, but everyone had to buy their own beers. (The management did, however, agree to a special rate, only $6945/liter for an excellent import from Heidelberg IV. The local branches of the major US brewers offered to provide beer free, but everyone naturally ignored them.) Citing impossible difficulties in deciding whether the solar system would have been stable if left alone, the committee concluded that no settlement of the bet was possible. "Moving Venus and Mercury out was not that big a deal, and we think we could have allowed for that, but the Arts Council grant of 3476876 for rearranging the asteroids into aesthetically pleasing formations by modulating the orbit of Jupiter just caused hopeless confusion, and when the Flat Ecliptic Society started tidying the orbits up in preparation for the Galactic Fair of 78654379, well, that was the last straw. Not even the generous donation of five milliseconds of Cray-94673 time by UUNET Intergalactic Communications Inc was sufficient to decide what would have happened if the upkeep of the solar system had been neglected for so long." -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 6 Dec 90 22:59:53 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Astro-1 Status for 12/05/90 [2130 CST] (Forwarded) Astro 1 Shift Summary Report #12 9:30 p.m. CST, December 5, 1990 3/20:40 MET Spacelab Mission Operations Control Marshall Space Flight Center The Astro-1 astronomy mission's pace of observation continued to show improvement Wednesday as crewmembers aboard Columbia, along with the ground support team, made further progress with operations. During the period from noon to 8 p.m. (CST), a variety of targets were acquired and observed by the three specialized ultraviolet telescopes. The range of data-taking periods continued to vary substantially, from just a few minutes in some cases to some of the longest so far in the mission. One significant procedural improvement evolved during this period, in an effort to most efficiently aim and stabilize the ultraviolet telescopes on each planned target. The plan involves making a decision prior to beginning each observation period whether the crew should use the automatic or manual mode of locking on desired targets with the Instrument Pointing System (IPS) and star trackers. The determination as to the most promising acquisition mode is being made by a team in the Spacelab Mission Operations Control Facility and then voiced up to the crew aboard Columbia. "We still want to get to routine use of the automatic mode of IPS acquisition, since the pointing accuracy will be higher," said Astro-1 Mission Scientist Ted Gull. But, he said, the case-by-case determination regarding acquisition modes appears to be the best approach at this point in the mission. Some of the observations during this period stood out as particular highlights for science teams on the ground. For instance, following an observation of the quasi-stellar object 3C273, Principal Investigator Dr. Arthur Davidsen of the Hopkins Ultraviolet Telescope was elated. A congratulatory message from Davidsen was passed up to the Astro-1 crew, noting "the great 3C273 spectrum." And a period of data acquisition on the hot supergiant star P Cygni brought enthusiastic comments from members of the Wisconsin Ultraviolet Photo-Polarimeter Experiment science team. Crew Interface Coordinator Debra Underwood relayed to Columbia the message that "the WUPPE team really appreciates your effort on this target. They say they got a very good signal-to-noise ratio in the data." Ground controllers for the Broad-Band X-ray Telescope continued to work on fine-tuning the alignment of their instrument with its pointing system. Prior to this period, they had been acquiring good data, but experienced alignment difficulties which caused them to miss several data opportunities. They reported making progress during the afternoon and evening but were not yet successful in able to consistently get X-ray photons into their telescope's central detector element. Nevertheless, they acquired useful spectral data today during pointings at the X-ray source LMC X-1 in the Large Magellanic Cloud and at two galactic binaries -- 3U 0614+09 and EXO 0748-676. ------------------------------ Date: 6 Dec 90 14:27:41 GMT From: pilchuck!seahcx!phred!petej@uunet.uu.net (Pete Jarvis) Subject: Re: Payload Specialist Selection In article yamauchi@cs.rochester.edu (Brian Yamauchi) writes: > >How are payload specialists selected for shuttle flights? >Do payload specialists need to meet the same criteria as mission >specialists? In particular, do they need to meet the vision >requirement? >Is their training the same as for mission specialists, or is it >limited to the skills they will need for their particular mission? *Payload Specialists do not have to meet the same requirements as do MS's. *An MS is a career Astronaut. A PS is not. PS training is mission dependent *with the addition of about 6 months training in Houston on Shuttle Systems. --- Peter Jarvis --- Physio-Control, Redmond, WA. ------------------------------ Date: 6 Dec 90 04:49:55 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!news.cs.indiana.edu!msi.umn.edu!cs.umn.edu!kksys!wd0gol!newave!john@ucbvax.Berkeley.EDU (John A. Weeks III) Subject: Re: Another Russian first In article <1990Dec3.231611.6288@isc.rit.edu> swd0170@ritvax.isc.rit.edu writes: > We had the first space station (Skylab) BZZZT! Wrong. Skylab launched 14 May 1973, Salyut 1 launched 19 April 1971. Interesting to note that the Soviets have had a string of workable space stations, while Skylab 2 is sitting inside of the National Air & Space Museum. -john- -- =============================================================================== John A. Weeks III (612) 942-6969 john@newave.mn.org NeWave Communications ...uunet!rosevax!tcnet!wd0gol!newave!john =============================================================================== ------------------------------ End of SPACE Digest V12 #645 *******************