Date: Wed, 9 Sep 92 05:00:14 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #177 To: Space Digest Readers Precedence: bulk Space Digest Wed, 9 Sep 92 Volume 15 : Issue 177 Today's Topics: 20 Questions About the Delta Clipper (2 msgs) Galileo Update - 09/08/92 Is NASA really planning to Terraform Mars? (5 msgs) Pluto Direct/ options QUERY Re: Pluto Direct/ options Star Chart STS-47 SAREX info and latest prelaunch elements Terraforming TSTO vs SSTO WANTED: Cheap cpu cycles and Megaflops What is the speed of light measured from? Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 8 Sep 92 14:44:13 GMT From: Greg Moore Subject: 20 Questions About the Delta Clipper Newsgroups: sci.space In article <1992Sep1.144007.3396@iti.org> aws@iti.org (Allen W. Sherzer) writes: >This was prepared as part of a packet of information on the SSRT project >and the DCX and DCY vehicles. Permission is granted to reproduce and >distribute any way you want. > > Allen >-------------------------------- > > 20 question about the Delta Clipper > >12> Will it be able to fly to the Moon? > A Delta clipper derivative vehicle, re-fueled in Low Earth Orbit, >would be able to fly to the Moon, land there, and then return to Earth. >The modifications required, however, would be substantial. > In other words, don't hold your breath. When I read substantial modifications, I start thinking "new ship". >16> Why should I believe all these claims for the Delta Clipper > when similar ones were made for the Shuttle twenty years ago? > > The Shuttle's design was "frozen" in the 1970's. Using the technology >available then would have resulted in a SSTO that was extremely large and >expensive. A Delta Clipper sized SSTO based on 1970's technology would not >have ben able to reach orbit. In the 20 years since then, we have learned >a lot about design, light-weight materials, trajectory optimization, avionics, >computers, and engine design. > This is all nice, but I think it is not really a good answer. So what if the shuttle's design was frozen? And so what if the technology available then would have resulting in a large SSTO. No-one claimed the shuttle wsa to be a SSTO. This paragraph sounds more like an answer to the question: "Why didn't we do this with the shuttle 20 years ago?" I think in general the real question being asked in this case is how you plan to meet turn-around requirements and cost requirements. The above tells me nothing that relates to that. > In addition, the Delta Clipper is being designed with supportability >and operability as priority considerations. For example, the engines >on the Delta Clipper won't run at 110% of their design capacity, as the >Shuttle's do, so they won't have to be torn down and repaired before each >flight. If on-board diagnostic instruments indicate a problem with a >Delta Clipper engine or any other component, it is designed so components >(called line replaceable units) can be pulled and replaced quickly after >landing. > This is actually more to the point of answering the above question. However, I now have a couple oif questions of my own. The point about not running engines to 110% is a good one. And I will grant that you probbaly won't have to tear them down after each flight. However, we have no real-world experience on this matter. Yes, the RL-10 has been fired for so long and refired so many times, but until you build the DC-Y and fly it a few times, you have little idea of the actual wear and tear on the engines. You may find the atmospheric transit has strange affects (look at the British Comet) that negatively affect wear and tear, requiring more maintainance than required. And this is assuming you use the RL-10. Also, what work is being done to develop the LRU's? Or can they in most cases simply be adapted from aircraft LRU's. > >-- >+---------------------------------------------------------------------------+ >| Allen W. Sherzer | "If they can put a man on the Moon, why can't they | >| aws@iti.org | put a man on the Moon?" | >+----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 8 Sep 92 15:45:38 GMT From: Paul Dietz Subject: 20 Questions About the Delta Clipper Newsgroups: sci.space In article <0#4ygqc@rpi.edu> strider@acm.acm.rpi.edu (Greg Moore) writes: >In article <1992Sep1.144007.3396@iti.org> aws@iti.org (Allen W. Sherzer) writes: >> The Shuttle's design was "frozen" in the 1970's. Using the technology >> available then would have resulted in a SSTO that was extremely large and >> expensive. A Delta Clipper sized SSTO based on 1970's technology would not >> have ben able to reach orbit. In the 20 years since then, we have learned >> a lot about design, light-weight materials, trajectory optimization, avionics, >> computers, and engine design. > This is all nice, but I think it is not really a good answer. So > what if the shuttle's design was frozen? And so what if the technology > available then would have resulting in a large SSTO. No-one claimed the > shuttle wsa to be a SSTO. This paragraph sounds more like an answer to > the question: "Why didn't we do this with the shuttle 20 years ago?" For a history of the SSTO idea, you might want to look at this paper: AAS 91-643 Gary C. Hudson, "History of the Phoenix VTOL SSTO and Recent Developments in Single-Stage Launch Systems", in "International Space Year in the Pacific Basin", vol 77, Advances in Astronautical Sciences, pages 329-351, Amer. Astro. Soc. 1991. Hudson argues that the reason SSTO's have become "feasible" is simply that the customer, the government, has started to ask for them. Delta Clipper will use no advanced, NASP-derived materials. Hudson argues, as a thought experiment, that expendable SSTOs are quite feasible using shuttle technology. A shuttle ET, fitted with 6 SSMEs, can put some 60 to 70 klb into orbit (more if some structural mods, like removing the unnecessary SRB and orbiter attach structures, are made on the ET). A SIVB stage with a single SSME could put ~12 klb into orbit. Hudson adds (* indicates italics): It remains to be seen whether VTOL SSTO will become part of the means to achieve inexpensive access to space, but if it does, the principal question future observers of the space transportation business will ask is: *why did it take so long*? ---- Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 9 Sep 92 01:36:16 GMT From: Ron Baalke Subject: Galileo Update - 09/08/92 Newsgroups: sci.space,sci.astro Forwarded from: PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 GALILEO MISSION STATUS September 8, 1992 The Galileo spacecraft is almost 107 million kilometers (66.5 million miles) from Earth. It is just three months until the second Earth gravity assist, when the spacecraft will gain enough energy to fly to Jupiter, arriving just three years later. It is now almost 230 million kilometers (143 million miles) from the Sun, and its speed in orbit is 24.4 kilometers per second or 54,640 miles per hour. Galileo is operating normally, transmitting coded telemetry at 40 bits per second. Today and tomorrow, the flight team are conducting a diagnostic test of the antenna-deployment mechanism, in preparation for activities planned for January to try to free the stuck ribs of the high-gain antenna. This week's test will involve two pulses, separated by a day-long warming period. A similar operation was carried out in July, when the spacecraft was farther from the Sun, and therefore somewhat cooler. Today, the antenna motor region is estimated to be about -13 degrees Celsius (8.6 Fahrenheit); tomorrow, after the warming, it is expected to be about +8 Celsius (46 F). The engineers are studying temperature effects on the operation; in January, conditions will be nearly the warmest, believed most favorable for releasing the ribs. ##### ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Anything is impossible if /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you don't attempt it. |_____|/ |_|/ |_____|/ | ------------------------------ Date: 8 Sep 92 16:10:25 GMT From: David Knapp Subject: Is NASA really planning to Terraform Mars? Newsgroups: sci.space In article <14941@mindlink.bc.ca> Nick_Janow@mindlink.bc.ca (Nick Janow) writes: >knapp@spot.Colorado.EDU (David Knapp) enquires: > >> Thomas, would you expound on which bacteria or fungi can exist in a hot >> sulfuric acid/sulfur dioxide environment [Venus' upper atmosphere]? > >I don't know if there are any microorganisms that can survive those conditions >(I don't know that there aren't, either). However, Perhaps advances in >understanding enzymes and other building blocks of life will lead to engineered >life forms that can survive--even thrive--in that environment. Since we cannot forcast the future, I cannot argue with you on that. >These new >building blocks needn't be based on Terran life; they need only meet the >requirements for life on Venus (survival and replication, and possibly >mutation). They could even be wild & weird, such as buckyballs stuffed with >sulfur and/or some metal available as dust in the upper atmosphere, and with >chlorine or fluorine inside or out. Hmm, have you ever considered writing science fiction ? ;=) >Of course, the real problem with Venus is the lack of hydrogen, or the excess >of oxygen. Might Venus lose oxygen at a significant rate if there was free >oxygen in the upper atmosphere? There *is* free oxygen in the upper atmosphere. >Might free metal in the crust take in some of >the excess oxygen? The oxygen in the troposphere is not free. It is predominantly CO2. >The possibilities are interesting to think about, if >nothing else. :) Yes. -- David Knapp University of Colorado, Boulder Perpetual Student knapp@spot.colorado.edu ------------------------------ Date: 8 Sep 92 15:49:21 GMT From: "John F. Woods" Subject: Is NASA really planning to Terraform Mars? Newsgroups: sci.space Nick_Janow@mindlink.bc.ca (Nick Janow) writes: >Of course, the real problem with Venus is the lack of hydrogen, or the excess >of oxygen. Might Venus lose oxygen at a significant rate if there was free >oxygen in the upper atmosphere? Might free metal in the crust take in some of >the excess oxygen? The possibilities are interesting to think about, if >nothing else. :) One suggestion I heard was to slam a few large comets into Venus, thus adding hydrogen and blowing off big chunks of the atmosphere in one fell swoop. Not exactly a low-budget operation, mind you... ------------------------------ Date: 8 Sep 92 17:11:47 GMT From: "Thomas H. Kunich" Subject: Is NASA really planning to Terraform Mars? Newsgroups: sci.space Without references it is difficult to remember, but isn't there water, water vapor and possible liquid water along the interface of the Martian north pole? If so, shouldn't this represent a possible seeding area for life forms? I also seem to remember that the upper atmosphere of Venus was mostly water vapor even though the bulk of the atmosphere was sulphuric acid. Perhaps I didn't make myself clear enough. I don't believe that Venus could ever be made earthlike. I see the chance, however, of seeding life there and letting it make it's own way. The same with Mars. All of the grandiose plans aside I can't see the bulk of the necessary machinery being transported to Mars to terraform it and then the project continued for thousands of years. Earth has been changed dramaticaly by the life forms inhabiting it and I think that, given a chance, life will find a way to change both Venus and Mars to suit itself -- or to change itself to suit the conditions there. The only necessary assistance that we need make is to supply a large enough gene pool with enough of the correct survival genes to allow life to survive while these changes take place. ------------------------------ Date: 8 Sep 92 16:53:33 GMT From: Sam Warden Subject: Is NASA really planning to Terraform Mars? Newsgroups: sci.space Re Venus: We seem to know more about the Venusian atmosphere than I knew we knew. :-) Since when are the _upper_ clouds H2SO4? And, do we really know what the overall composition of the crust and atmosphere is, to say that there is somehow an "excess" of oxygen? Were Venus ever to cool off, I would expect ferocious amounts of oxidation/carbonation weathering to occur, for example. Re Mars: I'm impressed with the Gaia approach, to this negative extent: the lack of a fixed atmosphere on Mars seems like strong evidence that life is not active there now, or it would exhale one. I'm not convinced that `seeding' Mars would be impossible, but it would have to be not isolated spores but a complete ecosystem capable of maintaining its own microenvironment. A blob with a crust, so to speak. Things like the Dead Sea plankton that secrete glycerol come to mind. This is pretty dependent on whether the Martian crust is a pre-biotic permafrost as has been speculated, but I'm uncomfortable with dismissing the possibility out of hand. As for the morality of this sort of thing, I don't share the comfortable expectation that we as a civilization _have_ future centuries at our disposal for a conservative planetary exploration. The spread of terrestrial life to other now lifeless environments seems _very_ moral to me, even a moral imperative, given a possibly limited window of ability to do so. My opinion; others of course are free to differ. ;-) -- samw@bucket.rain.com (Sam Warden) -- and not a mere Device. ------------------------------ Date: Tue, 8 Sep 1992 19:21:40 GMT From: Paul Dietz Subject: Is NASA really planning to Terraform Mars? Newsgroups: sci.space In article samw@bucket.rain.com (Sam Warden) writes: > Re Venus: We seem to know more about the Venusian atmosphere than I > knew we knew. :-) Since when are the _upper_ clouds H2SO4? And, > do we really know what the overall composition of the crust and > atmosphere is, to say that there is somehow an "excess" of oxygen? > Were Venus ever to cool off, I would expect ferocious amounts of > oxidation/carbonation weathering to occur, for example. The "excess" of oxygen is that if the CO2 is converted to biomass and oxygen, we now have 100x more oxygen that in Earth's atmosphere. What that really means is that it is impossible to convert more than a tiny fraction of the carbon to reduced form before it is oxidized back to CO2 again. So the planet doesn't cool off. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 8 Sep 92 23:21:11 GMT From: Ron Baalke Subject: Pluto Direct/ options Newsgroups: sci.space In article <1992Sep7.173253.1837@access.digex.com>, prb@access.digex.com (Pat) writes... > >I saw parts of the pluto direct flyby talk by staehle from JPL. >they are talking of sending a 1-200 kg orbiter to pluto. > >Did they consider using energia? most of the charts I remember >were using titan or delta class launchers? A Pluto mission has always been a high priority since it is the only planet we have not sent a probe to. Also, since 1979, Pluto is closer to the Sun than Neptune and will not cross back over until February 10, 1999, and this is the closest Pluto will be for another 248 years. The proposed plan is to send two small spacecraft on a direct trajectory to Pluto for a flyby encounter. There will be no gravity assists, not even from Jupiter. The cruise time would be from 7 to 8 years with a Titan-4/Centaur launch, or 10 to 12 years with a backup Proton/D1E launch vehicle. Each spacecraft would weigh 330 pounds and carry a science payload of 15 pounds consisting of an imaging system (expected resolution at 1km), an infrared spectrometer and an ultraviolet spectrometer. The atmosphere of Pluto would also be studied with radio occultation. The reason for two spacecraft is that Pluto/Charon have a 6.4 day rotation rate, and a single spacecraft can only study one side from close range with a flyby encounter. The launches of the two spacecraft will be staggered by 3.2 days to allow observations of both sides of Pluto and Charon. The total cost of the mission would be no more than 400 million dollars and the launch dates would be in 1998 or 1999. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Anything is impossible if /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you don't attempt it. |_____|/ |_|/ |_____|/ | ------------------------------ Date: 8 Sep 92 10:56:18 GMT From: Tom A Baker Subject: QUERY Re: Pluto Direct/ options Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: >prb@access.digex.com (Pat) writes: >>they are talking of sending a 1-200 kg orbiter to pluto. > >Actually, they'd like to send two so that they can image both sides of the >planet. >>I was thinking an energia would allow a bigger bird or possibility of >>more thrust to slow down the encounter. > Could you clarify whether this craft is supposed to just flyby (a la Voyager) or is truly a Pluto "orbiter"? From the discussion, it does sound like a 'quick encounter' mission, which also makes more sense from a budgetary standpoint. Tom Baker ------------------------------ Date: 8 Sep 92 09:11:50 GMT From: Ridley McIntyre Subject: Star Chart Newsgroups: sci.space Hi, Is it possible for me to find a star chart (or set of charts) that show Sol's position in the Milky Way compared to other stars? All I can find here are charts of the Milky Way *from Earth* which don't actually show where we fit in to the rest of the universe. Is there one on archive somewhere? Well, I was kinda hoping it would be in a planar format (like a topographical map - 2-dimensional) and I would need the distances between the stars in parsecs (3-dimensional... [or +5... -5 from the x-plane in parsecs]). Does this make any sense? I hope it does. Thanks in advance, -- **Ridley McIntyre - Ronin Ironpig** gdg019@cck.coventry.ac.uk ----------------------------------- "It'll be a cold night tonight... If it's cold." - Iain Morales ------------------------------ Date: 8 Sep 1992 16:08:29 GMT From: Jay Maynard Subject: STS-47 SAREX info and latest prelaunch elements Newsgroups: sci.space,sci.space.shuttle,rec.radio.amateur.misc [These are the latest elements from the JSC Amateur Radio Club...see the comments below. In case your tracking program cares, these elements, like all NASA element sets, are equator-based. --K5ZC] FROM: G.L.CARMAN SUBJECT: STS-47 elements for Sep 12 launch I'm not sure if I already send you this or not. It's my element set for a Sep 12 launch with the new post OMS-2 vector that's a couple of miles higher. STS-47 1 00047U 92256.65952624 .00092000 00000-0 29200-3 0 59 2 00047 57.0020 107.3007 0012178 278.2332 81.7337 15.89557971 29 Satellite: STS-47 Catalog number: 00047 Epoch time: 92256.65952624 =====> (12 SEP 92 15:49:43.06 UTC) Element set: JSC-005 Inclination: 57.0020 deg RA of node: 107.3007 deg Space Shuttle Flight STS-47 Eccentricity: .0012178 Prelaunch SGP4 Keplerian Elements Arg of perigee: 278.2332 deg Launch: 12 SEP 92 14:23 UTC Mean anomaly: 81.7337 deg Mean motion: 15.89557971 rev/day G. L. Carman Decay rate: 9.2000e-04 rev/day*2 NASA Johnson Space Center Epoch rev: 2 ----------------- [...and here's a reposting of the STS-47 SAREX fact sheet, in case you missed it the first time around. --K5ZC] Shuttle Amateur Radio Experiment (SAREX) Fact Sheet STS-47 Space Shuttle Endeavour When: Mid-September, 1992 for 6 days of 2 meter operations. Where: Earth Orbit. Altitude 300 kilometers, with radio coverage of latitudes from 70 degrees North to 70 degrees South. Operators: Dr. Jay Apt N5QWL and Dr. Mamoru Mohri 7L2NJY. N5QWL is the flight engineer for STS-47 and will operate the shuttle systems during the "night" shift, while 7L2NJY will be one of the scientists performing experiments in a laboratory in the shuttle's cargo bay during the "day" shift. Modes: FM Voice VOICE CALL SIGNS: N5QWL and 7L2NJY Packet (Beacons giving daily mission activities by N5QWL daily if I get a chance, and robot QSOs - successful connects will be issued a contact number by the robot) PACKET CALL SIGN: W5RRR-1 Frequencies: We will operate split. PLEASE DO NOT TRANSMIT ON THE DOWNLINK FREQUENCY! VOICE: Downlink (shuttle transmits) on 145.55 MHz Uplink (ground transmits) on 144.95, 144.91, 144.97 (except over Europe) - we'll listen on those 3 frequencies to spread out the pileup a bit. Uplink for Europe only: 144.80, 144.75, 144.70 Successful QSOs on voice will be facilitated by using standard international phonetics for your call sign. We will not answer any stations using non-standard phonetics. Use your entire call sign - we log with an audio tape recorder. Do not use our call sign - passes are very short, and we want to work as many folks as possible. PACKET: Downlink (shuttle transmits) on 145.55 Uplink (ground transmits) on 144.70 (worldwide) If you can, decrease your radio's deviation to 3 KHz (most are initially set at 5 KHz) and compensate for the Doppler shift. If you cannot, wait until a minute or 90 seconds after we come over your horizon to transmit - that will put you within our IF. If a station transmits without following these suggestions, we just hear what sounds like a noisy carrier. The above applies to both voice and packet. QSL via: N5QWL, 806 Shorewood Drive, Seabrook, Texas 77586 USA Include a self-addressed stamped envelope (SASE). Non-US stations include a self addressed envelope with $0.50 of US postage affixed or appropriate IRCs. Include the Callsign worked, Date, UTC, Mode, and Frequency. For packet contacts, include the QSO number issued by the robot. SWL QSL's: Include the Callsign heard, Date, UTC, Mode, and Frequency. Information during the mission: AMSAT bulletins, Compuserve, Genie, Prodigy, local packet bulletin boards, ARRL bulletins, and HF voice from NASA Johnson Space Center ARC, Houston, Texas, W5RRR, or NASA Goddard Spaceflight Center ARC, Greenbelt, Maryland, WA3NAN, frequencies listed below. W5RRR may be found on or near: 7.215, 14.280, 21.360, and 28.400. WA3NAN retransmits NASA Select Audio and SAREX bulletins simultaneously on or near 3.860, 7.185, 14.295, 21.395, and 28.650. The NASA Info BBS at Johnson Space Center, Houston, will also carry Keplerian elements and SAREX bulletins. (713) 483-2500, 1200 baud, 8-N-1. At the ENTER NUMBER: prompt, type 62511 and log onto the BBS. The Keps and bulletins will be in the welcome message. Disconnect rapidly to facilitate access by others. Operations Notes: N5QWL will be asleep over most USA passes, and 7L2NJY will be busy with laboratory duties for most US passes, so try us on packet over the USA. Remember, our packet call sign is W5RRR-1. We'll try to work voice (1) when we are not otherwise engaged, and (2) at night or when the ground is cloudy (we are generally busy taking pictures of the Earth during clear daylight passes). Our orbit will carry us over the Northern hemisphere in daylight. We plan to work 6 schools on this mission: 2 in the US, 3 in Australia, and 1 in Europe or Africa. We do not plan any orbiter maneuvers after the first 6 hours of the flight, so orbital elements obtained early in the flight ought to be pretty good for the entire flight. If I can get to it, I'll activate the SAREX about 3 hours into the mission; deactivation will occur at about 6 days, 8 hours after launch. The orbiter attitude is planned to be tail down, payload bay south. The SAREX antenna will be in the right forward window, so most contacts should have a good antenna pattern from AOS to TCA (time of closest approach). 73, N5QWL 12 July 1992 -- Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can jmaynard@oac.hsc.uth.tmc.edu | adequately be explained by stupidity. "Keep in mind that Amateur Radio As We Know It Today will cease to exist at midnight tonight." -- Dave Newkirk, WJ1Z ------------------------------ Date: Tue, 8 Sep 92 18:22:11 BST From: amon@elegabalus.cs.qub.ac.uk Subject: Terraforming Mars may not be so difficult to terraform after all, if Dr. Robert Zubrin is correct. Two standard large fission plants put to work for a decade producing Methane are sufficient to push Mars into a "runaway greenhouse" that will very quickly (ie ~ 10 years) lead to a 1/3 Bar atmosphere of CO2, shirtsleeve temperature range and liquid water on the surface. In a luncheon talk at the recent ISDC he showed graphs which showed how Mars fell into a deep freeze a billion or so years ago when it hit the upper unstable point. But in the ensuing years, the sun has warmed up and the lower unstable point is now within 5F average planetary temperature of a runaway back to the original state. This might even happen on its own if theories are correct about Mars going through warm up cycles when its orbital parameters bring it into a warmer climactic periond. Zubrin then, is only suggesting we hurry it up by a few 100K years. I warm, wet CO2 atmosphere will lead to rapid spread of plant life. (At least plant life that does not require bees & other pollinators!) This is both a blessing and a problem. If the atmosphere is changed from CO2 rich to an O2, it will become transparent and may go back into deep freeze. Of course this would all take so many centuries that I'm sure it will not be considered difficult to fix by the far future descendants who have to deal with it: even the most pessimistic among us would have to assume we have full nanotechnology within ten or twenty thousand years!! (They may well preserve the outer kilometer as a museum of ancient human history and the rest of the body for more important uses, like building a Dysan Sphere or billions and billions of O'Neill Cylinders.) This brings up an interesting idea (copyright, all rights reserved) what if there is a dormant form of photosynthesizing bacteria on Mars? Then, when Mars goes into a warm period, Zubrin's runaway green house would occur; followed by massive thaws, as suggested by the presence of flood outflow channels on the Martian surface; the native "plant" life would bloom hysterically. It would shift the atmosphere towards greater transparency and as Mars continued to precess away from the warm max, it would fall back into the runaway deep-freeze and kill of the plantlife... I can account for the lack of unambiguously positive findings by Viking by the sterilizing effects of heavy surface UV over the large interrignum between thaws. No real evidence for the idea, but if true it would suggest that there would be dormant cells in stable, out of the way, well protected places. And for the uninitiated, yes, cells (on Earth) have been found to be viable after thousands of years of dormancy. I have hopes that Ad Astra will publish a popular account of Zubrin's work. I think their Mars special issue will be due out soon... ------------------------------ Date: Tue, 08 Sep 92 15:18:49 EST From: PHARABOD@FRCPN11.IN2P3.FR Subject: TSTO vs SSTO In article SECRET AIRCRAFT ENCOMPASSES QUALITIES OF HIGH-SPEED LAUNCHER FOR SPACECRAFT (Aviation Week & Space Technology, August 24, 1992) William B. Scott writes: "............ Observers descriptions, discussions with industry experts, and AVIATION WEEK & SPACE TECHNOLOGY analyses suggest that the large aircraft could be the first of a two-stage system designed to launch small payloads into orbit. Released at Mach 6-8 from a raised section on the aircraft aft deck, an unmanned vehicle would accelerate to orbital velocities, then release a small satellite in space. It could remain in the atmosphere or fly a suborbital flight path, carrying its own suite of reconnaissance sensors. This concept, at present, has not been confirmed by any U.S. government agency or military service. However, aeronautics and space experts agreed the concept has considerable merit, particularly for orbiting payloads essential to national security. Such a two-stage-to-orbit concept is hardly a new one, having surfaced as a candidate U.S. launching system in the 1950s. It also is the basis for Germany's Saenger design. Advancements in strong, lightweight and heat-tolerant materials - as well as breakthrough in hybrid propulsion systems - may have made the two-stage concept attractive for limited-weight, critical payloads. According to William R. Laidlaw, a former vice president of advanced systems for North American Rockwell and current founder/ CEO of Aerotest, early studies defined the characteristics of such an aircraft. He said a high-speed, air-breathing vehicle would tend to be long, with a high fineness ratio; have a broad, delta planform; probably would have wingtip-mounted vertical fins; use a multi-cycle propulsion system capable of reaching the Mach 6-8 regime, and be large enough to carry hydrogene, methane or other advanced, high-energy cryogenic fuel. ...................." ._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. If this is not fiction, but reality, could this (or an improved version) be a rival of the SSTO ? This project was probably initiated some ten years ago, and now there is no longer cold war: a civilian version may appear. Have the U.S. enough money to make both the TSTO and the SSTO ? J. Pharabod ------------------------------ Date: 8 Sep 92 15:54:51 GMT From: keith@msmri.med.ubc.ca Subject: WANTED: Cheap cpu cycles and Megaflops Newsgroups: sci.image.processing,sci.math.num-analysis,sci.physics,sci.space,comp.graphics,comp.visualization Please post replies to sci.image.processing or e-mail me directly. I will post a summaries of replies to sci.image.processing. I am interested in inexpensive hardware for large amounts of images processing. By inexpensive I mean for only a few thousand dollars or less. I am thinking along the lines of a additional processor board for a PC or SUN. I have seen PC mother boards with a Intel i860 coprocessor. Does anyone have any experience with this chip. I understand the gcc compiler (a free C complier) will generate code for the chip. Again, does anyone have any experience with this product or any other inexpensive number crunchers. Thanks in Advance Keith S Cover Physics, UBC Vancouver, BC Canada keith@msmri.med.ubc.ca ------------------------------ Date: 8 Sep 92 03:03:41 GMT From: Keith Harwood Subject: What is the speed of light measured from? Newsgroups: sci.space In article <1992Sep2.153142.7358@unocal.com>, stgprao@st.unocal.COM (Richard Ottolini) writes: > In article <2SEP199204264283@reg.triumf.ca> vincent@reg.triumf.ca (pete) writes: > >Neglecting the engineering problems of high speed travel through an > >imperfect vacuum, you can travel light centuries in subjective > >hours if you accelerate long enough. If you arrive at the Andromeda > >galaxy 2 weeks after leaving earth, you could be justified in > >thinking you travelled faster than c. It's just that the rest of > >the universe will have aged 2x10^8 years. > > No. You would not feel you are going faaster, but the universe got smaller > and slower. These are stardard result of Special Relativity. Neither of the above. The trick is that you are measuring the distance in one reference frame and the time in different frame. Divide one by the other and you get a number bigger than c. (Interstellar travellers might find this useful for navigational purposes.) However, if you measure distance and time in the same frame, you always get an answer less than c. Keith Harwood. ------------------------------ End of Space Digest Volume 15 : Issue 177 ------------------------------