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 ; Sat, 28 Apr 90 02:49:09 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 28 Apr 90 02:48:26 -0400 (EDT) Subject: SPACE Digest V11 #327 SPACE Digest Volume 11 : Issue 327 Today's Topics: Galileo Update - 04/27/90 Re: [HELP] Re: YAPLI (Yet Another Pegasus Launch Idea) Re: The Drake Equation Re: [HELP] Re: PegBlimp (was Re: Pegasus launch from Valkyrie (or ...) Re: Fermi Paradox Re: Pegasus launch is a success! The Drake Equation ---------------------------------------------------------------------- Date: 27 Apr 90 23:50:08 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 04/27/90 GALILEO MISSION STATUS REPORT April 27, 1990 As of noon Friday (PDT), April 27, 1990, the Galileo spacecraft is 91,960,640 miles from the Earth, 18,762,160 miles from Venus and traveling at a heliocentric velocity of 71,230 miles per hour. Galileo is spinning at 3.15 rpm in a cruise mode-dual spin. The spacecraft attitude sun point angle is at 2.2 degrees. All thermal control temperature are within acceptable range. Round trip light time is 16 minutes, 24 seconds. The Venus-Earth (VE-3) sequence, which was successfully loaded onboard the spacecraft on April 20, went active as planned on April 23. Two SITURNS to lead the sun were successfully performed on April 23 and April 26. The spacecraft performance for these activities was as expected and without incident. Cruise Science Memory Readouts (MROs) were successfully completed for the Magnetometer (MAG), Dust Detector (DDS), and Extreme Ultraviolet (EUV) instruments on April 24 and 27. The eleventh RPM thruster "flushing" activity was successfully performed on April 27. The activity flushed the Z, L and S thrusters only. The P thrusters were not flushed since they are used periodically to perform the SITURNS. These activities were performed at 40 bps and consequently thruster temperature profiles were not available due to low telemetry sample rate. Successful flushing was inferred from other spacecraft measurements/events, including attitude control performance and thruster counts. The AC bus imbalance measurement remained nearly constant exhibiting very little change from about 47.5 to 48 volts. The DC bus imbalance measurement, however, fluctuated about 1.6 volts from 21.6 volts to about 20 volts with some fluctuations occurring during periods of relatively quiescent spacecraft operation; but some significant DC imbalance measurement changes (3 to 4 volts) were observed during some DC load switching events associated with the planned SITURN on April 23. However, during numerous earlier SITURNS no or very little (1-2 DN) imbalance measurement change was observed. During the SITURN activity on April 26, the DC bus imbalance measurement changed approximately 1 DN (.1 volt). During the uplink of the VE-3, the second command file was transmitted about two minutes earlier than requested by the Mission Control Team. This occurred after a ground uplink command abort and after the uplink had been restarted; the reason for the ground command abort is currently under investigation. The VE-3 sequence was properly loaded. The early transmission problem was later reproduced during ground tests and is associated with the particular procedure used to send the command files to the Command Processor Assembly (CPA) at the tracking station. A revised procedure to prevent the early transmission problem from reoccurring has been implemented while the Deep Space Network (DSN) investigates the problem further with the support of the Galileo Flight Control and Support Office. Investigation of the sinusoidal signature in the doppler residuals of the 70 meter antenna in Spain (DSS-63), which appeared shortly after launch prior to DSS-63 antenna bearing downtime, has been resumed now that DSS-63 doppler data from the Low Gain Antenna (LGA-1) is available again. Preliminary indications are that the previously observed variations are no longer present at DSS-63 and are not seen in the 70 meter antennas in Goldstone (DSS-14) or Australia (DSS-43). Assessment of the final data will be made before the matter is closed. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | Go Lakers! ------------------------------ Date: 28 Apr 90 02:22:35 GMT From: well!avery@apple.com (Avery Ray Colter) Subject: Re: [HELP] I've always been ticked that the DoD so blindly (except for research colleges) takes and takes and takes from education, and then turns around and wonders why there is a shortage of engineers and a predicted shortage of engineering faculty! Now, I'm not the highest GPA in my class (partly due to my reading netnews ), but it is clear to me that the current path of the Iron Triangle is not doing very well. The head of DARPA got demoted for trying to promote some civilian concentrations in technology projects. The next head is liable to be the classic militarist who will again train our best minds in skills which are of use only in milspec environments and don't count for shit in the capitalist battlefield that is the rest of the economy - you know, the part of the economy which actually PRODUCES something. Federal funding cuts do affect the states' abilities to fund school systems. If the general federal outlays to states are reduced, the states are forced to operate on a tighter belt. Which means education and many other local-level programs suffer. -- Avery Ray Colter Internet: avery@well.sf.ca.us | {apple|hplabs}!well!avery o/~ Mama, mama, mama, keep those skinny girls at home, o/~ `Cause this skinny boy wants a BIG FAT BLONDE! - The Rainmakers ------------------------------ Date: 27 Apr 90 14:54:06 GMT From: ccncsu!ncr-fc!mikemc@boulder.colorado.edu (Mike McManus) Subject: Re: YAPLI (Yet Another Pegasus Launch Idea) In article <9018@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: > > Kevlar cables should be ok for the above design. I not sure about > the pulleys (kevlar pulleys ok?). I have been trying to get some info > on kevlar stuff.0 I'm not an ME, nor am I a sailor, so my only real experience with pulleys was in physics lab, but... When I think of pulleys and block-and-tackle systems, I usually picture things moving rather slowly. Is it possible to have a pulley system running at thousands of miles an hour, or is that just asking for trouble? If the line got even slightly out of allignment with the pulleys, you would have a big mess, I would think. How could the alignment issue be addressed at such high speeds? -- Disclaimer: All spelling and/or grammer in this document are guaranteed to be correct; any exseptions is the is wurk uv intter-net deemuns,. Mike McManus (Mike.McManus@FtCollins.NCR.COM) <- This should work soon! NCR Microelectronics 2001 Danfield Ct. ncr-fc!mikemc@ncr-sd.sandiego.ncr.com, or Ft. Collins, Colorado ncr-fc!mikemc@ccncsu.colostate.edu, or (303) 223-5100 Ext. 307 uunet!ncrlnk!ncr-sd!ncr-fc!garage!mikemc ------------------------------ Date: 27 Apr 90 19:03:10 GMT From: sdd.hp.com!elroy.jpl.nasa.gov!jpl-devvax!lwall@ucsd.edu (Larry Wall) Subject: Re: The Drake Equation In article <10745@shlump.nac.dec.com> klaes@renoir.dec.com writes: : Needless to say, this formula is comprised mostly of currently : unknown factors; depending on various estimates, there may be as many : as one million or as few as ten advanced civilizations in our galaxy. ^^^ By some estimates there may be as few as one. We have too small a statistical sample of planets on which life developed to say Anything Whatsoever about the probability of life developing. Perhaps the probability is 1 in 10^28 and we just got lucky. By other estimates there may be as few as zero advanced civilizations in our galaxy... :-) I suppose a case could even be made that there are -1 advanced civilizations in our galaxy... :-) :-) :-) Larry Wall lwall@jpl-devvax.jpl.nasa.gov ------------------------------ Date: 26 Apr 90 18:50:23 GMT From: skipper!bowers@ames.arc.nasa.gov (Al Bowers) Subject: Re: [HELP] In article <650@gronk.UUCP> johnl@gronk.UUCP (John Limpert) writes: >That's what happens when public school systems hire people with >'education' degrees and refuse to set minimal standards. >I would like to see the public schools require courses in biology, >chemistry, physics and mathematics (statistics and algebra). >Why do they let students get away with 'business math' and >'general science'? There is no reason that most students couldn't >take and pass these courses. I would also require a secondary >school teacher to have majored in the field they are teaching. Both my in-laws are teachers. The fact that either of them are capable of tying their own shoelaces in the mornings amazes me sometimes (oh, that's right, they use Velcro! ;-). I have often thought about teaching high school math or physics or junior college level astronomy or... But I am told that even if I pass the California CBEST (teachers test) due to my lack of a degree in education (B.S. in Aero Engr and M of Engr in Aerothermo) and lack of experience (only 10 years as a working engineer here at NASA, 2 years as lead aerodynamics engineer on the F-18 high angle of attack vehicle project) that I would not be eligible for very many promotions. And these are the same educators that wonder why the U.S. can't compete against little countries like Japan. >-- >John Limpert johnl@gronk.UUCP uunet!n3dmc!gronk!johnl -- Albion H. Bowers bowers@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!bowers `In the changing of the times, they were like autumn lightning, a thing out of season, an empty promise of rain that would fall unheeded on fields already bare.' attributed to Abe Shosaburo by Dave Lowery ------------------------------ Date: 26 Apr 90 18:37:44 GMT From: phoenix!astro!michael@princeton.edu (Michael Woodhams) Subject: Re: PegBlimp (was Re: Pegasus launch from Valkyrie (or ...) In article <1990Apr22.184617.4836@kitenet.ann-arbor.mi.us> russ@m-net.ann-arbor.mi.us (Russ Cage) writes: >In article <15399@bfmny0.UU.NET> tneff@bfmny0.UU.NET (Tom Neff) writes: >>What about launching Pegasus from a dirigible? [stuff removed] >Yes, it matters a great deal. Mass-ratio requirements increase [stuff removed] >0 kg if launched with a 1134 m/sec penalty; >125 kg if launched with a 500 m/sec penalty; >247 kg if launched with a 0 m/sec advantage (blimp into polar orbit); >317 kg if launched with a 250 m/sec advantage (airplane into polar orbit); >385 kg if launched with a 470 m/sec advantage (eastward launch from equator); >469 kg if launched with a 720 m/sec advantage (eastward airplane launch). > >Note that a 9% advantage in launch speed gives a *90%* increase >in payload. This translates to a big cut in $/kg to orbit. I can't see any 9% advantages in launch speed, and certainly not any 90% increases in payload for small change in velocity. Almost doubling velocity increases the payload by 21% (from 250 m/s, 470 m/s figures.) >LTA craft have other problems: their lifting gas expands with >altitude, which gives them a service ceiling usually < 15,000 ft. >An airplane can climb above much more of the atmosphere, which >reduces drag penalties as well. In short, an airplane is a much >better launcher candidate than a blimp or dirigible. What ever gave you this idea? Balloons go higher than anything but rockets. If your balloon holds a fixed mass of gas, you simply enclose it in a much larger volume than the gas fills at ground level. More realistically, as you gain altitude you can let gas out of your balloon. Launching Pegasus at twice the velocity of the B52 is very hard and expensive, but launching from three times the height and zero velocity from a balloon should be simple. How does payload vary with launch altitude? Michael Woodhams. ------------------------------ Date: 26 Apr 90 08:37:25 GMT From: jtsv16!geac!sq!msb@uunet.uu.net (Mark Brader) Subject: Re: Fermi Paradox > Humans are very Chauvinist when it comes to carbon and water ] There are only 2 elements that are capable of being the basis of ] creating long, complex molecules, and those are carbon and silicon... } Actually, silicon makes a lousy carbon substitute. It's just different } enough chemically that it prefers to clump up in rings and the like ... Isaac Asimov (whose Ph.D. is in biochemistry, remember) addressed this question in a speculative 1961 essay called "Not As We Know It", reprinted in 1974 in the collection "Asimov on Chemistry". He proposed 5 hypothetical alternative chemistries for life, each suited to a different range of temperatures. Along with our own, the list from hottest to coldest is: Long-Chain Chemicals Reaction Medium 1. fluorosilicones simpler fluorosilicones 2. fluorosilicones sulfur 3. nucleic acids and proteins water 4. nucleic acids and proteins ammonia 5. lipids methane 6. lipids hydrogen The 6 cases fall into 3 pairs and the long-chain molecules would not necessarily be the same in each case; in particular, the proteins in number 4 would have more nitrogen and less oxygen than ours. -- Mark Brader "It can be amusing, even if painful, to watch the SoftQuad Inc., Toronto ethnocentrism of those who are convinced their utzoo!sq!msb, msb@sq.com local standards are universal." -- Tom Chapin This article is in the public domain. ------------------------------ Date: 26 Apr 90 23:41:21 GMT From: consp21@bingvaxu.cc.binghamton.edu (Ken Hoover) Subject: Re: Pegasus launch is a success! In article <89000015@ENO.Prime.COM> DWOLFF@ENO.Prime.COM writes: >[...] a winch sitting on the >ground that accelerates a Pegasus sitting on the ground (well, on a >dolly) to a high speed. Seems to me that a decent winch could get >our Peg up to several hundred miles per hour. > There's an amusement park just outside Pittsburgh, PA (Kennywood to all the natives) that has a loop-the-loop roller-coaster ride that consists of a long straight and level track with a single loop in it and two to reverse the direction of the train. The whole thing is powered by an 8' or so flywheel made from several layers of 2" steel plates that is kept spinning at high speed (3000+rpm?). To start the ride, the operator activates a clutch which makes the flywheel pull the train down the track toward the loop by the use of a sled that is reeled in by the flywheel, accelerating the train (10-12 cars) into and around the loop. An electric motor then kicks in to accelerate the flywheel back to its normal speed, and the whole thing is ready for the next trip. I suppose a similar thing might be useful for a small object to be projected at high speeds... >David Wolff >dwolff@eno.prime.com or DWOLFF%s41.prime.com@relay.cs.net >Disclaimer: the above posting is not intended to represent Prime >policy. - Ken ------------------------------------------------------------------------------ Ken Hoover [ consp21@bingvaxu.cc.binghamton.edu | consp21@bingvaxa.BITNET ] Senior undergraduate consultant, SUNY-Binghamton Computer Center - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - " Never trust a computer you can't lift. " - Stan Masor ------------------------------------------------------------------------------ ------------------------------ Date: 27 Apr 90 16:52:43 GMT From: shlump.nac.dec.com!renoir.dec.com!klaes@decuac.dec.com Subject: The Drake Equation The following formula, affectionately known as the Drake Equation, as it was created by Frank Drake (and Carl Sagan) in the 1960s, is set up thusly: N = R*fgfpneflfifaL N - The number of advanced technological civilizations in the Milky Way Galaxy. R* - The mean birth rate of stars in the Milky Way Galaxy. fg - The fraction of stars resembling the Sun which are not members of binary or multiple star systems. fp - The fraction of such stars with planetary systems. ne - The number of Earth-like planets in each system orbiting within the life-supporting zones of their stars. fl - The fraction of these planets where life has arisen. fi - The fraction of life-bearing planets on which life has developed intelligence. fa - The fraction of intelligent civilizations which have developed an advanced technology. L - The average lifetime of civilizations with advanced technology. Needless to say, this formula is comprised mostly of currently unknown factors; depending on various estimates, there may be as many as one million or as few as ten advanced civilizations in our galaxy. This equation also does not take into account intelligent races which may have developed in environments other than Earth-like worlds and do not possess and/or use technologies recognizable to humans. Larry Klaes klaes@wrksys.enet.dec.com or - ...!decwrl!wrksys.enet.dec.com!klaes or - klaes%wrksys.dec@decwrl.enet.dec.com or - klaes%wrksys.enet.dec.com@uunet.uu.net "The Universe, or nothing!" - H. G. Wells ------------------------------ End of SPACE Digest V11 #327 *******************