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 ; Fri, 19 Oct 1990 03:49:48 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 19 Oct 1990 03:48:57 -0400 (EDT) Subject: SPACE Digest V12 #470 SPACE Digest Volume 12 : Issue 470 Today's Topics: Re: Hubble Space Telescope (revisited) Re: disposal of N-waste into sun Re: You Can't Expect a Space Station to be Cheap Galileo Update - 10/16/90 PLUTO AND PIONEER 10 Magellan Update - 10/18/90 Re: Magellan/Venus Info Re: Where is 0 longitude, was re: Venus/Magellan, poles Theories needed on life Voyager Update - 10/18/90 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: 18 Oct 90 15:45:06 GMT From: agate!bionet!uwm.edu!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: Re: Hubble Space Telescope (revisited) In article <41353@eerie.acsu.Buffalo.EDU> v064lnev@ubvmsd.cc.buffalo.edu writes: > * It can be argued and supported that for many years our > government has witheld information from the people, > concerning extra-terrestrial life. A government that couldn't keep Iranscam secret for a few years has been hiding the biggest news in history for decades? When anyone in on the secret would know that spilling it would get his name not only in the news, but in the history books? Give me a break. -- "...the i860 is a wonderful source | Henry Spencer at U of Toronto Zoology of thesis topics." --Preston Briggs | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 16 Oct 90 13:55:50 GMT From: swrinde!cs.utexas.edu!sun-barr!newstop!texsun!convex!convex.COM@ucsd.edu (Dave Dodson) Subject: Re: disposal of N-waste into sun In article <1990Oct11.135855.353@helios.physics.utoronto.ca> neufeld@physics.utoronto.ca (Christopher Neufeld) writes: >In article <106611@convex.convex.com> dodson@convex.COM (Dave Dodson) writes: >>A launch into the sun requires sqrt (11^2 + 30^2) km/sec =~ 32 km/sec. >>This is so the payload, after having climbed out of the Earth's gravity >>well, is travelling away from the Earth at 30 km/sec. If the velocity >>vector is in the opposite direction from the Earth's velocity vector >>around the sun, the payload would fall into the sun. > > This is wrong. If something is fired away from the surface of the >Earth at Earth escape velocity of ~11 km/s, it will wind up pacing the >Earth in its orbit around the Sun at 30 km/s. This is regardless of the >direction in which the object is fired away from the surface. You still >need another 30 km/s to fall into the Sun. This makes a total of 41 km/s, >not 32 km/s. I don't understand why you felt you needed the Pythagorean >identity here. Recall from first-year physics classes that the "escape >velocity" is in fact a scalar, and that neglecting atmospheric effects, >any object fired in any trajectory which does not intersect the ground or >a mountain or something, will leave if fired in excess of 11 km/s. You have mistaken my statement of conservation of energy for an application of the Pythagorean Theorem. Let me explain... What I am going to do is break the trajectory into two parts. The first is when the object is near the earth and essentially under its gravitational influence. The second part is when the object is far from the earth and essentially under the sun's gravitational influence. This is the so-called "patched-conic" approximation to multibody orbital mechanics. I'll use the center of the earth as the origin of our coordinate system for the first part and the sun for the second part. The way I patch the parts together at the boundary is "good enough" for a first approximation. When you launch something from near the earth, some of the kinetic energy is transformed into potential energy as the object moves away. Conservation of energy states that PE(R) + KE(R) = PE(infinity) + KE(infinity) where R is the radius of the earthm, and by infinity, I mean "far enough from the earth that its influence is small compared to the influence of the sun." That is the boundary between parts 1 and 2 of the trajectory. If PE(R) is chosen to be zero, then we can compute PE(infinity) = integral from R to infinity of GmM/r^2 dr, where G = universal gravitation constant, m = mass of object, M = mass of earth, and r = distance from center of earth. Carrying out the integration gives PE(infinity) = GmM/R. So we have .5mV^2 = GmM/R + .5mv^2 or V^2 = 2GM/R + v^2 where V = speed at the surface and v = speed at infinity. If you set v=0 you get V = Vesc = sqrt(2GM/R), where Vesc = the escape speed from the surface. Hence, V^2 = Vesc^2 + v^2 This is the formula I was using in my earlier note. It looks like the Pythagorean Theorem, but it really is a statement of conservation of energy. To continue, we want to provide sufficient energy to the object, such that when it essentially has left the influence of the earth and is influenced mostly by the sun it will have a speed either of 30 km/sec backwards or 12 km/sec forwards, relative to the earth. In the former case, V^2 = 11^2 + 30^2 = 1021, so V ~= 31.95 km/sec In the latter case V^2 = 11^2 + 12^2 = 265, so V ~= 16.28 km/sec (I made an error in the latter calculation before. I computed the number whose value = 12 km/sec as 30/sqrt(2) instead of 30(sqrt(2)-1). The incorrect calculation gave a value close to 21 for what should have been 12. This gave 23.9 km/sec instead of 16.28 km/sec.) Thus, to launch into the sun, you must provide an object at the surface of the earth with a speed of 32 km/sec in the direction such that when it is a long way from the earth but before the sun makes too much difference, it is moving away from the earth in the opposite direction of the earth's motion around the sun. To launch into interstellar space, you provide 16.3 km/sec of speed in the such that when it is a long way from the earth but before the sun makes too much difference it is moving away from the earth in the same direction the earth is moving around the sun. I hope this helps you understand my posting. ---------------------------------------------------------------------- Dave Dodson dodson@convex.COM Convex Computer Corporation Richardson, Texas (214) 497-4234 ------------------------------ Date: 14 Oct 90 23:52:19 GMT From: eagle!news@ucbvax.Berkeley.EDU (Jeff Hojnicki) Subject: Re: You Can't Expect a Space Station to be Cheap In article ewright@convex.com (Edward V. Wright) writes: >Let's not mention that the last time NASA built a space station, with >Skylab, it took less than four years and about $1 billion to do it. Or >that we could build the equivalent using just one Space Shuttle external >tank today. Or that Lawrence Livermore National Labs has devised far >less costly space stations based on inflatible structures. Or that NASA >itself designed 50-man space stations, less than 20 years ago, that could >be built for less than the cost of the 8-man station proposed today.... There has been a lot of bandwidth lately devoted to the idea of using the shuttle ETs as habitable structure for a space station. The LLNL inflatible modules have also gotten a lot of press. However, each of these concepts only accounts for 1 part of a station, the habitable structure. Very little discussion has been voiced about the other important systems needed for a space station. So, my question is this. What does the LLNL scenario say about the following systems: - Power system - Thermal Control System - Communications - Propulsion & attitude control - Data management - etc. And while we are on the subject, what kind of systems would be used for the ET station? Hopefully, this will bring some interesting discussion. -- Jeff Hojnicki | jshoj@csd.lerc.nasa.gov | // // // // NASA/LeRC | jhojnicki@nasamail.nasa.gov | =====FREEDOM====== (216)-433-5393 | - - - - - - - - - - - - - - - - - -| // // () () // // "My opinions are my own, don't blame NASA for them!" | ------------------------------ Date: 16 Oct 90 18:55:40 GMT From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 10/16/90 Galileo Mission Status October 16, 1990 The Galileo spacecraft's performance continues to be excellent. Today, via the spacecraft 's stored sequence, the telemetry data rate was automatically increased from 40 bps to 1200 bps. This was the first opportunity based on link predictions to operate at 1200 bps since post-Venus flyby. However, ground data lock-up was unsuccessful due to use of the 34-meter station in Australia. Station coverage was recently altered to provide 70-meter coverage for Ulysses. However, several minutes later, as planned, the spacecraft was configured back to 40 bps with successful data lockup. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 18 Oct 90 02:33:37 GMT From: sdd.hp.com!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!dsinc!netnews.upenn.edu!vax1.cc.lehigh.edu!lehigh.bitnet!CK02@ucsd.edu Subject: PLUTO AND PIONEER 10 To elaborate, Pioneer 10 or 11 (or the Voyagers), didn't go on to Pluto because they took trajetories which concentrated their studies on the satilities of Saturn (for Pioneer 10 and 11 and Voyager 1) and of Neptune for Voyager 2. Therefore they couldn't get into the correct trajetory to whiplash the probe into an intersecting orbit with Pluto. I was disappointed myself since I believe Pluto should have been elected instead of the small moons of these planets. Also Pluto didn't become interesting till about 1985 which ruled out all but Voyager 2. Anyhow, according to the newsletter published by "The Planetary Society" there is a plan to attach a small phobe on a bigger probe which is heading for Jupiter or Saturn (I forget which one). This smaller probe would whiplash around the planet to Pluto ending up there sometime around 2015 or so. Chip Kerchner P.S. Is anyone out there from Univ of Arizona? If so, could you send me some electronic info on the PhD program in Computer Science and a bit about courses dealing with Astronomy. Mail to: ck02@lehigh.bitnet. ------------------------------ Date: 18 Oct 90 23:00:11 GMT From: agate!bionet!uwm.edu!caen!sdd.hp.com!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov!baalke@ucbvax.Berkeley.EDU (Ron Baalke) Subject: Magellan Update - 10/18/90 MAGELLAN STATUS REPORT October 18, 1990 The Magellan spacecraft has completed its 243rd orbit. The 7 star calibrations and 2 desaturations of the past 24 hours were successful with nominal attitude updates. All spacecraft systems are performing as expected while controllers continue to analyze the relationship between the gyro miscompares and the solar array drive position errors. It is possible that the spacecraft has developed a slight "shimmy," but the performance of the AACS (Attitude and Articulation Control Subsystem) for pointing the radar antenna and keeping the solar panels oriented to the sun is nominal. Final testing of the Superior Conjunction control sequences produced some changes and the command upload is expected later today. The radar system continues to operate normally, but there is still some degradation which may be due to the approach to Superior Conjunction. Several tests are planned and some temporary modifications to data processing methods are being considered to alleviate the adverse effects of the degraded data quality. The primary SAR (Synthetic Aperture Radar) processor is out of operation because of the failure yesterday of the input/output computer. Initial diagnosis and repair was started yesterday, and completion is expected late today. The Image Data Processing System is processing 13 mosaics to be used for scientific analysis and assess the radar system performance. Test altimeter swaths for orbits 604 and 605 were successfully processed. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 19 Oct 90 00:23:09 GMT From: munnari.oz.au!metro!news@uunet.uu.net (Tim Bedding) Subject: Re: Magellan/Venus Info From article <1990Oct13.181134.18861@jato.jpl.nasa.gov>, by baalke@mars.jpl.nasa.gov (Ron Baalke): > > ... since Uranus and Pluto are both rotating on their sides at about > 90 degrees ... Do you have a reference for that statement on Pluto? How did they find out? Surely not by radar. Tim Bedding Dept of Astrophysics Uni of Sydney ------------------------------ Date: 18 Oct 90 21:07:11 GMT From: agate!linus!philabs!briar!rfc@ucbvax.Berkeley.EDU (Robert Casey) Subject: Re: Where is 0 longitude, was re: Venus/Magellan, poles In article <901017.113902.EDT.JEFF@UTCVM> JEFF@UTCVM.BITNET (Jeffrey R Kell) writes: >One of the (more) unbelievable parts of "Close Encounters" (and others) >was the use of our latitude/longitude co-ordinate system. While latitude >can be inferred (or at least argued over as of late) what basis (if any) >is there for longitude? I suppose that you could, in your Sci-fi story, have the ETs watch our TV broadcasts, and have them see us show a map of the earth with the Greenwich longitude drawned on it. Like in a show on geography. But we're reaching for it here :-) ----------------------------------------------------------------------------- __/\/\__ o o My job is so secret, even I don't know what I'm doing! - ------------------------------ Date: 19 Oct 90 02:37:53 GMT From: eagle.wesleyan.edu!dlinder@CS.YALE.EDU Subject: Theories needed on life Could someone theorize on what humanoid life would be like on a planet 3 or 4 times the size of the Earth. I'm looking for theories on body structure, societies, technology, psychology, etc. Thanks, I appreciate any speculation. dml ------------------------------ Date: 19 Oct 90 03:00:06 GMT From: wuarchive!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@eddie.mit.edu (Ron Baalke) Subject: Voyager Update - 10/18/90 Voyager Status Report October 18, 1990 Voyager 1 The Voyager 1 spacecraft collected routine UVS (Ultraviolet Spectrometer) data on sources HD30614, HD217675 and HD27778. On October 8, one frame of high-rate PWS (Plasma Wave) was recorded. A TLC (Tracking Loop Capacity) was uplinked over the 70 meter antenna in Spain and completed over the 34 meter antenna in Australia. Voyager 2 The Voyager 2 spacecraft collected routine UVS data on sources PKS2155-304 and EG165. On October 9, one frame of high-rate PWS was recorded. Outages of 40 minutes and 1 hour 54 mintues occurred at the 34 meter antenna at Australia due to heavy rains on October 7 and 8. CONSUMABLE STATUS AS OF 10/18/90 P R O P E L L A N T S T A T U S P O W E R Consumption One Week Propellant Remaining Output Margin Spacecraft (Gm) (Kg) Watts Watts Voyager 1 5 36.3 + 2.0 367 55 Voyager 2 6 39.4 + 2.0 370 61 ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ End of SPACE Digest V12 #470 *******************