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 ; Sun, 13 Jan 1991 01:40:15 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 13 Jan 1991 01:39:43 -0500 (EST) Subject: SPACE Digest V13 #037 SPACE Digest Volume 13 : Issue 37 Today's Topics: Re: US buys Soviet reactor Re: Interstellar Travel C code for planet locations? Re: Salyut 7 burn-up Re: LOX/LH2 in the Shuttle Payload Bay Condensed Canopus December 1990 Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 10 Jan 91 21:26:50 GMT From: idacrd!mac@princeton.edu (Robert McGwier) Subject: Re: US buys Soviet reactor From article <15859@reed.UUCP>, by trost@reed.bitnet (Bill Trost,Box 607,ext 640,): > > I'm not certain about satellite uses, but nuclear power sources are > used for long-distance probes (such as _Ulysses_), mostly because > there ain't that much sun way out, and possibly for reliability > reasons --- solar cells have to be exposed in order to function and > > Bill Trost Hi Bill: There is one helluva big difference between an RTG and a full fledged nuclear reactor. An RTG has a relatively small amout of (say) PLutonium encased in special pellet coatings put together is such a way that they generate heat which makes electricity from thermocouples. A nuclear reactor is one where you have quite a bit of nuclear material, not well protected pieces, in close proximity to each other, just right at critical mass, spewing out high speed neutrons, and other ugly stuff in order to produce copious amounts of heat to drive a large electric generator. This is needed to power really big radarsats, etc. It wasn't clear from your posting whether or not this was clear and there does seem to be some confusion on the net as to the distinction between the two. There is clearly a lack of seperation of the identity of the two different things to the general public. Bob . -- ____________________________________________________________________________ My opinions are my own no matter | Robert W. McGwier, N4HY who I work for! ;-) | CCR, AMSAT, etc. ---------------------------------------------------------------------------- ------------------------------ Date: 9 Jan 91 22:49:18 GMT From: wang!fitz@uunet.uu.net (Tom Fitzgerald) Subject: Re: Interstellar Travel henry@zoo.toronto.edu (Henry Spencer) writes: > (For starflight in particular, it is a mistake to try to > hurry too much, because probes launched later are quite likely to get > there sooner due to improved technology.) I would think that the improved technology would result from all the things you learned building and launching the earlier probes, meaning that if you don't launch probe1, then probe2 won't arrive any earlier than probe1 would have. It's worth hurrying a little, anyway. --- Tom Fitzgerald Wang Labs fitz@wang.com 1-508-967-5278 Lowell MA, USA ...!uunet!wang!fitz ------------------------------ Date: 9 Jan 91 21:09:34 GMT From: vicorp!ron@uunet.uu.net (Ron Peterson) Subject: C code for planet locations? I am interested in generating a graphic display of the planets and moons of the solar system where the correct position can be plotted for any date and time in the past, present or future. I know there is no precise solution to the n-body problem but is there an approximation that has been derived? Or are there tables calculated by NASA? Would someone please email me some source code (preferably C but anything will do) or direct me to a reference? Thanks! ron@vicorp.com or uunet!vicorp!ron ------------------------------ Date: 10 Jan 91 00:43:00 GMT From: research!phacb@ucbvax.Berkeley.EDU (A.C.Beresford) Subject: Re: Salyut 7 burn-up Since it is already in atmosphere the question has no meaning It is however an observed fact that re-entring satellites have been observed at heights of 109Km in the self-luminous phase. You can model the process approximately both numerically and analytically ( DG King-Hele Satellite orbits in an atmosphere) which gives a figure something like 1 day left by time orbit height = 160Km ------------------------------ Date: 10 Jan 91 16:29:54 GMT From: eagle!news@ucbvax.Berkeley.EDU (Dave McKissock) Subject: Re: LOX/LH2 in the Shuttle Payload Bay >In article <2105.27874AD6@ofa123.fidonet.org> Wales.Larrison@ofa123.fidonet.org (Wales Larrison) writes: >>... what to do if there was a shuttle contingency requiring them to >>rapidly dump the cryo propellants overboard. ... and Mr. Spencer answered in article <1991Jan8.003307.24830@zoo.toronto.edu> ... >This perfectly begs the question, of course: why do contingencies require >dumping cryo fuels from Centaur when no other fuel system carried in the >payload bay -- including, as far as I know, the cryogenic extended-duration- >mission pallet -- has ever had provisions for dumping? If you assume an >absence of leaks, the balloon tanks are very strong and rigid and present >no structural-failure hazards as far as I know. If you assume leaks, you >are in trouble even with hypergolics, all the more so because the usual >hypergolics are both corrosive and poisonous. >So far I'm sticking to my guns: the exclusion of Centaur from the payload >bay was the result of superstitious fear in the absence of strong political >support, not of a rational engineering decision. Shuttle Centaur would have had approximately 40,000 pounds of fuel on-board. This load, in addition to the weight of the Centaur structure, mounting support structure, and the payload, would have exceeded the return-to-launch-site abort weight restrictrictions of the Shuttle (for one example). Hence, the requirement to dump the fuel on the Centaur prior to a RTLS abort. -- ----------------------------------------------------------------------- Dave McKissock sakissoc@mars.lerc.nasa.gov NASA Lewis Research Center, Cleveland Ohio. Opinions expressed herein probably bear absolutely no resemblance to the official NASA position. ------------------------------ ReSent-Message-ID: Resent-Date: Wed, 09 Jan 91 09:16:03 EST Resent-From: Harold Pritchett Resent-To: Space discussion group Date: Wed, 9 Jan 91 13:13 N From: "Rob A. Vingerhoeds / Ghent State University" Subject: Condensed Canopus December 1990 Here is the condensed CANOPUS for December 1990. There are five articles condensed or in full and five articles by title only. Some articles are taken from What's New (Robert L. Park , The American Physical Society). CANOPUS is copyright American Institute of Aeronautics and Astronautics, but distribution is encouraged. See full copyright information at end. -----------CONTENTS -- 5 ARTICLES CONDENSED OR IN FULL----------------- ROE LEAVES THE HOUSE SCIENCE, SPACE AND TECHNOLOGY COMMITTEE! Whatsnew - can901201.txt - 12/10/90 When Robert Roe (D-NJ) left the Public Works Committee four years ago to become Chairman of SS&T he made a little speech to a group of science policy types: "I have," he proclaimed, "gone from the sewers to the stars." But Wednesday, Roe leaped at the opportunity to go back to the sewers after the Democrats ousted the infirm and unpopular Public Works Chairman, Glenn Anderson (D-CA). The influence of SS&T declined under Roe as a result the Deficit Reduction Act. By authorizing everything, SS&T ceded the real decision making to Appropriations. -------------------- GEORGE BROWN JR (D-CA) WILL SUCCEED ROE AS CHAIRMAN OF SS&T. Whatsnew - can901201.txt - 12/10/90 One of the few members of Congress with a technical background, Brown fended off a strong challenge from Marilyn Lloyd (D-TN). Brown must now decide whether he also wants to head the Space Science Subcommittee. There are several other vacancies on SS&T to be filled, including Chairman of the Subcommittee on Science, Research and Technology. -------------------- AUGUSTINE PANEL IS EXPECTED TO RELEASE WIMPY REPORT ON MONDAY. Whatsnew - can901201.txt - 12/10/90 The Advisory Committee on the Future of the US Space Program has been described as "the last best hope" for the space program. Its report, however, which is due out on Monday, will hardly be a bold call for change. According to the Wall Street Journal, the report will call for development of a costly new launch vehicle and decreased reliance on the shuttle, plus a few modest changes in NASA organization. -------------------- AUGUSTINE COMMITTEE SAYS NASA SHOULD PUT SPACE SCIENCE FIRST! Whatsnew - can901202.txt - 12/20/90 The Advisory Committee on the Future of the US Space Program confounded the skeptics by releasing a report that would transform NASA. The panel ranked space science above space stations, aerospace planes, manned missions to Mars, and all the other engineering spectaculars on which NASA has focused. The panel also called for drastic rethinking of the space station: "We do not believe that Space Station Freedom, as we now know it, can be justified solely on the basis of the (non-biological) science it can perform, much of which can be conducted on earth, or by robotic spacecraft at lower cost." Dependence on the shuttle should be reduced by developing a new unmanned heavy-lift launch vehicle. But how could the panel finesse the delicate subject of a manned expedition to Mars--which President Bush personally established as a goal? The panel wisely proposed a "go-as-you-pay" plan, under which the schedule for the mission to Mars would be determined by the availability of funds. -------------------- ULYSSES NUTATION MAY CAUSE DATA PROBLEM can901203.txt - 12/21/90 Dec. 18, 1990 The Ulysses solar polar mission is facing a loss of data from an unexplained wobble that engineers are having trouble isolating. The wobble in the spacecraft's rotation that has been present since Nov. 4 has steadily decreased from about 6 degrees side-to-side to a current value of about 3 degrees side-to-side during the last week of November as a greater percentage of the spacecraft's axial boom moves into the shade and as the spacecraft's distance from the Sun increases. Project officials believe that solar heating of the axial boom exacerbates the wobble. They do not anticipate any immediate actions to attempt to reduce the wobble, but rather plan on watching its behavior over the next weeks as the axial boom moves into more complete shade. The 7.5-meter (24.3-foot) boom is used as an antenna for the mission's Unified Radio and Plasma-Wave experiment. However, in response to media queries, program officials conceded that 10 percent or more of the mission data could be lost if the wobble causes problems in pointing Ulysses at Earth tracking stations during the solar pole flyovers. Some minor ground problems have occurred as well. A mechanical failure at the Canberra station cost five hours of playback data. It has also been noted that when data are being acquired from the Madrid station, the frequency of data dropouts between the station and JPL is higher than from other stations. -----------------5 ARTICLES BY TITLE ONLY------------------------------- HAPPER IS EXPECTED TO BE THE NEW DIRECTOR OF ENERGY RESEARCH! Whatsnew - can901201.txt - 12/10/90 ERRATUM: WE HAD THE WRONG NORTH CAROLINA CONGRESSMAN MOVING Whatsnew - can901202.txt - 12/20/90 DID ANYBODY BRIEF THE AUGUSTINE PANEL ON THE BUDGET AGREEMENT? Whatsnew - can901202.txt - 12/20/90 DOES ASTRONOMY STIMULATE REPRODUCTION OF MT. GRAHAM SQUIRRELS? Whatsnew - can901202.txt - 12/20/90 IS THE NSF BEING EVICTED FROM THE DOWNTOWN WASHINGTON LOCATION Whatsnew - can901202.txt - 12/20/90 ------------------END OF CONDENSED CANOPUS--------------------------- This posting represents my own condensation of CANOPUS. For clarity, I have not shown ellipses (...), even when the condensation is drastic. New or significantly rephrased material is in {braces} and is signed {--RV} when it represents an expression of my own opinion. The unabridged CANOPUS is available via e-mail from me at any of the addresses below. Copyright information: ------------------------------------------------------------------------ CANOPUS is published by the American Institute of Aeronautics and Astronautics. Send correspondence about its contents to the executive editor, William W. L. Taylor (taylor%trwatd.span@star.stanford.edu). Send correspondence about business matters to Mr. John Newbauer, AIAA, 1633 Broadway, NY, NY 10019. Although AIAA has copyrighted CANOPUS and registered its name, you are encouraged to distribute CANOPUS widely, either electronically or as printout copies. If you do, however, please send a brief message to Taylor estimating how many others receive copies. CANOPUS is partially supported by the National Space Science Data Center. ------------------------------------------------------------------------ ------------------------------ End of SPACE Digest V13 #037 *******************