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, 20 Jul 1990 02:47:14 -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, 20 Jul 1990 02:46:44 -0400 (EDT) Subject: SPACE Digest V12 #99 SPACE Digest Volume 12 : Issue 99 Today's Topics: Re: Is an asteroid capture possible/feasible? Information needed on AEROSPIKE engine Re: World Space Agency Re: Is an asteroid capture possible/feasible? Re: Can a Twinkie survive launch to orbit? Galileo Update - 07/19/90 Re: Is an asteroid capture possible/feasible? Re: NSS elections Science article on HST Payload Status for 07/19/90 (Forwarded) New director named for Jet Propulsion Laboratory 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: 19 Jul 90 14:31:21 GMT From: usc!samsung!emory!hubcap!mephisto!prism!ccoprmd@ucsd.edu (Matthew DeLuca) Subject: Re: Is an asteroid capture possible/feasible? In article <3121@rwthinf.UUCP> dieter@rwthinf.UUCP (Dieter Kreuer) writes: >How about ice as a heat shield? In a SF story by Arthur C. Clarke (don't >remember the name of the book) they used hexagonal tiles of frozen water >to protect a spacecraft from being punctured by atoms at a speed close to c. Just for the record, the book is _The Songs of Distant Earth_. -- Matthew DeLuca Georgia Institute of Technology Do not meddle in the affairs of wizards, Office of Information Technology for they are subtle, and quick to anger. Internet: ccoprmd@prism.gatech.edu ------------------------------ Date: 19 Jul 90 15:42:34 GMT From: agate!shelby!portia.stanford.edu!etoyoc@ucbvax.Berkeley.EDU (aaron thode) Subject: Information needed on AEROSPIKE engine I would be very grateful if anyone could provide me with any of the following information: a) The location of a fluid dynamics code that has been configured to evaluate aerospike engine performance. A reference to an article in the literature would also be helpful. The codes at Los Alamos National Laboratory, where I work, can calculate the performance of conventional bell and certain plug nozzles, but not nozzles that utilize any sort of base bleed. b) The index numbers of any reports since 1984 that concern aerospike designs. I have conducted two database searches for papers on this subject, but the latest references I can locate are the work of Diem and Kirby (1977) and Reding and Jecmen (1984). Thank you, Aaron Thode ------------------------------ Date: 19 Jul 90 14:03:43 GMT From: eagle!news@ucbvax.Berkeley.EDU (Gregory Fedor) Subject: Re: World Space Agency In article <1231@unicorn.WWU.EDU> n8035388@unicorn.WWU.EDU (Worth Henry A) writes: > First, "the walls are tumbling down"...Ironically, in the very near >future the Soviets may become a member of the "reformed" NATO (Western >leaders have already been dropping some broad hints along this line), and >eventually, may even become one of the USA's best allies. A thought came to mind reading this...if the Soviets become our allies, whom would the group we'd be allied with them against? > But..., before anything like a WSA can come about, the major space >players, especially the USA, must be willing to give up CONTROL. Europe, >Japan and Canada can attest to the USA's insistence upon control over >joint projects, and an embarrassing tendency for the USA to back out from >its project commitments at the last minute (Europe and Japan currently seem I support the idea of a WSA especially since there are many compitent groups both public and private who've demonstrated their ability to use space effectively. I think that the USA needs to get its house in order above all else. IMHO it's been the attempts to perform joint projects that have have caused the USA to be the failing partner it is. Up until WWI the USA held to an isolationist policy that put us in the best position when the World Wars broke out. Maybe the same attitude needs to be done in the USA space program. I'm not talking about private USA concerns, this is still a free and open market, but rather the governments role. I`d like to see NASA return to what it has demonstrated it does best, research. Feed the research to industry, let them use it and they can participate in the WSA for the obvious commercial gains. Any thoughts on this idea??? DISCLAIMER: The views and comments expressed here do not reflect the policy of my employer or agency at which I work. Participation in this forum is done with knowledge of my employer and does not interfere with the course of my duties. . -- =============================================================================== Hailing frequencies closed... Gregory Fedor (216) 433-8468 FTS: 297-8468 Sverdrup Technology smfedor@lerc01.lerc.nasa.gov (128.156.10.14) NASA Lewis Research Center Cleveland, Ohio 44135 =============================================================================== ------------------------------ Date: 19 Jul 90 18:28:33 GMT From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: Is an asteroid capture possible/feasible? In article <3120@rwthinf.UUCP> dieter@rwthinf.UUCP (Dieter Kreuer) writes: >> As witness the Voyager navigation, zero-defects precision navigation is >> possible. It just has to be done right... > >Agreed, but the Voyagers don't have to be moved by nuclear charges. I'm no >expert, but I assume their thrusters to be based on simple retropulsion >of compressed gas, thus there is no ignition. What I mean to say is that >explosions or open flames are difficult to control... No, the Voyager thrusters ignite a monopropellant. Compressed-gas thrusters have relatively poor performance and are generally used only when there is some special reason (e.g. minimizing surface contamination). >... if the rock is rather massive and you need lots and lots of charges >to move it slightly, the effect of a single failure is negligible and you >can compensate for it with the next charges. The estimate I saw said one thousand 100MT bombs to shift a 1km asteroid, so it's definitely not something that happens suddenly, and there are plenty of chances to make corrections. >But then you need a whole lot of missiles to intercept the rock, and that >will cost mucho dinero. There ought to be enough mineral resources in the >asteroid, or the expenses won't pay off... The mass of that 1km asteroid is billions of tons, so it doesn't take very many dollars per kilogram to make it worthwhile. The sheer scale of the project is a more difficult problem, as the up-front investment is huge even if you expect a massive profit in the end. -- NFS: all the nice semantics of MSDOS, | Henry Spencer at U of Toronto Zoology and its performance and security too. | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 19 Jul 90 23:24:52 GMT From: uoft02.utoledo.edu!fax0112@tut.cis.ohio-state.edu Subject: Re: Can a Twinkie survive launch to orbit? In article <6181352956BF204C63@vaxsar.bitnet>, THBLERSCH@VASSAR.BITNET writes: > > In article <61AE5D13B7BF60047E@vaxsar.bitnet>, Bill Higgins (HIGGINS > %FNAL.BITNET@UICVM.uic.edu) writes: > >> A typical >>Twinkie was selected, placed into a plastic bag, and attached to a 2-meter >>rope. Our centrifuge operator first practiced by whipping an inert object (a >>roll of masking tape) around his head on a rope. Once he could sustain constant >>angular acceleration of the desired magnitude, we began the Twinkie run. > > I did not see the original post but I presume you are talking about a standard Hostess Twinkie. Well, since the official shelf life of said Twinkie is *20yrs* I think it could survive!!! Its amazing what they can do with plastics these days.... Robert Dempsey Ritter Observatory (That info is in the patent if you wish to check.) ------------------------------ Date: 20 Jul 90 00:44:49 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 07/19/90 GALILEO MISSION STATUS July 19, 1990 The Galileo spacecraft is 84.6 million miles from Earth, its orbit very slightly changed by Tuesday's successful trajectory correction maneuver. The round-trip communication time is now 15 minutes, 10 seconds. Speed relative to the Sun is more than 51,000 mph. This maneuver, the fifth since launch and third since the Venus gravity assist, was designed to refine the flight path toward the desired conditions for the Earth gravity assist. The spacecraft departed from Venus in February with, as expected, a heading almost but not quite toward its December 8 Earth rendezvous. A small part of the velocity change were to be contributed by spacecraft maneuvers in April and May and this week. The small maneuvers scheduled for October and November will do the final fine-tuning. The resulting Earth flyby will occur at 20:35 GMT or 12:35 p.m. PST December 8, more than 500 miles above the western Atlantic. This week's maneuver was itself small: 228 axial pulses and 160 lateral pulses changed the spacecraft velocity by 0.92 meters per second (about 2 mph), compared with 24 and 11 m/sec in the two previous maneuvers. Spacecraft health continues to be excellent, and system performance also excellent. The Deep Space Network provided round-the-clock tracking and telemetry coverage of Galileo for the few days around the maneuver; normal cruise coverage at this time is about one pass per day. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 19 Jul 90 12:42:01 GMT From: mcsun!unido!rwthinf!dieter@uunet.uu.net (Dieter Kreuer) Subject: Re: Is an asteroid capture possible/feasible? In article , heskett@titan.tsd.arlut.utexas.edu (Donald Heskett) writes: > Getting large chunks of astroidal mining products down to earth safely > involves non-trivial engineering, of course, but I think > straightforward theoretically. Chunks of metal larger than, say, > 1-foot on a side, seem to survive reentry from LEO without any > protection, although a considerable portion of their mass is ablated > away; larger bodies should make it through with proportionally less > ablation loss (Note: there will be absolutely more loss, but a larger > percentage of the original will survive until impact.). More > sophisticated approaches should do much better. How about ice as a heat shield? In a SF story by Arthur C. Clarke (don't remember the name of the book) they used hexagonal tiles of frozen water to protect a spacecraft from being punctured by atoms at a speed close to c. As water can absorb heat very effectively, especially when being vaporized, it should be possible to enclose a piece of metal as large as a football into a snow ball of cometary material and drop it into the atmosphere. I think the best place to aim at is a large dune of sand. Water, shallow or not, will be as hard as concrete for an object at about 1000 mph (my personal estimation). Or, drop it into the snows of Antarctica, so you don't risk to hit anybody's home, you get an effective shock absorber and you find the dark material more easily in the white snow (I don't think it will get covered with snow; most of the impact energy will vaporize snow, so that a crater will be formed; any material falling from the edge of the crater will melt from the hot metal; the rock may sink somewhat into the ice, but it will cool off fast enough to stay on the surface). ------------------------------------------------------------------------------- Dieter Kreuer, Lehrstuhl Informatik IV, RWTH Aachen, D-5100 Aachen dieter@informatik.rwth-aachen.de = dieter@rwthinf.uucp ------------------------------------------------------------------------------- ------------------------------ Date: 19 Jul 90 19:21:06 GMT From: usc!samsung!rex!uflorida!mephisto!utkcs2!mwauford@ucsd.edu (Melissa Wauford) Subject: Re: NSS elections In article <1990Jul18.164131.1504@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > >My own suggestion is the same as last year: if you vote for the petition >candidates and against the nominations-committee candidates, this is quite >a bit better than voting at random. Ah, but what do you do about people who are both petition candidates and chosen by the nominations-committee? The only person on the list that I actually know, Glenn Reynolds, fits this category. On the plus side he's young blood, smart, knowledgable, and has no ties to the aerospace industry. On the minus side he's a lawyer (well, ok, I probably shouldn't hold that against him) and tends to be a bit conventional in his thinking about space issues, though not stodgy. I suspect we shouldn't hold it against him that he's on the nominations committee slate. -- Melissa mwauford@utkvx1.utk.edu ------------------------------ Date: 19 Jul 90 21:48:29 GMT From: uvaarpa!murdoch!news@mcnc.org (Greg S. Hennessy) Subject: Science article on HST The 13 Jul 1990 issue of Science has a very nice article on HST, and what the point spread function looks like, verses what it was supposed to look like. The pictures are almost certainly not on the same scale however, the peak in the actual psf is lower than the peak of the desired psf. The article is one of the best I have seen so far. Near the end is an interesting bit about how early fears may have been overestimated. They mention that at least half a dozen radio astronomers have offered to help with the image deconvolution. One of the half dozen is probably Don Wells, who has posted several excellent (IMHO) articles to sci.astro and sci.space. WF/PC team member Todd Lauer is quoted as saying the (deconvolved) images look nice, but he isn`t sure he'd like to do science with them. The optical community is understandably cautious about the deconvolution, but as they get more used to it, it will be used more often. The article asserts that the image processing algorithms require supercomputer scale number crunching. This is misleading. I do image deconvolution on my Sun 3/260, althought naturally the more cpu power you have the better. -- -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w ------------------------------ Date: 19 Jul 90 17:52:50 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 07/19/90 (Forwarded) Daily Status/KSC Payload Management and Operations 07-19-90. - STS-35 ASTRO-1/BBXRT (at OPF) - Experiment monitoring continues. - STS-37 GRO (at PHSF) - The GRO/POCC end-to-end test continues today. - STS-40 SLS-1 (at O&C) - The STT will be transferred to the CITE stand today. - STS-41 Ulysses (at Hanger AO) - PAM-S integrated testing in CITE will begin today. - STS-42 IML-1 (at O&C) - Rack, floor, and module staging is continuing. - Atlas-1 (at O&C) - Freon line, electrical cable and experiment installations are continuing. - STS-46 TSS-1 (at O&C) - MLI installation will continue today. - STS-47 Spacelab-J (at O&C) - Rack staging continues. ------------------------------ Date: 19 Jul 90 21:21:42 GMT From: usc!jarthur!nntp-server.caltech.edu!deimos.caltech.edu!krs@ucsd.edu (Karl Stapelfeldt) Subject: New director named for Jet Propulsion Laboratory Dr. Edward C. Stone, Voyager Project Scientist and Caltech Vice-President for Astronomical Facilities, has accepted the job of director, Jet Propulsion Laboratory. He will succeed Dr. Lew Allen, who is retiring at age 65. After a transition period Dr. Stone will take over in December 1990. In my opinion, Dr. Stone is an excellent choice for the post. He knows the institution well, has an distinguished research record, and he has management experience with both academia and space projects. I must admit that I am slightly surprised that he took the job - he has several other significant science projects such as Chairman of the Board, CARA (the organization building the 10 meter Keck telescope) and Project Scientist for the Advanced Composition Explorer mission. It will be very interesting to see what he does in this post in the coming years. Karl Stapelfeldt Pasadena CA ------------------------------ End of SPACE Digest V12 #99 *******************