Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from holmes.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Tue, 25 Apr 89 05:16:43 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 25 Apr 89 05:16:34 -0400 (EDT) Subject: SPACE Digest V9 #393 SPACE Digest Volume 9 : Issue 393 Today's Topics: Re: Shuttle Acceleration Re: MUFON Journal "alien spacecraft" article Re: Proposed lunar simulation facility NSS Hotline Update Re: Is 'better than gravity assist' use Re: Is 'better than gravity assist' used? Condensed CANOPUS - March 1989 ---------------------------------------------------------------------- Date: 23 Apr 89 14:23:11 GMT From: b.gp.cs.cmu.edu!Ralf.Brown%B.GP.CS.CMU.EDU@pt.cs.cmu.edu Subject: Re: Shuttle Acceleration In article <1989Apr22.215957.4317@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: }In article V131Q5CG@UBVMSC.CC.BUFFALO.EDU (John Taylor) writes: }>>There are tradeoffs here. Higher acceleration is generally more efficient, }>>as you spend less time fighting gravity. }> }> Less time fighting gravity? I can't see what time has to do with it. } }Remember that slow, ponderous rise of the Saturn V off the pad? Well, of }those 7.5 million pounds of thrust, 6+ were doing nothing but holding the }thing up against gravity. Only the remaining 1.5- were accelerating the }rocket upwards. That's an expensive way to gain velocity, which is one of }the reasons why the shuttle takes off rather more briskly. As an analogy, consider a bank loan. The lower your payments (i.e. lower acceleration), the longer it takes to pay back, and the higher the total cost, since a larger portion of each payment goes to interest (i.e. fighting gravity) rather than the principal (i.e. accelerating). -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/31 Disclaimer? I claimed something? You cannot achieve the impossible without attempting the absurd. ------------------------------ Date: 23 Apr 89 19:18:59 GMT From: cs.utexas.edu!ut-emx!bonin@tut.cis.ohio-state.edu (Marc Bonin) Subject: Re: MUFON Journal "alien spacecraft" article In article <11322@tekecs.GWD.TEK.COM>, nobody@tekecs.GWD.TEK.COM (-for inetd server command) writes: > [much preceding baloney deleted] > The most interesting transmission occurred seven minutes later at 6:42 a.m. > EST, when one of the astronauts made this statement "Houston (from) Discovery, > we still have the alien spacecraft under observance." Don Ratsch called [more baloney deleted] April fools day was 3 weeks ago in case you missed it. > I will watch for additional material in the next MUFON UFO Journal and > post it to the net. May I suggest pseudo.sci.bs as the appropriate forum for this National Enquirer type garbage ??? Marc Bonin Dept. of Aerospace Engineering University of Texas at Austin ------------------------------ Date: 23 Apr 89 13:02:48 GMT From: mentor.cc.purdue.edu!l.cc.purdue.edu!cik@purdue.edu (Herman Rubin) Subject: Re: Proposed lunar simulation facility In article <1989Apr22.214455.3661@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: > In article <8904181746.AA07962@cmr.icst.nbs.gov> roberts@CMR.ICST.NBS.GOV (John Roberts) writes: > >>Los Alamos proposes to build a lunar-surface simulation facility for > >>testing lunar mining and construction hardware... > > > >Is that a computer simulation testbed, or an actual physical construction > >to emulate the lunar terrain? > > The latter, complete with vacuum chamber etc. And I suppose they will manage 1/6 g also? What about the differences between selenology and geology? Is our desert dry enough to simulate lunar aridity? There are construction and mining techniques which can be used in 1/6 g which cannot be used in 1 g and vice versa. It is not just the vacuum. -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907 Phone: (317)494-6054 hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP) ------------------------------ Date: 22 Apr 89 16:18:00 GMT From: arisia!cdp!jordankatz@lll-winken.llnl.gov Subject: NSS Hotline Update This is the National Space Society's Space Hotline for the week ending April 21, 1989. The National Space Society would like to congradulate all space advocates who urged defeat of Rep. Silivo Conte's proposed Space Station killer amendment. The move, which would have transferred FY'89 dollars for NASA to other domestic programs, was withdrawn by the Massachusetts republican. The first stone has been cast. Your voices have been heard, but a lot more talking will have to be done to save space! At Kennedy Space Center........ Preparations are being made for the launch of the Space Shuttle Atlantis and ultimately the deployment of the Magellan Venus Radar Mapping spacecraft. Close out of the orbiter had thus far gone smoothly, and the power up test of the Magellan spacecraft was nominal. The scheduled launch date for the mission is Friday April 28 at 2:24pm in the afternoon with a 23 minute launch window. The Space Shuttle Columbia continues to undergo testing this week, with checkouts of the main propulsion systems and life support systems. The orbiters main engines are scheduled to be installed next week. With the stroke of a pen President Bush signed the executive order this week establishing the National Space Council. During the ceremony in Vice President Dan Quayle's office, Bush stated that the National Space Council will provide coherence, continuity and commitment to the US exploration and development of space. Mark Albrecht, a former national security advisor for Sen. Pete Wilson, is director of the council. Administration sources say that the Defense Resources Board has recommended cutting all funding for the development of the National Aerospace Plane. Meanwhile, supporters of the research project scrambled to get high level support for the NASP. Currently at least seven members of congress have written President Bush to try to head off the decision. The project would be handed over to NASA dispite the fact that there is no extra money in NASA's budget to take on more than 20% of the development costs. By slashing the DoD's funding of the program, the project would effectively be killed. The much anticipated launch of the Hubble Space Telescope might be put off until 1990. Nasa's reassessment of the 1989 Shuttle schedule has shown that the Columbia orbiter will not be available for launch until July 31, 1989 instead of July 1, 1989. Meaning that a launch must be bumped in order to accommodate the launch window of the Galileo Jupiter Spacecraft. NASA currently does not have the Orbiters, hardware and manpower to support its full 1989 launch schedule. A rather large asteroid passed within half a million miles of the earth undetected last March 23rd. If the asteroid would have struck the earth it would have caused widespread damage to the planet. The impact would have been equal to setting off 20,000 one megaton nuclear weapons in the same spot, which would create a crater between 5 and 10 miles wide and about a mile deep. The half mile diameter asteroid orbits the sun at about 46,000 miles an hour in an elliptical orbit that crosses the Earth orbit about once a year. The passage was the closest since 1937, and could come even closer in the future. In order to save money the Soviet Union will vacate their Mir space station temporarily until a new research module is available for deployment. The three cosmonauts aboard the platform are preparing to return to Earth around April 27. Some foreign observers of the Soviet manned space program have reported difficulties with the station, including high temperature problems, a pressure leak, a faulty power supply, and a water leak behind a panel which could pose electrical problems. The Soviets have completely failed at all attempts of trying to reestablish communications with the Phobos-2 space probe. A three week effort by scientists to save the probe are over. The loss of the two Phobos spacecraft have cost the Soviets $435 million and its international partners $96 million. Due to vibration problems, Arianespace has delayed the launch of its Ariane 44L booster for several weeks. Based on the first three launches of the Ariane 4, there has been an indication that the 44L with its four liquid strap on boosters, will encounter severe vibrations in its third stage and payload sections of the core Ariane 4 vehicle. The launch which was scheduled for April 28, will be delayed till engineers can run additional tests on the same booster equipment. We would like to invite everyone to call our Dial-a-Shuttle service during the upcoming Atlantis mission. Hear the Astronauts and Ground Control 24 hours a day during the mission. Take part in the mission by calling 1-900-909-NASA (that's 1-900-909-NASA). Toll charges are 2.00 for the first minute and $.45 for each additional minute. This has been Jordan Katz reporting for the National Space Society's Space Hotline. I will be attending the launch of the Space Shuttle Atlantis, as well as the rest of the Space Hotline Staff, so the next update will be filed live from the Kennedy Space Center April 28, 1989. ------------------------------ Date: 22 Apr 89 20:13:00 GMT From: m.cs.uiuc.edu!s.cs.uiuc.edu!carroll@uxc.cso.uiuc.edu Subject: Re: Is 'better than gravity assist' use Yes, you do get "more" out of your fuel if you burn it at the bottom of a fly-by. This is because the fuel has gravitic potential energy that is converted to kinetic as you fall down the gravity well. This would normally be re-converted to potential as you leave the well, but not if you leave the fuel behind (i.e., burn it). So, by burning at the bottom, you gain not only the "normal" boost you would expect, but also get the gravitic potential. This is in addition to the momentum you steal from the planet's orbital momentum by doing the fly-by. I don't know the relative magnitudes though, and am too lazy to figure them out. Alan M. Carroll "And then you say, carroll@s.cs.uiuc.edu We have the Moon, so now the Stars..." - YES CS Grad / U of Ill @ Urbana ...{ucbvax,pur-ee,convex}!s.cs.uiuc.edu!carroll ------------------------------ Date: 21 Apr 89 12:51:07 GMT From: erc@tybalt.caltech.edu (Eric R. Christian) Subject: Re: Is 'better than gravity assist' used? In article <473@vice2utc.chalmers.se> d5kwedb@dtek.chalmers.se (Kristian Wedberg) writes: >Gravity assist has been used many times, by the Voyager-probes for instance. >The way I understand it, however, is that if you use a part of your fuel >just when you swing by the moon/planet/sun, you can reach a higher >velocity than if you use it all up when you start the voyage. > >Is this so and has it been used, or did I break something in the energy-laws? > > > -kitte There are two different processes involved here. A gravity assist uses the fact that you are falling into a moving gravity well (such as a planet) to give you a higher velocity in another reference frame (such as the Solar System). In the spacecraft-planet center of mass frame (essentially the planet CM) you come out of the gravity well with the same speed as when you went in just as you would expect. Your extra energy is taken from the planet. The other process comes about because thrusters give you DELTA V not DELTA E. Your DELTA E is proportional to V * DELTA V, so if you use your thrusters at your lowest point in the gravity well, when your velocity is the highest, you get more kinetic energy out of the same thrust. This will end up giving you more velocity when you come out of the gravity well than if you had fired your thrusters at another time. Dr. Eric R. Christian ALIEN SPACECRAFT STEALING EARTH'S ORBITAL erc@tybalt.caltech.edu ENERGY! Earth to spiral into Sun! echristian@lheavx.gsfc.nasa.gov Future Weekly World News article ------------------------------ Date: 23 Apr 89 08:35:27 GMT From: cfa!cfa250!willner@husc6.harvard.edu (Steve Willner P-316 x57123) Subject: Condensed CANOPUS - March 1989 Here is the condensed CANOPUS for March 1989. There are 7 articles. CANOPUS is copyright American Institute of Aeronautics and Astronautics, but distribution is encouraged. See full copyright information at end. -------------- CONTENTS -- 3 ARTICLES CONDENSED ----------------- INTENSE MAGNETIC STORM - can890301.txt - 3/13/89 CURRENT SOLAR ACTIVITY - can890303.txt - 3/17/89 NASA GODDARD CENTER REQUESTS COMMERCIAL LAUNCH SERVICES PROPOSALS - can890304.txt - 3/31/89 ----------------------------------------------------------------- INTENSE MAGNETIC STORM - can890301.txt - 3/13/89 "The Magnetic Storm of March 13, 1989: Good News and Bad News for Spacecraft Operators" (From the Space Environment Services Center, Boulder, CO) The most intense geomagnetic storm in 3 years (and possibly since 1960) began on 13 March, 1989. Under the category of BAD news, both surface and deep dielectric charging associated problems are expected to plague many spacecraft, especially platforms in high inclination orbits, during this period of high activity. In addition, owing to rapid fluctuations in the relative altitude of the magnetosphere, geosynchronous satellites will periodically be directly exposed to the space environment. For low altitude spacecraft, drag will become a problem due to increased atmospheric density caused by high solar fluxes and geomagnetic activity. Now for the GOOD news. Because of the relative increase in the density of solar wind plasma associated with this extreme geomagnetic activity, the flux of galactic cosmic rays is reduced over normal background levels (a Forbush decrease). Therefore, the number of galactic cosmic ray single event upsets (SEUs) are expected to be depressed over normal levels. Every cloud has a silver lining. CURRENT SOLAR ACTIVITY - can890303.txt - 3/17/89 Contributed by Joe Allen Since Monday morning, 6 March, there have been several large flares per day. The largest, measured by GOES sensors but off scale at maximum, was rated X15 in X-rays and 3B optically. It was long-lasting, about 16 hours. On Friday, 10 March, an X4 flare -occurred that was optically rated 4B -- the largest area and intensity rating possible (some have speculated the largest area flare ever seen). Because of its location near the Sun's East limb, the large Monday flare only caused a relatively minor geomagnetic storm on 8 March; however, a long- lasting proton event was announced by the NOAA Space Environment Lab's Space Environment Services Center (SESC). The X14/3B flare also was rich in par- ticles and radio bursts and would have had greater impact at Earth if it had occurred closer to Central Meridian. The Friday flare produced a much larger magnetic storm, possibly of historical significance. NASA GODDARD CENTER REQUESTS COMMERCIAL LAUNCH SERVICES PROPOSALS - can890304.txt - 3/31/89 NASA's Goddard Space Flight Center, Greenbelt, Md., has requested proposals from commercial sources to launch three satellites in the International Solar-Terrestrial Physics (ISTP) program, plus options for NASA to order up to 12 additional launches over the next 5 years. The three ISTP satellites for which launch services would be be procurred under the RFP are the Wind, Geotail and Polar. Their launches are scheduled in 1992 and 1993. Under the agreement, the contractor would furnish all supplies, including the launch vehicle, facilities, personnel, and services necessary to design, produce, test, integrate and launch the missions into the required orbit. ---------------- Other Articles by Title Only----------------------- NEXT CDAW WORKSHOP SERIES SCHEDULED - can890302.txt - 3/15/89 {Coordinated Data Analysis Workshops} NASA AND JAPAN SIGN SPACE STATION MEMORANDUM OF UNDERSTANDING - can890305.txt - 3/31/89 CONTRACTS AWARDED FOR ADVANCED LAUNCH SYSTEM ADVANCED DEVELOPMENT PROPULSION - can890306.txt - 3/31/89 RECENT NASA RESEARCH ANNOUNCEMENTS - can890307.txt - 3/31/89 ----------------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 {--SW} 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; e-mail to canopus@cfa.uucp will probably be forwarded). 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. ------------------------------------------------------------------------ -- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA Internet: willner@cfa.harvard.edu ------------------------------ End of SPACE Digest V9 #393 *******************