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 ; Thu, 2 Nov 89 01:30:50 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 2 Nov 89 01:30:26 -0500 (EST) Subject: SPACE Digest V10 #186 SPACE Digest Volume 10 : Issue 186 Today's Topics: Re: Pegasus Re: NASA Headline News for 10/26/89 (Forwarded) Galileo Questions Re: how is Voyager gaining speed as it encounters Jupiter ? Re: how is Voyager gaining speed as it encounters Jupiter ? Condensed CANOPUS - August 1989 ---------------------------------------------------------------------- Date: 26 Oct 89 18:07:58 GMT From: mailrus!sharkey!itivax!vax3!aws@tut.cis.ohio-state.edu (Allen W. Sherzer) Subject: Re: Pegasus In article <21102@uflorida.cis.ufl.EDU> rs0@beach.cis.ufl.edu (Bob Slaughter) writes: >Any word on when the first launch of Pegasus was/will be? There is a note about it in the current Avation Week. Launch is currently set for December 7. They are having problems connecting Pegasus with the B-52. >Also, could someone point me to a good overview article on Pegasus, with >design illustrations and other basic info. There was a good one in a recent (last 8 weeks) Avation Week. Allen ---------------------------------------------------------------------------- | You know you have hit bottom when you sleep in a pool of your friends | | vomit because it's warmer then the sidewalk. | ---------------------------------------------------------------------------- ------------------------------ Date: 27 Oct 89 02:05:11 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: NASA Headline News for 10/26/89 (Forwarded) In article <34510@ames.arc.nasa.gov> NASA writes: >NASA yesterday awarded a $64 million contract to General Dynamics >Corporation to launch a government satellite. The satellite, >which is a joint venture of NASA and the Air Force, is scheduled >to be launched in June 1990. It will mark the first commercial >launch by General Dynamics and will use an Atlas 1 launch >vehicle. Um, it would be too much to ask the *name* or *mission* of this satellite? -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Thu, 26 Oct 89 15:38:31 CDT From: Will Martin Subject: Galileo Questions Thanks to Peter Yee for the posting of the STS-34 Press Kit. There's a lot of good info in there and it answered most of my questions about Galileo right at the start! I do have a few minor queries: 1) I seem to recall some traffic on the SPACE Digest some months or even years back about litium batteries in space-rated hardware. As I recall the discussion, it seemed to be that lithium batteries were not allowed in payloads going up in the Space Shuttle, due to the risks of their exploding or outgassing or doing something else nasty. The Galileo probe, however, is powered by lithium batteries. I assume nothing else would give the long 5-year dormancy followed by a brief 75-minute spasm of glory as the probe executes its brief mission. :-) Am I recalling the earlier discussion correctly? If so, was the restriction on lithium batteries only on *commercial* versions? I am assuming these probe batteries are not "stock" off-the-shelf items but instead specially constructed custom components designed for this mission, and thus may be made far safer than ordinary versions. Is this the case? If so, can anyone describe briefly how these differ from commercial versions? Are we likely to see a spinoff from this for very-high-reliability commercial batteries, or very-safe versions for use in explosive atmospheres or other critical applications? 2) This is actually much more general than just Galileo-related: the "T-minus" countdown chart included in the press kit listed a number of "built-in holds", such as the one at T-27 hours and so forth. Why is the countdown constructed this way? Why build in a "hold" of 8 hours instead of just lengthening the countdown period by 8 hours and scheduling the actions that take place during this hold at the same relative time? It would appear on the surface that a "hold" should always be an exceptional condition -- something caused by a problem -- as opposed to a regular scheduled event expected to occur at some scheduled time. There must be a good reason for these built-in holds, but I can't figure it out. I'd appreciate enlightenment on the subject. 3) This is purely speculative -- I've been trying to figure out some in-flight use for the many pounds of ablative heat shield that burns off the probe during Jupiter-atmosphere entry. The problem is that it can't be anything consumable, like maneuvering-thruster fuel, which would be used during the flight, because that mass has to be there to be burned off as heat shielding when the probe enters. Also, it has to be dense and massive and approachng homogeneous, so it will function adequately as ablative material. So far, the only thing I've been able to think of is densely-packed electronics embedded in some potting compound. Or perhaps some really futuristic crystalline mass of computing circuits based on nanotechnology? (How about an AI that takes measurements during the flight but then dies a fiery death during the probe entry? Shades of HAL -- what a motivation to sabotage the mission! :-) Maybe some sort of entirely-solid-state scanning mechanism to take detailed star-chart type images during those long lonely years of travel between slingshot points? Any other ideas? (I'm sure better minds than I had spent many long hours trying to come up with some sort of productive use for that otherwise-inert and extremely-expensive-to-ship weight; anyone from NASA care to post any notes on what might have been proposed, if anything? Regards, Will Martin ------------------------------ Date: 26 Oct 89 22:55:14 GMT From: att!drutx!dlo@ucbvax.Berkeley.EDU (DL Olson) Subject: Re: how is Voyager gaining speed as it encounters Jupiter ? In article <1641@irisa.irisa.fr>, thomas@sigle.irisa.fr (Henry Thomas) writes: > Could someone explains me spacecraft like Voyager or Galileo can gain speed > when they encounters Jupiter (resp. Venus)? I suspect it is linked to the > loss of propellant at perihelie, but I need a clear explanation. Thank you. It is called the "slingshot effect". If you have a stone in a sling, each time you pull the sling around you, the stone picks up speed. If you pull it fast enough, the stone will break away from the sling at that increased speed. With that in mind, let the planet represent you, its gravitational pull be the sling, and the spacecraft be the stone. Since the planet is also moving in its orbit around the sun, the planet pulls the spacecraft around with it (kind of like your pulling the stone in the sling around you). If the spacecraft is pulled along fast enough, it breaks "orbit" at the increased speed. The planet actually slows down, because it gives up a little of its orbital energy to the spacecraft. David Olson ..!att!drutx!dlo ------------------------------ Date: 28 Oct 89 15:55:15 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: how is Voyager gaining speed as it encounters Jupiter ? I must say that in the days when I didn't understand gravity assist, describing it as the "slingshot effect" (and explaining how a kids' slingshot works) never helped me understand anything! The nickname is fanciful and there's no real connection except that something gets accelerated. The easiest explanation is this: When we guide a spacecraft into a near-miss encounter with (for instance) Jupiter, it falls INTO and escapes AWAY FROM Jupiter with the same kinetic energy *relative to Jupiter*; but because Jupiter is moving in its orbit, the net effect *relative to the rest of the Solar System* is to tack part or all of Jupiter's orbital velocity onto that of the spacecraft. By choosing the proper near-miss trajectory, and optionally by tweaking the motors near closest approach, we can "apply" this extra momentum to move the spacecraft someplace specific. This has been asked ad nauseam recently; I think it goes in FAQ. -- "NASA Announces New Deck Chair Arrangement For \_/ Tom Neff Space Station Titanic" -- press release 89-7654 \_/ tneff@bfmny0.UU.NET ------------------------------ Date: 29 Oct 89 19:09:40 GMT From: frooz!cfa250!willner@husc6.harvard.edu (Steve Willner) Subject: Condensed CANOPUS - August 1989 Here is the condensed CANOPUS for August 1989. There are 6 condensed articles and 18 articles by title only. CANOPUS is copyright American Institute of Aeronautics and Astronautics, but distribution is encouraged. See full copyright information at end. ---------- CONTENTS -- 6 ARTICLES CONDENSED OR IN FULL ---------- NASA AWARDS GRANTS FOR FUTURE EXPLORATION STUDIES - can890801.txt - 8/3/89 SCIENCE OBSERVATIONS SELECTED FOR HUBBLE SPACE TELESCOPE; TELESCOPE IS ROTATED FOR SHIPMENT - can890802.txt - 8/3/89 QUAYLE SAYS FLIGHT ACCIDENTS TO BE EXPECTED - can890806.txt - 8/3/89 UNUSUAL CLOUD: A GAS RELEASE OR A "SMALL COMET" BREAKUP? - CAN890819.TXT - 8/25/89 LONG PLANETARY "DATA STREAM" ABOUT TO START, KELLER SAYS - can890824.txt - 8/30/89 ------------------------------------------------------------------------ NASA AWARDS GRANTS FOR FUTURE EXPLORATION STUDIES - can890801.txt - 8/3/89 NASA's Office of Exploration has awarded a series of study contracts to various organizations to provide NASA with ideas, concepts, devices, systems, trajectories, operations or implementations which could be applied to furthering human exploration of the solar system. The 20 winners, selected from 115 proposals submitted in response to the April 12, 1989, NASA Research Announcement, are located in 12 different states and come from five industry-related firms, two space support-related organizations, and 13 universities. SCIENCE OBSERVATIONS SELECTED FOR HUBBLE SPACE TELESCOPE; TELESCOPE IS ROTATED FOR SHIPMENT - can890802.txt - 8/3/89 162 proposals were accepted following an intensive scientific peer review of 556 proposals submitted by astronomers from 30 countries. Approximately 20 percent of the proposals were from member nations of the European Space Agency, a joint partner with NASA on the HST project. Observing time was heavily oversubscribed. During the first 12-month observing cycle {really only the last 5 of the 12 months were available, though, because of checkout and time for "guaranteed time observers"}, 11,000 hours of observing time were requested, with only 1200 hours available. The average length of an accepted observation is 10 hours. To utilize every moment of observing time and hence maximize efficiency, HST is "over-booked" with accepted general observer proposals by a ratio of 3:1. One hundred eight accepted proposals are high priority and represent 90 percent of HST observing time. The remaining 54 supplemental proposals essentially "fly standby." They will only be executed if appropriate scheduling opportunities arise. {The next proposal cycle will have more time available.} QUAYLE SAYS FLIGHT ACCIDENTS TO BE EXPECTED - can890806.txt - 8/3/89 Vice President Daniel Quayle said that space flight accidents involving loss of life are to be expected, but should not be a reason for halting manned space flight. Quayle spoke to reporters as he arrived in Huntsville, Ala., for a quick tour of NASA's Marshall Space Flight Center today. Earlier in the day the Congressional Office of Technology Assessment released a report asserting that there is an 88 percent chance of loosing a Space Shuttle orbiter within the next 40 or so missions. The report did not say it would be a Challenger-type accident, with loss of crew, but did say that the orbiter would be so seriously damaged as to remove it from action. "I don't necessarily go along with that forecast at all," Qualye said. "Of course there are risks [in space flight]. Let's face it, this is a dangerous mission," but added that "it's part of the American culture to be pioneers.... I don't think that [risk] should be a reason to shut the door." When asked by a reporter whether he would like to travel in space, Quayle said, "There are people who think I'm already there." UNUSUAL CLOUD: A GAS RELEASE OR A "SMALL COMET" BREAKUP? - CAN890819.TXT - 8/25/89 Contributed by Patricia Reiff/Rice University On the evening of Saturday, August 19, 1989, at 9:30 pm CDT, I spotted a small (less than 1/2 degree across), very bright cloud. It was as bright as a typical dense cumulus cloud illuminated by sunlight; however, the sun had set over an hour earlier. Since the sky was otherwise completely cloudless (the Milky Way was visible) I called it to the attention of my family and friends immediately. It expanded and dimmed rather quickly. By 9:35 it had acquired the shape of a symmetric, stylized fish or space shuttle (about 1 x 2 degrees) angled about 45 degrees to the horizon with the fins in the lower left and the nose pointed to the upper right. It fluctuated in brightness as it continued to expand and dim. Examination of the cloud through 11 x 80 astronomical binoculars revealed no central object and no striations but a fairly sharp edge all around. No sonic boom was heard. By 9:40 it had expanded to about 2 x 5 degrees, still at 45 degrees to the horizon. By 9:45 it was subvisual but still observable through the binoculars, although the edge was difficult to discern. By 9:48 it was not distinguishable against the sky haze at all (the moon, two days past full, was just beginning to rise). The object was roughly halfway between Arcturus and Spica, and did not appear to move. Our location was roughly ten miles north of Hockley, Texas (45 miles northwest of Houston). {more details omitted} So what was it? {many obvious possibilities ruled out} Reiff would appreciate hearing other ideas or information on this cloud. Patricia H. Reiff, Senior Research Scientist Internet REIFF@SPACVAX.RICE.EDU (128.42.10.3) HIPPARCOS UPDATE - can890821.txt - 8/29/89 ESA officials have stated that the Hipparcos mission should observe the planned number of stars, but that the accuracy will be lower. "The Tycho catalog mapping 400,000 stars, and the Hipparcos catalog giving the positions of 120,000 stars, can still be compiled by the satellite," said ESA Project Scientist Michael Perryman. "The precision will be a factor of 10 less than expected. However, we still hope to achieve a positional accuracy 15 times greater than from the ground." Each star probably will be observed only 10 times rather than 80, and the mission may last only 6 months to two years, depending on radiation degradation of the solar cells. That rate should become known in about a month. "We hope at least to get the positions and magnitudes of stars, if not the measurement of the parallaxes and proper motions," Perryman said. {Unfortunately, it was the parallaxes and to a lesser extent the proper motions that were the major scientific interest of the mission. This is a serious loss.--SW} LONG PLANETARY "DATA STREAM" ABOUT TO START, KELLER SAYS - can890824.txt - 8/30/89 A stream of planetary data that will last into the 21st century is about to begin, NASA Associate Deputy Administrator Sam Keller told reporters Tuesday afternoon at Marshall Space Flight Center in Huntsville, Ala. In reviewing the future of planetary exploration, Keller said that with Magellan (Venus), Galileo (Jupiter), and Ulysses (solar interplanetary) launched or about to be, and with other planetary spacecraft planned or in development, "the U.S. will have a continuous stream of data to the year 2006." But those spacecraft will be targeted to orbit specific bodies rather than playing interplanetary billiards. "The chances of returning to Triton, as exciting as it was, are not very good now" he said, and would probably rely on a high-energy mission with a single gravity assist at Jupiter. When asked whether the science community would see on Space Station a repeat of the "Famous 40," Keller said that, "We will try not to pick what we can't fly." The "Famous 40" refers to Shuttle/Spacelab payloads selected in the late 1970's. Most have not flown on Shuttle and at least one appears to have been recycled for Space Station. "We will attempt to honor the commitments that have been made," he said, and "not make any commitments that cannot be honored in a particular time." Among other topics that Keller discussed with reporters: A joint manned Mars mission with the USSR cannot be decided for at least another decade since it will take that long to get such an effort into early planning following Space Station and the Moon. Meanwhile, joint efforts involving the Mars Observer, ozone mapper on Meteor 3, and gamma-ray burst detector on the International Solar-Terrestrial Physics program are providing the "first engineer-to-engineer discussions" between the two nations. The Mars Observer still costs less than an all-new mission despite cost growth that has gone far beyond the "production line" spacecraft concept. Keller admitted NASA was "overly optimistic" on how low the price could be held, but said that "the goal of not reinventing the wheel is one that we should not lose sight of." ----------------- 18 ARTICLES BY TITLE ONLY ------------------------- MAGELLAN WEEKLY STATUS - can890803.txt - 8/3/89 VOYAGER STATUS REPORT - can890804.txt - 8/3/89 VOYAGER STATUS REPORT - can890805.txt - 8/3/89 VOYAGER DISCOVERS 3 ADDITIONAL MOONS AROUND NEPTUNE - can890807.txt - 8/4/89 MSFC CONDUCTS SUCCESSFUL ENGINE TEST - can890808.txt - 8/4/89 [advanced Space Shuttle main engine] JSC's COHEN TO LEAD NASA PREPARATION FOR NEW CIVIL SPACE GOALS - can890809.txt - 8/4/89 VOYAGER STATUS REPORT - can890810.txt - 8/14/89 MAGELLAN WEEKLY STATUS - can890811.txt - 8/14/89 EUROPE WORKING ON HIPPARCOS BOOSTER PROBLEM - can890812.txt - 8/18/89 VOYAGER STATUS REPORT - can890813.txt - 8/18/89 EUROPE WORKING ON HIPPARCOS BOOSTER PROBLEM - can890814.txt - 8/21/89 GALILEO FINALLY GETTING "OFF THE GROUND" - can890815.txt - 8/21/89 TV SCHEDULE FOR THE VOYAGER NEPTUNE ENCOUNTER - can890816.txt - 8/22/89 LAST PICTURE SHOW DRAWING TO A CLOSE - can890817.txt - 8/24/89 VOYAGER IMAGES SHOW STRIKING DETAILS - can890818.txt - 8/24/89 NASA RESEARCH ANNOUNCEMENT (NRA) 89-OSSA-17 - can890820.txt - 8/29/89 [Origins of Solar Systems Research Program] NASA RESEARCH ANNOUNCEMENT(NRA) 89-OSSA-18 - can890822.txt - 8/30/89 [Long-Term Space Astrophysics Research Program] NASA RESEARCH ANNOUNCEMENT(NRA) 89-OSSA-19 - can890823.txt - 8/30/89 [Astrophysics Data Program] ----------------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). 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 V10 #186 *******************