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 ; Sat, 5 May 90 02:29:44 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 5 May 90 02:29:16 -0400 (EDT) Subject: SPACE Digest V11 #361 SPACE Digest Volume 11 : Issue 361 Today's Topics: NASA Article concerning Orbital Debris Re: Galileo Update - 05/03/90 ---------------------------------------------------------------------- Date: 4 May 90 17:30:51 GMT From: eagle!news@ucbvax.Berkeley.EDU (Dave McKissock) Subject: NASA Article concerning Orbital Debris With the recent postings concerning orbital debris, I thought the readers on the net might be interested in the following article which just appeared in the April 1990 copy of Station Break, a monthly newsletter on the Space Station Freedom Program. Anyone wishing to be added to the Station Break mailing list should place their requests in writing on business letterhead to the editor at the following address: Lee Ann Landers, Station Break/TADCORPS, 600 Maryland Ave., SW, #200, Washington D.C. 20024 (202) 554-8677 I don't believe it costs anything to subscribe to the newsletter (i.e. its FREE). Any typo's aren't my fault, as I am a perfect typist. There must be a problem with your copy of RN :) --------------------------------------------------------------------------- NASA Steps Up Ability to Track Man-Made Debris, Info to Aid Station Designers Since an orbiting paint fleck could cause some damage to Space Station Freedom, NASA is aggressively researching ways to deal with even the most minute orbital debris. Learning to detect the man-made debris is important to the design of Freedom and other future spacecraft. "We must learn the population density and occurrence of the orbital debris, so our space station engineers and designers will know how to protect it from the hits it may receive," said William Djinis, program manager of the NASA Orbital Debris program at Headquarters in Washington, D.C. "NASA has made a considerable effort over the years and is striving toward understanding the orbital debris environment and its trends," he added. However, neither NASA nor any other space-faring nation can currently accurately detect man-made orbital debris from 0.1 centimeters (smaller than a period) to 1 centimeter (smaller than a penny) [see charts at the end of this]. While the trackable orbital debris encompasses 3,000 used rocket stages, inactive satellites, and a few active satellites, information about the debris measuring less than 10 centimeters in diameter is slim. Using new radar systems, NASA hopes to more accurately measure debris less than 10 centimeters. Estimates are based on a linear extrapolation, which has an uncertainity factor of two to five. The ability to detect tiny objects may be important because, for example, a .3-centimeter aluminum sphere traveling at 6.17 miles per second (32,360 feet per second) has the same energy as a bowling ball flying down an alley at 60 miles per hour (88 feet per second). Currently, mathematical models indicate population densities as a function of orbital altitude, debris particle size, and future time. The data are collected from radars, optical telescopes, and materials returned from space. Because more data are necessary to build mathematical with a reasonable certainty for spacecraft design, NASA and the U.S. Space Command are looking toward the Haystack radar and its auxiliary, the new Near Earth Assessment Radar (NEAR), close to Boston, Mass., for some answers. NASA will spend $15 million in 1990 and 1991 to develop and build NEAR and NASA will get observation time on Haystack and NEAR. NASA will use Haystack data until useable data starts filtering in from NEAR in about two years. The agency is planning to build a new radar near the equator in the late 1990s to aid the measuring of orbital debris. "Space Station Freedom engineers can use the data to conduct a sound, well-structured design process," Djinis said. Data from the Long Duration Exposure Facility, which was returned to earth in February, also will help designers understand how to protect Freedom from near microscopic bombardments of orbital debris to larger pieces of space junk. As new data have been collected from other sources, the math models have been updated. The current 1984 model, being used for spacecraft design, has been updated as a result of obtaining new data. This 1988 update is being used for hazard and risk analyses, but not yet for spacecraft design, as it has the same degree of error (factor of 2 to 5) as the 1984 model. Graphic #1 SOURCES OF TRACKED OBJECTS BY ALTITUDE Active/Inactive Rocket Fragmentary Total Spacecraft Bodies & Other Debris Low Earth Orbit 1134 651 4138 5293 Medium Earth Orbit 232 302 149 683 Geosynchronous Earth Orbit 239 123 1 453 Total 1695 1076 4288 7059* * 472 tracked objects pending entry Graphic #2 KINETIC ENERGY AND DEBRIS EFFECTS tiny dot Less than .01 cm ==== Surface Erosion medium dot Less than .03 cm ==== Possibly Serious Damage good size dot .3 cm at 10 km/sec ==== Bowling Ball at (32,630 ft/sec) 60 mph (88 ft/sec) big ink 1 cm Aluminum Sphere ==== 400 lb. Safe at smear at 10 km/sec 60 mph (88 ft/sec) -- ----------------------------------------------------------------------- Dave McKissock sakissoc@csd.lerc.nasa.gov = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = NASA LeRC: Responsible for the remarkable & ingenious Space Station Freedom Electrical Power System = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Opinions expressed herein probably bear absolutely no resemblance to the official NASA position. ----------------------------------------------------------------------- ------------------------------ Date: 4 May 90 21:42:09 GMT From: mcsun!ukc!cam-cl!cet1@uunet.uu.net (C.E. Thompson) Subject: Re: Galileo Update - 05/03/90 In article <3569@jato.Jpl.Nasa.Gov> baalke@mars.jpl.nasa.gov (Ron Baalke) writes: > > The Galileo spacecraft is about 94 million miles from Earth, >and 89.3 million miles from the Sun. ... Supposing that it is till reasonably close to the ecliptic, it can't be far off one of the Earth's Trojan (L4/L5) points. Is it keeping an eye out for associated phenomena? Chris Thompson JANET: cet1@uk.ac.cam.phx Internet: cet1%phx.cam.ac.uk@nsfnet-relay.ac.uk ------------------------------ End of SPACE Digest V11 #361 *******************