Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Received: from po2.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 ; Mon, 1 Aug 88 04:22:17 -0400 (EDT) Received: from andrew.cmu.edu via qmail ID ; Mon, 1 Aug 88 04:09:14 -0400 (EDT) Received: by andrew.cmu.edu (5.54/3.15) id for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl; Mon, 1 Aug 88 04:06:07 EDT Received: by angband.s1.gov id AA07796; Mon, 1 Aug 88 01:05:04 PDT id AA07796; Mon, 1 Aug 88 01:05:04 PDT Date: Mon, 1 Aug 88 01:05:04 PDT From: Ted Anderson Message-Id: <8808010805.AA07796@angband.s1.gov> To: Space@angband.s1.gov Reply-To: Space@angband.s1.gov Subject: SPACE Digest V8 #308 SPACE Digest Volume 8 : Issue 308 Today's Topics: Special communications system prepared for Neptune encounter (Forwarded) RE: Re: International agreements on space station astronomy newsletters Re: Orbital Launch Methods Lithium Batteries Re: Solar Sails Proposals sought for space-based laser to study global winds (Forwarded) Trust Fund Proposed for Space Ventures ---------------------------------------------------------------------- Date: 20 Jul 88 20:03:57 GMT From: yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Special communications system prepared for Neptune encounter (Forwarded) Jeff Vincent Headquarters, Washington, D.C. July 20, 1988 Paula Cleggett Headquarters, Washington, D.C. James H. Wilson Jet Propulsion Laboratory, Pasadena, Calif. Release: 88-102 SPECIAL COMMUNICATIONS SYSTEM PREPARED FOR NEPTUNE ENCOUNTER Scientists and engineers from NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., and the National Radio Astronomy Observatory (NRAO), Socorro, N.M., are working together in the high plains of central New Mexico to improve the ability to receive spacecraft signals from the vicinity of planet Neptune. The researchers are currently testing a new deep-space communications system with NASA's Voyager 2 spacecraft, which will fly past the eighth planet next year. When Voyager 2 reaches Neptune in August 1989 to take close- up pictures and thousands of other measurements, the spacecraft will be nearly three billion miles from home. Its signal received on Earth will be extremely faint. Adding the 27 radio telescopes of the NRAO's Very Large Array (VLA) to JPL's Deep Space Network (DSN), which communicates with interplanetary spacecraft, will more than double the ability to capture Voyager's signal. The signal will be received eight hours per day for 40 days of the encounter -- the period that Voyager and Neptune will be above the horizon at the New Mexico desert site. Under an agreement between NASA and the National Science Foundation, which sponsors NRAO, engineers are installing new receivers and microwave horns, tuned to Voyager's X-Band radio frequency, on all the 82-foot dish antennas at the VLA. Special signal-processing and communication equipment has been added so that the VLA will be linked by satellite to the DSN's Deep Space Communications Complex at Goldstone, Calif. The new X-Band receiver systems were designed and built cooperatively by JPL, VLA, and NRAO's Central Development Laboratory at Charlottesville, Va. Like those of the DSN, the advanced receiver circuits are kept chilled with liquid helium to suppress internal electronic noise. NASA also has provided an independent power generator for the array, which has suffered power failures from summer lightning storms. This month's system test is the first chance to preview Neptune operations with the whole worldwide communication system, including elements at the VLA. The Voyager spacecraft, now 2.4 billion miles from Earth, will transmit in its planetary encounter mode, at data rates up to 21,600 bits per second (the rate used for Voyager's encounter of Uranus in 1986). Linked electronically, the two systems -- 23 VLA antennas that now have their X-Band receivers, and the 112-foot and 230-foot dishes at Goldstone -- will function as a single receiving system. The VLA, located about 100 miles southwest of Albuquerque, has, since 1980, enabled radio astronomers to study distant stars, nebulae and galaxies by collecting and analyzing radio emissions from these objects. The 27 mobile dishes are arrayed along a Y-shaped railroad track and can be rearranged for different observations. William D. Brundage, VLA project engineer, is responsible for Voyager preparations at Socorro. Voyager 2 was launched in August 1977, and has subsequently explored the planetary system of Jupiter, Saturn, and Uranus. The DSN has been developing and operating as a NASA system for nearly 30 years. It has communicated with spacecraft and astronauts on the Moon; tracked and commanded Earth-orbiting, unmanned spacecraft, and those sent to explore comets and six of the nine planets; and to probe the outer reaches of the solar system. Besides the Goldstone complex, the DSN includes stations in Spain and Australia, where Australia's Parkes Radio Telescope was linked with the DSN's antennas in 1986 to support Voyager 2's encounter of Uranus. This link will be made again for next year's encounter. JPL's Donald W. Brown is interagency arraying manager for the DSN, with overall responsibility for the Socorro link. ------------------------------ Date: Thu, 21 Jul 88 05:14 EDT From: RON PICARD Subject: RE: Re: International agreements on space station > Why do so many people forget the first "A" in "NASA"? Good question...I have to plead guilty. Probably because the "S" is the only thing that makes the popular press. I'd be interested to hear what some of the "A" work includes although it might not be suitable for the space network. Ron Picard (PICARD@GMR.COM) ------------------------------ Date: 21 Jul 88 19:14:20 GMT From: fsimmons@ub.d.umn.edu (Frank Simmons) Subject: astronomy newsletters I represent the Arrowhead Astronomical Society. I am interested in knowing if there are other club members reading this ; if you would be interested in exchanging newsletters; and if you have an electronic newsletter you would not mind sharing. Frank Simmons BITNET: FSIMMONS@UMNDUL.BITNET UMD Information Services INTERNET : fsimmons@ub.d.umn.edu Univ of Minn,Duluth ATT : (218) 726-8849/7587 10 University Drive SYSTEM : VAX/VMS 4.7 JNET 3.0 Duluth MN 55812-2496 ------------------------------ Date: 20 Jul 88 16:17:45 GMT From: ns!logajan@umn-cs.arpa (John Logajan x3118) Subject: Re: Orbital Launch Methods In article <492@ns.UUCP>, logajan@ns.UUCP (John Logajan x3118) writes: > >>get into orbit more cheaply by first going straight up and then going > >>horizontal at an altitude where the orbital speed would be much lower. Okay, I put this scenario into a simulator and found that if I shoot a projectile straight up at orbital velocity (from the surface of the earth) it will reach an altitude of 4000 miles (just double its starting height from the center of the earth -- hmmm coincidence?) Orbital velocity at 4000 miles is quite significant, so I would say that it is not cheaper to go straight up first and then fire horizontally. Unless of course you have some form of launcher that is earth based, such as an electro-magnetic launcher. Then the economies of the launch system might overcome the additional energy requirements needed for the "tennis ball serve" launch. - John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428 - - {...rutgers!umn-cs, ...amdahl!bungia, ...uunet!rosevax!bungia} !ns!logajan - ------------------------------ Date: Thu, 21 Jul 88 09:22:27 EDT From: Peter Allsop Subject: Lithium Batteries The BITNET summaries of Space Digest can be a bit behind, so if this has already been said, sorry ... In Digest 8 # 871 Paul Hass wrote: > {stuff on explosive potential} I have also heard of lithium batteries >"outgassing" ie. spewing out the nasty electrolyte. Lithium batteries >are usually made of lithium and something from the other side of the >periodic chart, iodine, bromine, chlorine, etc... You heard correctly, Lithium batteries can excrete a real nasty (read corrosive) liquid. A few years ago the Canadian government made it manditory for all civil aviation aircraft to carry an Emergency Locator Transmitter (ELT) powered by a Lithium battery. (Actually they required it run for a minimum number of hours at low temperature, and it worked out that a Lithium battery was the most feasible one to use). Everybody complied and things seemed great for about 6 months ... then the failure reports starting coming in. First came the reports of explosions, ELT's blowing holes in the hulls of (fortunately) parked aircraft. As I recall these were attributed to overheating (solar), not shorts. Then came the reports of corrosion problems. Several people had the batteries leak so badly that they ate right through the housing of the ELT *and* the hull of the aircraft (I saw one such case). Not long after that came the NOTAM - pull all ELT's with Lithium batteries from aircraft & inspect for damage. When we pulled ours I opened it up & literally poured the electronics out of the case ... the components had been liquified! The 1/8" aluminium case of the ELT had been eaten almost all the way through in a few spots ... far too close for comfort! NASA may be taking a rather conservative approach in banning Lithium batteries, but their history is not encouraging. Peter Allsop (old form) (new form) Science is truth, don't be mislead by facts. ------------------------------ Date: 21 Jul 88 15:48:08 GMT From: palmer@tybalt.caltech.edu (David Palmer) Subject: Re: Solar Sails In article <10922@oberon.USC.EDU> robiner@ganelon.usc.edu (Steve) writes: >In article <1988Jul19.235426.15443@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>Easy. Special relativity tells us that there is no such thing as mass or >>energy in isolation: you always have both. That means that energy, e.g. >>light, has mass. And so it does, and hence it has momentum, and bouncing >>it off a reflective surface imparts momentum to said surface. Light does > >If the light bounces off the sail, how does it impart momentum. What >energy of the photon is now reduced? I think the photons must be >ABSORBED by the sail for this to work. > >=Steve= Momentum is a vector. When a photon bounces vertically off a light-sail, its momentum reverses itself, so the momentum it gives the light-sail is twice its original momentum (in its original direction). The energy given to the sail is taken away from the photon and appears as a redshift. N.B. the energy is equal to momentum transfer times the velocity of the sail, so when the sail is stationary, there is no energy transfer as well as no redshift. (I know what I'm talking about, so if you disagree, mail me first and I'll explain it.) David Palmer palmer@tybalt.caltech.edu ...rutgers!cit-vax!tybalt.caltech.edu!palmer "Flowers -- Just say NO!!" - Mighty Mouse ------------------------------ Date: 21 Jul 88 02:41:22 GMT From: yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Proposals sought for space-based laser to study global winds (Forwarded) Charles Redmond Headquarters, Washington, D.C. July 21, 1988 Bob Lessels Marshall Space Flight Center, Huntsville, Ala. RELEASE: 88-103 PROPOSALS SOUGHT FOR SPACE-BASED LASER TO STUDY GLOBAL WINDS NASA's Marshall Space FLight Center, Huntsville, Ala., today issued a request for design proposals for a new, space-based remote sensing instrument to measurement wind characteristics, thereby permitting scientists to better understand and contribute to weather predictions on Earth. The Laser Atmospheric Wind Sounder will be an advanced light detection and ranging (LIDAR) instrument. Just as radar operates by bouncing radio waves off distant objects and sonar bounces sound waves off underwater objects, LIDAR bounces light waves, generated by a laser, off atmospheric particles. Analysis of the reflected light will reveal the direction and speed of the winds and provide information on the amount of particulate matter, known as "aerosols", suspended in the atmosphere. The sounder will provide real-time global wind profiles for the lowest weather-producing layer of the Earth's atmosphere. Whether obtained globally using the polar-orbiting Earth Observing System platform or from the tropics and subtropics using the manned Space Station, the wind profiles will provide essential data to improve understanding of the global biogeochemical and hydrologic cycles and understanding of large scale atmospheric circulation and climate dynamics. This new information also can be used by weather forecasters worldwide as an aid in improving their numerical predictions. According to Carmine E. De Sanctis, chief of the Space Science and Applications Group at the Marshall center, the sounder could be operational by 1996 as one phase of NASA's larger Earth Observing System initiative. The sounder would enable meteorologists at the National Oceanic and Atmospheric Administration to develop more accurate 5-day weather forecasts. At present, severe weather warnings can be issued only for broad areas of the United States. A major problem is an inability to obtain global wind velocity measurements. "Most atmospheric wind velocity data is obtained using sounding balloons," Dr. Vernon Keller, the sounder's assistant project manager, said. "Unfortunately, most of these balloons are, of necessity, launched from land. More than two-thirds of the Earth's surface, however, is water, thus there exist large areas of the globe -- particularly in the southern hemisphere -- which receive only minimal measurement coverage." The sounder will allow worldwide coverage with special emphasis given to tropical and subtropical areas where, previously, measurements have been sparse to non-existent. According to Richard Beranek, the sounder's project manager, "It will enable forecasters to obtain wind velocity data from ground level up to an altitude exceeding 40,000 feet. Preliminary concepts involve using a proven carbon dioxide coherent laser, operated at an eye-safe infrared wavelength, to survey winds over Earth's entire surface at least once a day. Data would be provided to meteorologists worldwide to assist in developing weather projections to benefit all mankind." In addition to weather projections, researchers anticipate the data will assist in analyzing the impact natural occurences, such as volcanic eruptions, and human activity, such as the slash and burn land clearing now under way in many developing countries, are having on the global environment, Beranek said. Dr. Keller said the earliest work on the sounder began at the Marshall center in 1967 with various designs being tested on the ground. In 1981, tests began using a laser atmospheric wind sounder-like system aboard an aircraft. Results obtained during the last 21 years have left Marshall engineers feeling confident in proposing the space-based system. "We hope to see a design emerge which will be flexible enough to permit us to incorporate state-of-the-art advances in lasers, optics and other related systems as they emerge over the sounder's projected lifespan," De Sanctis said. "The beneficial impact it will have on enhancing our understanding of the environment is certain to be very significant." ------------------------------ Date: 21 Jul 88 16:47:04 GMT From: att!lzaz!lznv!psc@ucbvax.berkeley.edu (Paul S. R. Chisholm) Subject: Trust Fund Proposed for Space Ventures < "Would you buy a used operating system from these guys?" > from Design News, 7/4/88, p. 26: "With tight federal budgets, how can the nation pay to meet growing opportunities in space? New Jersey's Rep. Robert A. Roe, chairman of the House Science, Space, and Technology Committee, proposes a trust fund like the one that financed the interstate highway system. He thinks Americans would gladly buy bonds to support thrusts across space frontiers. Roe doubts that Uncle Sam alone could finance such costly proposals as an inhabited base on the moon or a joint U.S.-Soviet manned mission to Mars. The National Aeronautics and Space Administration has a tough enough fight getting funds for a manned orbiting space facility. . . . --Walter S. Wingo, Washington Editor" [Typical of N.J. reps; "I'm in favor of the space program, if you can build an interstate to orbit."] -Paul S. R. Chisholm, {ihnp4,cbosgd,allegra,rutgers}!mtune!lznv!psc AT&T Mail !psrchisholm, Internet psc@lznv.att.com I'm not speaking for my employer, I'm just speaking my mind. ------------------------------ End of SPACE Digest V8 #308 *******************