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 ; Wed, 10 Oct 1990 02:49:11 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 10 Oct 1990 02:48:40 -0400 (EDT) Subject: SPACE Digest V12 #440 SPACE Digest Volume 12 : Issue 440 Today's Topics: Re: Lifeless interplanetary travellers - where are they now? NASA Headline News for 10/09/90 (Forwarded) Re: disposal of N-waste into sun Re: deep space comm. protocols Any news on lightcraft? 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: 9 Oct 90 16:46:03 GMT From: sun-barr!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@apple.com (Henry Spencer) Subject: Re: Lifeless interplanetary travellers - where are they now? In article <1281@mpirbn.mpifr-bonn.mpg.de> p515dfi@mpirbn.UUCP (Daniel Fischer) writes: >Who can tell what has become of all those Upper Stages that were used in the >past 1.5 years to launch Magellan, Galileo and Ulysses? They were separated >from the spaceprobes after those had reached their escape velocity, so they >should be on similar orbits - what steps have been taken to increase their >distance from the S/C so that accidental collisions or electrical interference >are excluded? ... Generally, arrangements are made to give the payload a small velocity difference from the final stage. This can be anything from just springs in the separation mechanism up to a separation burn by a sophisticated rocket stage. The IUS is relatively smart and, as I recall, does a separation burn with the last of its attitude-control fuel. Relatively dumb stages, like the final boost motor for Ulysses, just use spring or pyrotechnic separation and hope for the best. :-) Actually, even a little bit of separation velocity generally does the job quite adequately, provided that subsequent velocity changes don't act to bring the objects together again. The most notorious case of this was the amateur-radio satellite (Oscar 10?) that got rear-ended by the Ariane third stage that had just deployed it -- the stage was dumping propellants before shutting down, and the dumping gave it enough forward delta-V to catch up with the satellite. Space is so big and even small perturbations add up sufficiently over time that the risk of collision long after separation is slight. The stuff ends up in semi-random orbits and blends into all the natural space junk out there. >... what has happend to the Galileo-IUS which should have >been on a rather similar trajectory? Will it also come close to earth again? I would be surprised. Gravity-assist maneuvers require hitting a fairly narrow window at the assist planet. Galileo's IUS probably ended up somewhere nearly random after Venus encounter. Ditto for Magellan's. >paper in the ESA BULLETIN #63 speaks of 11.4km/s relative to earth, while >several U.S. media repeatedly talked of 15.2km/s - any explanations welcome]. This might be velocity at infinity vs. velocity at motor burnout. >And finally: where will Phobos-1 end up? It couldn't orbit-insert at Mars, so >will it return to earth on its Hohmann-style trajectory? When? ... My guess would be that it came close enough to Mars to have its perihelion changed. Failing that, it would return to Earth's orbit, but the odds are roughly zero that Earth would be nearby at the time -- Earth's orbit is half a billion kilometers long. >... Phobos-2 as well as the >Viking-Orbiters should be in stable Martian orbits ... Well, stable except for air drag, which is noticeable even for Mars's thin atmosphere. As I recall, Mariner 9 is scheduled to go down circa 1997, and the Viking orbiters will follow early in the 21st century. There was originally hope that serious exploration of the Martian surface would be underway before these unsterilized spacecraft crashed, but... >...whether somebody takes care of the whereabouts of the interplanetary >space debris. The pollution of earth's LEO and GEO is well-known by now, and >steps to protection are being taken (er, planned (er, talked about)) - but >who protects interplanetary space? At present, protection really is not needed. Tons of human junk are lost in the gigatons of natural junk already present. Near-Earth space has a debris problem because it is small and there is intense activity there. Ignoring the narrow belt around Clarke orbit for the moment, near-Earth space essentially ends 1000km up, where the inner Van Allen belt starts to really make itself felt. That's about 500 billion [North American billion, 10^9] cubic km. Even just cislunar space -- within the average radius of the Moon's orbit -- is *268 million* billion cubic km, half a million times larger. The space between Venus's orbit and Mars's orbit within, say, five million km of the ecliptic, is very roughly one million billion billion cubic km. -- Imagine life with OS/360 the standard | Henry Spencer at U of Toronto Zoology operating system. Now think about X. | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 9 Oct 90 03:47:53 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 10/09/90 (Forwarded) Headline News Internal Communications Branch (POC) NASA HQ Tuesday, October 9, 1990 Audio Service: 202/755-1788 This is NASA Headline News for Tuesday, October 9, 1990 The crew of STS-41 had a very successful weekend starting with their launch just a few minutes into their window on Saturday, and continuing with the deployment of the Ulysses solar probe later that day. The crew spent yesterday working on cabin experiments and taking photographs of Tropical Storm Klaus and other Earth features. Today's agenda has the crew closing up their experiments and preparing for entry tomorrow morning. Discovery is set for landing tomorrow morning at 9:57 am EDT at Edwards Air Force Base. Weather for Edwards is predicted to be fine for landing. * * * * * * * * * * * * * * * * * * * * * * * * * * At the Kennedy Space Center, Columbia is set to be rolled back to the Vehicle Assembly Building this morning. This rollback is based on Tropical Storm Klaus' trajectory representing a potential threat to Florida's Space Coast. Atlantis, still in the VAB, is currently set for roll out to launch pad 39-A, possibly this Thursday. Columbia could be rolled back out to Pad 39-B as early as Friday, with a tanking test possibly next week. The investigation into Atlantis' aft compartment beam incident last week continues, but so far indications are that the damage is very minor. A broken purge duct and a small section of a manifold relief line in the main propulsion system will be replaced. * * * * * * * * * * * * * * * * * * * * * * * * * * Galileo is now about 32 million miles from Earth and closing at a rate of more than 52,187 miles per hour. The trajectory correction maneuver, for fine-tuning the spacecraft's incoming trajectory to Earth, is scheduled to take place today. This will change Galileo's velocity by about 1.1 mph. Spacecraft health continues to be excellent. * * * * * * * * * * * * * * * * * * * * * * * * * * On Magellan, one of the high power transmitters experienced a spurious shutdown on Sunday, causing the normal fault protection procedures to operate. Thirty-seven minutes of radar mapping data was lost while the ground system reconfigured. The shutdown occurred in the B-side of the traveling wave tube amplifier, a system which has experienced spurious shutoffs during the earlier cruise mode. An investigation of the problem is being conducted. * * * * * * * * * * * * * * * * * * * * * * * * * * Ulysses is on its way to Jupiter at a velocity of more than 34,000 mph. This is the fastest departure speed of any craft ever to have left Earth. On Sunday, Ulysses deployed its radial boom, slowing the craft's revolution from 6.8 to 4.7 revolutions per minute - as planned. The next scheduled event is the pointing of Ulysses' high gain antenna towards Earth, set to occur later this week. A trajectory correction maneuver is also planned for Monday, Oct. 15. Here's the broadcast schedule for Public Affairs events on NASA Select TV. All times are Eastern. **indicates a live program. Tuesday, 10/9/90 2:07 pm **Earth views and SSBUV operations from Discovery. 6:00 pm Replay of STS-41 day 4 activities from JSC. 6:30 pm **Change-of-Shift briefing from JSC. Wednesday, 10/10/90 2:30 am **Change of Shift briefing from JSC. 8:12 am **Begin landing coverage from DFRF. 9:57 am **Expected landing of Discovery at DFRF. 11:30 am **Post-landing briefing from DFRF. 1:15 pm **Magellan at Venus status briefing from JPL. All events and times may change without notice. This report is filed daily, Monday through Friday, at 12:00 pm, EDT. It is a service of Internal Communications Branch at NASA Headquarters. Contact: CREDMOND on NASAmail or at 202/453-8425. NASA Select TV: Satcom F2R, Transponder 13, C-Band, 72 degrees West Longitude, Audio 6.8, Frequency 3960 MHz. ------------------------------ Date: 10 Oct 90 00:03:48 GMT From: usenet.ins.cwru.edu!abvax!iccgcc!herrickd@tut.cis.ohio-state.edu Subject: Re: disposal of N-waste into sun In article , jpc@fctunl.rccn.pt (Jose Pina Coelho) writes: > In article <14177@hydra.gatech.EDU> ccoprmd@prism.gatech.EDU (Matthew DeLuca) writes: >> But, what is wrong with dumping the waste sealed in glass into a subduction >> zone on the ocean floor? The waste would disappear into the mantle of the >> earth...what could possibly be wrong with that? > > Nothing, just you can't explain a lamp to a troglodite (ecohisterics) > > > You should dump it in a stable (and open) volcano. The waste would be > dissolved by several cubic meters of granite. > > "But that would make the granite radioactive" > > No, because granite is already radioactive (you receive a bigger > ammount of rad. in a granite house than near a nuclear generator > (ignoring accidents)) > > -- > // Pina > > - If all men were brothers, would you let one marry your sister ? Do the arithmetic on dissolving the "high grade" waste in a suitable solvent and then dispersing it over a few square miles of ocean. I think you will find it disappears into the background. It is high grade only because the ecohysterics have insisted on concentrating it into minimum volume. dan herrick ------------------------------ Date: 9 Oct 90 15:26:42 GMT From: n3dmc!gronk!johnl@uunet.uu.net (John Limpert) Subject: Re: deep space comm. protocols sean@cs.utexas.edu (Sean William O Malley) writes: >I would like to present a deep space communcations >protocol to my networks class. Does anyone have >a good reference for such a protocol. I would like >to cover the error correction and retransmission >strategy used. You would get a better answer from someone at JPL but I will give it a shot. The telemetry links use convolutional coding to reduce the bit error rate. The ground station uses a sequential decoder to recover the data. There is no "protocol" in the conventional sense. Engineering measurements are cyclically digitized and transmitted. Science data can be retransmitted by a ground command if it was logged on the spacecraft's tape recorder. It's best to think of it as a unidirectional link. -- John Limpert johnl@gronk.UUCP uunet!n3dmc!gronk!johnl ------------------------------ Date: 9 Oct 90 20:49:08 GMT From: sco!jjones@uunet.uu.net (Vulture on the Launch Pad) Subject: Any news on lightcraft? A professor at Rensselaer Polytechnic was going to do some preliminary tests with models for a laser-powered spacecraft propulsion system this summer, according to a UPI story I read on Clarinet some time back. Somebody from RPI later posted to say that they knew some of the people involved in the lightcraft experiment. Well? Does anyone know if the experiments took place and/or what happened? I'm truly curious. If anyone wants the original UPI story on lightcraft, I'll forward it. Apparently some people at NASA admit that the idea is neat (laser + mirror + spacecraft + supercomputer = cheap spacecraft) but think that implementation would take decades. At any rate, NASA has thrown partial funding at this experiment. -- ________________________________________________________________________________ Jim Jones, jjones@sco.com Where logic fails, ego may still prevail. The Santa Cruz Operation ------------------------------ End of SPACE Digest V12 #440 *******************