Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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, 20 Mar 91 02:23:10 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 20 Mar 91 02:23:05 -0500 (EST) Subject: SPACE Digest V13 #284 SPACE Digest Volume 13 : Issue 284 Today's Topics: Abstract of articles in ESA Journal 90/4 Salyut 7 in Argentina Shuttle size Re: railguns and electro-magnetic launchers Magellan Update - 03/19/91 Re: Titan IV Launch - March 8, 1991 Re: German conference highlights doubts about ESA's manned space plans Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 17 Mar 91 13:25:07 GMT From: mcsun!hp4nl!phigate!philtis!munk@uunet.uu.net (Harm Munk) Subject: Abstract of articles in ESA Journal 90/4 Summary of articles in ESA-journal, Volume 14, nr. 4 (1990/4) Inter-Operability of Europe's Hermes Spaceplane with the Columbus Free-Flying Laboratory, and with 'Freedom' and 'Mir'-type Space Stations [F. Di Mauro, D. Cornier, L. Marechal, W. Fehse, A. Tobias] The European Hermes spaceplane, which development is primarily targeted towards servicing the Columbus Free-Flying Laboratory (during 7 day missions every 180 days), will also be able to provide the Space Station 'Freedom' with complementary servicing, and, alternatively, crew-rescue, exchange of international crews and supplying the European experiments. 'Mir'-type space stations will be visited in the course of a common scientific programme. This will be accomplished through the use of an expendable Hermes Resource Module (HRM), attached to the rear of the Hermes spaceplane, which carries the docking ports, berthing mechanisms and utilities interfaces (with different requirements for all three types of space stations) as well as cargo for the station being visited. The Hermes system will consist of a fleet of two spaceplanes, with three missions per year. Each spaceplane will have a lifetime of 15 years and 30 missions. The article describes, besides the rendez vous and docking scenario's for the three space stations, several organisatorial aspects and issues to be resolved of the Hermes operations. The Newton Mission - A Proposed Manmade Planetary System in Space to Measure the Gravitational Constant [A.M. Nobili, A. Milani, E. Polacco, I.W. Roxburgh, F. Barlier, K. Aksnes, C.W. F. Everitt, P. Farinella, L. Anselmo, Y. Boudon] The Newton mission was one of 22 mission proposals submitted in response of a recent Call for Proposals for the second medium- size mission to be considered for incorporation into ESA's Space Science: Horizon 2000 Programme. Although dropped in favour of the STEP mission (to test the Equivalence Principle), the Newton proposal generated considerable interest during the evaluation. The purpose of the Newton mission is to measure the gravitational constant, G, to an accuracy of 1 part in 10 000. (The best Earth based measurements of G can do no better than 1 part in 100.) In effect, Newton consists of a spin stabilised cylinder with a base diameter of about 3 meters and a height of 3.5 meters. Inside the cylinder, a miniature planetary system consisting of a planet with a mass of 75 kg and a satellite with a mass of 2 kg, performs an almost perfect free fall. An inward looking camera will track the motion of the system and small thrusters on the outside of the cylinder will adjust the trajectory of the cylinder. The cylinder will so follow the trajectory of a drag free satellite. An added benefit is the ability to map the gravitational field surrounding Earth, and, by keeping track of the corrections done by the small thrusters, to measure the variation of the solar radiation flux. If an accelerometer is added to the Newton payload, it can be very accurately calibrated. Precise Satellite Skin-Force Modelling by Means of Monte-Carlo Ray Tracing [. Klinkrad, Ch. Koeck, P. Renard] In order to increase the precision of orbit predictions of satellites, in particular for geodetic satellites, it becomes essential to model non-gravitational forces. Matra has developed software to model four of the so-called skin forces acting on satellites. These forces are: aerodynamic forces (lift and drag), direct solar radiation pressure, earth albedo radiation pressure and earth IR radiation pressure. The forces can be computed for a satellite of arbitrary shape complexity and surface properties. Also, multiple reflections will be included in the computation. The computation is based on Monte Carlo ray tracing techniques. The trade-off between computing time and accuracy can be tailored to user needs by the parameters of the ray tracing. Attitude and Orbital Modelling of Solar-Sail Spacecraft [F. Angrilli, S. Bortolami] The fifth centenary of the discovery of America by Columbus will be commemorated by the Space Sail Cup in 1992 between the continents of America, Europe and Asia. The spacecraft will be lifted to an orbit with an perigee of 1 000 km and an apogee of 36 000 km, free of charge to the design groups. Each spacecraft may not have a weight of more than 500 kg at launch. Using solar radiation pressure alone, the spacecraft must then escape from the Earth gravitational field and, after a lunar flyby, head towards Mars in an interplanetary orbit around the Sun. The winner of the first part of the Space Sail Race will be the spacecraft first to fly by the moon at a distance below 10 000 km, which may take up to 2 years, and the second part by the spacecraft first to fly by Mars at a distance less than 10 000 km, which may take up to 5 to 7 years. The European entry will consist of an aluminium-coated mylar sail of 100 x 100 meters. At the centre of the sail a truss is attached by means of a joint with two degrees of freedom. A service unit is attached to the other end of the truss. By manipulating the attitude of the truss with hull with respect to the sail, the location of the centre of mass of the spacecraft can be changed with respect to the centre of pressure of the solar radiation. In this way, the attitude of the spacecraft can be manipulated. A spacecraft flight simulator model has been developed for the first part of the race to study strategies for controlling orbital flight and attitude. Using this simulator, it was possible to develop a strategy which will result in lunar fly-by in about 650 days, while earlier studies gave a journey time of some 1100 days. The flight simulator made it also possible to study the spacecraft gyroscopic behaviour and the effects of torque caused by gravity gradients. Navigation of ERS-1 Along-Track Scanning Radiometer (ATSR) Images [D.M. O'Brien, A.J. Prata] The ERS-1 satellite, to be launched in may 1991, contains an Along Track Scanning Radiometer, which measures the temperature of the sea-surface. This instrument uses a conical scan beam, which permits each point on Earth to be scanned twice: the first time when the point passes the forward scan of the ATSR, the second time, approximately two minutes later, when the point passes the downward scan of the ATSR. Precise navigation of the images of the ATSR require detailed modelling of the orbit and the attitude of the satellite. However, simplified algorithms to implement a navigational procedure will be required by the user community, leaving the detailed calculations to ESA. The article describes such procedures which enable the user to predict position and velocity of ERS-1, to calculate latitude and longitude of an ATSR pixel, and to calculate the time when a target is under the forward or downward scan. Investigations into Multipactor Breakdown in Satellite Microwave Payloads [A. Woode, J. Petit] Multipactor is a discharge caused by the release of secondary electrons. These secondary electrons are released by the impact of free electrons accelerated by the electric field in RF equipment in spacecraft. Multipactor discharge can have serious effects on the short term and long term functioning of microwave equipment. ESA has built a test facility in which multipactor discharge can be studied. In parallel, a computer simulation has been developed. Results of this study are a better understanding of multipactor theory and the parameters that affect multipactor discharge, and the ability to achieve multipactor free high- power payload designs. ------------------------------ Date: 16 Mar 91 19:00:41 GMT From: isis!scicom!wats@uunet.uu.net (Bruce Watson) Subject: Salyut 7 in Argentina Spaceflight magazine (official publication of the British Interplanetary Society) states: "The Salyut 7 space station met its end shortly before 04.00 GMT on February 7. According to the TASS news agency, the station plunged into the Earth's atmosphere at latitude 34.9 degrees south, longitude 63.8 degrees west. A statement from the Argentine Defence Ministry said that debris fell in the Paymun and Catriel districts in the Neuquen province and the adjacent area in the La Pampa and Rio Negro Provinces. Eye witnesses described how they could see "fiery rain" as the debris from the space station burnt up. A fragment "the size of a washing machine" crashed into the backyard of a house in Rosario, the Bueno Aires Herald reported." -- wats@scicom | One of the things I like about this job is that I'm | never bothered by life-insurance salesmen. | -- Red Adair ------------------------------ Date: 18 Mar 91 00:11:08 GMT From: zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!p2112.f69.n233.z1.fidonet.org!David.Bloomberg@tut.cis.ohio-state.edu (David Bloomberg) Subject: Shuttle size Well, I sort of asked this before, but didn't get any answers, so I'll come out and just ask the question: Does anyone know the weight of the U.S. Space Shuttle (including booster rockets)? If so, what is it? Thanks. --- msged 1.999.7 * Origin: Religion doesn't belong on a Science Echo! (1:233/69.2112) -- David Bloomberg Internet: David.Bloomberg@p2112.f69.n233.z1.fidonet.org Compuserve: >internet:David.Bloomberg@p2112.f69.n233.z1.fidonet.org -------------------------------------------------------------------------- ------------------------------ Date: 19 Mar 91 23:53:04 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: Re: railguns and electro-magnetic launchers In article <1991Mar17.224947.16238@ariel.unm.edu> prentice@triton.unm.edu (John Prentice) writes: >I thought the real problem was surviving the initial acceleration... >... Has anyone ever attempted to >launch a payload out of a EM launcher that is at all complicated, in the >sense of having telemetry, etc... ? Nobody's done this with an EM launcher. However, it has been done many times with old-fashioned chemical guns, starting with radar proximity fuzes in WW2 and progressing to upper-atmosphere research instruments in the 1960s with Project HARP. (The proximity fuzes were particularly impressive because the electronics in them used *vacuum tubes*...) -- "[Some people] positively *wish* to | Henry Spencer @ U of Toronto Zoology believe ill of the modern world."-R.Peto| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 20 Mar 91 01:09:57 GMT From: agate!bionet!uwm.edu!caen!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucbvax.Berkeley.EDU (Ron Baalke) Subject: Magellan Update - 03/19/91 MAGELLAN STATUS REPORT March 19, 1991 The Magellan spacecraft and its radar system are performing nominally. All of the STARCALS (star calibrations) and DESATS (desaturations) yesterday were successful. Later today the weekly mapping command sequence, M1079, with its radar control parameter and mapping quaternion files will be sent to the spacecraft. Also being sent to the spacecraft today will be a command sequence to perform Test #2 on the Flight Tape Recorder "A". If approved later today, the final files to reload AACS (Attitude and Articulation Control Subsystem) Memory "B" will be sent tomorrow. Spacecraft engineers have determined the cause of the heartbeat loss counts and the protected memory warnings observed last week while trying to reactivate Memory B, so the process of restoring the full redundancy of the AACS memories can now be completed. The new on-board sequence includes fault detection which will quickly isolate the memory in the event of a chip failure. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant. /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | |_____|/ |_|/ |_____|/ | ------------------------------ Date: 17 Mar 91 04:43:54 GMT From: skipper!shafer@ames.arc.nasa.gov (Mary Shafer) Subject: Re: Titan IV Launch - March 8, 1991 In article gaserre@isis.isis.cs.du.edu (Glenn A. Serre) writes: >According to the Lompoc something-or-other, a Titan IV was launched from >VAFB on March 8, 1991. The payload was said by "space analysts" to be a >Lacrosse. Really early in the morning, because by 0530 the contrail/exhaust trail had drifted so far east that I saw it in the east when I went out for the paper. Lancaster is about 100-120 miles east of Vandenberg. They mentioned it on the Los Angeles news. >The launch went great, and all parties appear to be satisfied. Including me, because I scampered back in for my camera and got some pretty nice pictures. -- Mary Shafer shafer@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!shafer NASA Ames-Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA ------------------------------ Date: 11 Mar 91 10:36:00 GMT From: agate!linus!philabs!ttidca!quad1!bohica!mcws!p0.f851.n102.z1.fidonet.org!Nick.Szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: German conference highlights doubts about ESA's manned space plans From: szabo@crg5.UUCP (Nick Szabo) Path: wciu!elroy.jpl.nasa.gov!usc!zaphod.mps.ohio-state.edu!wuarchive!uunet!zephyr.ens.tek.com!tektronix!sequent!crg5!szabo Newsgroups: sci.space Subject: Re: German conference highlights doubts about ESA's manned space plans Message-ID: <21318@crg5.UUCP> Date: 11 Mar 91 02:36:00 GMT In article <9466@exodus.Eng.Sun.COM> agn@bovic.Eng.Sun.COM (Andreas G. Nowatzyk) writes: >True, but I read the original argument slightly differently: It is possible >to design Solar Max, etc. for in-orbit repair by robots, which was not done. I didn't mean this, but this is a good point. Incidentally, Solar Max did need special design changes to allow repair (as opposed to retrieval and relaunch) by astronauts. It would be interesting to compare the cost of redesign for robotic vs. the cost of redesign for human repair, and then factor in the costs of human EVA time vs. telerobotic repiar time. >....For example, a lot of consumer equipment (VCRs & such) and >some computer gear (Mac's, printers, etc.) are now routinely designed for >robotic assembly. Lots of tiny details reqire attention: aviod screws, >avoid round screw-in connectors, provide guide-paths for modules, >snap-into-place things are king, locking mechanisms that require tools to >push in several places are fine, but ones that require rotary action are not, >avoid ill shaped objects like cable harnesses, ... nothing really fancy, but >it is quite a departure from the way current space probes are designed. > >Furthermore, in-orbit repairs are limited to module swaps. It's hard to >imagine someone replacing a 300+ pin surface mounted chip during EVA. Good point. Are there any large differences between design for robotic and astronautic EVA repair? -- Nick Szabo szabo@sequent.com "What are the _facts_, and to how many decimal places?" -- RAH -- : Nick Szabo - via FidoNet node 1:102/851 (818)352-2993 : ARPA/INTERNET: Nick.Szabo@p0.f851.n102.z1.fidonet.org : UUCP: ...!{elroy!bohica,elroy!wciu,cit-vax!wciu}!mcws!851.0!Nick.Szabo : Compu$erve: >internet:Nick.Szabo@p0.f851.n102.z1.fidonet.org ------------------------------ End of SPACE Digest V13 #284 *******************