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, 9 May 90 01:47:07 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 9 May 90 01:46:04 -0400 (EDT) Subject: SPACE Digest V11 #375 SPACE Digest Volume 11 : Issue 375 Today's Topics: Re: space garbage Voyager Update - 05/08/90 Re: CD-ROMs Re: Voyager Update - 05/08/90 Re: Black Holes (was Dyson spheres, heat flow) Re: Re: Dyson spheres? Astrodynamic analysis software (personal computers) Re: Fermi Paradox Re: space garbage Re: Manned mission to Venus ---------------------------------------------------------------------- Date: 8 May 90 15:06:36 GMT From: cs.utexas.edu!texbell!nuchat!steve@tut.cis.ohio-state.edu (Steve Nuchia) Subject: Re: space garbage In article <19259@crg5.UUCP> gsmith@crg5.UUCP (Greg Smith) writes: >caused by a very small particle, (was it a paint chip?) a similar collision >during EVA would pass cleanly through the unlucky person in the suit, or is it >somehow reinforced to stop most particles? TIA for any insights. The suits include several layers of meteor blanket material. That's the reflective "foil" stuff that you see wrapped around spacecraft. In a suit it is between the wear layer and the air barrier. Impact with the faceplate might be exciting though. In case you missed it, the shielding works like this: the outer layers, together with the impacting object, vaporize. The heat released is reflected by the intact inner layers. End of event. ------------------------------ Date: 8 May 90 15:46:24 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Voyager Update - 05/08/90 Voyager Mission Status Report May 8, 1990 Voyager 1 Voyager 1 continues to collect routine cruise science data. Two high-rate Ultraviolet Spectrometer (UVS) observations of HD 217675 were conducted on April 27. On May 2 one frame of high-rate Plasma Wave (PWS) data was recorded. On April 27 a real time command mini-sequence was transmitted. This sequence executed as scheduled on May 1, and provided the successful playback and recovery of the remaining "family portrait" imaging data, as well as three frames of PWS data. Real-time observation of the playback images indicated that four imaging frames were fragmented as processed by the Multimission Image Processing Subsystem (MIPS) however, three of the images appeared to have all of the necessary data to build a complete frame. MIPS indicated that there were indeed internal problems during the real-time processing and these images would be reprocessed as soon as possible. A real-time command file to reset the Computer Command Subsystem (CCS) status telemetry was also transmitted on May 1. A CCS memory read-out was performed and verified the reset of the CCS status telemetry. The time offset between the CCS and the Flight Data Subsystem (FDS) reported previously was ascribed to an FDS Power On Reset (POR) that occurred during a tracking gap. Real-time commanding was performed in an attempt to correct the offset. On April 30, a CCS timing offset determination was transmitted that confirmed the offset. On May 1, a clock reset sequence was transmitted to correct the offset, followed by another CCS timing offset determination (to verify the correction). Unfortunately, the clock reset sequence was not properly integrated with other activities (the planned transmission time was insufficienty delayed from a reset of the CCS integrated telemetry status word) and the sequence was not acted upon by the CCS. Another attempt at removing the offset is being planned, and a CCS clock adjustment is now scheduled for May 16. A spacecraft roll manuever (MAGROL) was also executed on May 1. This resulted in the successful execution of the ten revolution roll turn maneuver and subsequent power down of the Attitude and Articulation Control Subsystem (AACS) B and C gyros. Voyager 2 Voyager 2 also continues to collect routine cruise science data. High-rate UVS observations of HD 200120 were conducted on April 30 and May 3. (Most of these observations were not acquired due to limited Deep Space Network (DSN) station availability.) One frame of high-rate PWS data was recorded on May 1. Memory compares of the AACS and CCS memory read-outs performed on April 25 have been completed. These compares indicate that memory contents for the AACS and CCS are as expected. CONSUMMABLE STATUS P R O P E L L A N T S T A T U S P O W E R Consumption One Week Propellant Remaining Output Margin Spacecraft (Gm) (Kg) Watts Watts Voyager 1 42 36.5 + 2.0 370 59 Voyager 2 6 39.6 + 2.0 374 66 Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | Go Lakers! ------------------------------ Date: 8 May 90 18:47:23 GMT From: usc!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!haven!uvaarpa!murdoch!astsun8.astro.Virginia.EDU!gsh7w@ucsd.edu (Greg S. Hennessy) Subject: Re: CD-ROMs Darik Datta writes: #Could anyone please mail me the address of the NSSDC. Since several people have asked, I will post the info. I get all my data from the NSSDCA by mailing to Dr. Wayne H. Warren Jr. Astronomy Data Center NASA NSSDC GSFC 633 Greenbelt MD 20771 -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w ------------------------------ Date: 8 May 90 21:38:34 GMT From: usc!samsung!umich!sharkey!amara!khai@ucsd.edu (S. Khai Mong) Subject: Re: Voyager Update - 05/08/90 In article <3608@jato.Jpl.Nasa.Gov> baalke@mars.jpl.nasa.gov (Ron Baalke) writes: > One Week Propellant Remaining Output Margin > Spacecraft (Gm) (Kg) Watts Watts > Voyager 1 42 36.5 + 2.0 370 59 What does the +2.0 mean? -- Sao Khai Mong: Applied Dynamics, 3800 Stone School Road, Ann Arbor, Mi48108 (313)973-1300 (uunet|sharkey)!amara!khai khai%adi.com ------------------------------ Date: 8 May 90 22:05:56 GMT From: zaphod.mps.ohio-state.edu!uwm.edu!ux1.cso.uiuc.edu!dino!ceres.physics.uiowa.edu!pjz@tut.cis.ohio-state.edu Subject: Re: Black Holes (was Dyson spheres, heat flow) In article <2802@legs.UUCP>, rodentia@legs.UUCP (Tom Roden) writes: > in article <1990Apr27.130448.8228@watdragon.waterloo.edu>, jdnicoll@watyew.waterloo.edu (Brian or James) says: > [Stuff Deleted] > | [I'm saying this badly, but if you drop an object > | into an existing black hole, you won't see it cross the event horizon, > | but just get closer and closer as its velocity approaches C]. > > I thought that it would never see itself cross the event > horizon (due to time dilation), but that you could see it > from the outside just fine. Is that correct? The outsider detects the object by measuring its radiations. You can think of the frequency of the radiation as a kind of clock, since frequency is 1/period of the radiation wave. As a result of time dilation, the outsider observes an increase in the period of the wave, so that the frequency decreases. Thus, the radiation becomes redshifted in the frame of the outsider. As the object approaches the horizon, the outsider observes the object being redshifted out of existence;outsider never observes the object crossing the horizon. In the frame of the object, the clock appears to run normally. Ie., the radiation frequency of the object in the frame of the object is the rest frequency. So the observer riding with the object is able to observe the approach and entry into the horizon. > > -- > Thomas A. Roden uucp: ...!uunet!ccicpg!legs!rodentia > AST Research Inc. Dept 659 > P.O. Box 19658 Voice: (714) 727-8611 > Irvine, CA 92713-9658 Fax: (714) 727-9358 ------------------------------ Date: 9 May 90 04:10:35 GMT From: cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca!neufeld@tut.cis.ohio-state.edu (Christopher Neufeld) Subject: Re: Re: Dyson spheres? In article <1990May8.233921.28784@helios.physics.utoronto.ca> neufeld@physics.utoronto.ca (Christopher Neufeld) writes: > > Yes, but that makes the sphere less useful as a heat engine. BTW, in >the scenario I described in the first section, each surface would see >about three times the solar momentum flux (twice on absorption and once >on emission) or about 1.4E-5 kg / m s. In real units, that's one >kilogram for 425 m^2 of exposed surface, assuming solar momentum flux is >the only force which opposes the gravitational attraction. > I left out some geometric factors in the integrals. Unless I missed some others, it should be closer to 9E-6 kg / m s^2 (correct units this time), or one kilogram for 630 m^2 of exposed surface. This is because non-orthogonal incidence changes that "three times the solar momentum flux" to about twice the solar momentum flux (only the radial component of the flux is important). -- Christopher Neufeld....Just a graduate student | "Spock, comment?" neufeld@helios.physics.utoronto.ca | "Very bad poetry cneufeld@pro-generic.cts.com Ad astra! | captain." "Don't edit reality for the sake of simplicity" | ------------------------------ Date: 8 May 90 08:00:16 GMT From: fernwood!portal!cup.portal.com!jpser@uunet.uu.net (John Paul Serafin) Subject: Astrodynamic analysis software (personal computers) Cygnus Engineering has developed two software products for doing astrodynamic analysis on IBM compatible personal computers running under the MS-DOS operating system. Versions for the Apple Macintosh computer are under development. Other platforms are under consideration. Much effort has gone into making these products accurate, fast, useful, easy to learn, and convenient to use. Orbital Workbench is a comprehensive package for performing a wide range of orbital mechanics and mission analysis tasks. Several modules graphically display simulation status and results as they are calculated. OrbitView enables three-dimensional visualization of animated satellite orbits to aid in mission planning and orbit selection. Both programs support output to the video screen, hardcopy, and data files and both are driven by an intuitive menu interface which works equally well with a mouse or cursor keys. --------------------------------------------------------------------------- Seven modules comprise Orbital Workbench: Ephemeris Generation and Coverage - with user selectable perturbations and over 20 possible data plots, including orbital elements, relative motion, ground station contact times, and Earth shadow periods. Ascent Trajectories - select from rocket database or customize parameters Optimal 2-Impulse Orbit Transfers - computes minimum delta-V orbit transfers Relative Motion - creates plots of intrack, crosstrack, and radial motion Astrodynamic Calculator - any of over 30 orbital parameters may be entered in any order. As each parameter is entered, any parameter dependent on previous entries is calculated and displayed. Planetary Positions - accurate to one arc-minute over a 600 year time span --------------------------------------------------------------------------- The original version of OrbitView was developed for the US Air Force. OrbitView allows you to select a viewpoint in Earth centered inertial space, onboard a satellite, or on the Earth's surface for visualization of orbits above a rotating Earth. Features include: Earth surface updated several times per second, sattelite positions over 20 times per second User selectable time step Multiple satellites animated simultaneously with or without space tracks Effects of J2 oblateness included Interactive control of field-of-view (zoom), view direction (pan), view position, and time step. Interactive toggles for: Display of Sun, Moon, and planet positions Day/Night terminator display Orbit traces (space tracks) Status window Help window --------------------------------------------------------------------------- For more detailed technical information, a free demonstration disk, and price list please contact: Cygnus Engineering 918 Leighton Way Sunnyvale, CA 94087 USA (408) 773-8366 jpser@cup.portal.com ------------------------------ Date: Tue, 8 May 90 18:56:22 -0500 From: thomas@csvax.csc.lsu.edu (Thomas A. Bitterman) Subject: Re: Fermi Paradox The role playing game Traveller (tm) by Game Designer's Workshop has a ready made solar system generation method, part of a galaxy generation method. A patient player could build his own universe :>. I'm not sure of the accuracy of this method, but it works for the purpose intended (that is, a role-playing setting). The game as a whole seems reasonably well thought out as far as technology goes, no magic, just good engineering. Anyone who knows some astronomy and the Traveller system would be more illuminating. Look in the Scout advanced character generation system booklet. It might be out of print, so good luck. - Thomas Bitterman thomas@csvax.csc.lsu.edu - a budding technocrat, just ask my friends ------------------------------ Date: 8 May 90 15:13:53 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: space garbage In article <19259@crg5.UUCP> gsmith@crg5.UUCP (Greg Smith) writes: >Does anyone know what kind of survival procedure NASA has in place in the >event of a suit puncture, during EVA, by 'space garbage' or other particles? >Is there some type of automatic mechanism that would seal small holes? No, they simply rely on the suit being tough. >Also I would assume that judging by the degree of damage to the shuttle window >caused by a very small particle, (was it a paint chip?) a similar collision >during EVA would pass cleanly through the unlucky person in the suit, or is it >somehow reinforced to stop most particles? ... The major outer layer of the suits is combination thermal insulation and debris/micrometeorite armor. Windows are unusually vulnerable because their materials are brittle; a similar collision with a suit probably would do no significant damage. -- If OSI is the answer, what is | Henry Spencer at U of Toronto Zoology the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 7 May 90 18:13:55 GMT From: decvax.dec.com!zinn!ubbs-nh!siia!drd@mcnc.org (David Dick) Subject: Re: Manned mission to Venus msdos@quiche.cs.mcgill.ca (Mark SOKOLOWSKI) writes: >I would like to start a new discussion about a manned mission to Venus. >I know that given the inferno that's there, it sounds crazy, but Venus has >many advantages over Mars: ... >- 8 times the mass of Mars, which means that it can trap any spaceship more > easily than the red planet. I would think the deep planetary gravity well would make things worse by requiring more energy to go in and come back out. David Dick Software Innovations, Inc. [the Software Moving Company(sm)] ------------------------------ End of SPACE Digest V11 #375 *******************