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 ; Fri, 4 May 90 02:46:53 -0400 (EDT) Message-ID: <8aEGIXK00VcJM4iU5N@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 4 May 90 02:45:56 -0400 (EDT) Subject: SPACE Digest V11 #354 SPACE Digest Volume 11 : Issue 354 Today's Topics: Re: (How to get rid of) space garbage Gravity (was Re: Radar (was Re: Drake Equation Re: Re: Dyson spheres? Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) Re: Decompression Two communications satelllites to be launched in May (Forwarded) Re: NASA Headline News for 05/02/90 (Forwarded) Re: (How to get rid of) space garbage Manned mission to Venus Re: Voyager Update - 05/02/90 ---------------------------------------------------------------------- Date: 3 May 90 17:17:26 GMT From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!aristotle!pjs@ucsd.edu (Peter Scott) Subject: Re: (How to get rid of) space garbage In article <1990May2.204013.29461@helios.physics.utoronto.ca>, neufeld@physics.utoronto.ca (Christopher Neufeld) writes: > In article <1990May2.170219.5992@elroy.jpl.nasa.gov> pjs@aristotle.jpl.nasa.gov writes: > >Of course, one would hope that it wasn't in the wrong position when > >Hubble came around one orbit, or whoops... > > > Well, I chose 80000km for my proposal. It's out of the way of pretty > well everything. This scheme wouldn't be workable in LEO because of the > very low density of the sail needed to hold up against 1g of acceleration > (remember, the object isn't orbiting, so there is no "centrifugal > pseudo-force"). Well, actually I was thinking of accidentally shining the beam down the barrel of the HST... there are a number of other satellites out there one would not want to do this to, the aiming of this thing would have to be carefully worked out. After all, it doesn't sound as though it would be practical to turn it off. This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@aristotle.jpl.nasa.gov) ------------------------------ Date: 3 May 90 14:09:53 GMT From: vu0104@bingvaxu.cc.binghamton.edu (David Salzberg) Subject: Gravity (was Re: Radar (was Re: Drake Equation In article <63290002@hpsmdca.HP.COM> phil@hpsmdca.HP.COM (Philip Walden) writes: -Actually you are all right. Close to the array or high gain antenna -(probably about a few aperture lengths) the radiation will exhibit -a more linear effect with distance. Much farther away, everything -looks like a point source and exhibits the inverse-square relationship. -This applies to all fields, such as gravity. A flat earth of infinite -radius would have a constant gravitational field with height. This is -true even on our spherical earth. Within a few thousand feet of the -surface, most calculations can consider the strength of gravity as -a constant. In fact, geophysicists who study gravity anomolies assume a flat earth. This is not a bad approxmiation because on the scales event of a thousand km, the earth is essentially flat (that is, the curvature would change baseline measurements by 1.3%, which is far lower than observational errors). This approximation of a flat earth does not work on large, planet scale observations (such as free oscliations) or for highly precisie measurements (such as VLBI), but for some work, the earth is considered to be flat (for mathmatical simplifications). ------------------------------ Date: Thu, 3 May 90 18:10:37 EDT From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Re: Dyson spheres? >From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!maytag!watdragon!watyew!jdnicoll@ucsd.edu (Brian or James) >Subject: Re: Re: Dyson spheres? > I'd like to point out that my 'second rate' Dyson sphere at least >requires no superstrong materials or phenominal orbit coordination >to build and maintain. The heat problem is a pain, but I suspect it >can be dealt with, with perhaps a minor cost in the Sun's life >expectancy :). > JDN No offense intended - it's a clever idea. The only shortcoming (other than possibly burning out the sun) is the low density of the spherical surface - it would have to be mostly sail. If a person plus habitat is 500kg, than the sphere could support about 1.5 people per square kilometer. On a sphere with a radius of 1.4 AU, you could only have about 8.8E17 people, a mere 200 million times the current population. :-) I'm interested in spheres held apart by electromagnetic forces. This might not be practical with fixed magnetic fields, but changing fields and active control might make it possible. I suspect electromagnetism could support a much greater mass than light pressure alone. By the way, heating of the center star is a problem with *any* Dyson sphere, unless the inner surface is kept cold by active pumping of heat. This active pumping would take up much of the solar energy available. This might be a fundamental limit on the utility of Dyson spheres. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 3 May 90 07:23:59 GMT From: xavax!alvitar@uunet.uu.net (Phillip Harbison) Subject: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) In article <1990Apr30.045547.18649@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>>Have you heard of a Rocket called Saturn V ? There are 2 still available >>>for your contemplation if you haven't ... >> Only two?!?!?!? Last I checked, there was one at Kennedy, Johnson, and >>one at Huntsville... I believe there are two in Alabama. One is laid out on the ground at the Space and Rocket Center. You can walk up inside the huge F1 engines. The other is on display at the welcome center on I-65 just south of the AL and Tennessee border. I've seen S-Vs on display at both locations at different times, although its possible they were the same rocket. The Space and Rocket Center also has examples of most of the other US rockets and missiles (at least the NASA and Army stuff), including a Saturn I, Nike-Herc, Nike-Ajax, Little John, etc. and a mockup of the shuttle assembly. I also recall they recently got a mockup of the upcoming space station. It is a worthwhile attraction to visit if you are ever down this way. >The one at Huntsville is a "test article", a pre-production prototype that >was never considered flight-ready. (I've seen it, and read the signs on >it carefully.) So one can argue that it wasn't a "real" Saturn V. Marshall Space Flight Center does most of the stress testing. They take the prototype, strap it to one monster of a test stand, then shake the piss out of it. The prototype is "real", otherwise not much would be learned by the testing. Usually, the test vehicle undergoes enough stress that it wouldn't be prudent to place it in service. Would you want to take a flight in the Enterprise knowing it was shaken within a few milliseconds of mechanical fracture? :-) Of course some changes may occur between the test vehicle and the production vehicle, especially if the testing turns up a problem. The real fun takes place when one of these babies breaks loose from the stand with the engines ignited. Can you say "loose cannon"? I knew you could. This has happened with some smaller prototype missiles. Kinda hurts the value of real estate near MSFC and Redstone Arsenal, wouldn't you think? :-) -- Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807 Uucp: alvitar@xavax.com Bell: 205-539-1672, 205-880-8951 -- Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807 Uucp: alvitar@xavax.com Bell: 205-539-1672, 205-880-8951 ------------------------------ Date: 1 May 90 14:02:29 GMT From: mcsun!ukc!stl!stc!root44!gwc@uunet.uu.net (Geoff Clare) Subject: Re: Decompression In article <9004261818.AA06738@aqua.whoi.edu> capnal@AQUA.WHOI.EDU (Alan Duester) writes: >Note: Locking your nose shut so air doesn't leak out is a tricky thing. >The first time you try it, you'll also lock your throat if you are >anything like the normal SCUBA student. We're not used to doing it >without training. If in doubt, hold your nose and keep the throat open. I disagree - it's not difficult at all. Just pretend you're blowing up a balloon. -- Geoff Clare, UniSoft Limited, Saunderson House, Hayne Street, London EC1A 9HH gwc@root.co.uk (Dumb mailers: ...!uunet!root.co.uk!gwc) Tel: +44-71-315-6600 ------------------------------ Date: 3 May 90 21:24:54 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Two communications satelllites to be launched in May (Forwarded) Jim Cast Headquarters, Washington, D.C. May 3, 1990 (Phone: 202/453-8536) Jean Drummond Clough Langley Research Center, Hampton, Va. (Phone: 804/864-6122) Jan Bodanyi Department of Defense, Washington, D.C. (Phone: 202/695-0192) RELEASE: 90-64 TWO COMMUNICATIONS SATELLLITES TO BE LAUNCHED IN MAY Two Mulitiple Access Communications Satellites (MACSATs) are scheduled to be launched by NASA aboard a Navy-owned Scout rocket on May 9 from Vandenberg Air Force Base, Calif. The 90-minute launch window opens at 1:49 p.m., EDT. The program is sponsored by the Department of Defense Advanced Research Projects Agency (DARPA). The MACSATs, developed by Defense Systens Inc., will provide a global store-and-forward message relay capability at UHF frequencies for a variety of Department of Defense users during test demonstrations to be conducted this year by DARPA. The Scout program is managed by NASA's Langley Research Center, Hampton, Va. The 73-feet-long, four stage, solid- propellant rocket motor launch vehicle is built by the Missiles Division of LTV Missiles and Electronics Group, Dallas, Texas. First launched in 1960, Scout has had 98 successful missions in 112 attempts, including 56 successes in 57 launches since 1967. - end - NOTE TO EDITORS: The Scout/MACSAT launch will be carried live on NASA Select television via Satcom F-2R, Transponder 13, C-Band located at 72 degrees west longitude, frequency 3960.0 MHz, vertical polorization, audio monaural 6.8 MHz. Media representatives may view the launch in the NASA Headquarters auditorium, 400 Maryland Ave., S.W., 6th floor, room 6104. ------------------------------ Date: 3 May 90 15:45:27 GMT From: sdd.hp.com!samsung!sol.ctr.columbia.edu!IDA.ORG!pbs!pstinson@ucsd.edu Subject: Re: NASA Headline News for 05/02/90 (Forwarded) In article <48517@ames.arc.nasa.gov>, yee@trident.arc.nasa.gov (Peter E. Yee) writes: > ----------------------------------------------------------------- > Wednesday, May 2, 1990 Audio Service: 202/755-1788 > ----------------------------------------------------------------- > This is NASA Headline News for Wednesday, May 2... > (several news items deleted) > ******** > The Apollo 204 spacecraft will be moved from the Langley Research > Center, May 20 and placed in permanent storage in an abandoned > missile silo at Cape Canaveral Air Force Station in Florida. The > Apollo has been in storage at Langley Research Center since 1967. > Is this just the command module (CM) or the whole command & service module (CSM) assembly? Being a block I spacecraft this would have to be modified to reflect later safety standards impossed after the Apollo fire destroyed a capsule of nearly identical internal design. However, if this can be done with resonable effort, Apollo 204 could become a nearly off the shelf Orbital Transfer Vehicle. I know from studying my 1/144 scale models that an Apollo CSM will fit inside a Shuttle cargo bay. Lift the Apollo into orbit with a Shuttle and leave it there. (Perhaps after space station construction is far enough along to serve as a base of operations.) Serviced in orbit it could then ferry payloads from LEO to GEO or even to lunar orbit. ------------------------------ Date: 3 May 90 18:03:04 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca!neufeld@ucsd.edu (Christopher Neufeld) Subject: Re: (How to get rid of) space garbage In article <1990May3.171726.9791@elroy.jpl.nasa.gov> pjs@aristotle.jpl.nasa.gov writes: >In article <1990May2.204013.29461@helios.physics.utoronto.ca>, >neufeld@physics.utoronto.ca (Christopher Neufeld) writes: >> In article <1990May2.170219.5992@elroy.jpl.nasa.gov> >pjs@aristotle.jpl.nasa.gov writes: >>>Of course, one would hope that it wasn't in the wrong position when >>>Hubble came around one orbit, or whoops... >>> >> Well, I chose 80000km for my proposal. It's out of the way of pretty >> well everything. This scheme wouldn't be workable in LEO > >Well, actually I was thinking of accidentally shining the beam down the >barrel of the HST... there are a number of other satellites out there >one would not want to do this to, the aiming of this thing would have to >be carefully worked out. After all, it doesn't sound as though it would >be practical to turn it off. > No, it can't be turned off in a reasonable period of time. The beam isn't a death-ray, though. It has the same intensity as sunlight. The beam would be seen to come from a point somewhat east of straight up when you were at local midnight, to make its closest approach to the Earth just darkside of the day-night terminator to the west of the observer at local midnight. (By local midnight I mean a person on the opposite side of the Earth from the Sun). This beam always shines into the faces of incoming particles, so the HST wouldn't be pointed at the beam, since it would also be scooping up atomic oxygen in that configuration. Local overheating in some satellites, which are suddenly lit with normal intensity sunlight from both sides might be a problem, but they wouldn't stay in the beam for more than five minutes at a time, and would pass into the Earth's shadow partway through this interval. >This is news. This is your | Peter Scott, NASA/JPL/Caltech >brain on news. Any questions? | (pjs@aristotle.jpl.nasa.gov) -- 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: 4 May 90 02:56:07 GMT From: news-server.csri.toronto.edu!clyde.concordia.ca!mcgill-vision!quiche!calvin!msdos@rutgers.edu (Mark SOKOLOWSKI) Subject: Manned mission to Venus 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: - 3 month flight instead of 9, and lower energy requirements to go there. - 8 times the mass of Mars, which means that it can trap any spaceship more easily than the red planet. - Notwithstanding its athmosphere, Venus is the TRUE twin of our Earth, and it should be therefore our main target from the cultural point of view. - The athmosphere of Venus has the same quantity of oxygen as here. And for those that doubt about my seriousness, I am glad to tell that I will be the first to volunteer to go there... After all our technology can enable us to make life bearable even at 900 F and 90 athmospheres Mark S. ------- ------------------------------ Date: 3 May 90 17:21:38 GMT From: sdd.hp.com!elroy.jpl.nasa.gov!aristotle!pjs@ucsd.edu (Peter Scott) Subject: Re: Voyager Update - 05/02/90 In article <3558@jato.Jpl.Nasa.Gov>, baalke@mars.jpl.nasa.gov (Ron Baalke) writes: |> |> |> Voyager Mission Status Report |> May 2, 1990 |> |> On April 17, Attitude and Articulation Control Subsystem (AACS), |> Computer Command Subsystem (CCS), and Flight Data Subsystem (FDS) memory |> readouts and a playback of PWS and Imaging Science (ISS) data were performed. |> (The ISS data consisted of the "family portrait" images lost due to rain ^^^^ |> during the March 23 playback.) Due to a maser failure at the 70 meter antenna |> in Spain (DSS-63),[...] ^^^^^ The rain in Spain affects mainly antenna gain...? This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@aristotle.jpl.nasa.gov) ------------------------------ End of SPACE Digest V11 #354 *******************