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, 3 Nov 89 03:27:47 -0500 (EST) Message-ID: <8ZIIiHG00VcJE90U5I@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 3 Nov 89 03:26:06 -0500 (EST) Subject: SPACE Digest V10 #195 SPACE Digest Volume 10 : Issue 195 Today's Topics: Re: Manned Jupiter Mission Balloon Launch attempt of a High Power Rocket (40 miles) NASA Headline News for 10/31/89 (Forwarded) a glimpse behind Venus's veil Rock sizes in space Voyager trajectory diagram Re: Manned Jupiter Mission (was Re: ---------------------------------------------------------------------- Date: 31 Oct 89 01:56:50 GMT From: terry@astro.as.utexas.edu (Terry Hancock) Subject: Re: Manned Jupiter Mission In article <4772@mentor.cc.purdue.edu> f3w@mentor.cc.purdue.edu (Mark Gellis) writes: >Regarding long term manned missions in space... > >I've heard talk of using magnetic fields to deflect cosmic rays, particles, >etc. This would supposedly lower the mass of the hull necessary to protect >the crew of a spacecraft from radiation. Is this true? Workable? What is >involved in setting up such a "radiation shield"? > Yes ... in principle. This is what protects us on Earth and in LEO. However, there are serious problems. There is a significant danger of actual *increasing* the radiation levels this way. I've also heard mention (I think) of an electrostatic shield (repel charged particles by direct Coloumb force law rather than trapping them in magnetic fields). The problem, basically, is with controlling large enough magnetic fields to act as shields, and preventing the trapped particles from being dumped onto the spacecraft. Consider, for example, the problem of turning the field off safely -- if you shut it off suddenly, a good number of your trapped shielding particles will spray through your ship on their way to inifinity. The last description I read on this was published in the mid-70's, so with the improvements in superconducting materials, it may be easier to do. They said it was beyond their technology, however, to build the necessary magnets -- or rather that they would be far too massive to be practical. >In addition, because I am interested in space colonization, I was wondering >what kind of shielding would be necessary (assuming magnetic fields, etc. >won't work as well as people would like) to protect people from the long >term background radiation of space. I heard something around two meters of >asteroid/lunar rock should be enough to stop pretty much everything; I was >wondering if this was true. > I heard (same source as above -- an L5 station design study, but I don't remember the name), that 10 tonnes per square meter of exposed surface would be required. Suppose you use lunar rock (a sort of slag, let's say) -- 10 Mg/m^2 is about 3.3 m thick. If you built out of a Ni-Fe asteroid, it'd be about 1.4 m thick. This is not exactly true, since density doesn't directly map to radiation cross-sections, but it's good enough for speculation. In any case, this thing will be HEAVY. It will almost certainly outweigh your spacecraft. There are other options though. Mostly what you're worried about are sporadic outbursts of solar activity (not the continuous level of radiation). So, you can design a short-term use shield -- perhaps covering only one hemisphere (roughly speaking) of your ship, or just thicker on one side. You just point that end towards the Sun during flares. Or, how about finding uses for your sheild? Water will stop a fair amount of radiation, so will your fuel. So, why not just put all that stuff in an orientation so that you can point it at the Sun during high activity. This is, as I understand it, the solution planned for the Mars mission (if & when...). Yes, I know that charged particles don't follow straight paths, but since it's the fast ones you're worried about, it's not a bad approximation. And, yes, you do need to have some sheilding all-around, I'm merely suggesting that it be concentrated on one side. >One final question. If magnetic fields for radiation shielding will work, >how much power would it require. Also (okay, I know this is two questions), > Good question. Depends on how efficient you can get your magnets to be. Also, since the radiation flux is highly variable, so will be your power losses. Perhaps, if indeed you CAN get away with only shielding during flares, you can turn it completely off except when needed. >can it operate if the object is moving relatively fast, like a spacecraft >moving from one location in a solar system to another? > Shouldn't affect it -- other than that it will be heavy. By the way, developing electromagnetic sheilding technology is probably vaguely related to developing a Bussard ram scoop. Any thoughts about that? >Thanks in advance. > > Mark Gellis > f3w%mentor.cc.purdue.edu ************************************* Terry Hancock terry@astro.as.utexas.edu ************************************* ------------------------------ Date: 31 Oct 89 00:35:33 GMT From: megatest!ivan@decwrl.dec.com (Ivan Batinic) Subject: Balloon Launch attempt of a High Power Rocket (40 miles) in article <2517@cbnewsd.ATT.COM>, R. Michael Jungclas Writes: >...For now, he's going to be launching a >2.6" diam. rocket from a balloon at an alititude of about 120,000' ^^^^^^^ ... >...A TV camera on the balloon will be able to cover the launch ^^ ^^^^^^ >(hopefully). The rocket will carry a flight computer and transmitter ^^^^^^ ^^^^^^^^ ^^^^^^^^^^^ ... I am very interested in such a venture. A few engineering problems come to mind (besides the balloon/rocket separation!). I'm curious about environment control: It seems to me that even some MIL- Spec components cannot function in the temperatures you can expect at those altitudes. Particularly since the balloon launch will prolong the flight computer's idle stay in the upper atmosphere. Was such an environment control device also placed on-board, or deemed not neces- sary? >... I will keep you informed of any further developments. If the net is inappropriate for more detailed discussions on this subject (and if I am not intruding) I would appreciate E-Mail correspondance. Thankyou for submitting this interesting article! Ivan Email: {sun,decwrl,fortune,pyramid}!megatest!ivan DisClaimer: My opinions are my own and do not necessarily reflect those of this organization. ------------------------------ Date: 31 Oct 89 21:06:23 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 10/31/89 (Forwarded) ----------------------------------------------------------------- Tuesday, October 31, 1989 Audio: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Tuesday, October 31.... The STS-33 crew completed the Countdown Demonstration Test for Discovery at Kennedy Space Center yesterday. Commander Fred Gregory, Pilot John Blaha and Mission Specialists Manley Carter, Story Musgrave and Kathryn Thornton showed a sense of humor by wearing costume hats and carrying artificial jack-o-lanterns on their way to the launch pad. Target date for the launch of the DoD mission is November 20. A firm date is expected to be set at the conclusion of the Flight Readiness Review on November 6 and 7. (Correction) The NASA budget, a part of the VA, HUD and Independent Agencies Appropriations Bill was n-o-t sent to the White House Friday. The Senate sent the bill back to the House for a vote on an amendment not associated with the NASA appropriation. Action on that amendment is expected today. The bill will then go to the White House with signing by the President expected sometime next week. With the Hubble Space Telescope now powered up at Kennedy Space Center, engineers have begun a series of checks of onboard instruments and systems. A satellite link between the Lockheed plant in Sunnyvale, Calif., and KSC is being used for data transmission during the tests. Other tests will be conducted between the Hubble Payload Operations Control Center at Goddard Space Flight Center and KSC also using the new satellite link. Launch of the telescope is scheduled for March 1990. The flap over Avtex Fibers' Front Royal, Virginia, rayon yarn plant continues. The state water control board is being asked by the state attorney general to revoke Avtex's permit to discharge toxic waste into the Shenandoah River. The plant produces special rayon yarn used in the manufacture of DoD and NASA solid rocket motors. If the board revokes the permit the plant would shut down. If closed Avtex would most likely appeal the decision in court. And....a new Intelsat V communications satellite is scheduled to achieve geostationary orbit today and deploy antennas later this week. The spacecraft was launched aboard an Ariane booster last Friday. * * * * ----------------------------------------------------------------- Here's the broadcast schedule for public affairs events on NASA Select TV. All times are Eastern. Wednesday, November 1.... 2:00 P.M. STS-34 post flight news conference from Johnson Space Center. 2:30 P.M. Following news conference...the quarterly (approx.) "Aeronautics and Space Report". Thursday, November 2..... 11:30 A.M. NASA Update will be transmitted. All events and times are subject to change without notice. ----------------------------------------------------------------- These reports are filed daily, Monday through Friday, at 12 noon, Eastern time. ----------------------------------------------------------------- A service of the Internal Communications Branch (LPC), NASA Headquarters, Washington, D.C. ------------------------------ Date: 1 Nov 89 00:38:12 GMT From: bridge2!3comvax!michaelm@apple.com (Michael McNeil) Subject: a glimpse behind Venus's veil Avid tourists of the Solar System won't want to miss the geological tour of a portion of Venus's surface that's included in the 20 October 1989 article in *Science* "Styles of Volcanism on Venus: New Arecibo High Resolution Radar Data." After some preparation -- moseying, say, down to your local U.S. Geological Survey office (for example, the office at 345 Middlefield Road in Menlo Park, California), there purchasing the "Altimetric and Shaded Relief Map of Venus" (a beautiful map, color coded for the elevations of Venusian terrain), and after orienting oneself to the scale and locations of Venusian features described in the article -- thereupon is revealed unparalleled high-resolution radar "photographs" of Venusian mountain and plain, complete with analysis. I think it's a tour de force (comparable in its way to Voyager in revealing an un-Earthly realm to us), and the team that accomplished this feat all the way from Earth is certainly due multiple huzzanahs! (And mucho thanks to the authors of the article, a beautiful job....) Anyway, the radar "photographs" show glaring, obvious, spouting-all- over-the-landscape examples of volcanism on Venus. It's completely garish in the case of Theia Mons (a major peak in the Venusian region known as Beta Regio, where several major rift zones intersect). It's as if someone had squirted spaghetti all over the country, dribbling down every little fault -- it's quite a sight, go check it out.... (And how about this -- in only one week, not only a tour of Venus, but another brilliantly lucid [IMHO] article "The Chemistry of Solid-State Electronics," by E. Yablonovitch -- and an honorable mention: "Burgess Shale Faunas and the Cambrian Explosion." Sock it to me, oh "National Enquirer" of *Science*! Week after week; I can take it! "Ahhh...!!!") -- Michael McNeil michaelm@vax.3Com.COM (3comvax.UUCP) 3Com Corporation hplabs!oliveb!3comvax!michaelm Mountain View, California work telephone: (415) 969-2099 x 5-208 References [1] "Altimetric and Shaded Relief Map of Venus," Atlas of Venus, 1:50,000,000 Topographic Series, V50M 6/60 RKT, 1981, published by the U.S. Geological Survey. [2] Donald B. Campbell, James W. Head, Alice A. Hine, John K. Harmon, David A. Senske, Paul C. Fisher, "Styles of Volcanism on Venus: New Arecibo High Resolution Radar Data," *Science*, 20 October 1989 (vol. 246), pp. 373-376. [3] E. Yablonovitch, "The Chemistry of Solid-State Electronics," *ibid.*, pp. 347-351. [4] S. Conway Morris, "Burgess Shale Faunas and the Cambrian Explosion," *ibid.*, pp. 339-346. ------------------------------ Date: 1 Nov 89 02:03:53 GMT From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!radio.astro!helios.physics!neufeld@tut.cis.ohio-state.edu (Christopher Neufeld) Subject: Rock sizes in space I read something recently in a science fiction book, and would like to know where the science ends and the fiction begins. The book made mention of a rule which stated that for each object in the solar system of a given diameter, you could expect to find ten objects with a diameter one third as great. Is there any real evidence of a rule to this effect? Note: new path. I can finally get rid of that annoying disclaimer. -- Christopher Neufeld....Just a graduate student | New degree, new cneufeld@pro-generic.crash | supervisor, new neufeld@helios.physics.utoronto.ca | project, and a "Don't edit reality for the sake of simplicity" | new path. NOTE. ------------------------------ Date: 1 Nov 89 03:02:24 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Voyager trajectory diagram A little while ago, in one of my AW&ST summaries, I was quite taken with a perspective diagram of the trajectories of the Voyagers with respect to the planets. I've just discovered the original; it's in JBIS (the Journal of the British Interplanetary Society), Oct 1985, page 440. In black&white rather than pretty color, but larger and more legible (and incidentally, much easier to reproduce). -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 31 Oct 89 17:50:40 GMT From: gem.mps.ohio-state.edu!wuarchive!brutus.cs.uiuc.edu!samsung!shadooby!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Manned Jupiter Mission (was Re: In article <36600004@ux1.cso.uiuc.edu> daniel@ux1.cso.uiuc.edu writes: >... one of the greatest challenges of >even a manned trip to Mars is that of radiation shielding from cosmic >radiation... Unless the general opinion has changed since I last heard it, cosmic rays are a big issue only if you plan to spend a significant fraction of your life outside the Van Allen belts. A couple of years is a significant exposure but not a particularly worrisome one. No Mars-expedition plan that I'm aware of uses cosmic-ray shielding en route, although ideas for significant stays on the surface tend to involve buried living quarters. >... If astro/cosmonauts spent 18 months flying to Mars in the >traditional 5-10 cm thick hulled tin can that has been the tradition for space >crafts flown under the Earth's Van Allen belts... Uh, 5-10 *centimeters*?!? More like a few millimeters, unless you count a certain amount of equipment in as shielding. >If humans did make it to Jupiter, I would think that, unless they have very >good shielding, would head either for the cover of >5 m of Jovian moon dirt or >for the underside of the Jovian radiation belts! It depends on how long they're staying there. For a lengthy stay, local dirt would be a good thing to have. The problem with getting inside the Jovian Van Allen belts is that you have to pass through them -- and that is a radiation problem that makes cosmic rays look insignificant. A human passenger aboard one of the Voyagers, which zipped through at very high speed, would have taken a very-probably-lethal dose. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ End of SPACE Digest V10 #195 *******************