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 ; Mon, 15 Jan 90 01:26:30 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 15 Jan 90 01:26:08 -0500 (EST) Subject: SPACE Digest V10 #428 SPACE Digest Volume 10 : Issue 428 Today's Topics: Re: Nuclear Reactors in Space Re: Why did Solar Max fall but space junk stays up? Re: Airlocks & Life support Re: Nuclear Reactors in Space Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space) Re: Question: Was American Moon landings on China's news back in 1969? AEROSPACE SOFTWARE Re: Payload Status for 01/08/90 (Forwarded) Re: Any NASA COBE Personnel Out There? Re: Nuclear Reactors in Space ---------------------------------------------------------------------- Date: 14 Jan 90 17:32:51 GMT From: rochester!dietz@rutgers.edu (Paul Dietz) Subject: Re: Nuclear Reactors in Space In article <9678@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes: >In article <1990Jan12.201706.21933@cs.rochester.edu> dietz@cs.rochester.edu >(Paul Dietz) writes: >>No, superconducting batteries could not give a sufficiently high >>specific energy to replace RTGs. The reason is fundamental, and >>cannot be avoided by design changes. > >Which would be very interesting information, if the question had been >whether superconductive loops could equal the energy density of RTGs. I said to replace RTG's, not have equal specific energy. As I argued, SMES specific energy faces the same theoretical limits as chemical batteries. About the best specific energy you can get with chemical batteries is to use a fuel cell with hydrogen/oxygen. At 100% efficiency, 500 watt-years of electricity would require about a ton of LOX + LH2, plus the mass of insulation, tanks, fuel cell, and so on. Too much. If you have a nonnuclear way of storing energy that has much better performance than hydrogen/oxygen, NASA would *love* to talk to you. The specific energy limits of chemical rocket fuels are a major reason why it's hard to get into space. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Sun, 14 Jan 90 16:30:37 PST From: pjs@aristotle.Jpl.Nasa.Gov (Peter Scott) Subject: Re: Why did Solar Max fall but space junk stays up? cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) writes: >>And every so often the Soviets render a dying >>military satellite worthless to scavengers by simply exploding it! > >Normally this is done only for birds that are about to make an uncontrolled >reentry anyway. The Soviet Asat tests were a different, and much more >troublesome, story, but they haven't run one of those for years. Thereby propelling back into orbit fragments that otherwise wouldn't be there. Space debris is more of a problem than what's left of a satellite making an uncontrolled reentry hitting the ground. Peter Scott (pjs@grouch.jpl.nasa.gov) ------------------------------ Date: Sun, 14 Jan 90 15:13:08 PST From: pjs@aristotle.Jpl.Nasa.Gov (Peter Scott) Subject: Re: Airlocks & Life support att!watmath!watserv1!utgpu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) writes: >The EVAs themselves are lengthy because work in free fall while wearing >a clumsy suit is difficult. Preparation for them is lengthy because keeping >the suits' clumsiness to a minimum requires running with an absolute minimum >of pressure in them. To do that, one has to run the suits on something >approaching pure oxygen. For various reasons, current preference is to >run spacecraft cabins at near one atmosphere and use a near-normal mix >of oxygen and nitrogen. The transition from a high-pressure atmosphere >rich in nitrogen to a low-pressure one requires lengthy pre-breathing >of pure oxygen to get the nitrogen out of the astronauts' bodies. (The >alternative is a strong possibility of decompression sickness, "the >bends", potentially crippling or fatal, as that nitrogen comes out of >solution as bubbles.) I wonder if this could be solved by going to an oxygen-helium mixture in the main cabin? The research and experience has already been performed in deep diving, and they could electronically correct the astronauts' voice frequencies. Then pre-breathe time should be much shorter. Peter Scott (pjs@grouch.jpl.nasa.gov) ------------------------------ Date: 13 Jan 90 08:16:06 GMT From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!leonard@uunet.uu.net (Leonard Erickson) Subject: Re: Nuclear Reactors in Space gsh7w@astsun.astro.Virginia.EDU (Greg S. Hennessy) writes: >In article <6732@lynx.UUCP> neal@lynx.UUCP (Neal Woodall) writes: >#which you you rather be hit by, a bunch of fast neutrons or a bunch of beta >#particles? >As if there was a difference. This is quite a difference. Which would you rather have me drop out a window on your head, shot puts, or tennis balls? That's a pretty good analogy. Fast neutrons will penetrate deeply and deposit most of their energy inside you, causing all sorts of damage. It takes multiple *feet* of shielding to stop them effectively. Beta particles are lucky to penetrate as much as half an inch of paper. They can cause surface damage to you. But they aren't likely to penetrate far enough to do serious damage. Oh yeah, the beta particle deposit their energy and that's that. But since your body is mostly water which is good at slowing neutrons, the neutrons are liable to end up by creating radio-isotopes inside you. And then you have to worry about them decaying. -- Leonard Erickson ...!tektronix!reed!percival!bucket!leonard CIS: [70465,203] "I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters." -- Solomon Short ------------------------------ Date: 13 Jan 90 08:01:58 GMT From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!leonard@uunet.uu.net (Leonard Erickson) Subject: Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space) leonard@bucket.UUCP (Leonard Erickson) writes: >So let's say the probe masses 1 metric tonne. And you have an hour to chop >the velocity from 20 km/sec to 10 km/sec. We start with 4e11 joules. At >the end we'll have 1e11. The difference is 3e11 joules. So we need to >dump 8.3333e7 joules/sec. That's over 83 Megawatts!!! Unless you have a >good way of using (or at least getting rid of) that much power, your >probe will be a rapidly expanding cloud of plasma. Ooops! I goofed. I forgot to multiply by .5.... So we start with 2e11 joules. At the end we have 5e10 joules. And the difference is 1.5e11 joules. We need to dump 4.166667e7 joules/sec. Which gives us *only* 41.66666 Megawatts. Still an unreasonable amount. I wrote a quick and dirty program to check on the energy required to chop 10 km/sec of off the velocity of a 1000 kg object. The graph of energy vs initial velocity is a straight line. So it increases linearly with the velocity. I ran into numeric overflow problems before I got up to .01 c though.... :-) -- Leonard Erickson ...!tektronix!reed!percival!bucket!leonard CIS: [70465,203] "I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters." -- Solomon Short ------------------------------ Date: 14 Jan 90 11:37:09 GMT From: munnari.oz.au!cluster!metro!bunyip!moondance!batserver.cs.uq.oz.au!anthony@uunet.uu.net (Anthony Lee) Subject: Re: Question: Was American Moon landings on China's news back in 1969? rfc@briar.philips.com (Robert Casey;6282;3.57;$0201) writes: >So, was it true that the Man on the Moon landing didn't make it onto >the News in China back in July 1969 (that's when it happened). Why >would the Chinese goverment not tell its citizens about the Moon >landing? (I'm just a dumb ordinary American.) I realize that many of >you college students were very young then (0 to 4 years old), and would not >remember this anyway. I was 15 years old then. So, anyone my age Well, I am not your age neither, I was only 5 then, but I have heard the same thing from a lot of other people. I believed the reasons why the Chinese government did not tell her citizens about the Moon landing is because of the culture revolution. After all, the Chinese communist party have to show that she is better then everyone else. In a way it is also related to the fact that China play such a big deal about her first hydrogen bomb and the first satellite. Actually talking about moon landing, I saw a space magazine a few months back and there was a mention that China is training her own astronauts. With the current playload of the LongMarch when would they be able to send anyone ? Also does anyone know what Soviet ICBM family does the LongMarch belongs to ? -- Anthony Lee (Humble PhD student) (Alias Time Lord Doctor) ACSnet: anthony@batserver.cs.uq.oz TEL:+(61)-7-371-2651 Internet: anthony@batserver.cs.uq.oz.au +(61)-7-377-4139 (w) SNAIL: Dept Comp. Science, University of Qld, St Lucia, Qld 4067, Australia ------------------------------ Date: 12 Jan 90 05:00:00 GMT From: samsung!umich!netnews.engin.umich.edu!caen.engin.umich.edu!talk@think.com (Thomas A Kashangaki) Subject: AEROSPACE SOFTWARE I AM A GRADUATE STUDENT IN THE AERO DEPARTMENT AT THE UNIVERSITY OF MICHIGAN AND AM WORKING ON THE NASA SPACE EDUCATION GRANT PART TIME. ONE OF THE ACTIVITIES WE ARE TRYING TO ORGANIZE IS A SERIES OF PROGRAMS FOR MIDDLE AND HIGH SCHOOL STUDENTS TO TRY AND INCREASE INTEREST IN ENGINEERING IN GENERAL AND AEROSPACE ENGINEERING IN PARTICULAR. I AM POSTING THIS TO SCI.SPACE IN THE HOPE THAT YOU SPACE JUNKIES CAN HELP ME LOCATE SOME AERO RELATED SOFTWARE FFOR THE MAC II OR UNIX MACHINES. I AM LOOKING FOR ANYTHING WITH A LOT OF GRAPHICS SUCH AS SHUTTLE SIMULATORS, ASTRONOMY CHARTS, ORBITAL MECHANICS PROGRAMS, AIRCRAFT DESIGN, JJUST ABOUT ANYTHING THAT WILL HOLD THE INTEREST OF A BUNCH OF 11-17 YEAR OLDS. IF YOU HAVE ANY INFO ON SOFTWARE, MANUFACTURERS, DOCUMENTATION,ETC PLEASE RESPOND TO "talk@caen.engin.umich.edu" I APPRECIATE ANY INPUT. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ Thomas A-L Kashangaki | TALK@caen.engin.umich.edu ~ ~ University of Michigan | kashangaki@ub.cc.umich.edu ~ ~ 111 Research Activities Building | ~ ~ Aerospace Engineering Department | phone: 313-764-5229 ~ ~ Ann Arbor, Mi 48104 | ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ . ------------------------------ Date: 15 Jan 90 02:49:42 GMT From: munnari.oz.au!cluster!metro!bunyip!brolga!ggm@uunet.uu.net (George Michaelson) Subject: Re: Payload Status for 01/08/90 (Forwarded) yee@trident.arc.nasa.gov (Peter E. Yee) writes: > >- STS-35 ASTRO-1/BBXRT (at O&C) - > >Cite testing continued over the weekend and will pick up >again this morning. Broken backshell has been repaired. >The fuse area was evaluated and the bad fuse on the SPDB >was removed and replaced. During Saturday's testing the same >fuse blew again. Today will work troubleshooting steps to >evaluate the fuse. Ok, so a volt is a volt is a volt. if a fuse blows twice, how come "troubleshooting steps to evaluate the fuse" are done? I thought once this happened you jammed a coin in between the slots in the fusebox, and switched it back on with a long wooden pole or got your mother to do it. Gee, it always seems to work at home, we just follow the smell of burning bakelite and try shaking the conduit a bit. Two blowouts and they start looking at the fuse. No comments on the circuit which makes the fuse blow? Is this NASA jargon for "hit the f**ker with a wrench and see where the sparks come from"? I guess NASA buys fuses from T*ndy just like everybody else. Apologies, George Internet: G.Michaelson@cc.uq.oz.au Phone: +61 7 377 4079 Postal: George Michaelson, Prentice Computer Centre Queensland University, St Lucia, QLD Australia 4067. ------------------------------ Date: 14 Jan 90 23:31:58 GMT From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Any NASA COBE Personnel Out There? In article <1730001@hpislx.HP.COM> gvg@hpislx.HP.COM (Greg Goebel) writes: >"Spectral Resolution" for FIRAS: > > 0.2 cm^-1 > >I must've stared at that for five or ten minutes. Either that's a typo or >I'm missing something. Any illumination out there? Looks fine to me. The spectroscopists have this curious habit of using waves per unit length ("wavenumber") rather than length per wave (normal, conventional "wavelength"). A wavenumber resolution of 0.2 cm^-1 is a wavelength resolution of 5cm. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 14 Jan 90 23:01:38 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@tut.cis.ohio-state.edu (Brian or James) Subject: Re: Nuclear Reactors in Space I am curious about the source of information Mr. Maroney is using that allows him to say "... Or we can be patient and wait for the considerably safer fusion technologies. Though a fusion drive probably shouldn't operate in the atmosphere, obviously there's no problem with it being lifted into orbit (or returning to Earth) by chemical means...". Since there are no currently functioning 'fusion drives' I am unclear as to how Mr. Maroney managed to assess their safety. The constraints on the design of a hypothetical 'fusion drive' are both physical and social. While there could easily be a fusion powerplant design that meets the limitations placed on it by the laws of physics and which is 'considerably safer' than existing fission (or other, perhaps less expensive fusion) power plants, I see no reason to expect that such a technology would inevitably be developed and used. Humans have a talent for folly. Short term political or economic goals have lead to foolish design choices in the past. The Challenger mishap, the difficulties experienced at Chernoble, and the less than masterful management techniques that lead to the current size of the British Empire are all examples of this. As well, while there are fusion techniques we now believe could be possible that do cause smaller and/or safer waste management problems that we now face, it is also quite posible that we are unaware of flaws in our models that make these hypothetical designs either usable or more dangerous than we now realise. I find the use of terms like 'considerably safer fusion technologies' difficult to justify, given the current absence of these systems. It is easy to proclaim that fusion -will- be safer that other power sources, since disproof of these statements is difficult, if not impossible. It is just as easy to say that God Himself will descend from the heavens to solve all our problems, if we all just *believe* purely enough. It is, however, difficult to use absolutist and unverifiable statements like these to plan a coherent plan of action. On a slightly different note, does anyone know of research into the effects of chemical boosters on the atmosphere? I dimly recall something about this being discussed in the mid '70s, but don't recall the details. If the propellant exhaust does have unfortunate side effects (Degradation of the ozone layer, catalysis of ice ages/run away green house effects, continual victories by the Republicans :), what limits on tonnage to orbit does this place on us? James Nicoll of the atmosphere ------------------------------ End of SPACE Digest V10 #428 *******************