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 Oct 1990 01:27:19 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 15 Oct 1990 01:26:46 -0400 (EDT) Subject: SPACE Digest V12 #459 SPACE Digest Volume 12 : Issue 459 Today's Topics: Re: Cost comparison: Apollo/Saturn vs. Shuttle Capsule parachute reliability Former astronaut Scott Carpenter to attend Chicago Hobby Show Re: Deep Space Network use (Was: Ulysses Update - 10/06/90) Re: disposal of N-waste into sun Re: Magellan/Venus Info North and South off Earth [was Magellan/Venus Info] Re: Manned/unmanned tradeoffs Re: Atmospheric nitrogen Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 14 Oct 90 18:22:54 GMT From: uceng!minerva!dmocsny@iuvax.cs.indiana.edu (Daniel Mocsny) Subject: Re: Cost comparison: Apollo/Saturn vs. Shuttle In article <143708@sun.Eng.Sun.COM> jmck@norge.Eng.Sun.COM (John McKernan) writes: >And if we want to get a few men >up into LEO all we need to do is put a simple capsule on one of our >cheap private boosters. Remember, a capsule is a simple thing, at least >compared to other space hardware. It's just a few retro rockets, O2 >bottles, and parachutes. This reminds me of something I have wondered about: What is the reliability of the parachutes used in space capsules? From my exposure to sport skydiving, I recall a figure of about 1 parachute malfunction in 300 dives for skilled parachutists. (That is why they need reserve chutes. The reserve chute is similarly reliable, meaning that the parachutist can expect to "bounce" in 1 out of 300^2 dives or so.) Do space capsule designers plan to lose 1 in 300 flights to parachute malfunctions? Do they have reserve chutes and procedures to cut-away malfunctioning main chutes? Or are capsule chutes inherently more reliable than the sport parachutist's gear? -- Dan Mocsny Snail: Internet: dmocsny@minerva.che.uc.edu Dept. of Chemical Engng. M.L. 171 dmocsny@uceng.uc.edu University of Cincinnati 513/751-6824 (home) 513/556-2007 (lab) Cincinnati, Ohio 45221-0171 ------------------------------ Date: 14 Oct 90 19:17:09 GMT From: world!ksr!clj%ksr.com@uunet.uu.net (Chris Jones) Subject: Capsule parachute reliability In article <6393@uceng.UC.EDU>, dmocsny@minerva (Daniel Mocsny) writes: > >What is the reliability of the parachutes used in space capsules? > Do they have reserve chutes and procedures to cut-away >malfunctioning main chutes? Or are capsule chutes inherently more >reliable than the sport parachutist's gear? > I'm pretty sure Mercury and Gemini had a reserve chute for their one main chute. Apollo had three main chutes, and I don't know if they had any in reserve. I know it was possible to land safely using only two chutes, because at least one of the flights did just that. As for the Soviets, I assume the Vostok cosmonauts had their own personal reserve chute to go with the personal chute. It wouldn't surprise me to learn that Voskhod had no reserve chute since that whole project was a slapped together headline grabber, and the fact that they flew without a launch escape system or space suits shows that crew safety was going to be sacrificed to meet mission goals. I know Soyuz has a reserve chute. The one fatality attributed to parachute failure (Vladimir Komarov in Soyuz 1) is said to have occurred after he opened his reserve chute following the failure of his main chute. Details are sketchy, but many accounts have the capsule spinning in an attempt to keep it stabilized, and the spinning possibly contributing to the parachute failure. As to your last point, I think they probably are more reliable than sports chutes. If would certainly expect them to be packed more carefully. -- Chris Jones clj@ksr.com {world,uunet,harvard}!ksr!clj ------------------------------ Date: 8 Oct 90 18:29:21 GMT From: att!cbnewsd!rjungcla@ucbvax.Berkeley.EDU (R. M. Jungclas) Subject: Former astronaut Scott Carpenter to attend Chicago Hobby Show Former American astronaut Scott Carpenter will be attending the model rocket demonstration launch between noon and 1 p.m. and will be on Saturday Oct. 20th and at the Chicago Hobby Show (Estes booth #1235) from 5 p.m. to 9 p.m. Friday, Oct. 19th, from 10 a.m. to 11:30 am. and 2:30 p.m. to 6 p.m. on Saturday, October 20th and from 10 a.m. to noon and 1 p.m. to 3 p.m. on Sunday Oct. 21st. Further details may be found in "rec.models.rockets". R. Michael Jungclas UUCP: att!ihlpb!rjungcla AT&T Bell Labs - Naperville, IL. Internet: rjungcla@ihlpb.att.com ------------------------------ Date: 14 Oct 90 17:22:12 GMT From: unmvax!nmt.edu!nraoaoc@ucbvax.Berkeley.EDU (Daniel Briggs) Subject: Re: Deep Space Network use (Was: Ulysses Update - 10/06/90) In article <1990Oct13.033850.29726@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <5757@mace.cc.purdue.edu> dil@mace.cc.purdue.edu >(Perry G Ramsey) writes: >>The VLA (Very Large Array) radiotelescope near Socorro, New Mexico >>was pressed into service for Voyager's Neptune pass. > >And several others. A large fraction of the Free World's total radiotelescope >aperture was pointed at Voyager for the Neptune encounter. Not so much as you might think, Henry. Besides the normal DSN antennas (which are fairly large, even by todays standards), I believe that there were only three non-DSN stations involved. Namely, the VLA, Parkes Australia, and Usuda Japan. At one point, the Parkes antenna was 64 m diameter, with a wire mesh surface. While this doesn't inspire great confidence of terrific X band performance, (the Voyager downlink was at about 3.5 cm), it may have been upgraded and my information out of date. I'm afraid that I have never heard of Usuda before, so I don't have any information on it. (I couldn't find it in the '90 Astronomical Almanac, so it's either listed under a different name, or it could be a non astronomical site.) The point is, that while several large radio telescopes were used for the Voyager Neptune encounter, it was far short of 'A large fraction of the Free World's total radiotelescope aperture.' I think this statement is starting to grow to folklore proportions, since I have heard it from several other people before. -- This is a shared guest account, please send replies to dbriggs@nrao.edu (Internet) ["Life's a Beech, and then you Dive."] Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801 (U.S. Snail) ------------------------------ Date: 8 Oct 90 22:38:51 GMT From: wuarchive!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton!lamontg@decwrl.dec.com (Lamont Granquist) Subject: Re: disposal of N-waste into sun [..discussion on sun-dive vs. solar escape methods of N-waste disposal del..] How about dumping the N-waste into the trojan points 60 deg. head of and behind the moon in its orbital path. Would this be a very stable orbit or would there be a high probability of the N-Waste escaping from the trojan point due to outside forces (sun, asteroids, comets, etc...)? and what would be the radiation risk in the area around the trojan points and on the moon? would it be possible to collect waste in the trojan points and then periodically send a large asteroid from the belts to capture all the trash and sling-shot the whole mess around the sun and out of the system? ------------------------------ Date: 14 Oct 90 18:19:19 GMT From: unmvax!nmt.edu!nraoaoc@ucbvax.Berkeley.EDU (Daniel Briggs) Subject: Re: Magellan/Venus Info In article <1990Oct13.181134.18861@jato.jpl.nasa.gov> baalke@mars.UUCP (Ron Baalke) writes: >In article <1990Oct13.034912.29819@zoo.toronto.edu> henry@zoo.toronto.edu >(Henry Spencer) writes: >>In article <1990Oct12.041832.6403@jato.jpl.nasa.gov> baalke@mars.jpl.nasa.gov >>(Ron Baalke) writes: >>>... Also, there is a universal convention >>>on planets other than Earth that the longitude will be measured in the >>>opposite direction that the planet rotates. Venus rotates backwards... >> >>Sorry, no, this is not universally agreed on, for a different reason: >>there is a difference of opinion on which is the north pole. Various >>groups are on opposite sides of the question. > >Since Venus axis tilt is nearly straight up and down, its North pole is >assumed to be pointing in the same direction as that of the Earth's, even >though this would mean Venus rotates backwards. I've got to side with Henry on the question regarding poles. What Ron is assuming is essentially the IAU definition of 'North Pole'. (The North pole of a planet points north of the ecliptic.) This definition can cause violent controvery at meetings. Many people think that this definition is just plain wrong. (Usually these are people whose job includes studying the planet in question, rather than just cataloging the orbital parameters. The IAU definition makes bookkeeping simpler, at cost of screwing up the planetary physics.) Bottom line: Ron's definition is the most common one, but it is by no means universal. I don't happen to know how longitiude is defined, although a thought occurs to me. Isn't Ron's definition of longitude independent of which direction is north? The spin of the planet is independent of the coordinate system in which you measure it. You can change the numerical sign of the spin by swapping which pole you call north, but that also changes the coordinate system to which you refer the number. The end result would be that any given spot on the planet is assigned the same numerical longitude, no matter which pole definition you use. (This is only speculation on my part, BTW.) -- This is a shared guest account, please send replies to dbriggs@nrao.edu (Internet) ["Life's a Beech, and then you Dive."] Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801 (U.S. Snail) ------------------------------ Date: 14 Oct 90 15:52:28 GMT From: van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu!watserv1!maytag!watdragon!watyew!jdnicoll@ucbvax.Berkeley.EDU (Brian or James) Subject: North and South off Earth [was Magellan/Venus Info] If you were to stand on the surface of Venus with a magnetic compass in your hand, would 'north:compass' be the same as 'north:clockwise convention',or the opposite? I know Venus doesn't have a strong magnetic field, so it might not be useful for this. For that matter, the north magnetic pole might not be anywhere near the north/south axis of rotation pole. Just look at Uranus. James Nicoll ------------------------------ Date: 8 Oct 90 22:26:57 GMT From: uceng!dmocsny@iuvax.cs.indiana.edu (daniel mocsny) Subject: Re: Manned/unmanned tradeoffs While we are on the subject of dealing with time delays, I wonder if anyone has considered hiring whales to teleoperate bulldozers on the Moon. The speed of nerve signal propagation is not very high in biological systems. I seem to remember an upper limit in the low hundreds of feet per second, for the fastest (myelinated) axons. (Anybody know the actual numbers?) That would mean that very large animals, such as the biggest cetaceans, would run into round-trip teleoperation delays on the order of 1 sec for moving, say, their hindmost extremities. This would seem to create some peculiar problems for coordination, because different parts of the whale's body would have noticeably different propagation delays. The whale must be aware of this, because it also senses its environment with sonar, which is probably faster than its tactile nerves. I.e., a sperm whale doing battle with a giant squid probably senses collisions first by sonar before it feels them, if the contact areas are far from its brain. As far as I know, whales can deal with this problem and be very successful in their environments anyway. The longest animals which have lived (the sauropods) apparently coped with propagation delays by off-loading a portion of their control to a large nerve ganglion located about halfway back along the spine. Perhaps a tail that was too slow to react was a competitive disadvantage to a sauropod. The sauropod could have had its tail stepped on, or munched on, and reacted too slowly to avoid injury. dmocsny@uceng.uc.edu ------------------------------ Date: 14 Oct 90 17:50:33 GMT From: world!ksr!clj%ksr.com@uunet.uu.net (Chris Jones) Subject: Re: Atmospheric nitrogen In article <9010140013.AA08274@cmr.ncsl.nist.gov>, roberts@CMR (John Roberts) writes: > >>From: Richard Ristow >>Subject: Re: gravity and atmosphere (nitrogen > >>>For that matter, we don't know for sure that long-term absence of major >>>quantities of nitrogen doesn't have some obscure harmful effect. > >>I suggest that for planetary atmospheres (as opposed to short-term breathing >>and managed biospheres) the absence of nitrogen has a harmful effect that's >>far from obscure: atmospheric nitrogen is the substrate from which combined >>nitrogen is produced by biological and abiological 'fixing' processes >>(the former mainly an enzyme chain in certain prokaryotes, the latter >>including nitrogen oxydation in lightning strokes). > >Good point, but that in itself does not not imply that a full 78% will be >required. I don't have a reference, but I recall reading that we may be paying a penalty for having so much nitrogen in the air. As divers know, nitrogen impairs judgement, an effect that increases as the partial pressure of nitrogen increases. For this reason, it is dangerous to dive using compressed air much below 200 feet. Experiments have been done substituting some other gas for nitrogen at 1 atmosphere, and the results show that we're all walking around a little more sluggish and stupid than we would be if nitrogen weren't so prevalent. (Of course, modifying the atmosphere in any major way is likely to have effects on living organisms we haven't even begun to consider yet, so it may very well be that an earth-like atmosphere is the ideal for all you terra-former-wannabes out there.) -- Chris Jones clj@ksr.com {world,uunet,harvard}!ksr!clj ------------------------------ End of SPACE Digest V12 #459 *******************