Date: Sun, 2 May 93 05:00:25 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #504 To: Space Digest Readers Precedence: bulk Space Digest Sun, 2 May 93 Volume 16 : Issue 504 Today's Topics: ASTRONAUTS---What does weightlessness feel like? Commercials on the Moon (2 msgs) DC-X news Gamma Ray Bursters. positional stuff. (3 msgs) Gamma Ray Bursters. WHere are they. (4 msgs) Gamma Ray Bursters How energetic could they be? HST Servicing Mission HST Servicing Mission Scheduled for 11 Days HyperKnowledge Lindbergh and the moon (was:Why not give $1G) Long term Human Missions Vandalizing the sky. (2 msgs) What planets are habitable Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 29 Apr 93 16:15:01 GMT From: Jerry Liebelson Subject: ASTRONAUTS---What does weightlessness feel like? Newsgroups: sci.space,sci.astro I understand the when one is in orbit, the inward force of gravity at one's center of mass is exactly balanced by the outward centrifugal force from the orbiting motion, resulting in weightlessness. I want to know what weightlessness actually FEELS like. For example, is there a constant sensation of falling? And what is the motion sickness that some astronauts occasionally experience? Please reply only if you are either a former or current astronaut, or someone who has had this discussion first-hand with an astronaut. Thanks! -- Jerry Liebelson jlieb@is.morgan.com 73477.2740@compuserve.com ------------------------------ Date: Thu, 29 Apr 93 12:39:11 GMT From: Hans Erik Martino Hansen Subject: Commercials on the Moon Newsgroups: sci.space I have often thought about, if its possible to have a powerfull laser on earth, to light at the Moon, and show lasergraphics at the surface so clearly that you can see it with your eyes when there is a new moon. How about a Coca Cola logo at the moon, easy way to target billions of people. Do you know if its possible? -- Erik M. Hansen | Email u920496@daimi.aau.dk Fuglsangsalle 69 | Aarhus University DK-8210 rhus V | Denmark, Europe | ------------------------------ Date: Thu, 29 Apr 1993 14:25:26 GMT From: Tom O'Reilly Subject: Commercials on the Moon Newsgroups: sci.space u920496@daimi.aau.dk (Hans Erik Martino Hansen) writes > How about a Coca Cola logo at the moon, easy way to target billions of > people. Arthur C. Clarke was way ahead of you on this one... he wrote a short story (title?) in the 1950s describing exactly your proposal! Tom O'Reilly Department of Geology Arizona State University ------------------------------ Date: 29 Apr 1993 15:08:19 GMT From: Andy Cohen Subject: DC-X news Newsgroups: sci.space Static test firings are now scheduled for this Saturday.....after many schedule changes..... It may be difficult to get test status during the next two weeks....the number of contacts are drying up as they all go to New Mexico......GO DELTA CLIPPER!! ------------------------------ Date: 29 Apr 93 01:08:47 -0600 From: belgarath@vax1.mankato.msus.edu Subject: Gamma Ray Bursters. positional stuff. Newsgroups: sci.space,sci.astro In article <1rmh4eINN95h@gap.caltech.edu>, kwp@wag.caltech.edu (Kevin W. Plaxco) writes: > In article <27APR199320210230@stdvax.gsfc.nasa.gov> abdkw@stdvax.gsfc.nasa.gov (David Ward) writes: > >>Given that fact, and the spacecraft attitude knowledge >>of approx. 2 arcmin, we might be able to figure out how well BATSE can >>determine the location (rotational) of a Gamma Ray burster from knowledge >>of the all-sky map's accuracy. PR material for the other three instruments >>give accuracies on the order of "fractions of a degree", if that's >>any help. > > But I believe that there is a fundamental difference here. The other x > three instruments are focusing instruments, that, more or less, form > an image, so positional errors are limited by craft attitude and the > resolving power of the optics. BATSE is an altogether different > beast, effectively just 8 coincidence counters, one on each corner of > the craft. Positional information is triangulated from the > differential signal arrival times at each of the detectors. > Positional error would be predominantly determined by timing errors > and errors in craft attitude. Since none of the 8 BASTE detectors have > any independant angular resolution whatsoever, they can not be used to > determine parallax. Indeed, parallax would just add a very small > component to the positional error. > > Demonstrating that these puppies are beyond the oort cloud would > require resolution on the order of arcseconds, since the oort > cloud is postulated to extend to about 0.5 parsec (all together > now: "Parallax ARc SECond", a parsec is the distance of an object > that demonstrates one arc second of parallax with a 2 AU base line). > If the 3 degree accuracy reported above is true, we're going to > have to add a BASTE to the pluto fast flyby to get enough baseline. > > The beauty of BASTE is that it both gives positional information and > watches the entire sky simultaneously, a realy handy combination > when you have no idea where the next burst is coming from. > > -Kevin Batse alone isn't always used to determine position. WHen a particularly bright burst occurs, There are a couple of other detectors that catch it going off. Pioneer 10 or 11 is the one I'm getting at here. This puppy is far enough away, that if a bright burst happens nearby, the huge annulus created by it will hopefully intersect the line or general circle given by BATSE, and we can get a moderately accurate position. Say oh, 2 or 3 degrees. That is the closest anyone has ever gotten with it. Actually, my advisor, another classmate of mine, and me were talking the other day about putting just one detector on one of the Pluto satellites. THen we realized that the satellite alone is only carrying something like 200 pounds of eq. Well, a BATSE detector needs lead shielding to protect it, and 1 alone weighs about 200 pounds itself. We decided against it. -jeremy ------------------------------ Date: Thu, 29 Apr 1993 11:04:12 GMT From: Paul Dietz Subject: Gamma Ray Bursters. positional stuff. Newsgroups: sci.space,sci.astro In article <1993Apr29.010847.1@vax1.mankato.msus.edu> belgarath@vax1.mankato.msus.edu writes: > getting at here. This puppy is far enough away, that if a bright > burst happens nearby, the huge annulus created by it will hopefully > intersect the line or general circle given by BATSE, and we can get a > moderately accurate position. Say oh, 2 or 3 degrees. That is the > closest anyone has ever gotten with it. You can do a whole hell of a lot better than 2 or 3 degrees with the differential timing measurements from the interplanetary network. Ignore the directional information from BATSE; just look at the time of arrival. With three detectors properly arranged, one can often get positions down to ~arc minutes. BTW, about Oort cloud sources: shouldn't this be testable in the fairly near future? Some of the GRBs have very short rise times (< 1 ms). We could detect the curvature of the burst wavefront out to a distance of on the order of b^2/(t c) where b is the detector spacing and t the time resolution. For t = 1 ms and b = 2 AU, this is on the order of 16 light years. I understand statistics will reduce this number considerably, as would geometry if the burst is coming from the wrong direction. Paul ------------------------------ Date: Thu, 29 Apr 1993 15:29:14 GMT From: Henry Spencer Subject: Gamma Ray Bursters. positional stuff. Newsgroups: sci.space,sci.astro In article <1993Apr29.010847.1@vax1.mankato.msus.edu> belgarath@vax1.mankato.msus.edu writes: > Actually, my advisor, another classmate of mine, and me were talking >the other day about putting just one detector on one of the Pluto satellites. >THen we realized that the satellite alone is only carrying something like 200 >pounds of eq. Well, a BATSE detector needs lead shielding to protect it, >and 1 alone weighs about 200 pounds itself. Actually, the situation is even worse than that. The *total mass* of the Pluto Fast Flyby spacecraft is only 250ish pounds, and most of that is support equipment like power and communications. The mass available for instruments is maybe 10% of that. I don't think a BATSE will fit... Actually, would you need the shielding? My understanding is that it's mostly there to give the detectors some directionality. No point in doing that if you've only got one. I'm sure the burst detectors that have flown on other deep-space missions haven't weighed that much. (Mind you, they're probably still too heavy -- the PFF people would put more Pluto-specific instruments on first, if they had any mass to spare.) -- SVR4 resembles a high-speed collision | Henry Spencer @ U of Toronto Zoology between SVR3 and SunOS. - Dick Dunn | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 29 Apr 93 06:29:35 GMT From: Ethan Bradford Subject: Gamma Ray Bursters. WHere are they. Newsgroups: sci.astro,sci.space In article steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes: This does not propose a _mechanism_ for GRBs in the Oort (and, no, anti-matter annihilation does not fit the spectra at least as far as I understand annihilation spectra...). Big difference. That's ignoring the question of how you fit a distribution to the Oort distribution when the Oort distribution is not well known - in particular comet aphelia (which are not well known) are not a good measure of the Oort cloud distribution... Merging neutron stars is at least a mechanism with about the right energy, except it doesn't explain why there is no apparent correlation with galaxies or galaxy structure, there is no mechanism for getting all the energy out in gamma rays (with any significant amount of baryons around there will be a lot of pair production, which makes a plasma, which thermalizes the energy), it has trouble generating enough energy to explain the most powerful bursts (10^52-53 ergs), it happens too fast compared to the burst duration, and it is hard to make tight-binaries of neutron stars. Another cosmological mechinism is the catalytic conversion of a neutron star to a strange star or the merger of two strange stars, but that uses pretty far-out physics. My point is that we don't have a good mechanism at any distance, so GRB's are likely to be happening by an unknown mechanism, so we can't rule out the Oort cloud. What would be the spectrum of an event which converts a comet to strange matter? The spectra for primordial black holes eating comets and antimatter comets colliding with matter comets aren't quite right, but perhaps there is an unusual mechanism which modifies the spectrum. The energy matches very well for both of these mechanisms. According to Trevor Weeks, if the "Tunguska Meteorite" was a mini-black hole collision with the earth, then there are likely to be enough mini-black holes around that the rate for BH-comet collisions matches the GRB rate well. The fact that we don't know the distribution of comets in the Oort cloud isn't a reason to rule them out; it makes it harder to rule them out. The point of the cited paper was that if we assume they got the right distribution for the Oort cloud, it is hard but not impossible to match that up with the distribution of GRB's. If they got the wrong distribution for the Oort cloud, they can't constrain any Oort- cloud GRB's at all. Executive summary: we don't know enough to rule out out the Oort cloud. ------------------------------ Date: 29 Apr 93 07:16:20 GMT From: Ethan Bradford Subject: Gamma Ray Bursters. WHere are they. Newsgroups: sci.astro,sci.space u9263012@wampyr.cc.uow.edu.au (Walker Andrew John) writes: Also,if they did come from the Oort cloud we would expect to see the same from other stars Oort Clouds. That's a very good point. Perhaps none of the nearby stars have Oort clouds? Alpha-centauri is a multiple-star system; you wouldn't expect an Oort cloud in it. What's the nearest single-star that is likely to have a planetary system? ------------------------------ Date: 29 Apr 1993 16:19:15 GMT From: "David M. Palmer" Subject: Gamma Ray Bursters. WHere are they. Newsgroups: sci.space prb@access.digex.com (Pat) writes: >... >4) we know it's not real close, like slightly extra solar, because >we have no parallax measurements on the bursts. We can only say that they are beyond about 25 AU, due to the low accuracy of position determination by single detectors. >what i am wondering, is this in people's opinion, A NEW Physics problem. >Einstein got well known for solvingthe photoelectric effect. >Copernicus, started looking at irregularities in planetary motion. >Is this a big enough problem, to create a new area of physics? >just a little speculative thinking folks. It may be a NEW Physics problem (i.e. a problem involving new physics). However, the data is not good enough to rule out the >100 models which use old physics. New physics is a big step, and is only tolerated when there is no alternative. For example , the Dark Matter Problem (there's more to the universe than meets the eye) is a question of comparable mystery to GRBs, but we have much better data regarding it. Theoreticians postulate new particles all the time to explain it, but no one will actually believe that these particles are real until an experimentalist (or several) detects them in the lab. -- David M. Palmer palmer@alumni.caltech.edu palmer@tgrs.gsfc.nasa.gov ------------------------------ Date: 29 Apr 1993 11:42 CDT From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: Gamma Ray Bursters. WHere are they. Newsgroups: sci.space In article <1rlrpv$5ta@access.digex.net>, prb@access.digex.com (Pat) writes... > >Is this a big enough problem, to create a new area of physics? >just a little speculative thinking folks. > >pat Well pat for once I agree with you and I like your first idea that you had. IT probably is the gamma ray signature of the warp transitions of interstellar spacecraft! :) Well it makes as much sense as some things. I was at the first Gamma Ray Burst conference here at UAH and had great fun watching the discomfiture of many of the Gamma Ray scientists. Much scruitiny was given to the data reductions. I remember one person in particular who passionately declared that the data was completely wrong as there were no explanation for the phenomena of the smooth sky distribution. (heck it even shoots down the warp transition theory :(. The next conference is soon and I will endeavour to keep in touch with this fun subject. Dennis ------------------------------ Date: 29 Apr 1993 16:03:28 GMT From: "David M. Palmer" Subject: Gamma Ray Bursters How energetic could they be? Newsgroups: sci.space,sci.astro prb@access.digex.com (Pat) writes: >In article <1993Apr26.200406.1@vax1.mankato.msus.edu> belgarath@vax1.mankato.msus.edu writes: >|energetic for close by. for the coronal model, we found around 10^43 erg/sec. >|And lastly, for the cosmological model an L=10^53. That's what you'd call >|moderately energetic, I'd say. Any suggestions about what could put out that >|much energy in one second? >> -jeremy >big Capacitor :-) Real Big capacitor. It's been suggested. (Specifically, lightning strikes between clouds in the interstellar medium.) -- David M. Palmer palmer@alumni.caltech.edu palmer@tgrs.gsfc.nasa.gov ------------------------------ Date: Thu, 29 Apr 1993 15:01:57 GMT From: dempsey@stsci.edu Subject: HST Servicing Mission Newsgroups: sci.space,sci.space.shuttle,sci.astro In article <1993Apr28.132251.1@stsci.edu>, zellner@stsci.edu writes: > > I have never heard of any serious consideration that HST might be brought > down for refurbishment. You would have the horrendous cost of transporting, Back in January and February there were several articles (Wash Post, Time...) saying that NASA was "considering" the option just as it is now "considering" a followup mission 6-12 months after the servicing mission. However, the down time was estimated to be a year+ (servicing, checkout, sceheduling and training another shuttle, orbit verification...) and to be quite expensive. I think it may have been more a mental exercise than a real plan. Don't know. ---------------------------------------------------------------------------- Robert Dempsey (410) 338-1334 STScI/PODPS "He which hath no stomach for this fight, Let him depart; his passport shall be made, and crowns for convoy put into his purse: We would not die in this man's company that fears his fellowship to die with us." -Shakespeare ------------------------------------------------------------------------------ ------------------------------ Date: Wed, 28 Apr 1993 19:19:04 GMT From: Greg Moore Subject: HST Servicing Mission Scheduled for 11 Days Newsgroups: sci.space,sci.space.shuttle,sci.astro In article <1rd1g0$ckb@access.digex.net> prb@access.digex.com (Pat) writes: > >My guess is why bother with usingthe shuttle to reboost? > >why not grapple, do all said fixes, bolt a small liquid fueled >thruster module to HST, then let it make the re-boost. it has to be >cheaper on mass then usingthe shuttle as a tug. that way, now that >they are going to need at least 5 spacewalks, then they can carry >an EDO pallet, and sit on station and even maybe do the solar array >tilt motor fix. > As Herny pointed out, you have to develop the thruster. Also, while much lighter, you still have to lift the mass of the thruster to orbit, and then the thruster lifts its own weight into a higher orbit. And you take up room in the payload bay. >pat ------------------------------ Date: 29 Apr 1993 11:34 CDT From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: HyperKnowledge Newsgroups: sci.space In article <1993Apr28.200843.83413@embl-heidelberg.de>, tuparev@EMBL-Heidelberg.DE (Georg Tuparev) writes... > > >ANNOUNCEMENT: The "HyperKnowledge" PROJECT for NeXTSTEP > >Motivation > >We are a heterogeneous group of scientists and students who feel that our >work is continuously hindered by computer environments dominated by >incompatible scientific tools and monstrous software packages (too often >claiming to do everything). >What we need is an object-oriented scientific environment where the tools >we choose to use are integrated without being parts of a closed system, >highly interactive, and extendable (both by the addition of our own >specialized objects and by combining the available tools - graphically). >The use of such an environment should be a natural extension of our work, >requiring a very short learning phase and practically no >user-documentation. I know this is kinda off the subject of sci.space, but not really, I want to answer this for their, as well as everyone else's information. What these people are proposing, by and large already exists and can be purchased today. It is called labview by National Instruments. IT is a wonderful object oriented graphical programming language. IT has been implemented on both Mac's PC's and VME unix boxes. IT is fare superior to any programming approach that I have ever seen and allowed us to decrease the software development time for our shuttle payloads by 90 percent. This program is not dependendant on specific hardware and already has exensive analysis capability. Why re-invent the wheel on a platform that may not exist? It is a great idea but look out there at what is available today. The Hydrogen leak on the Shuttle was found using this software. All SSME control and simulation studies, along with the real testing at MSFC is handled with LabVIEW. There are tons of applications, with the ability to create "virtual" instruments that can accomplish any specific custom task the maker desires. With the addition of IEEE-488 support, the computer becomes a virtual control station, allowing the graphic representation of remote instrumentation. With serial I/O support that instrument can be anywhere. The ground control software for the main control of SEDSAT 1 will utilize this approach. Dennis, University of Alabama in Huntsville ------------------------------ Date: Thu, 29 Apr 1993 13:26:31 GMT From: "Daniel M. Newman" Subject: Lindbergh and the moon (was:Why not give $1G) Newsgroups: sci.space In article pgf@srl03.cacs.usl.edu (Phil G. Fraering) writes: >gnb@baby.bby.com.au (Gregory N. Bond) writes: > >>In article jbh55289@uxa.cso.uiuc.edu (Josh Hopkins) writes: > >> [re: voyages of discovery...] >> Could you give examples of privately funded ones? > Much of Cook's later exploration was privately funded, by Joseph Banks among others (eg in Resolution & the earlier Endeavour). Colnett's voyage to the Galapagos was substantially privately funded by the owners of British whaling vessels. Chancellor and Willoughby were privately funded by London merchant companies in their voyages to Muscovy. The list is almost endless. Those doing the funding were about eighty percent motivated by potential profit, ten percent by potential glory and ten percent by the desire to advance the sum of human knowledge. -- Dan Newman Aeronautical Engineering University of Sydney Sydney NSW 2050 AUSTRALIA From: dan@key3.ae.su.oz.au (Daniel M. Newman) Path: key3.ae.su.oz.au!dan Newsgroups: sci.space Subject: Expires: References: Sender: Reply-To: dan@key3.ae.su.oz.au (Daniel M. Newman) Followup-To: Distribution: world Organization: Aeronautical Engineering, Sydney University Keywords: ------------------------------ Date: Thu, 29 Apr 1993 06:43:47 GMT From: Ward Paul Subject: Long term Human Missions Newsgroups: sci.space,sci.space.shuttle,sci.astro In article <1993Apr28.133101.25145@rpslmc.edu> rek@siss81 (Robert Kaye) writes: > >Just a few contributions from the space program to "regular" society: > >1. Calculators >2. Teflon (So your eggs don't stick in the pan) >3. Pacemakers (Kept my grandfather alive from 1976 until 1988) I don't think touting contributions is a good idea. World War II produced many many beneficial spinoffs. Eg. Radar, jet aeroplanes, rocket technology. I don't think anyone would argue that World War II was, in and of itself, a good thing. If you want people to back the space program it must be a good thing in and of itself. -- Paul ------------------------------ Date: Thu, 29 Apr 1993 08:18:55 GMT From: Peter J Card Subject: Vandalizing the sky. Newsgroups: sci.astro,sci.space In <1rls95$9aj@access.digex.net> prb@access.digex.com (Pat) writes: >Planes ruin the night sky. Blimps ruin the night sky. Radio towers >ruin the night sky. >Like i said, get a vote, and create some more national parks. which >include onobstructed air space. You should have heard Prof. McNally , from my days as an astronomy undergraduate, denouncing photon pollution. It was easy to imagine him taking practical steps to modify the sodium lamps on the street outside Mill Hill observatory with a 12-gauge shotgun :-) However, seriously, it is possible to limit the effects of streetlights, by adding a reflector, so that the light only illuminates the ground, which is after all where you need it. As a bonus, the power consumption required for a given illumination level is reduced. Strangely enough, astronomers often seek to lobby elected local authorities to use such lighting systems, with considerable success in the desert areas around the major US observatories. At least, thats what McNally told us, all those years ago. ( British local authorities couldn`t care less, as far as I can see ) I suppose that the "right" to dark skies is no more than an aspiration, but it is a worthwhile one. Illuminated orbital billboards seem especially yukky, and are presumably in the area of international law, if any, although I do find the idea of a right to bear anti-satellite weapons intriguing. -- __._____.___._____.__._______________________________________________________ __|_. ._| ._|_._._|__| Peter Card, Joint European Torus, Abingdon | | | |_. | | | Oxfordshire OX14 3EA UK. tel 0235-464867 FAX 464404 | | | _| | | | email pjc@jet.uk or compuserve 100010,366 ._| | | |_. | | | It wasnt me. It was the others. They made me do it. --`--~'-+---+-+-+----+------------------------------------------------------- - Disclaimer: Please note that the above is a personal view and should not be construed as an official comment from the JET project. ------------------------------ Date: Thu, 29 Apr 1993 15:08:08 GMT From: hathaway@stsci.edu Subject: Vandalizing the sky. Newsgroups: sci.astro,sci.space In article <1rls95$9aj@access.digex.net>, prb@access.digex.com (Pat) writes: > In article gfk39017@uxa.cso.uiuc.edu (George F. Krumins) writes: > |I say: > |What I'm objecting to here is a floating billboard that, presumably, > |would move around in the sky. I, for one, am against legislating > |at all. I just wish that people had a bit of common courtesy, and > |would consider how their greed for money impacts the more ethereal and >>aesthetic values that make us human. This includes the need for wild >>and unspoiled things, including the night sky. > > > Sorry that's an aesthetics argument. maybe this string shoudl mofe to > sci.space.aesthetics. > > Planes ruin the night sky. Blimps ruin the night sky. Radio towers > ruin the night sky. > > Like i said, get a vote, and create some more national parks. which > include onobstructed air space. > > Hokay - I am hereby voting my backyard to be a sanctuary - one acre where I can object to anything I do not like for aesthetic reasons. <::-) What a relief to know we both can be happy. ------------------------------ Date: Thu, 29 Apr 1993 12:23:12 GMT From: Paul Dietz Subject: What planets are habitable Newsgroups: sci.space > I would appreciate any thoughts on what makes a planet habitable for > Humans. I am making asumptions that life and a similar atmosphere > evolve given a range of physical aspects of the planet. The question > is what physical aspects simply disallow earth like conditions. This is a good question. There are major blind spots in our understanding of what makes the earth habitable. For example, why does the earth's atmosphere have the concentration of oxygen it does? The naive answer is "photosynthesis", but this is clearly incomplete. Photosynthesis by itself can't make the atmosphere oxygenated, as the oxygen produced is consumed when the plants decay or are eaten. What is needed is photosynthesis plus some mechanism to sequester some fraction of the resulting reduced material. On earth, this mechanism is burial in seafloor sediments of organic matter, mostly from oceanic sources. However, this burial requires continental sediments (in the deep ocean, the burial rate is so slow that most material is consumed before it can be sequestered). This suggests that a planet without large oceans, or a planet without continents undergoing weathering, will have a hard time accumulating an oxygen atmosphere. In particular, an all-ocean planet may have a hard time supporting an oxygen atmosphere. There is also the problem of why the oxygen in the earth's atmosphere has been relatively stable over geological time, for a period at least 2 orders of magnitude longer than the decay time of atmospheric O2 to weathering in the absence of replenishment. No convincing feedback mechanism has been identified. Perhaps the reason is the weak anthropic principle: if during the last 500 MYr or so, the oxygen level had dropped too low, we wouldn't be here to be wondering about it. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ End of Space Digest Volume 16 : Issue 504 ------------------------------