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 ; Sat, 28 Apr 90 01:42:38 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 28 Apr 90 01:41:39 -0400 (EDT) Subject: SPACE Digest V11 #323 SPACE Digest Volume 11 : Issue 323 Today's Topics: NASA Prediction Bulletins: Space Shuttle Three unconnected thoughts on STS-31 and the HST Re: Decompression Re: Three unconnected thoughts on STS-31 and the HST Re: IMPORTANT MESSAGE for Shuttle Landing Viewers Re: Our galaxy Re: Space Station Distribution Frequency Re: Our galaxy Re: Krystall addition to Mir delayed until June 1 Black Holes Forever! (Was: Re: Dyson spheres? ) ---------------------------------------------------------------------- Date: 27 Apr 90 04:17:16 GMT From: ncis.tis.llnl.gov!blackbird!tkelso@lll-winken.llnl.gov (TS Kelso) Subject: NASA Prediction Bulletins: Space Shuttle The most current orbital elements from the NASA Prediction Bulletins are carried on the Celestial RCP/M, (513) 427-0674, and are updated several times weekly. Documentation and tracking software are also available on this system. As a service to the satellite user community, the most current elements for the current shuttle mission are provided below. The Celestial RCP/M may be accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1 stop bit, no parity. STS 31 1 20579U 90037 A 90116.05462219 .00000000 00000-0 00000-0 0 00023 2 20579 028.4813 221.1360 0002583 316.9075 043.1762 14.84048541000232 HST 1 20580U 90 37 B 90115.92007935 -.00019413 00000-0 -22999-2 0 416 2 20580 28.4631 222.0038 0005784 272.7940 87.2151 14.84112255 202 -- Dr TS Kelso Assistant Professor of Space Operations tkelso@blackbird.afit.af.mil Air Force Institute of Technology ------------------------------ Date: 25 Apr 90 14:50:19 GMT From: eru!luth!sunic!mcsun!unido!mpirbn!p515dfi@bloom-beacon.mit.edu (Daniel Fischer) Subject: Three unconnected thoughts on STS-31 and the HST Now that HST is where it belongs - that was the most dramatic launch ever, with the exception of STS-26 perhaps - I cannot resist posting some thoughts...: a) How could it go up at all?! In AW&ST of 16 March 1987 p.64 it said that every time something stops the countdown during the final 5 minutes, there will inevitably be a scrub for this day, because the procedures to check out what precisely went wrong are so complicated now. So this story was wrong, and NASA still gan go ahead when they want to?! (Not a criticism, just asking!) b) Where did the '14 billion light year' myth originate? I must have heard it about 20 times yesterday on TV & radio that "til now we could only see for two billion light years, but now we can see 7 times farther with the HST" - every few months the media celebrate a new quasar at 15+ billion light years, and nobody realizes this contradiction. I've found the 'factor of 7' nonsense even in NASA press kits and brochures - w h y must they tell everybody this?? c) Finally, I'd like to add something to the 'how can we get HST pictures in machine-readable form?' debate. On 23 Feb 1990 I talked with Benoit Pirenne who is at the ST European Coordinating Facility, dealing with data distribution. He told me that - after the 12...18 month priority interval, of course - almost *everybody* can have all HST data on tape, optical disk etc. *for free*. This option is open to amateur astronomers and space fans as well as for any scientist: all you'll need is an account on their computer (at Garching, FRG; but it should be very similar at Baltimore). And if you just want to browse through the data catalog, you can even log in as a guest. This is a really fascinating option, and in late '91/early '92 there might be more HST images on the net or ftp-able than anybody is thinking about yet... +- p515dfi@mpifr-bonn.mpg.de --- Daniel Fischer --- p515dfi@mpifr-bonn.mpg.de -+ | Max-Planck-Institut f. Radioastronomie, Auf dem Huegel 69, D-5300 Bonn 1,FRG | +----- Enjoy the Universe - it's the only one you're likely to experience -----+ ------------------------------ Date: Thu, 26 Apr 90 10:11 EDT From: KEVIN@A.CFR.CMU.EDU Subject: Re: Decompression X-Envelope-To: space@ANDREW.CMU.EDU In regards to 'breathing space': Once you have exhaled what's in your lungs, thus preventing them from exploding (always unpleasant), you will probably want to prevent the O2 in your arteries from leaving. In addition is seems a poor idea to allow the water in your lung tissue to vacuum-boil away. I suspect that this would cause a lot of damage. The partial pressure of water at room temperature is 25 torr, out of the 760 torr in one atmosphere. At body temp I believe it's about 35 torr. This means that if the pressure is under this exposed water will boil. Keeping the mouth open would allow a continuous low temperature steam to exit the lungs. (Can you say 'dry mouth'?) In addition, the O2 in your blood would be diffusing out as well. Were I to be in this situation I would blow out until I had just about all the air in my lungs exhausted, then close up to prevent my internal supplies of water and O2 from leaving. I think that the pressure generated by ~35 torr of water vapor plus whatever pressure of diffusing O2 would damage the lungs less than letting the water and oxygen leave. If it indeed is not high enough to cause damage such a tactic would give you more time to act in the vacuum - the rising pressure in the lungs would slow the diffusion of oxygen from the blood. Comments from anyone? Kevin Ryan Internet: kr0u@andrew.cmu.edu ------------------------------ Date: 26 Apr 90 14:27:44 GMT From: ogicse!plains!bakke@uunet.uu.net (Jeffrey P. Bakke) Subject: Re: Three unconnected thoughts on STS-31 and the HST In article <935@mpirbn.UUCP> p515dfi@mpirbn.UUCP (Daniel Fischer) writes: >Now that HST is where it belongs - that was the most dramatic launch ever, with >the exception of STS-26 perhaps - I cannot resist posting some thoughts...: > b) Where did the '14 billion light year' myth originate? I must have heard it >about 20 times yesterday on TV & radio that "til now we could only see for >two billion light years, but now we can see 7 times farther with the HST" - >every few months the media celebrate a new quasar at 15+ billion light years, >and nobody realizes this contradiction. I've found the 'factor of 7' nonsense >even in NASA press kits and brochures - w h y must they tell everybody this?? Feel free to correct me if I'm wrong but the 2 billion light years represents the distance that we can 'see' with our current scopes. This means using visible light to identify objects. When hear of 15+billion light year objects being detected, more than likely it was found by radio telescopes which operate on wavelengths other than those of visible light. Radio waves are not affected nearly as much by the cloud cover and ozone layer of the earth. Jeff Bakke bakke@plains.NoDak.edu ------------------------------ Date: 26 Apr 90 17:13:22 GMT From: usc!venera.isi.edu!raveling@ucsd.edu (Paul Raveling) Subject: Re: IMPORTANT MESSAGE for Shuttle Landing Viewers In article , shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: > > For those of you who will be Official Guests, the Usenet RDV will be > in front of the black F-18 (the HARV) 30 minutes after the landing. > See you there. Here's a followon thought -- if we all come prepared, we could have a USENET picnic breakfast sometime after meeting at the F-18. Considering space available, something like beach blankets on the ramp might work better than competing for the local picnic tables. If there are USENETers with only hillside (not Official Guest) passes we could find a different spot that would be suitable to all. I've been thinking about bringing something very slightly elegant, but may wind up just bringing coffee and donuts ala Twin Peaks. Maybe "the elegant" will be "damn good coffee -- and hot, too!". If you have thoughts about this I'd welcome them by email. (Mary and Steve Jay have already) ---------------- Paul Raveling Raveling@isi.edu ------------------------------ Date: 26 Apr 90 15:06:04 GMT From: mcsun!ukc!acorn!ixi!mike@uunet.uu.net (Mike Moore) Subject: Re: Our galaxy In article <880@spitfire.nsc.com> alan@spitfire.nsc.com (Alan Hepburn) writes: >In article <5015@jhunix.HCF.JHU.EDU> gwollman@jhunix.UUCP (Garrett A Wollman) writes: >> >>Of course, that's cheating. What we need is a numbering system that's >>not so geocentric; we should chose some other center (perhaps that >>hypothetical point 10 kpc away?) from which to base our system...still >>purely arbitrary, but it would at least free us to speak in less charged >>terms about our home. >> >> > > Actually, I think that referring to Earth as SOL-3 is more >heliocentric than geocentric. To be really detached, maybe we >should refer to it on the basis of our position in the galaxy, or >something along those lines. > > Wouldn't that be galactocentric? Einstein was right, relativity is everything. So (apart from the maths) why not just assume that we *are* the centre of the universe, then we can be self-centred and proud of the fact :-) Disparate co-ordinate systems are a part of life, on a map we use a grid system, but for me to tell you where I live I would give you an address (i.e. I would use a different co-ordinate system) but I _could_ use _either_ system and you would still understand where I lived so long as you knew what I was talking about. Then there is a third system, zip codes (or postal codes), each defines a specific tract of land, so, you use your system and I'll use mine, and when we have to communicate we'll get a computer to do the translating!!:-) BTW, do satellites have their own internal co-ordinate system, and is this system different depending whether the satellite is orbiting earth or travelling between planets? What about non-ecliptic orbiters? Mike -- -------------------------------------------------------------------------- Usual disclaimer..... etc | mike@ixi.uucp True Intelligence is not knowing all the answers, | it's knowing the right questions. | ------------------------------ Date: 26 Apr 90 23:35:36 GMT From: zaphod.mps.ohio-state.edu!usc!cs.utexas.edu!texbell!nuchat!steve@tut.cis.ohio-state.edu (Steve Nuchia) Subject: Re: Space Station Distribution Frequency In article <15414@bfmny0.UU.NET> tneff@bfmny0.UU.NET (Tom Neff) writes: >so my question still remains, Why does anyone think 20kHz was ever >the right way to go? I am sure there are concrete answers to some The main argument in favor of it is that you can build a switching mode power converter without putting a rectifier/filter/inverter in front of it. Essentially the whole power system is one big inverter front end. You want to run your *converters* at high frequency so they respond quickly to control inputs and so their magnetic components can be smaller. Most of the mass in an electronic gizmo is transformer iron, followed by packaging, then capacitors, usually. The calculation of the amount of iron required is complicated, but at 60Hz it is outrageous, while at 400 Hz it is merely painful. At 20 KHz it is well under control, like comparable to the copper in the windings. The capacitance required to filter the converter output also decreases rapidly with frequency. Big capacitors are bulky, but their mass is considerable too. The argument against 20KHz is that you have to do a bunch of research into how to build converters and switchgear for it, how to control stray inductances in your wiring, etc ad nauseam. The argument in favor of 400 Hz is that it is widely used in aircraft, and a lot of equipment is available off-the-shelf to run from it. Even if NASA couldn't bring themselves to fly off-the-shelf hardware, the manufacturers would be used to working with it, so one could expect their performance to be more predictable on custom work. Similar arguments would apply to 60Hz, but the weight penalty is pretty severe. A quick glance in the catalogs shows a shipping weight of 8 pounds for a 190 Watt 60 Hz transformer. The power supply in your typical AT clone is rated at 200 Watts and the whole supply, including case and fan, weighs less than five pounds. There is also a great deal of experience with DC, but I wonder how the voltage was chosen? Looks suspiciously like sqrt(2)*120, which is the nominal value for rectified line current. That's what you work with before the inverter in a transformerless switching mode power supply, like the ones in PCs. 160 VDC is higher than you'd like from a shock hazard standpoint, but I suppose that 48V would increase the mass of copper and/or the copper losses too much. One argument against DC is that, since the current doesn't reverse several times a second, your fuses and circuit breakers have a harder job to do. This won't be much of a problem at the power levels they are working at, and even when it is a problem the main penalty is cost, not mass. An argument in favor of DC is that there will be no conversion loss when running from batteries. If they had used any AC there would have been losses just getting it onto the bus, which would have been wasted if the load was resistive. Of couse they may decide to *regulate* the DC bus, in which case you get those losses anyway. ------------------------------ Date: 25 Apr 90 19:32:15 GMT From: hpcc01!hpcuhb!hpindda!dfc@hplabs.hp.com (Don Coolidge) Subject: Re: Our galaxy >In a related topic, is there any "better" name for our galaxy than "the >Milky Way"? Something that sounds more like a proper name and is more >dignified? ---------- We have it from a somewhat reliable source that the Time Lords of Gallifrey refer to it as "Mutter's Spiral". If that's good enough for The Doctor, it's good enough for me. ;-) Only marginally more seriously, isn't that pretty much an accurate English translation of "galaxy"? So we're left with Sol, Terra, and Galaxy as the Latin/Greek equivalents of The Sun, The Earth, and The Milky Way. Names of prominent natural features stick around for millennia. The local language may change, but the name remains. Folks come to consider it as just a name after awhile, and they no longer think of the original meaning. So, "The Galaxy" _is_ "The Milky Way". An even better example is Mt. Monadnock in New England. Three tongues are layered here, and the full translation is "Mt. MountainMountain". I like "Mt. Monadnock" better, but it doesn't mean anything different... - Don Coolidge ------------------------------ Date: 26 Apr 90 15:00:38 GMT From: manta!simpkins@nosc.mil (Michael A. Simpkins) Subject: Re: Krystall addition to Mir delayed until June 1 In article <9004252053.AA18763@vdd.VLSI.LL.MIT.EDU> glenn@VLSI.LL.MIT.EDU (Glenn Chapman) writes: > > On board the Mir space station cosmonauts Anatoly Solovyov and Alexander >Balandin, now in orbit for 72 days, >In addition an insulation >blanket on the Soyuz TM-9 has come free, and is flapping when the station >moves. This movement is distracting the station's star trackers used in Mir's >alignment system and making that problem worse. Originally it was planned >that repair materials for the blanket would be sent up with Krystall. > > Glenn Chapman > MIT Lincoln Lab ---------------------------------------------------------------------------------------------------------------------------------------------------------------- I guess we all know what they DON'T carry in their tool box! :-) Maybe the Shuttle boys and girls can float them a roll on the way by. "What is dis DUCK tape?!" -simpkins- P.S. We used to call it racers tape "Good for an extra 20 M.P.H." ------------------------------ Date: 26 Apr 90 07:02:30 GMT From: bigbang.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Black Holes Forever! (Was: Re: Dyson spheres? ) In article <1990Apr24.140922.28552@ncsuvx.ncsu.edu> noble@shumv1.ncsu.edu (Patrick Brewer) writes: > > Last I heard (Playboy interview) Hawking has decided the black-holes >can't exist. And he is now trying to prove it. Not true. He decided that singularities can't exist, because of violations of current quantum theory. Black holes still exist, as far as we can tell :-) ******************************************************************************* George William Herbert JOAT For Hire: Anything, Anywhere: My Price UCB Naval Architecture undergrad: Engineering with a Bouyant Attitude :-) ------------------------------------------------------------------------------- "Who?" the man managed. Whip me, Beat Me, Make me learn C... "The Rastafarian Navy," Case said, ++++++++++ gwh@ocf.berkeley.edu OR "...and all we want is a jack into your ========== gwh@soda.berkeley.edu OR custodial system." -neuromancer """""""" maniac@garnet.berkeley.edu ------------------------------ End of SPACE Digest V11 #323 *******************