waashk/20ng huggingface dataset:
shag@aero.org (Rob Unverzagt) writes:  >In article <5APR199318045045@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: >> According the IAU Circular #5744, Comet Shoemaker-Levy 1993e, may be >> temporarily in orbit around Jupiter.  The comet had apparently made a >> close flyby of Jupiter sometime in 1992 resulting in the breakup of the >> comet.  Attempts to determine the comet's orbit has been complicated by >> the near impossibility of measuring the comet's center of mass. >>  >Am I missing something -- what does knowing the comet's center >of mass do for you in orbit determination?  >Shag  I'm not sure, but it almost sounds like they can't figure out where the  _nucleus_ is within the coma. If they're off by a couple hundred miles, well, you can imagine the rest...
In article <C5LJG5.17n.1@cs.cmu.edu> mwm+@cs.cmu.edu (Mark Maimone) writes: >In article <734975852.F00001@permanet.org> Mark.Prado@p2.f349.n109.z1.permanet.org (Mark Prado) writes: >>If anyone knows anyone else who would like to get sci.space, >>but doesn't have an Internet feed (or has a cryptic Internet >>feed), I would be willing to feed it to them.	 > >	Kudos to Mark for his generous offer, but there already exists a >large (email-based) forwarding system for sci.space posts:  Space Digest. >It mirrors sci.space exactly, and provides simple two-way communication. > I think Mark was talking about making it available to people who didn't have email in the first place.  If anybody in the Boston area wants a sci.space feed by honest-to-gosh UUCP (no weird offline malreaders), let me know.  I'll also hand out logins to anyone who wants one, especially the Boston Chapter of NSS (which I keep forgetting to re-attend).  >Questions, comments to space-request@isu.isunet.edu >--  >Mark Maimone				phone: +1 (412) 268 - 7698 >Carnegie Mellon Computer Science	email: mwm@cmu.edu
hausner@qucis.queensu.ca (Alejo Hausner) writes: >rek@siss81 (Robert Kaye) writes: >> >>Just a few contributions from the space program to "regular" society: >> >>2.	Teflon (So your eggs don't stick in the pan) > >Sorry to split hairs, but I just read in "The making of the atomic >bomb"(*) that teflon was developed during world war 2.  A sealant was >needed for the tubing in which uranium hexafluoride passed as it was >gradually enriched by difussion.  UF6 is very corrosive, and some very >inert yet flexible material was needed for the seals.  I think you're both right.  Teflon was actually discovered by accident before WWII.  From what I've heard, they had some chemical (I assume it was tetrafluoroethylene) in a tank and but the valve got gummed up. Cutting it open revealed that it had polymerized.  The material was useful for seals, but it had a major problem for, say the linings of vessels: it wouldn't stick to metal.  What the space program did was to find a way to get it to stick.  Thus we had no-stick frypans on the market in the late '60s.
In article <1t4pkc$ovf@almaak.usc.edu> ajayshah@almaak.usc.edu (Ajay Shah) writes: >If this idea goes through, it's the thin end of the wedge.  Soon >companies will be doing larger, and more permanant, billboards in the >sky.  I wouldn't want a world a few decades from now when the sky >looks like Las Vegas.  That would _really_ make me sad.  Think for a moment about the technology required to do that.  By  the time they could make the Earth's sky look like Las Vegas,  the people could afford to go backpacking on the Moon. Round trip costs for 500 kg to the Moon would be about the same as 5000 kg in a Low Earth "advertising" orbit: Very roughly the same cost as a smallish billboard, therefore. If such ads were to become common place, that would have to be a very low price...  The night sky on a Lunar backpacking trip would still be very  pristine...   There's always been a problem of having to get  away from civilization before you can really find "natural" scenery. 100 years ago, this usually didn't take a trip of over 5 miles. Today, most people would have to go 100 miles or more. If we ever get to the point where we have billboards on orbit, that essentially means that no place on Earth is still "wild." While that may or may not be a good thing, the orbital billboards aren't the problem: They are just a symptom of  growing, densely-populated civilization. Banning such ads will not save your view of the night sky, because by the time  such ads could become widespread you will probably have trouble finding a place without street lights, where you can _see_ the stars...  >Coca Cola company will want to paint the moon red and white.  (Well, >if not this moon, then a moon of Jupiter)...   An ad on a moon of Jupiter would be rather pointless, since you need a telescope to see them. However, I'd love to see them get all the publicity they could from underwritting the "Coca Cola Io Orbital Mapping Probe."    >...Microscum will want to >name a galaxy `Microscum Galaxy'.  They already can, to some extent: The IAU allows names derived from sponsors or patrons of scientific research. If Microscum donates money to a university astronomy program, one of the galactic  astronomers could easily get a newly discovered galaxy named after them.
Reading from a Amoco Performance Products data sheet, their ERL-1906 resin with T40 carbon fiber reinforcement has a compressive strength of 280,000 psi.  It has a density of 0.058 lb/cu in, therefore the theoretical height for a constant section column that can just support itself is 4.8 million inches, or 400,000 ft, or 75 Statute miles.  Now, a real structure will have horizontal bracing (either a truss type, or guy wires, or both) and will be used below the crush strength. Let us assume that we will operate at 40% of the theoretical  strength.  This gives a working height of 30 miles for a constant section column.    A constant section column is not the limit on how high you can build something if you allow a tapering of the cross section as you go up.  For example, let us say you have a 280,000 pound load to support at the top of the tower (for simplicity in calculation).  This requires 2.5 square inches of column cross sectional area to support the weight.  The mile of structure below the payload will itself weigh 9,200 lb, so at 1 mile  below the payload, the total load is now 289,200 lb, a 3.3% increase.  The next mile of structure must be 3.3% thicker in cross section to support the top mile of tower plus the payload.  Each mile of structure must increase in area by the same ratio all the way to the bottom.  We can see from this that there is no theoretical limit on area, although there will be practical limits based on how much composites we can afford to by at $40/lb, and how much load you need to support on the ground (for which you need a foundation that the bedrock can support.  Let us arbitrarily choose $1 billion as the limit in costruction cost.  With this we can afford perhaps 10,000,000 lb of composites, assuming our finished structure costs $100/lb.  The $40/lb figure is just for materials cost.  Then we have a tower/payload mass ratio of 35.7:1.  At a 3.3% mass ratio per mile, the tower height becomes 111 miles.  This is clearly above the significant atmosphere.  A rocket launched from the top of the tower will still have to provide orbital velocity, but atmospheric drag and g-losses will be almost eliminated.  G-losses are the component of rocket thrust in the vertical direction to counter gravity, but which do not contribute to horizontal orbital velocity.  Thus they represent wasted thrust.  Together with drag, rockets starting from the ground have a 15% velocity penalty to contend with.  This analysis is simplified, in that it does not consider wind loads.  These will require more structural support over the first 15 miles of height.  Above that, the air pressure drops to a low enough value for it not to be a big factor.  Dani Eder
dennisn@ecs.comm.mot.com (Dennis Newkirk) writes: The Centaur is controlled technology.. State Dept will not allow it to be used outside of US. Sorry. >In article <1993Apr20.211638.168730@zeus.calpoly.edu> jgreen@trumpet.calpoly.edu (James Thomas Green) writes: >>Has anyone looked into the possiblity of a Proton/Centaur combo? >>What would be the benefits and problems with such a combo (other >>than the obvious instability in the XSSR now)?  >I haven't seen any speculation about it. But, the Salyut KB (Design Bureau)  >was planning a new LH/LOX second stage for the Proton which would boost >payload to LEO from about 21000 to 31500 kg. (Geostationary goes from >2600 kg. (Gals launcher version) to 6000 kg.. This scheme was competing >with the Energia-M last year and I haven't heard which won, except now >I recently read that the Central Specialized KB was working on the  >successor to the Soyuz booster which must be the Energia-M. So the early >results are Energia-M won, but this is a guess, nothing is very clear in  >Russia. I'm sure if Salyut KB gets funds from someone they will continue  >their development.   >The Centaur for the Altas is about 3 meters dia. and the Proton  >is 4 so that's a good fit for their existing upper stage, the Block-D >which sets inside a shround just under 4 meters dia. I don't know about >launch loads, etc.. but since the Centaur survives Titan launches which >are probably worse than the Proton (those Titan SRB's probably shake things >up pretty good) it seems feasible. EXCEPT, the Centaur is a very fragile >thing and may require integration on the pad which is not available now. >Protons are assembled and transported horizontially. Does anyone know  >how much stress in the way of a payload a Centaur could support while >bolted to a Proton horizontally and then taken down the rail road track >and erected on the pad?    >They would also need LOX and LH facilities added to the Proton pads  >(unless the new Proton second stage is actually built), and of course >any Centaur support systems and facilities, no doubt imported from the >US at great cost. These systems may viloate US law so there are political >problems to solve in addition to the instabilities in the CIS you mention.
In <C5y4t7.9w3@news.cso.uiuc.edu> gfk39017@uxa.cso.uiuc.edu (George F. Krumins) writes:  >It is so typical that the rights of the minority are extinguished by the >wants of the majority, no matter how ridiculous those wants might be.  Right?  What right?  And don't you mean something more like: It so typical that the wants of the minority can obstruct the wants of the majority, no matter how ridiculous those minority wants might be or what benefits those majority wants might have?  [My sole connection with the project is that I spent a lot of time in classes at the University of Colorado.]  --  "Insisting on perfect safety is for people who don't have the balls to live  in the real world."   -- Mary Shafer, NASA Ames Dryden
prb@access.digex.com (Pat) writes:  >  What  evidence  indicates that Gamma Ray bursters are very far away?  >Given the enormous  power,  i was just wondering,  what if they are >quantum  black holes or something  like that  fairly close by?  >Why would they have to be at  galactic ranges?     Gamma Ray Bursts (GRBs) are seen coming equally from all directions. However, given the number of bright ones, there are too few faint ones to be consistent with being equally dense for as far as we can see--it is as if they are all contained within a finite sphere (or a sphere with fuzzy edges) with us at the center.  (These measurements are statistical, and you can always hide a sufficiently small number of a different type of GRB with a different origin in the data.  I am assuming that there is only one population of GRBs).  The data indicates that we are less than 10% of the radius of the center of the distribution.  The only things the Earth is at the exact center of are the Solar system (at the scale of the Oort cloud of comets way beyond Pluto) and the Universe.  Cosmological theories, placing GRBs throughout the Universe, require supernova-type energies to be released over a timescale of milliseconds.  Oort cloud models tend to be silly, even by the standards of astrophysics.  If GRBs were Galactic (i.e. distributed through the Milky Way Galaxy) you would expect them to be either concentrated in the plane of the Galaxy (for a 'disk' population), or towards the Galactic center (for a spherical 'halo' population).  We don't see this, so if they are Galactic, they must be in a halo at least 250,000 light years in radius, and we would probably start to see GRBs from the Andromeda Galaxy (assuming that it has a similar halo.)  For comparison, the Earth is 25,000 light-years from the center of the Galaxy.  >my own pet theory is that it's  Flying saucers  entering >hyperspace :-)  The aren't concentrated in the known spacelanes, and we don't see many coming from Zeta Reticuli and Tau Ceti.  >but the reason i am asking is that most everyone assumes  that they >are  colliding nuetron stars  or  spinning black holes,  i just wondered >if any mechanism could exist  and place them  closer in.  There are more than 130 GRB different models in the refereed literature. Right now, the theorists have a sort of unofficial moratorium on new models until new observational evidence comes in.
Habital planets are also dependent on what kind of plant life can be grown.. and such.. Length of growing season (that is if you want something more than VAT food, argh, Id ratehr eat an MRE for  along period of time).  I know in Fairbanks (Furbanks to some) the winter can get to -60 or so F, but in the summer can get to +90 and such.. I know of worse places..         Incans and Sherpa and other low pressure atmosphere and such are a limit in human adaptability(someone mentioend that Incan woman must come to lower elevations to have babies brought to term? true?) I remember a book by Pourrnelle I think that delt with a planet was lower density air..  I wonder what the limit on the other end of atmospheres?  I am limiting to human needs and stresses and not alien possibilties.. Thou aliens might be more adapted to a totally alien to human environment, such as the upper atmosphere of Jupiter or??  Almost makes bio-engineered life easy...
In article <C5ros0.uy@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: |> [Pluto's] atmosphere will start to freeze out around 2010, and after about |> 2005 increasing areas of both Pluto and Charon will be in permanent |> shadow that will make imaging and geochemical mapping impossible.  Where does the shadow come from?  There's nothing close enough to block sunlight from hitting them.  I wouldn't expect there to be anything block our view of them either.  What am I missing?
There is the Army Ballistic Missile Defense Organization.  They were the precursors to SDIO.  and still exist under that umbrella.  Army Signal Corp's  and DCA  defense Comm Agency oops  DISA, they just changed names  do space work.  that's the point of all those defense comm sats.
I posted this over in sci.astro, but it didn't make it here. Thought you all would like my wonderful pithy commentary :-)  What? You guys have never seen the Goodyear blimp polluting the daytime and nightime skies?  Actually an oribital sign would only be visible near sunset and sunrise, I believe.  So pollution at night would be minimal.  If it pays for space travel, go for it.  Those who don't like spatial billboards can then head for the pristine environment of Jupiter's moons :-)
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
>>>>> On Fri, 23 Apr 93 09:06:09 BST, nicho@vnet.IBM.COM (Greg Stewart-Nicholls) said: GS> How about transferring control to a non-profit organisation that is GS> able to accept donations to keep craft operational.  I seem to remember NASA considering this for some of the Apollo equipment left on the moon, but that they decided against it.  Or maybe not...
Some birds require constant management for survival.  Pointing a sensor at the sun, even when powered down, may burn it out.  Pointing a parabolic antenna  at Sol,  from venus orbit  may trash the foci  elements.  Even if you let teh bird drift,  it may  get hosed by some cosmic phenomena.
In article <C512wC.B0M.1@cs.cmu.edu>, nickh@CS.CMU.EDU (Nick Haines) writes: |> In article <1993Apr2.170157.24251@ke4zv.uucp> gary@ke4zv.uucp (Gary Coffman) writes: |>  <stuff deleted> |> Of course the units of force have the same names as those of weight, |> but in order to use them you need to keep useful constants like the |> omnipresent 32.???? ft/sec^2 around. |>  |> Maybe you'd like to go over again how this system is _so_ natural and |> _so_ easy to use, Gary? While you're at it, you can figure out for us |> the weight of 17 barrels and a quart of foo (density 17lb 2 3/4 oz per |> cubic foot) on the moon (gravity 5 ft 7 3/32 in/sec^2). Let's face it, |> even the imperial system uses a basically metric way of relating |> quantities (i.e. that would be written as 5.59 ft/sec^2); the only |> thing you're hanging on to is the right to express the same quantity |> as 1731 inches, 144.25 feet, 48.0833 yards or 2.186 chains. What |> everyone else is saying is _why_ do you want to do that? |>  |> Any apparent remaining complexity in the SI system is due to the |> multiplicity of the aforesaid prefixes. In fact what's going on (and |> the fundamental difference between SI and imperial) is that you have |> exactly one unit of each type, and all values of that type are |> expressed as some multiple of the unit.  You mean like: seconds, minutes, hours, days, months, years. . .  :-)  Remember,  the Fahrenheit temperature scale is also a centigrade scale.  Some revisionists tell the history something like this:  The coldest point in a particular Russian winter was marked on the thermometer as was the body temperature of a volunteer (turns out he was sick, but you can't win 'em all). Then the space in between the marks on the thermometer was then divided into hundredths. 								:-)  FWIW,  Doug Page
In article <1993Apr21.024423.29182@mnemosyne.cs.du.edu+ wdwells@nyx.cs.du.edu (David "Fuzzy" Wells) writes: + +I love the idea of an inflatable 1-mile long sign.... It will be a +really neat thing to see it explode when a bolt  (or even better, a +Westford Needle!) comes crashing into it at 10 clicks a sec.   + Pageos and two Echo balloons were inflated with a substance which expanded in vacuum. Once inflated the substance was no longer needed since there is nothing to cause the balloon to collapse. This inflatable structure could suffer multiple holes with no  disastrous deflation.
In article <1993Apr28.185206.3501@news.arc.nasa.gov> moses@pan.arc.nasa.gov (julie moses) writes: >...radiation field has been measured and modeled by various groups.  If I >remember things correctly, the models involved contributions from three >different BB sources, so there's no obvious "temperature" of background >radiation in our local area...  Indeed, the sky doesn't look much like a black body if you look carefully enough; in particular, its temperature at radio frequencies is quite a bit higher than you would see from a black body.  Morgan&Gordon's fat "Communications Satellite Handbook" has a graph of sky temperature vs. wavelength, in fact, for communications design.  However, in terms of energy content, the RF frequencies are negligible. For thermal purposes, at very large distances from the Sun the sky looks like a black body at 3.5K (Allen, "Astrophysical Quantities"). I haven't found a number for non-large distances, since solar radiation tends to be something you can't just ignore :-), but M&G says "about 4K" in a brief discussion of why solar radiation dominates the problem.
I would like to find out about space engineering employment and educational opportunities in the Tucson, Arizona area.  E-mail responses appreciated. My mail feed is intermittent, so please try one or all of these addresses.
Oddly, enough,  The smithsonian calls the lindbergh years the golden age of flight.  I would call it the granite years, reflecting the primitive nature of it.  It was  romantic, swashbuckling daredevils,  "those daring young men in their flying machines".  But in reality, it sucked.  Death was a highly likely occurence,  and  the environment blew.  Ever see the early navy pressure suits,  they were modified  diving suits.  You were ready to star in "plan 9 from outer space".   Radios  and Nav AIds were a joke,  and engines ran on castor oil.  They  picked and called aviators "men with iron stomachs",  and it wasn't due to vertigo.  Oddly enough, now we are in the golden age of flight.  I can hop the shuttle to NY for $90 bucks,  now that's golden.  Mercury gemini, and apollo were romantic,  but let's be honest. Peeing in bags,  having plastic bags glued to your butt everytime you needed a bowel movement.  Living for days inside a VW Bug. Romantic,  but not commercial.   The DC-X  points out a most likely new golden age.  An age where  fat cigar smoking business men in loud polyester space suits will fill the skys with strip malls and used space ship lots.  hhhmmmmm,  maybe i'll  retract that golden age bit.   Maybe it was better in the old days.  Of course, then we'll have  wally schirra telling his great grand children, "In my day,  we walked on the moon. Every day.  Miles.  no buses.  you kids got it soft".
In article <1993Apr5.220610.1532@sequent.com>, bigfoot@sequent.com (Gregory Smith) writes: |> mccall@mksol.dseg.ti.com (fred j mccall 575-3539) writes: |>  |> >In <1phv98$jbk@access.digex.net> prb@access.digex.com (Pat) writes: |>  |>  |> >>THe SR-71 stopped being a real secret by the mid 70's. |> >>I had a friend in high school who had a poster with it's picture. |>  |> >It was known well before that.  I built a model of it sometime in the |> >mid 60's, billed as YF-12A/SR-71.  The model was based on YF-12A specs |> >and had a big radar in the nose and 8 AAMs in closed bays on the |> >underside of the fuselage.  The description, even then, read "speeds |> >in excess of Mach 3 at altitudes exceeding 80,000 feet." |>  |> L.B.J. publically announced the existance of the Blackbird program |> in 1964.   He's also the one who dubbed it the SR-71 - it was the RS-71 until LBJ mippselled (sic) it.  FWIW,  Doug Page
higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes:  ... >Like others involved in sci.space, Mr. Adams shows symptoms of being a >fledgling member of the technoculture, and I think he's soaking it up >fast.  I was a young guy with dreams once, and they led me to get a >technical education to follow them up.  Too bad I wound up in an >assembly-line job stamping out identical neutrinos day after day... >(-:  How can you tell they're identical?  You got one of them "Star Drek: The Next Syndication" neutrino scanners?
Sorry but I forgot this ps.  Right now my sight is getting news about two weeks behind so it's  kind of necessary (to me) that any responses be sent to me directly.   Thanks a lot