Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_4/V16NO409.TXT

Internet Message Format | 1993-07-13 | 34KB

Date: Fri,  2 Apr 93 06:03:41
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #409
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri,  2 Apr 93       Volume 16 : Issue 409

Today's Topics:
                       Abyss: breathing fluids
                     Another Kuiper Object Found?
                        Atlas rocket question
            Help! Deep Space Communications: info needed.
                       Info on Probe Computers
                   lie low netters! UFO's want you!
                            nuclear waste
               Small Astronaut (was: Budget Astronaut)
                    Space FAQ 04/15 - Calculations
           the call to space (was Re: Clueless Szaboisms )
                         Why is Venus so bad?
                  Why use AC at 20kHz for SSF Power?

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 1 Apr 93 18:09:35 GMT
From: Pat <[e-mail]>
Subject: Abyss: breathing fluids
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
|In <1pcjmt$[e-mail]> [e-mail] (Pat) writes:
|
|>|But, I've heard reports that's a similar emulsion has been approved for
|                                                    ^^^^^^^^^^^^^^^^^^^^^
|>|use in neonates who are experiencing lung problems due to underdeveloped
|  ^^^
|>Of course, by the Time the FDA approves it for wide spread use,
                        ^^^^^^^^^^^^^^^^
|>the EPA will have finished Banning CFC's, so it will be back to
||the drawing board.  Of course, it may make a pretty good non-dairy
|>dessert topping.
|
|You're not paying attention, Pat.  See underlined above.
|
|Already been approved.  Is in widespread use.  No, you can't go down
|to the local 7/11 and buy a few hundred gallons, but then you can't do
|that with most drugs.
|

Somehow I always thought there was a significant difference between
Something being approved for a rather special care need and for widespread
use.  Note the underlining.  So can I order this stuff from my
Local hospital supply store because my mother has emphysema?
Or can I get it for testing dive gear?

>[I just happened to know someone who worked for the company the
>developed it.]
>

Did they try it out as a Dessert topping?

>Hey, I'd think you would approve of the FDA's attitude.  It so matches
>your own with regard to programs looking into innovations like 20kHz
>power, after all.  ;-)
>

Actually I do like the FDA approach.  Test rigorously,  Show safety
and efficacy.  Issue waivers in critical cases (AIDS, Cancer).
Develope a good population and then broaden approved use.

------------------------------

Date: 2 Apr 93 00:10:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Another Kuiper Object Found?
Newsgroups: sci.space,sci.astro

According to IAU Circular #5730, Luu and Jewitt, using the 2.2 meter
telescope at the University of Hawaii, have discovered a faint object that
may be another Kuiper object.  The object is designated 1993 FW and is
similar in motion and brightness to 1992 QB.  Computations done by Brian
Marsden indicates that 1993 FW is currently between 38 to 56 AU from the
Earth.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Being cynical never helps
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | to correct the situation
|_____|/  |_|/       |_____|/                     | and causes more aggravation
                                                  | instead.

------------------------------

Date: 1 Apr 93 18:25:28 GMT
From: Mark Taylor <[e-mail]>
Subject: Atlas rocket question
Newsgroups: sci.space

The Atlas ICBM was designed as a stage an a half missile.  It has
an extremely light weight structure.  This is achieved by making the
tanks (RP-1 and LOX) the external skin.  This skin is so thin that
while the vehicle is empty the tanks must be presurized to prevent
booster from collapseing of its own weight.
After launch, as propellants are consumed, acceleration increases.
There is no way to throttle the three engines so at a certain point
two of the three engines are dropped.  The middle, or sustainer engine
continues to burn until the proper velocity is achieved.  Remember,
Atlas was originally planed to lob a nuclear warhead 9000 miles and
this sudden switching off was a bit crude so the vierniers (sp?)
continue to fire as a triming maneuver to regulate the speed and
adjust the attitude.
The three main engines could only gimble (swivel) on one axis the
other two were taken care of by the vierniers (sp?).
Atlas was a truely remarkable booster.

------------------------------

Date: 3 Apr 93 02:26:26 GMT
From: [e-mail]
Subject: Help! Deep Space Communications: info needed.
Newsgroups: sci.space

Hi,

For a communications course I'm taking this year, I have been landed with the
job of doing a (fortunately not very long) introductory talk on 'Deep Space
Communications'.

Unfortunately I am having a _very_ hard time finding any info on this topic at
all. There are screeds of papers dealing with satellite comms, but very little
on deep space vehicles (such as the Pioneer & Voyager probes).

If anyone can point me towards anything that might help I would be _most_
grateful. Specifically I would be interested in

    - problems involved in communicating with deep space vehicles. eg
      distance, time delay, noise, tracking etc.
    - coding, compression & error correction techniques used.

and any general background info on the subject. Nothing too heavy and technical
please (I'm only an undergraduate! :-) ). Anything online would be great - the
library here at Waikato is not what you would call enormous and we don't get a
lot of the relevant journals.

Thanks in advance to anyone who can help. Sorry if this isn't the appropriate
group for this sort of thing - we obviously don't get comp.dcom.deepspace in
New Zealand ;-)

Cheers,
    Scott.


--------------------------------------------------------------------
Scott Mitchell, University of Waikato, Hamilton, New Zealand
([e-mail])

------------------------------

Date: 2 Apr 93 02:04:27 GMT
From: Seth the Lesser <[e-mail]>
Subject: Info on Probe Computers
Newsgroups: sci.space,alt.folklore.computers

[e-mail] (The Arch-Deviant) writes:
>
>I'm after _detailed_ technical information on the on-board computers used in
>early probes (Ranger, Mariner, Pioneer, Voyager) - system architecture,
>programming model, command codes, basically everything needed to write a
>true-to-life simulator of the probe as seen by programmers/flight engineers.

If anyone has a pointer for this, please post it publicly--I'm sure there
are even more people who would like to see such data.

Seth L. Blumberg          \    "The whole thing was an accident.  No saboteur
[e-mail] (play)   \ could have been so wildly optimistic as to think
[e-mail] (work) \    he could destroy an airplane this way."
    > No one I know shares my opinions, least of all Columbia University. <

------------------------------

Date: Thu, 1 Apr 1993 18:23:35 GMT
From: Martin Connors <[e-mail]>
Subject: lie low netters! UFO's want you!
Newsgroups: sci.space,sci.astro

This from todays Global Mail (Canada's 'national newspaper'):
===
Toronto - The Canadian Research Association for Cosmic Knowledge of
Phenomena, Observations, and Technology is investigating UFO abductions
connected with use of a global computer network. Banesh Swura, research
director, claims that monitoring computer networks allows aliens to target
individuals with knowledge or talents which interest them. These people
may become targets for abductions and possible reprogramming. By reading
the flow of information on computer discussion groups about astronomy and
space exploration, Swura has found cases of people who stop participating
for a period of time and then return. In many cases, he claims, there is
no valid reason for this and an abduction is suspected. "In one case
earlier this year, an asteroid researcher at the University of Hawaii
disappeared and later came back with excuses that his connection to the
world computer network had failed", he said. Investigation showed that the
connection had not failed during that period. Another case involved local
space enthusiast Henry Spenser, who disappeared at about the same time.
"There is a clear pattern of mysterious disappearances of people widely
known as space experts who use computer systems. The only consistent
explanation is UFO abductions, especially given the global extent of the
problem", Swura claims in a press release today. "Hopefully the current
documentary film Fire in the Sky will stimulate research in this area."
Mr. Spenser could not be reached for comment.
===
This news leaves me shaking at my keyboard. I have been having strange
dreams recently. Has anyone noticed if my posts were unexplainedly
interrupted for a while?
--
Martin Connors         |
Space Research         | [e-mail]  [phone]
University of Alberta  |

------------------------------

Date: 1 Apr 93 20:46:57 GMT
From: fred j mccall 575-3539 <[e-mail]>
Subject: nuclear waste
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Paul Dietz) writes:

>In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
>>
>>>    It has been proposed that by using SDI designed particle accelerators
>>>that most of the waste could be tranmutated to more useable forms.  Why not
>>>build a few proccessing plants to do this?
>>
>>'It has been proposed' by *who*?  Sounds like someone need s a science
>>lesson or three if they think that is feasible -- or does having the
>>magic initials in it (SDI) somehow make it workable contrary to
>>physical constraints?
>>
>>[Hint:  Think energy requirements.]

>Hint: don't talk about things on which you are ignorant.

Hint: Now think 'out of the lab'.

[descriptions of implementations deleted]

>This system would produce enough energy to drive the accelerator,
>perhaps with some left over.  A very high power (100's of MW CW or
>quasi CW), very sharp proton beam would be required, but this appears
>achievable using a linear accelerator.  The biggest question mark
>would be the lead target chemistry and the on-line processing of all
>the elements being incinerated.

Paul, quite frankly I'll believe that this is really going to work on
the typical trash one needs to process when I see them put a couple
tons in one end and get (relatively) clean material out the other end,
plus be able to run it off its own residual power.  Sounds almost like
perpetual motion, doesn't it?  After all, there are a number of fusion
power schemes that 'ought to be able to' be net power producers; I'll
believe we can seriously propose practical nuclear fusion power
sources when someone builds a power plant out of them.

[Actually, even getting *close* to break-even energy might be enough
to make such a scheme practical, from a societal point of view.  Just
what quantities per time do you see such a system handling, and how
much would it cost?  Do you really think they can get even close to
actually having it power itself, or will they 'waste' that power in
the name of other 'efficiencies'?  Yes, the decay process can be sped
up with particle beams, but do you really think this is going to be a
feasible process from an industrial standpoint?]

--
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
------------------------------------------------------------------------------
[e-mail] - I don't speak for others and they don't speak for me.

------------------------------

Date: Thu, 1 Apr 1993 18:33:30 GMT
From: Josh Hopkins <[e-mail]>
Subject: Small Astronaut (was: Budget Astronaut)
Newsgroups: sci.space

[e-mail] (Brenda Kalt) writes:

>In article <[e-mail]>, [e-mail] (Frank Crary) writes:

>|> Definitely possible: George is 6'2" and insists that any project
>|> he works on be large enough to, in theory, fit himself. You could
>|> probably cut the mass of his manned Pegasus capsule by 5% to 10%,
>|> just by insisting on a 5'0" astronaut...
>|>

>I've wondered about this for a long time. For space missions lasting
>months or years, wouldn't it be more efficient to use small astronauts?
>The beds and other equipment can be smaller or, in the case of
>off-the-shelf equipment, the astronauts would get less claustrophobic.
>Food requirements would be less (somebody help me out on this).

I've been wondering about this too.  Hiring women (or short men) as astronauts
would seem to be beneficial for future long term spaceflight.  Lower mass means
less fuel.  Smaller size means smaller quarters for less mass (and Frank Lloyd
Wright would approve).  A lower caloric intake means the food facities can be
smaller.  All of these factors are, of course, lost in the noise when we fly
huge gigabuck space ships.  However, the economics might start showing up if
one postulates that longer term spaceflights might become much more common,
such as in an asteroid mining society.  This isn't entirely irrelevant to the
present, however.  I've been told that one of the concerns about using Soyuz
as the return vehicle for Freedom is that it's just a tad small.  There are a
couple of taller astronauts who are quite concerned about whether they would
be eligible for station duty, and a number of women who are quite happy about
the whole thing.

--
Josh Hopkins                                          [e-mail]
          "Tout ce qu'un homme est capable d'imaginer, d'autres hommes
                     seront capable de la realiser"
             -Jules Verne

------------------------------

Date: 1 Apr 1993 14:56:14 -0500
From: Jon Leech <[e-mail]>
Subject: Space FAQ 04/15 - Calculations
Newsgroups: sci.astro,sci.space,sci.answers,news.answers

Archive-name: space/math
Last-modified: $Date: 93/04/01 14:39:12 $

PERFORMING CALCULATIONS AND INTERPRETING DATA FORMATS

    COMPUTING SPACECRAFT ORBITS AND TRAJECTORIES

    References that have been frequently recommended on the net are:

    "Fundamentals of Astrodynamics" Roger Bate, Donald Mueller, Jerry White
    1971, Dover Press, 455pp $8.95 (US) (paperback). ISBN 0-486-60061-0

    NASA Spaceflight handbooks (dating from the 1960s)
    SP-33 Orbital Flight Handbook (3 parts)
    SP-34 Lunar Flight Handbook   (3 parts)
    SP-35 Planetary Flight Handbook (9 parts)

    These might be found in university aeronautics libraries or ordered
    through the US Govt. Printing Office (GPO), although more
    information would probably be needed to order them.

    M. A. Minovitch, _The Determination and Characteristics of Ballistic
    Interplanetary Trajectories Under the Influence of Multiple Planetary
    Attractions_, Technical Report 32-464, Jet Propulsion Laboratory,
    Pasadena, Calif., Oct, 1963.

    The title says all. Starts of with the basics and works its way up.
    Very good. It has a companion article:

    M. Minovitch, _Utilizing Large Planetary Perubations for the Design of
    Deep-Space Solar-Probe and Out of Ecliptic Trajectories_, Technical
    Report 32-849, JPL, Pasadena, Calif., 1965.

    You need to read the first one first to realy understand this one.
    It does include a _short_ summary if you can only find the second.

    Contact JPL for availability of these reports.

    "Spacecraft Attitude Dynamics", Peter C. Hughes 1986, John Wiley and
    Sons.

    "Celestial Mechanics: a computational guide for the practitioner",
    Lawrence G. Taff, (Wiley-Interscience, New York, 1985).

    Starts with the basics (2-body problem, coordinates) and works up to
    orbit determinations, perturbations, and differential corrections.
    Taff also briefly discusses stellar dynamics including a short
    discussion of n-body problems.


    COMPUTING PLANETARY POSITIONS

    More net references:

    Van Flandern & Pullinen, _Low-Precision Formulae for Planetary
    Positions_, Astrophysical J. Supp Series, 41:391-411, 1979. Look in an
    astronomy or physics library for this; also said to be available from
    Willmann-Bell.

    Gives series to compute positions accurate to 1 arc minute for a
    period + or - 300 years from now. Pluto is included but stated to
    have an accuracy of only about 15 arc minutes.

    _Multiyear Interactive Computer Almanac_ (MICA), produced by the US
    Naval Observatory. Valid for years 1990-1999. $55 ($80 outside US).
    Available for IBM (order #PB93-500163HDV) or Macintosh (order
    #PB93-500155HDV). From the NTIS sales desk, (703)-487-4650. I believe
    this is intended to replace the USNO's Interactive Computer Ephemeris.

    _Interactive Computer Ephemeris_ (from the US Naval Observatory)
    distributed on IBM-PC floppy disks, $35 (Willmann-Bell). Covers dates
    1800-2049.

    "Planetary Programs and Tables from -4000 to +2800", Bretagnon & Simon
    1986, Willmann-Bell.

    Floppy disks available separately.

    "Fundamentals of Celestial Mechanics" (2nd ed), J.M.A. Danby 1988,
    Willmann-Bell.

    A good fundamental text. Includes BASIC programs; a companion set of
    floppy disks is available separately.

    "Astronomical Formulae for Calculators" (4th ed.), J. Meeus 1988,
    Willmann-Bell.

    "Astronomical Algorithms", J. Meeus 1991, Willmann-Bell.

    If you actively use one of the editions of "Astronomical Formulae
    for Calculators", you will want to replace it with "Astronomical
    Algorithms". This new book is more oriented towards computers than
    calculators and contains formulae for planetary motion based on
    modern work by the Jet Propulsion Laboratory, the U.S. Naval
    Observatory, and the Bureau des Longitudes. The previous books were
    all based on formulae mostly developed in the last century.

    Algorithms available separately on diskette.

    "Practical Astronomy with your Calculator" (3rd ed.), P. Duffett-Smith
    1988, Cambridge University Press.

    "Orbits for Amateurs with a Microcomputer", D. Tattersfield 1984,
    Stanley Thornes, Ltd.

    Includes example programs in BASIC.

    "Orbits for Amateurs II", D. Tattersfield 1987, John Wiley & Sons.

    "Astronomy / Scientific Software" - catalog of shareware, public domain,
    and commercial software for IBM and other PCs. Astronomy software
    includes planetarium simulations, ephemeris generators, astronomical
    databases, solar system simulations, satellite tracking programs,
    celestial mechanics simulators, and more.

    Andromeda Software, Inc.
    P.O. Box 605
    Amherst, NY 14226-0605


    COMPUTING CRATER DIAMETERS FROM EARTH-IMPACTING ASTEROIDS

    Astrogeologist Gene Shoemaker proposes the following formula, based on
    studies of cratering caused by nuclear tests.

             (1/3.4)
    D = S  S  c  K  W        : crater diameter in km
     g  p  f  n

           (1/6)
    S = (g /g )            : gravity correction factor for bodies other than
     g      e  t              Earth, where g = 9.8 m/s^2 and g    is the surface
                        e              t
                  gravity of the target body. This scaling is
                  cited for lunar craters and may hold true for
                  other bodies.

        (1/3.4)
    S = (p / p )        : correction factor for target density p  ,
     p      a   t                                t
                  p  = 1.8 g/cm^3 for alluvium at the Jangle U
                   a
                  crater site, p = 2.6 g/cm^3 for average
                  rock on the continental shields.

    C                : crater collapse factor, 1 for craters <= 3 km
                  in diameter, 1.3 for larger craters (on Earth).

                                (1/3.4)
    K                : .074 km / (kT TNT equivalent)
     n                  empirically determined from the Jangle U
                  nuclear test crater.

          3           2               19
    W = pi * d    * delta * V  / (12 * 4.185 * 10  )
                : projectile kinetic energy in kT TNT equivalent
                  given diameter d, velocity v, and projectile
                  density delta in CGS units. delta of around 3
                  g/cm^3 is fairly good for an asteroid.

    An RMS velocity of V = 20 km/sec may be used for Earth-crossing
    asteroids.

    Under these assumptions, the body which created the Barringer Meteor
    Crater in Arizona (1.13 km diameter) would have been about 40 meters in
    diameter.

    More generally, one can use (after Gehrels, 1985):

    Asteroid        Number of objects  Impact probability  Impact energy
    diameter (km)               (impacts/year)       (* 5*10^20 ergs)

     10                10             10^-8        10^9
      1             1 000             10^-6        10^6
      0.1           100 000             10^-4        10^3

    assuming simple scaling laws. Note that 5*10^20 ergs = 13 000 tons TNT
    equivalent, or the energy released by the Hiroshima A-bomb.

    References:

    Gehrels, T. 1985 Asteroids and comets. _Physics Today_ 38, 32-41. [an
    excellent general overview of the subject for the layman]

    Shoemaker, E.M. 1983 Asteroid and comet bombardment of the earth. _Ann.
    Rev. Earth Planet. Sci._ 11, 461-494. [very long and fairly
    technical but a comprehensive examination of the
     subject]

    Shoemaker, E.M., J.G. Williams, E.F. Helin & R.F. Wolfe 1979
    Earth-crossing asteroids: Orbital classes, collision rates with
    Earth, and origin. In _Asteroids_, T. Gehrels, ed., pp. 253-282,
    University of Arizona Press, Tucson.

    Cunningham, C.J. 1988 _Introduction to Asteroids: The Next Frontier_
    (Richmond: Willman-Bell, Inc.) [covers all aspects of asteroid
    studies and is an excellent introduction to the subject for people
    of all experience levels. It also has a very extensive reference
    list covering essentially all of the reference material in the
    field.]


    MAP PROJECTIONS AND SPHERICAL TRIGNOMETRY

    Two easy-to-find sources of map projections are the "Encyclopaedia
    Brittanica", (particularly the older volumes) and a tutorial appearing
    in _Graphics Gems_ (Academic Press, 1990). The latter was written with
    simplicity of exposition and suitability of digital computation in mind
    (spherical trig formulae also appear, as do digitally-plotted examples).

    More than you ever cared to know about map projections is in John
    Snyder's USGS publication "Map Projections--A Working Manual", USGS
    Professional Paper 1395. This contains detailed descriptions of 32
    projections, with history, features, projection formulas (for both
    spherical earth and ellipsoidal earth), and numerical test cases. It's a
    neat book, all 382 pages worth. This one's $20.

    You might also want the companion volume, by Snyder and Philip Voxland,
    "An Album of Map Projections", USGS Professional Paper 1453. This
    contains less detail on about 130 projections and variants. Formulas are
    in the back, example plots in the front. $14, 250 pages.

    You can order these 2 ways. The cheap, slow way is direct from USGS:
    Earth Science Information Center, US Geological Survey, 507 National
    Center, Reston, VA 22092. (800)-USA-MAPS. They can quote you a price and
    tell you where to send your money. Expect a 6-8 week turnaround time.

    A much faster way (about 1 week) is through Timely Discount Topos,
    (303)-469-5022, 9769 W. 119th Drive, Suite 9, Broomfield, CO 80021. Call
    them and tell them what you want. They'll quote a price, you send a
    check, and then they go to USGS Customer Service Counter and pick it up
    for you. Add about a $3-4 service charge, plus shipping.

    A (perhaps more accessible) mapping article is:

    R. Miller and F. Reddy, "Mapping the World in Pascal",
    Byte V12 #14, December 1987

    Contains Turbo Pascal procedures for five common map projections. A
    demo program, CARTOG.PAS, and a small (6,000 point) coastline data
    is available on CompuServe, GEnie, and many BBSs.

    Some references for spherical trignometry are:

    _Spherical Astronomy_, W.M. Smart, Cambridge U. Press, 1931.

    _A Compendium of Spherical Astronomy_, S. Newcomb, Dover, 1960.

    _Spherical Astronomy_, R.M. Green, Cambridge U. Press., 1985 (update
    of Smart).

    _Spherical Astronomy_, E Woolard and G.Clemence, Academic
    Press, 1966.


    PERFORMING N-BODY SIMULATIONS EFFICIENTLY

    "Computer Simulation Using Particles"
    R. W. Hockney and J. W. Eastwood
    (Adam Hilger; Bristol and Philadelphia; 1988)

    "The rapid evaluation of potential fields in particle systems",
    L. Greengard
    MIT Press, 1988.

        A breakthrough O(N) simulation method. Has been parallelized.

    L. Greengard and V. Rokhlin, "A fast algorithm for particle
    simulations," Journal of Computational Physics, 73:325-348, 1987.

    "An O(N) Algorithm for Three-dimensional N-body Simulations", MSEE
    thesis, Feng Zhao, MIT AILab Technical Report 995, 1987

    "Galactic Dynamics"
    J. Binney & S. Tremaine
    (Princeton U. Press; Princeton; 1987)

        Includes an O(N^2) FORTRAN code written by Aarseth, a pioneer in
        the field.

    Hierarchical (N log N) tree methods are described in these papers:

    A. W. Appel, "An Efficient Program for Many-body Simulation", SIAM
    Journal of Scientific and Statistical Computing, Vol. 6, p. 85,
    1985.

    Barnes & Hut, "A Hierarchical O(N log N) Force-Calculation
    Algorithm", Nature, V324 # 6096, 4-10 Dec 1986.

    L. Hernquist, "Hierarchical N-body Methods", Computer Physics
    Communications, Vol. 48, p. 107, 1988.


    INTERPRETING THE FITS IMAGE FORMAT

    If you just need to examine FITS images, use the ppm package (see the
    comp.graphics FAQ) to convert them to your preferred format. For more
    information on the format and other software to read and write it, see
    the sci.astro.fits FAQ.


    SKY (UNIX EPHEMERIS PROGRAM)

    The 6th Edition of the Unix operating system came with several software
    systems not distributed because of older media capacity limitations.
    Included were an ephmeris, a satellite track, and speech synthesis
    software. The ephmeris, sky(6), is available within AT&T and to sites
    possessing a Unix source code license. The program is regarded as Unix
    source code. Sky is <0.5MB. Send proof of source code license to

    E. Miya
    MS 258-5
    NASA Ames Research Center
    Moffett Field, CA 94035-1000
    [e-mail]


    THREE-DIMENSIONAL STAR/GALAXY COORDINATES

    To generate 3D coordinates of astronomical objects, first obtain an
    astronomical database which specifies right ascension, declination, and
    parallax for the objects. Convert parallax into distance using the
    formula in part 6 of the FAQ, convert RA and declination to coordinates
    on a unit sphere (see some of the references on planetary positions and
    spherical trignometry earlier in this section for details on this), and
    scale this by the distance.

    Two databases useful for this purpose are the Yale Bright Star catalog
    (sources listed in FAQ section 3) or "The Catalogue of Stars within 25
    parsecs of the Sun" (in pub/SPACE/FAQ/stars.data and stars.doc on
    ames.arc.nasa.gov).


NEXT: FAQ #5/15 - References on specific areas

------------------------------

Date: 2 Apr 93 04:04:07 GMT
From: Henry Spencer <[e-mail]>
Subject: the call to space (was Re: Clueless Szaboisms )
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>>... But have U.S. rules apply to Canada?  I hadn't
>>even heard we'd annexed them yet.  ;-)
>
>Annex?  No, they're going to ask to be members of the United States, once
>Quebec decides to make it on their own.

Hmm, time to start keeping a sharp eye on some of our more objectionable
politicians... what's obviously going on here is that the US doesn't dare
try to move in uninvited, so they're going to try to wangle an invitation.

(It's not hard to figure out why they're being chicken -- the last time
they tried moving in uninvited, in 1812, it was the biggest military
disaster in US history.  A small mob of Canadian militia and a handful
of our British buddies utterly destroyed a much larger US army, smashed
the invasion of Canada completely, and occupied a couple of US states
for a while in retaliation.  Clearly an experience that the US is not
anxious to repeat.)
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

------------------------------

Date: Thu, 1 Apr 1993 19:01:05 GMT
From: Oivind Toien <[e-mail]>
Subject: Why is Venus so bad?
Newsgroups: sci.space,rec.scuba

In article <1pchne$[e-mail]> [e-mail] (Pat) writes:
> In article <[e-mail]> [e-mail] (Oivind Toien) writes:
> |
> |In a previous record dive (dry) at NUTEC, Bergen, Norway to about 500
> |m they used a Heliox mixture most of the time except during the descent
> |were the gas mixture contained some nitrogen. The idea was the the
> |effect of N2 narcosis should reduce the effect of high pressure nerve
> |syndrome.
> |Several of the divers suffered serious injury. Although technology
> |seems to develop infinitely, physiology sets certain limits...
> |
> >In a program on the Norwegian channel 2 yesterday it was said that 1
> >of 7 divers are injured (per dive...) in dive operations in the North
> >Sea occuring at more than 300 m.


> My understanding is that Commercial diving  has some real problems
> following the Navy Dive tables.  Even if  you rigorously follow them,
> that multiple diving causes some form of Micro Nitrogen bubbles
> in the nervous tissue.  Long term studies of the spinal tissues
> of commercial divers shows large amounts of nerve damage.

> There is some movement to require deep diving bells, where the divers
> can live  underwater for extended periods and  undergo
> slow decompression.

> pat

They *are* of course doing saturation dives from bells where they stay
pressurised for an extended period of time. I do not have any details
here, but I think the 500m test dive took more than a month. Btw, the
safety requirements in the Norwegian sector of the North sea are said
to be some of the strictest in the world. Obviously this is'nt enough
when physiology sets the limits...

Oivind
--
Oivind Toien  <[e-mail]>

Dept. of Arctic Biology, Institute of Medical Biology, University of Tromso
---------------------------------------------------------------------------
9037 Tromso, NORWAY                     Phone[phone]   Fax[phone]

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Date: 1 Apr 93 17:53:25 GMT
From: Pat <[e-mail]>
Subject: Why use AC at 20kHz for SSF Power?
Newsgroups: sci.space

In article <[e-mail]| [e-mail] (fred j mccall 575-3539) writes:
|In <1ovfa9$[e-mail]> [e-mail] (Pat) writes:
|
|>In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
|>>
|>>But not nearly as weight conscious as spacecraft have to be.  In
|>>addition, needs are somewhat different between an aircraft and a space
|
|>Yeah,fred.  The difference is that aircraft have to fly.
|
|Oooo, he's such a clever boyo, he is!
|

I am going to make a prediction.  Something I really dislike doing.
The texas Senate race is going to be done.   The shea team will come
in with their new design.  The congress will look at it, and say.
It's 20 Billion, but it's 1/4 the station we last voted on and kill it.
They may get money to work with the russians,  they may get some
money to do some fancy SHuttle adaptions.  But I don't think
we are ever going to see SSF.
And it will be due to management failure.
|>>station.  Personally, I think 20kHz was a bad idea, but I also think
|>>that this insistence of yours that if it was good enough for the
|>>Wright brothers it's good enough for SSF is just a bit silly.
|
|
|>Don't try to misrepresent my position, fred.  It's intellectually
|>dishonest.  I am all for 20KHz power as part of a engineering
|>research and developement test bed.  TO make it the defined
|>Prime power on an OPERATIONAL station is absolutely  stupid.
|
|I don't have to misrepresent your position, nor did I.  No one should
|ever actually *use* anything until it's a catalog item -- except it
|ain't gonna become a catalog item until after it's in widespread use.
|

Actually,  most things become catalog items, after some reasonable
engineering developement program.  Something i've never seen
SSF engage in.

>>You just can't believe that someone wwants to see proven trackrecord
>>before commiting a 40Billion dollar program.
>
>Nice to be told what I "can't believe".  And here all this time I
>thought that *I* would be the one to tell people that.  You don't get
>a 'proven trackrecord' until it's in widespread use, Pat.  Except it
>can never go into widespread use because it must have a 'proven
>trackrecord' before anyone should use it for anything.
>
I guess the X-15 doesn't count for proving technology?

>Where do chickens come from, Pat?
>

The other side of the road.

>[Really?  Where'd you get the egg?]
>

My refrigerator.

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End of Space Digest Volume 16 : Issue 409
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