Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_2/v11_230.txt

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Subject: SPACE Digest V11 #230

SPACE Digest                                     Volume 11 : Issue 230

Today's Topics:
                 Comet Austin
          Removal from SPACE discussion list
            Re: orbit definitions
               Re: Velikovsky's Theory
        Re: Gif pictures, Accessing Finnish Listserver
            Re: orbit definitions
               Re: Velikovsky's Theory
       Re: Reports of Io's vulcanism before VOYAGER 1 ?
   Re: "Brilliant Pebbles" vs. "Smart Rocks" (was Re: Railgun ...)
      Re: What does it cost to push a pound into orbit?
----------------------------------------------------------------------

Date:     Fri, 6 Apr 90 13:23:50 MDT
From: DC 352 <[e-mail]>
Subject:  Comet Austin

Bill Higgins:
  I saw Comet Austin just a couple days ago, using binoculars.  It was
very hard to see - the Sun is quite close, and the Moon is high in the
sky.  But I guess it's brightness is just enough to overcome the bright
sky.  Couldn't be much - we could only see it with averted vision, and
no detail was visible other than a small spot in the sky was a bit
brighter than it should be.
  Guess we'll have to wait until it comes up in the morning before
we get our good views at it.
         Dan Charrois

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

Date: Fri, 6 Apr 90 11:59 EDT
From: [e-mail]
Subject: Removal from SPACE discussion list
Sender: Russ Opland <[e-mail]>
Reply-To: [e-mail]
X-Envelope-To: [e-mail]
X-Vms-Cc: RUOPLAND

Please remove me from the distribution list. I have tried sending the SIGNOFF
command with the (GLOBAL option to the LISTSERV@UGA, and one other place, but
to no avail. I keep receiving the digest.

Thank you.
Russ Opland

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

Date: 6 Apr 90 16:41:20 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: orbit definitions

In article <[e-mail]> [e-mail] (Bart_Eleveld) writes:
>Would some kind soul(s) out there post definitions for the various types of
>orbits that are often talked about on the net; e.g., Clarke, geosynchronous,
>geostationary...

Well, let's see...

LEO        Low Earth Orbit, generally somewhere between 250-300 km
        (where air drag starts to get serious) and 1000 km (where
        the inner Van Allen belt starts to get serious).  Usually
        implicitly at a modest inclination to the equator, i.e. the
        lowest achievable from the launch site.

Polar orbit    Technically, an orbit with an inclination of 90 degrees.
        More usually, LEO with an inclination near 90 degrees.

Retrograde    Technically, an orbit with an inclination over 90 degrees.
orbit        More usually, an orbit with an inclination a lot over 90
        degrees.  Rare; pretty useless.

Geosynchronous    Any orbit synchronized with the rotation of the Earth, i.e.
orbit        with a period which is some multiple or divisor of 24 hours.
        Often used sloppily to mean geostationary.

Geostationary    The 24-hour equatorial orbit, where a satellite appears to
orbit        hang motionless in the sky.  Most comsats are found here,
        as are an assortment of others that want a constant view
        of the Earth (early-warning satellites, some weather sats)
        or just easy communications in high orbit (some astronomy
        satellites).

Clarke orbit    Some people prefer this to "geostationary", given that
        Arthur C. Clarke was the first person to realize how useful
        this orbit would be for comsats.

HEO        High Earth Orbit.  Rather vaguely defined.  Usually means
        anything from Clarke orbit up; the region between LEO and
        Clarke orbit is very unhealthy due to the Van Allen belts.

GTO        Geostationary Transfer Orbit, an orbit at modest inclination
        with perigee at LEO and apogee at Clarke orbit.  The usual
        intermediate step en route to Clarke orbit; Ariane launches
        directly into GTO, some other launchers launch into LEO and
        then boost into GTO.

Molniya orbit    Elliptical orbit at a specific inclination, 60-odd degrees,
        usually with apogee above the Northern Hemisphere.  The
        Earth's equatorial bulge normally causes the position of
        apogee&perigee to rotate in the plane of an elliptical
        orbit, but at the particular inclination of the Molniya
        orbits, this effect is zero and the apogee stays where
        it's put.  The Soviets use it for their Molniya comsats
        (whence the name) because it makes them more visible from
        very high latitudes than Clarke orbit.  The inclination is
        high enough to miss the worst part of the inner Van Allen
        belt, which is near the equator.

Sun-synchronous    Another effect of the Earth's bulge is rotation of the plane
orbit        of the orbit.  With the right combination of altitude and
        inclination, the rotation can be set to 360 degrees/year,
        keeping the orbital plane in a roughly constant relation to
        the Earth-Sun line.  For low orbits, the inclination turns
        out to be slightly over 90 degrees.  Very popular for remote
        sensing, weather, and spy satellites that want to view the
        ground at constant Sun angle.

>... Also, how much more
>energy (in relative terms) does it take to launch a payload to the west, or
>to the poles (N or S) rather than to the east?

The difference is the Earth's rotation, which is 460m/s times the cosine
of the latitude.  Launching due east from the equator gets you a free
460m/s contribution toward orbital velocity.  Launching due north or south
eliminates that freebie.  Launching due west adds 460m/s to the necessary
velocity.  Orbital velocity is about 8km/s, so the difference is not huge
but is quite noticeable.  This is why spaceports are at the lowest possible
latitudes and maximum payload is had by launching due east.
--
Apollo @ 8yrs: one small step.|     Henry Spencer at U of Toronto Zoology
Space station @ 8yrs:        .| uunet!attcan!utzoo!henry [e-mail]

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

Date: 6 Apr 90 17:16:11 GMT
From: swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!uflorida!haven!aplcen!aplvax.jhuapl.edu![e-mail]  (Jim Meritt)
Subject: Re: Velikovsky's Theory


If you think his astronomy was bad, take a look at his biology and chemistry!

He could not tell carbohydrates from hydrocarbons, and thought a beastie
(a fly, in fact) could metabolize quite well in both a reducing and
an oxidizing atmosphere (and survive reentry).

Whatta twit.


And yes, I did read his original works.  I could not believe anyone would be
so stupid as the reviewers made him out to be.

He was.


That that is is that that is. That that is not is that that is not.
That that is is not that that is not.  That that is not is not that that is.
And that includes these opinions, which are solely mine!
[e-mail]  - or - [e-mail]  - or - meritt%aplvm.BITNET

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

Date: 5 Apr 90 13:15:25 GMT
From: mcsun!ukc!tcdcs!swift.cs.tcd.ie!ccvax.ucd.ie![e-mail]  (Brian J Haughey)
Subject: Re: Gif pictures, Accessing Finnish Listserver

In article <[e-mail]>, [e-mail] ("Joe Desbonnet, UCG Ireland.") writes:
> Could anyone point me to a source where I can get some impressive
> space pictures preferably in Gif format? I recently saw a posting about
> some pictures stored somewhere in Finland but I unfortunatly I can
> only access US servers. As a Bitnet user I must use [e-mail] which
> does not support Finish nodes. BTW are there other Bitnet FTP connections out
> there?).
> Thanks in advance for any help,
> Joe.

Joe, sine you have Bitnet access to *can*  access the Finnish files. (At least
until June - after that, access may be terminated).

To access the files, use the following syntax :

   Tell listserv at Fintuvm /PDDIR FUNIC.FUNET.FI:disk1/pub/* (DIR

This will get u a listing of all subdirs there. The one u want is something
like "disk1/pub/misc/pics/gif/space", but as I can't remember exactly ask
for the directory listing as I showed above.

Once u get the listing, it's an easy matter to get the file :

   Tell listserv at fintuvm /PDGET FUNIC.FUNET.FI:disk1/pub/.../file (UUE

N.B - case of filenames *is* important - most filenames will be lowercase.

Any poblems, mail me at HAUGHD88@Irlearn or B_Haughey@CCVAX

-- bjh
  University College Dublin, Ireland.    "There's no future in time travel"

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

Date: 6 Apr 90 23:15:19 GMT
From: zaphod.mps.ohio-state.edu!usc!jarthur![e-mail]  (John H. Kim)
Subject: Re: orbit definitions

In article <[e-mail]> [e-mail] (Dan Tilque) writes:
>
>There's a variation on the Geostationary orbit but I'm not sure if it
>has a name.  I suppose it could be called a Geosynchronous, but it's
>more specific than the definition of geosynchronous that Henry gives.
>
>The orbit is 24-hour but has a non-zero inclination.  From the ground
>it would appear to move up and down on a daily basis while staying over
>the same meridian.

Actually, it does a figure eight.  Those who know this can skip
the next two paragrahs.  Those who don't, you're probably thinking
"huh?"  That's what I thought when I first heard this, so...

Since the satellite's period and the earth's rotation period are
both 24 hrs (this is a simplification, no flames about 23h 56(?)m
sidearal period please), the satellite's ground track (GT) and the
earth's surface at the equator (EQ) move along at the same velocity.
If the satellite's orbit is inclined, it doesn't stay at the EQ.
As the GT moves north from the EQ, it is at an angle to the EQ.
Since the velocities of the GT and EQ are the same, the GT has a
smaller component of its velocity heading the same way as the EQ,
so it "falls behind" the meridian it crossed the EQ at.  Once the
GT reaches its maximum latitude, it is moving along at its maximum
velocity, but the ground at that latitude isn't moving as fast as
the EQ, so the GT "catches up" and passes the meridian.  As the GT
heads back to the EQ, it "falls behind" back to the meridian, where
it crosses the EQ again. Repeat for the southern track.

If you're a really observant, you'll realize this argument isn't
perfect (as GT moves north, the earth's velocity underneath it also
decreases and could conceivably cancel out the GT "falling behind").
But if you work out all the sines, cosines and spherical trig, it
really does a figure eight.

>I'm not sure how much it's used now, but as the geostationary orbit
>slots get filled up ...
> ...
>Thus it could have virtually the same longitude
>as a comsat and without interfering with it.

Not quite.  It still crosses the equator through the geostationary
orbits.  I'd rather have a collision between two geostationary sats
(small relative velocity) that between a geostationary and a geosynch
(high relative velocity in the north-south direction).

>Another advantage is that, if you can live with the inclination of the
>launch site, it should take less delta-V to get to than a true
>geostationary orbit.  This advantage may be wiped out if you then have
>to add a scan platform which keep the instruments pointed correctly on
>a 24-hour basis.

More importantly, the area you want to observe may disappear over the
horizon once each day (like if you wanted weather photos of Alaska).
Look at the next US/Canada weather satellite picture closely.  You'll
see there's a lot of distortion as you get to the higher latitudes.
--
John H. Kim
[e-mail]

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

Date: 2 Apr 90 08:02:56 GMT
From: mcsun!hp4nl!dnlunx!spex1![e-mail]  (Henk van der Griendt)
Subject: Re: Velikovsky's Theory


I am interested too to hear from the scientist about Velikovsky's
theories.
I know in the past most scientists simply did not like him and did not
want to take his theories serious.

Henk van der Griendt (internet: [e-mail])

--

================================================================================
|    Henk van der Griendt            E-mail: [e-mail] (internet)|
|    Speech Processing EXpertise centre        [e-mail]    |

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

Date: 6 Apr 90 09:48:19 GMT
From: mcsun!unido!mpirbn![e-mail]  (Daniel Fischer)
Subject: Re: Reports of Io's vulcanism before VOYAGER 1 ?


                    In <Apr 4 13:53 1990> Larry Klaes asks:
> Were there any science reports... which "anticipated volcanic activity on
> Jupiter's Galilean moon Io *before* the flyby of VOYAGER 1 in 1979?
                  In <Apr 5 14:20 1990> Jim Sullivan replies:
> I do remember a paper was published or released just before Voyager got to
> Jupiter that predicted volcanic activity based on tidal forces on Io.
   The paper was: "Melting of Io by Tidal Dissipation" in Science Vol.203
p.892-894 which was published on 2 March 1979, three days before Voyager's
closest approach. At that time, it was obvious that Io was by far the strangest
body in the Jovian system (the famous 'pizza photo' was already in), and specu=
lations about volcanic activity based on its surface morphology had already
begun. But S.J.Peale, P.Cassen and R.T.Reynolds had *submitted* their paper
on 26 January 1979: at _that_ time Io was resolved already by the narrow angle
camera, but no details were seen yet - these researchers worked from orbital
theory and basic planetary geology alone.After some calculations they concluded:
] The result of this runaway melting process is a planet with a large molten
] core and a solid outer shell... a thin shell indeed... Io might currently be
] the most intensely heated terrestrial-type body in the solar system. The
] surface of the type of body postulated here has not been directly observed...
] one might speculate that widespread and recurrent surface volcanism might
] occur... Voyager images of Io may reveal evidence for a planetary structure
] and history dramatically different from any previously observed.
The discovery of two *active* volcanoes some days after the encounter verified
these clever thoughts quicker than anyone would have suspected.

+- [e-mail] --- Daniel Fischer --- [e-mail] -+
| 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 -----+

P.S.: What do you think - does Io or Triton deserve the title "strangest body
in the solar system? As shown above, Io has a good reason to be active, but
Triton...?

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

Date: 3 Apr 90 15:45:19 GMT
From: sun-barr!newstop!texsun!smunews!ti-csl!m2![e-mail]  (Mark Meyer)
Subject: Re: "Brilliant Pebbles" vs. "Smart Rocks" (was Re: Railgun ...)

>In article <[e-mail]> [e-mail] (John F Nixon) writes:
>-Actually, I am proposing "Savant Sand" as an SDI weapon....
>[e-mail]                    ...steinmetz!atl.decnet!jnxion

In article <[e-mail]> [e-mail] (Dave Tiller N2KAU) writes:
>How about:
>    -Intelligent Igneous
>    -Loquatious Limestone
>    -Precocious Perovskovites
>    -Brainy Boulders
>    -Cerebral Coral


Or even:
    Genius Gypsum
    Sentient Sediment
    Pedantic Pumice

--
Mark Meyer          USENET: {ut-sally!im4u,convex!smu,sun!texsun}!ti-csl!mmeyer
Texas Instruments, Inc.                                   CSNET : mmeyer@TI-CSL
Every day, Jerry Junkins is grateful that I don't speak for TI.
                                          Who says I should question authority?

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

Date: 6 Apr 90 16:08:11 GMT
From: zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: What does it cost to push a pound into orbit?

In article <[e-mail]> [e-mail] (Tom Betz) writes:
>Geostationary
>L[1-5]
>Lunar Landing
>Solar "Landing" (into the Sun)

You're not likely to get any useful cost figures for the Lagrange points
or lunar landing, since there are no operational systems to do either.
I strongly suspect that the same is true of the "solar landing", although
it might be possible to get a rough idea of costs for stacking rocket stages
on top of a large booster like a Commercial Titan.  Costs into Clarke orbit
ought to be available, although I don't have them handy.
--
Apollo @ 8yrs: one small step.|     Henry Spencer at U of Toronto Zoology
Space station @ 8yrs:        .| uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V11 #230
*******************