Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_3/V15NO390.TXT

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Date: Sat,  7 Nov 92 05:03:42
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #390
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat,  7 Nov 92       Volume 15 : Issue 390

Today's Topics:
              "Earth Gains a Retinue of Mini-Asteroids"
                 Automated space station construction
                        clarke's law (2 msgs)
                      Comet deflection & mining
                   Coverup - gravity doesn't exist?
                      Galileo Update - 11/06/92
           Gloveless in Vacuum? (was Re: Man in space ... )
                                 HST
                           Hubble's mirror
                       JPL GIF Images Available
                          Man in space ... )
                            Marsquakes...
                               Mascons
                        NASA Coverup (2 msgs)
                            Slush Hydrogen

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: 7 Nov 92 01:16:56 GMT
From: Jim Scotti x2717 <[e-mail]>
Subject: "Earth Gains a Retinue of Mini-Asteroids"
Newsgroups: sci.astro,sci.space

In article <[e-mail]> [e-mail] (Dan Tilque) writes:
>[e-mail] (Jim Scotti x2717) writes:
>>[e-mail] (Paul Dietz) writes:
>>>
>>>Since the Tunguska event is thought to have been due to a 40 meter
>>>body, and such events were calculated to occur once every 2 to 3
>>>centuries, something is screwy here.
>>
>>Not really screwy.  The number of 50 meter objects is enhanced by
>>about 10 times and the Tunguska type events probably happen once
>>or a few times per century.
>
>This sparked a memory, but unfortunately not a detailed one.
>
>There was a second (but less powerful) Siberian meteor-explosion
>sometime after Tunguska.  I seem to remember that it was in either the
>20's or the 40's, but the name of it totally eludes me.
>
>Anyone know about this?

Yup, I do.  You are remembering the meteorite fall called "Sikhote-Alin"
which happened in 1947 in Siberia.  The fall created about 200 small
craters of the non-explosive type created by the fall of large objects
traveling relatively slowly, perhaps at terminal velocity.  The largest
crater was about 26.5 meters in diameter.  I think that about 50 tons of
material was recovered and the progenitor was estimated as being about
200 tons before atmospheric entry.  I suppose the object would have been
around 5 meters diameter before entry and was probably a stoney iron.

This size object probably hits the Earth around 10 times per year and
I suppose about 1% of them are stoney iron, so a fall of this type
probably happens on the order of once a decade.

>---
>Dan Tilque    --     [e-mail]

Jim.
---------------------------------------------
Jim Scotti
{[e-mail]}
Lunar & Planetary Laboratory
University of Arizona
Tucson, AZ 85721 USA
---------------------------------------------

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

Date: 7 Nov 92 00:14:27 GMT
From: "Richard A. Schumacher" <[e-mail]>
Subject: Automated space station construction
Newsgroups: sci.space

In <[e-mail]> ssi![e-mail] ("Louis F. Adornato") writes:

>communities in this country have, IMHO, paid for those programs.  If
>you want to think that the NASA bias toward crewed programs is based on
>funding, I'm certainly not going to change your mind.  However, there
>are an awful lot of people who just don't think that firing toys into
>the solar system is as awe inspiring as having _people_ out there,
>regardless of the volume of raw data rerturned.

Well, NASA's current (shuttle) and planned (Fred) manned programs manage
to spend awe-inspiring amounts of money and keep awe-inspiring numbers
of people employed in proportion to the amount of work done and
data returned, but I can't seem to find these particulars in NASA's
charter. I thought that exploring space was the whole idea? Yet Fred
has consumed eight billion dollars so far without one piece of flight
hardware being bolted to another, while Magellan is about to be turned
off in the middle of collecting new and unique data on the structure of
Venus for want of a miserable $20 million.

If NASA can't get out of the astronaut, aerospace worker and bureaucrat
welfare business it's liable to find its plug unceremoniously pulled one
day.

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

Date: 6 Nov 92 23:14:32 GMT
From: Kurt Hillig <[e-mail]>
Subject: clarke's law
Newsgroups: sci.space,sci.astro,sci.physics.fusion

In article <[e-mail]> [e-mail] (Thomas Clarke) writes:

>Someone recently posted Clarke's law.  The one about
>if a senior scientist says possible he's probably right,
>if he says impossible he's probably wrong.
>
>Could you e-mail me the exact quotation?  I need to cite it
>in a paper and don't want to go digging in the library.
>
>Thanks.
>--
>Thomas Clarke
>Institute for Simulation and Training, University of Central FL
>12424 Research Parkway, Suite 300, Orlando, FL 32826
>[phone], FAX: [phone], [e-mail]
>
>no relation

Funny, the one I learned as "Clarke's Law" is:

"Any sufficiently advanced technology is indistinguishable from magic."

--
Kurt Hillig
Dept. of Chemistry                     [e-mail]
University of Michigan           Telephone [phone]
Ann Arbor, MI  48109-1055      [e-mail]

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

Date: 7 Nov 92 01:16:15 GMT
From: Bob Pendleton <[e-mail]>
Subject: clarke's law
Newsgroups: sci.space,sci.astro,sci.physics.fusion

From article <L_A=lF#@engin.umich.edu>, by [e-mail] (Kurt Hillig):
> In article <[e-mail]> [e-mail] (Thomas Clarke) writes:
>
>>Someone recently posted Clarke's law.  The one about
>>if a senior scientist says possible he's probably right,
>>if he says impossible he's probably wrong.
>>
>>Could you e-mail me the exact quotation?  I need to cite it
>>in a paper and don't want to go digging in the library.
>>
>>Thanks.
>>--
>>Thomas Clarke
>>Institute for Simulation and Training, University of Central FL
>>12424 Research Parkway, Suite 300, Orlando, FL 32826
>>[phone], FAX: [phone], [e-mail]
>>
>>no relation
>
> Funny, the one I learned as "Clarke's Law" is:
>
> "Any sufficiently advanced technology is indistinguishable from magic."
>
> --
> Kurt Hillig
> Dept. of Chemistry                     [e-mail]
> University of Michigan           Telephone [phone]
> Ann Arbor, MI  48109-1055      [e-mail]

Clarke is allowed to have many laws. Both of these are known as
"Clarke's Law."


--
Bob Pendleton             | As an engineer I hate to hear:
[e-mail]              |   1) You've earned an "I told you so."
Speaking only for myself. |   2) Our customers don't do that.
                   <<< Odin, after the well of Mimir. >>>

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

Date: 6 Nov 92 22:46:06 GMT
From: Nick Szabo <[e-mail]>
Subject: Comet deflection & mining
Newsgroups: sci.space,alt.sci.planetary

Deflecting anything but the strongest nickle-iron asteroid
with a nuclear explosive is silly.  Many asteroids are probably
rubble piles, not single big rocks, and comets are so fragile we've
seen some calve off big chunks and obliterate themselves just from
internal gas pressure.  For a comet, farting can be suicide!

10^11 tonnes about equals the annual U.S. consumption of
fresh water, so P/Swift-Tuttle wouldn't make make much difference
down here even if you could get it through the atmosphere
without damaging things.  A much better use is Earth orbit,
in suitably small wrapped pieces.  If we're to have any significant
manufacturing industry in space, we're going to need tons of volatiles.
For example, here is the water used to make various kinds of products
on earth:

            gallons/unit
            ------------
finished steel, ton    40,000
automobiles, unit    12,000
trucks, buses, unit    20,000
ref: Mark's Standard Handbook for Mechanical Engineers, 1987

Presumably we could economize and recycle more than we do on Earth,
but life is much nicer when there's a lot of water handy -- not to
mention the nitrogen, methane, etc. found mainly on comets.  Also
not included in those figures is the copious amount of air for cooling
and lubrication assumed by most industrial processes, eg milling.
Furthermore, most of the mass launched into space is propellant
for orbit-transfer and stationkeeping.  We can easily convert from comet
ice to various kinds of propellant or use as is in thermal rockets.

P/Swift-Tuttle at 50 km/s delta-v is extremely difficult
to get to.  It doesn't make sense to try to capture it; there
are many Jupiter-family comets with periods of 3.5-6 years
and only 8-10 km/s away.  There may be ice closer still in
some of the "mini-asteroids" or larger Apollo-Amors, but that
requires more exploration to confirm or eliminate.

With automated equipment we form a reasonably pure cylindrical
ice shape, attach a small thermal rocket, and capture over 10% of
that ice mass into Earth orbit, or 25% into Mars orbit, while
expelling the rest as thermal rocket exhaust.  Moving the same mass
of material from a gravity well would require rocket with five or
more orders of magnitude power.  Economics hinge on the mass-thruput
ratio of the extraction equipment, which could be similar to water-wells
and ice-makers on Earth.  At around 2,000:1 MTR it becomes economical
to capture Jupiter-family comet ice into Earth orbit.

Back to the P/Swift-Tuttle deflection problem.

If upper-stage technology advances sufficiently over the next 30-40
years, eg magsails powered by the solar wind + a very advanced nuclear
electric second stage, we might be able to catch up with P/Swift-Tuttle
at perihelion in 2057 to track it.  Alternately, we might develop very
good telescopes capable of tracking it that far out, eg huge microgravity-
based reflectors combined with optical interferometry.  Who knows what
technology we will have after 2100, but one possibility is to focus
sunlight with a large parabolic mirror over the period of several
months to change the time P/Swift-Tuttle crosses earth orbit by one day.
Anyone want to tackle the math on how large a mirror would be needed?
Even with this gentle method, we need to gaurd against the possibility
of disrupting the comet rather than deflecting it.  Rendesvous with 50 km/s
incoming will also be a challenge, perhaps several years with a tacking
magsail.


--
Nick Szabo                     [e-mail]
Hold Your Nose: vote Republocrat  ////////  Breathe Free: vote Libertarian

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

Date: Fri, 6 Nov 92 21:19:25 EST
From: John Roberts <[e-mail]>
Subject: Coverup - gravity doesn't exist?

-From: [e-mail] (Roger Wilfong)
-Subject: Re: Coverup - gravity doesn't exist?
-Date: 6 Nov 92 18:03:00 GMT
-Organization: UofM Hospitals

-There's always Alway's Speculation on Physical Laws.

-   "Until a physical law is discovered, compliance is not mandatory."

-It's kind of like "if a tree fell in the woods ...".  As applied to gravity,
-Alway's Speculation is that before Newton, objects fell because they wanted
-too (but when no one was looking, they sometimes fell up) - after Newton,
-objects were required to fall under force of law (a force much greater than
-gravity).
-:-)

"Just you wait - as soon as someone discovers gravity, they'll all fall down
and hit the ground." (Caption of "Herman" cartoon.)

This concept is discussed in a slightly more serious context in the
Heinlein novel "Waldo".

Come to think of it, if this Speculation is valid, then those people who
are looking for "dark matter" are trying to destroy the universe! Maybe they
should be arrested - conspiring to destroy the universe must violate *some*
federal law!

:-)  :-)

John Roberts
[e-mail]

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

Date: Sat, 7 Nov 1992 08:19:12 GMT
From: Ron Baalke <[e-mail]>
Subject: Galileo Update - 11/06/92
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Fowarded from Neal Ausman, Galileo Mission Director

                                    GALILEO
                        MISSION DIRECTOR STATUS REPORT
                                  POST-LAUNCH
                        October 30 - November 5, 1992

SPACECRAFT

1.  On October 31 and November 1, delta Differenced One-Way Range (DOR) passes
were performed over DSS-14/63 (Goldstone/Madrid) and DSS-14/43
(Goldstone/Canberra).  Initial results indicate three of the four delta DOR
passes were successfully performed.

2.  On November 2, a NO-OP command was sent to reset the command loss timer
to 264 hours, its planned value for this mission phase.

3.  On November 3, real-time commands were sent to change the downlink
telemetry rate from 1200 bps coded to 7.68 kbps coded.  This allowed the Heavy
Ion Counter (HIC) instrument to transmit Low Rate Science (LRS) data two days
earlier than planned in the background sequence, collecting data on recent
solar flare activity.

4.  On November 3, after the telemetry configuration to low rate science data
(7.68 kbps), visibility into the full engineering channels revealed that four
of the Ultraviolet Spectrometer (UVS) channels were not in their expected
state.  Preliminary analysis indicates that a bit flip in one memory location
apparently occurred between the first and second instrument memory readouts on
October 15, 1992.  The UVS team is still investigating the possible cause of
this anomaly.  The instrument health and safety are not threatened.

5.  On November 4, delta DOR passes were performed over DSS-14/63 and
DSS-14/43.  Initial results indicate the one of the two delta DOR passes were
successfully performed.

6.  On November 4, real-time commands were sent to verify the status of the
UVS microprocessor memory.  The memory readouts confirm that a bit flip is
still present in the same memory location.  Investigation into the cause of
the anomaly and actions to take are continuing.

7.  On November 5, real-time commands were sent to configure the System Fault
Protection (SFP) for the near Earth 2 operations.  Commanding was interrupted
for 1 hour 8 minutes due to a low power transmitter problem at DSS-63 (Madrid
70 meter antenna).  Commanding was then resumed and all command activities
completed.  Specifically, the Energetic Particle Detector (EPD) science
monitor was updated, thruster firing all clear response was enabled, and the
Plasma Wave (PWS) cold flag parameter was changed.

8.  The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 16DN to 17DN and now reads 17 DN (3.9 volts).
The DC measurement has changed significantly from 133 DN (15.6 volts) to
160 DN (18.9 volts) and now reads 137 DN (16.1 volts).  These measurement
variations are consistent with the model developed by the AC/DC special
anomaly team.

9.  The Spacecraft status as of November 5, 1992, is as follows:

       a)  System Power Margin -  82 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15 rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 7 degree
           off-sun (leading) and 8 degrees off-earth (lagging)
       e)  Downlink telemetry rate/antenna-7.68kbps (coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- UVS, DDS, MAG, EPD, and HIC are
           powered on
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 260 hours


GDS (Ground Data Systems):

1.  A Ground Data System Data Flow Test was conducted Tuesday, November 3
with the NIMS (Near Infrared Mapping Spectrometer) Processing Equipment (NPE)
following its relocation from 264-316 to 264-721.  The data flow test was
successful.  In addition, the 26 October Probe MRT (Mission Readiness Test)
post test analysis has been completed.  All test objective were met and the
test was considered successful.

2.  Since the start of 1200 bps telemetry operations last month, random
losses of data blocks have been noticed during Madrid passes.  The problem is
currently under investigation with resolution targeted by November 16th
before the start of the Probe Mission Sequence Test (MST) with the spacecraft
(November 20th).  Occurrences of the problem during the Madrid pass Thursday
were correlated with heavy communication loading including simultaneous passes
and VLBI (Very Long Baseline Interferometry) data replays.  The DSN (Deep
Space Network) is establishing procedures to monitor and minimize the
communication loads at Madrid during critical Earth 2 support.

TRAJECTORY

     As of noon Thursday, November 5, 1992, the Galileo Spacecraft trajectory
status was as follows:

    Distance from Earth         27,366,500 km (.18 AU)
    Distance from Sun           174,661,900 km (1.17 AU)
    Heliocentric Speed           111,600 km per hour
    Distance from Jupiter        944,473,000 km
    Round Trip Light Time        3 minutes, 0 seconds

SPECIAL TOPIC

1.  As of November 5, 1992, a total of 8636 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3659  were initiated in the
sequence design process and 4977 initiated in the real-time command process.
In the past week, 52 real time commands were transmitted: 46 were initiated in
the sequence design process and 6 initiated in the real time command process.
In addition, 5911 mini-sequence commands have been transmitted since March
1991; 3753 were pre-planned and 2158 were not.  In the past week, no
mini-sequence commands were transmitted.  Major command activities this week
included commands to reset the command loss timer, switch to 7.68 coded
telemetry data, perform memory readouts of the UVS instrument, and update
system fault protection for near Earth 2 operations.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Give people a second
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | chance, but not a third.
|_____|/  |_|/       |_____|/                     |

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

Date: Thu, 5 Nov 1992 20:11:36 GMT
From: Frank Crary <[e-mail]>
Subject: Gloveless in Vacuum? (was Re: Man in space ... )
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>The reason I'm writing, instead of just allowing the discussion to
>peter out, is to mention that a suggestion of Hermann Oberth's:
>Astronauts might wear spacesuits without gloves for delicate work!

>He reasoned that your skin can stand up to low pressure without major
>medical problems, so maybe you could work without pressure gloves in
>space.

>Now, here's Henry...
>==================
>    HOW LONG CAN A HUMAN LIVE UNPROTECTED IN SPACE

>    Various minor problems (sunburn, possibly "the bends", certainly some
>    [mild, reversible, painless] swelling of skin and underlying tissue)
>    start after ten seconds or so.

The sort of swelling refered to is more severe, if one's lungs (and therefore
blood vessels) are at atmospheric pressure. Exposing one's bare hands to zero
pressure wouldn't _kill_ anyone, but it would still cause alot of minor
damage.

                                                      Frank Crary
                                                      CU Boulder

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

Date: Fri, 6 Nov 92 21:31:20 EST
From: John Roberts <[e-mail]>
Subject: HST

-From: [e-mail]
-Subject: Re: Hubble's mirror  or Really Costar.
-Date: 6 Nov 92 16:56:38 GMT
-Organization: Space Telescope Science Institute

-...Interestingly, we use the Earth as a flat field source
-all the time with the FGS's paused.  WFPC doesn't mind a bit.

-Also, we don't close the aperture door under normal operations.  It only
-closes in a deep safe mode.

I gather from this that earthlight doesn't damage the sensors - it's just
too bright for the gathering of useful information. That's impressive -
sunlight on clouds is pretty bright.

That also answers my question on what HST does when its view is eclipsed
by the Earth - it just stops collecting data, and the aperture door doesn't
have to close.

-As for an annoying problem, the South Atlantic Anomaly and flapping of
-the solar arrays give a lot more headaches around here than solar avoidance.

--Bill Gawne,  Space Telescope Science Institute

Do you know whether replacement of the onboard computer with a more powerful
model is scheduled for the upcoming service mission?

John Roberts
[e-mail]

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

Date: 6 Nov 92 21:51:23 GMT
From: "Stick,CommoSigop" <[e-mail]>
Subject: Hubble's mirror
Newsgroups: sci.astro,sci.space

In <[e-mail]> [e-mail] (Gerard M. Foley) writes:

>[e-mail] (Donald H. Locker) writes:

>> Now that I know a little about mirror-making, I'd like to hear again
>> how the Hubble mirror contractor messed up the figure of the main
>> mirror.  I understand it has spherical aberration, but wonder how
>> [Rockwell?] managed to do that.
>>
>It wasn't Rockwell (I forget axactly who it was, but it was an
>otherwise reputable New England outfit) and put briefly, they
>fouled up the test, performing it incorrectly, and never
>checked by any independent method.

   According to Dr. Steve Maran, who works on the HST project at the
Goddard Flight Center, and who was recently a guest lecturer at my college,
none of the above is true.  The company that ground the mirror did it
exactly to the specs they were given.

   The specs were wrong.

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

Date: Sat, 7 Nov 1992 08:58:11 GMT
From: Ron Baalke <[e-mail]>
Subject: JPL GIF Images Available
Newsgroups: sci.space,sci.astro,alt.sci.planetary

                         ==========================
                               JPL GIF IMAGES
                              November 6, 1992
                         ==========================

     I've placed seven JPL-related GIF images at the Ames site.  These
images are courtesy of the Public Information Office at JPL.  The images
are available using anonymous ftp:

        ftp:      ames.arc.nasa.gov (128.102.18.3)
        user:     anonymous
        cd:       pub/SPACE/GIF
        files:
                  earthmoo.gif - Parting view of the Earth and Moon taken by
                                 Voyager 1 shortly after launch in 1977.
                  gllhga.gif   - Galileo's backup High Gain Antenna (HGA) at
                                 JPL.
                  hrms.gif     - Opening ceremony for HRMS (High Resolution
                                 Microwave Survey), formerly SETI, at
                                 Goldstone, California.  70 meter antenna
                                 shown in background.  October 12, 1992.
                  hrms.txt     - Caption file for hrms.gif.
                  jpl.gif      - Aerial photo of the Jet Propulsion Lab (1988).
                  mo.gif       - Mars Observer spacecraft in clean room in
                                 Florida being prepared for launch (1992).
                  molaunch.gif - Mars Observer launch from Cape Canaveral,
                                 Florida - Sept 25, 1992.
                  topex.gif    - Topex/Poseidon launch from French Guiana -
                                 August 10, 1992.

                                 #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Give people a second
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | chance, but not a third.
|_____|/  |_|/       |_____|/                     |

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

Date: Thu, 5 Nov 1992 20:28:45 GMT
From: Frank Crary <[e-mail]>
Subject: Man in space ... )
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Andrew Haveland-Robinson) writes:
>I would guess that space suits and space biosphere pressures are
>substantially less than trophospheric pressure ~ 5 psi?

I believe the current suits are 4.7psi pure oxygen. However, the
current goal of suit design is to raise the pressure to 8.5 psi,
without increasing the stiffness of the joints (e.g. without
making them even more awkard to work in...) That would eliminate
the need to "pre-breath" pure oxygen for hours, before getting
into the suit. Currently, this proceedure is required to avoid
the bends...

>With an oxygen enriched supply, and spacesuits at 5psi, naked hands in space
>should be quite feasible.

I don't think so: One's blood vessels are at the same pressure as
one's lungs. There would be 5psi of pressure across the walls of
blood vessels. I'm fairly sure some would rupture. It wouldn't
kill you, but it's bad enough to avoid if possible... (By the way,
this isn't a problem in the case of sudden decompression, because the
lungs and therefore the blood vessels are also at zero pressure...)

                                               Frank Crary
                                               CU Boulder

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

Date: Fri, 6 Nov 92 22:23:58 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Marsquakes...

The article Ron Baalke posted talked about magnitude
five and six and whatever quakes happening on Mars...

Is that the Ricter scale or something else?


--
Phil Fraering

We'll not fade out too soon
Not in this finest hour
Whistle your favorite tune

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

Date: Fri, 6 Nov 92 20:46:11 EST
From: John Roberts <[e-mail]>
Subject: Mascons

-From: [e-mail] (Gary Coffman)
-Subject: Re: NASA Coverup
-Date: 6 Nov 92 16:49:19 GMT
-Organization: Gannett Technologies Group

-In article <[e-mail]> [e-mail] writes:
->   Beiser states , on page 118 , "A spherical object behaves  gravitationally
->   as  if  it's  mass  were concentrated at it's center" . He also states,on
             ----                             ----

Beiser doesn't have a very good proofreader, does he? :-)

->   page 119, that  the  earth's  gravitational  pull  on  an  object  varies
->   inversely  with the square of it's distance FROM THE CENTER OF THE EARTH.
->   I also assume that a similar rule applies to the moon.

-It doesn't even apply to the Earth. One of the things learned from early
-satellite launches is that the Earth, and to an even greater extent the
-Moon, have what are called mascons, mass concentrations. These are unevenly
-distributed areas of higher density inside the body. Beiser's assumption
-holds up as a close approximation when the two bodies are far enough
-apart that their radius is an insignificant part of their separation
-distance, say Earth-Sun distance. But they fail miserably when the
-separation is less than a few body radiuses. The mascons will warp the
-orbit of the satellite a measurable amount.

The moon has both positive (filled crater) and negative (unfilled crater)
surface mascons that perturb its gravitational field to such an extent that
an object in low lunar orbit is essentially guaranteed to crash into the
moon fairly quickly. The Earth, being a geologically active planet, is in
isostatic equillibrium, so that an object in even a 200-mile circular orbit
will retain pretty much the same orbit until atmospheric drag gets it. The

Lageos satellites (one just launched on the latest Shuttle mission), orbiting
at about one Earth radius above the surface, are expected to remain there
for about eight *million* years (and being passive reflectors, they should
continue to be usable "indefinitely"). The Earth does have an equatorial
bulge (mentioned later in your post), which is caused by the rotation of the
planet, which I believe has the main effect of perturbing the ascending node
of high-inclination orbits. This is what makes sun synchronous orbits
possible, and since Mars Observer is scheduled to take up a sun synchronous
orbit, I presume Mars has a similar equatorial bulge.

-The existance of tides is a direct result of the effect
-of differentials in gravitational potential across the diameter of a
-body. Using Beiser's simplifing assumption, there could be no tides on
-Earth. Since we can easily observe that there are, his assumption is
-invalid for bodies as close together as the Earth and the Moon.

That's a little bit misleading - a point-source moon would still cause
tides on the Earth. I don't have any idea whether the fact that the moon
is a distributed mass has any significant influence on the magnitude of the
tides.

John Roberts
[e-mail]

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

Date: Fri, 6 Nov 92 22:11:39 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Nasa Coverup

Dale Amon and Paul Dietz:


da> I mentioned Paul Dietz: he is part of our community here, and is a
da> very respected part of it at that. If he is not busy with life outside
da> of cyberspace, I'm sure he could address what you have said, and far
da> better than most of us. If he is listening in now, it is up to him.

pd>Oh, good grief.  This snarfy person is either a leg-puller or a
pd>clueless, paranoid buffoon.  I am surprised Henry made even one reply.
pd>The suggestion that Apollo was faked is just too much for any sane,
pd>moderately informed person to believe.

pd>    Paul

Sorry, Dr. Dietz. We were tricked by the fact that he didn't
overuse ALL of those UPPER CASE letters, and therefore we simply
WEREN'T SURE that he WAS or WASN'T CRAZY.

Then again, maybe he as emacs set up to automatically convert the
all UPPER CASE letters to all LOWER CASE. I've FORGOTTEN the command
myself.

--
Phil Fraering

We'll not fade out too soon
Not in this finest hour
Whistle your favorite tune

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

Date: 6 Nov 92 20:41:01 GMT
From: Henry Ptasinski <[e-mail]>
Subject: NASA Coverup
Newsgroups: sci.space

> [e-mail] writes:
> >   [garbage erased]
>
> >   equipment  in the the backpack. While a Scuba diver's dual tanks weigh in
> >   at about 80 pounds and are designed to aid the diver in  sinking  to  the
> >   bottom

Scuba tanks are NOT designed to "aid the diver in sinking".  Most tanks are
actually negatively bouyant in salt water, especially when not completely full.
Thus they actually aid the diver in floating to the surface (even if that isn't
what he wants to do at the time).  The weight of the tanks is due to the amount
of material necessary to contain air at pressures of over 3000 psi without a
catastrophic failure.

I'm sorry I missed the original post.  There's just not enough to laugh about
on the net lately.

Henry P.
[e-mail]

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

Date: Fri, 6 Nov 92 20:58:58 EST
From: John Roberts <[e-mail]>
Subject: Slush Hydrogen

-From: [e-mail] (Jordin Kare)
-Subject: Re: Slush Hydrogen
-Date: 6 Nov 92 18:50:17 GMT
-Organization: LLNL

->What exactly is "slush hydrogen?"

-    It's the stuff that covers the sidewalks after a
-snowstorm on Jupiter :-)

No, it's an undocumented fuel reserve that can be used for covert and
unauthorized maneuvers (like retrieving an astronaut who was clowning
around in the Shuttle bay and lost his grip, and not telling anybody
about it. :-)

John Roberts
[e-mail]

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

End of Space Digest Volume 15 : Issue 390
------------------------------