Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_3/V15NO355.TXT

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Date: Thu, 29 Oct 92 05:02:52
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #355
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 29 Oct 92       Volume 15 : Issue 355

Today's Topics:
                                <None>
        active planetary probes; should someone update the FAQ
              Alternate nets? (was Re: planetary motion)
                     Amber (Was: Re: Population)
                       another sad anniversary
                      Clinton and Space Funding
                             DCX Status?
                   Galileo High Gain Antenna Update
                      Info on Nasa X-20 project
                 Mariner Mark II vs smaller missions
                         NASA shakeup rumor?
                PLANETLIKE OBJECT SPOTTED BEYOND PLUTO
         Seeking Correlation of Solar Activity to S/C Events
                             Solar Sails
                   Space and Presidential Politics
                Swift-Tuttle Comet a threat to earth?
             Toutatis impact in 2000 AD? (was Re: Help !)

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

Date: Fri, 23 Oct 1992 02:47:11 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: <None>
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (David B. Snyder) writes:
> In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>>It worked, too.  Southerners put us on the Moon.  I don't think
>>Yankees could have done it in eight years.
>
> At Lewis there is a persistant rumor that they could not have done it
> without some help from North of the Mason-Dixon line.  Unfortunately
> I don't remember the details.  Was it something about fuel type? or
> something about restarting engines in free-fall?  |-)

I suppose I owe the Clevelanders an apology (apollogy?) for my glib
overstatement.  Heck, I'm a Great Lakes boy myself.  Yes, there were a
lot of Yankees involved.  But when the days of Apollo are recounted,
one hears a remarkable number of Southern accents (including the mixed
German-Alabama accents).

Bill Higgins                           | Every so often, Innumeracy
Fermi National Accelerator Laboratory  | strikes.  Out of all Americans,
Bitnet:     [e-mail]        | a lot suffer from it.  But
Internet:  [e-mail]       | we can win the fight against
SPAN/Hepnet:      43011::HIGGINS       | Innumeracy with your help.
                                       | All it takes is a few pennies a day.

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

Date: 28 Oct 92 22:23:18 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: active planetary probes; should someone update the FAQ
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>There is also DSPSE (Deep Space Project Science Experiment) to be launched
>in Jan 94...it will do 2.5 phasing loops about the Earth and enter Lunar
>orbit on or about 21 Feb 94.

Cool.  Is this a funded mission, or just a proposed one?  Where will it launch
from and what launcher will be used?

Mike

--
Michael Kent                                   [e-mail]
McDonnell Douglas                              Rensselaer Polytechnic Institute

Tute Screwed Aero Class of '92                              Apple II Forever !!

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

Date: 23 Oct 92 03:52:25 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Alternate nets? (was Re: planetary motion)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Jordin Kare) writes:
> In article <[e-mail]> [e-mail] writes:
>>hi i'm an aerosapce engineer at Penn State (not a good field to be in now) and
>>in my senior year design class we are sending a pair of probes to the Phobos
>>and Deimos ...
>
> Obviously a message from the distant future.  Or perhaps an alternate
> timeline....

Jordin, you may have hit on an explanation for various recent Usenet
problems!

Perhaps Mr. Robert "Gravity-NEUTRALIZING Spacecraft" McElwaine is
writing LEGITIMATE sci.space postings-- but from an ALTERNATE Eau
Claire.

Or the Federationers are posting from an alternate Alaska, where they
still have nobility ("Lady" Rhavyn) and you can find a molecular-beam
epitaxy setup in every Kinko's.

No wonder these people seem perplexed by *our* reality.

(I think Jordin and I live in the same one... I mean, I've seen him in
mine... or was that an alternate Jordin?)

Where I come from, we need machines a little bigger than a 51-cm
crystal to tickle the Strong Nuclear Force.  And counter-rotating
discs hardly ever neutralize gravity.  Your mileage may vary.

     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
 /       \                          (_) (_)                    / | \
 |       |     Bill Higgins   Fermi National Accelerator Laboratory
 \       /     Bitnet:     [e-mail]
   -   -       Internet:  [e-mail]
     ~         SPAN/Hepnet:      43011::HIGGINS

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

Date: 1 Oct 92 11:35:46 GMT
From: Ron Baalke <[e-mail]>
Subject: Amber (Was: Re: Population)
Newsgroups: sci.space,sci.geo.geology

In article <[e-mail]>, [e-mail] (John Roberts) writes...
>-From: [e-mail] (Doug Mohney)
>-I suppose we should next try to restore the dinosaurs to the prominance they
>-had a couple million years ago?
>
>That's a *little* beyond our current capability. I believe the current
>(and recent) record for DNA extraction is ~25 million years, for a termite
>trapped in amber. Reconstructing the entire genetic code from DNA fragments
>and using that code to produce a living organism are additional challenges.
>
>I'd like to see the restoration of the wooly mammoth. With frozen tissue
>available, there's a pretty good chance that they could be cloned.

The basic premise of the book "Jurassic Park" is that dinosaurs were brought
out of extinction by extracting their DNA from mosquitos preserved in amber
which had the dinosaur's blood still in them.  Real interesting book, and I
believe it is being made into a movie.

The termite that the DNA was extracted from was Dominican amber, which is
dated to be in the Oligocene period.  So, this makes the insect to be
25 to 36 million years old.  If they can extract DNA from Dominican amber,
they'll be able to extract it from even older amber.

There are other critters that have been trapped in amber besides insects
that potentially can have their DNA extracted.  For example, I have a
piece of Dominican amber with a lizard tail in it, and an African amber
(20 million years old) with about 15 strands of hair of an unidentified
mammal.  Complete frogs have also been found in amber.

While I would very much like to keep this discussion going, I don't think it is
appropriate for sci.space, and I have temporarily cross posted this
article to sci.geo.geology.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Quiet people aren't the
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | only ones who don't say
|_____|/  |_|/       |_____|/                     | much.

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

Date: 1 Oct 92 02:19:15 GMT
From: Scott Fisher <[e-mail]>
Subject: another sad anniversary
Newsgroups: sci.space

[e-mail] (Ron Baalke) writes:

>May 15, 1993 may mark another sad anniversary.  That's when Magellan is
>scheduled to be turned off.  It will be the first time that NASA has turned
>off a functioning spacecraft.  NASA has recently communicated to JPL that
>this will still happen.  The reason is similiar, to save money.

How do you save money by turning off a spacecraft or an instrument on the moon,
is someone charging for the bandwith they take up in the electromagnetic
spectrum? :-)  I can understand that there may nolonger be funding to
operate the craft/instruments but who cares if it is sending back a stream
of data that nobody is listening to?  Why not get some amatures/groups
around the world to take on the projects?

Regards Scott.
_______________________________________________________________________________
Scott Fisher [[e-mail]]  PH: Aus [61] Perth (09) Local (380 3272).
                                                             _--_|\       N
Department of Psychology                                    /      \    W + E
University of Western Australia.                 Perth -->  *_.--._/      S
Nedlands, 6009.  PERTH, W.A.                                      v

Joy is a Jaguar XJ-6 with a flat battery, a blown oil seal and an unsympathetic wife, 9km outside of a small remote town, 3:15am on a cold wet winters morning.
-------------------------------------------------------------------------------

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

Date: 1 Oct 92 03:30:31 GMT
From: Jeff Privette <[e-mail]>
Subject: Clinton and Space Funding
Newsgroups: talk.politics.space,sci.space

In article <[e-mail]>, [e-mail] (Gary Coffman) writes:

|> vacuum. The Democrat Congress dominates where, when, and how much is
|> spent on various programs. They have a 50 year track record of ignoring
|> Presidential budgets and doing as they please.

Then vote out your Congress members.  Don't use your fear of Congress
to justify keeping fresh ideas and leadership out of the White House.
Bush is perpetuating this "fear" vote and you seem to have bitten.  (check
your history by the way.  In many of the last 12 years Congress has spent
*less* than the President proposed in his budget.)

  A Democrat in the White
|> House has a slightly better chance of getting some of his programs
|> enacted, but only at the cost of rubber stamping a lot of other programs
|> demanded by Congress.

Only slightly better than Bush's chance?  You are deceiving yourself (or
listening to campaign pitches too much).  Even Reagan was more successful
with Congress, but that is because he *worked* with Congress to pass his
agenda.  Most conservative writers that I've read readily admit disappointment
in Bush's neglect of pressuring/working/leading/bargaining with Congress
to pursue his agenda.  No wonder Congress views Bush as weak and goes on
as it wishes.  As the leading moderate voice in the Democratic Party for the
last 10 years, Clinton can expect more success I believe at leading
Congress and even enjoy some support from moderate conservatives.  Wouldn't
that be a nice change: seeing the cogs of government begin turning again (you
will pay their salaries whether this happens or not...).  In the last 4
years, we have only seen the Federal government get mired down and basically
not work for anybody, anywhere  (except, arguably, for the richest 1%).
That is the biggest tragedy of all.

|> Many of the leading economists say that the US would already be well
|> into recovery if it weren't for the massive tax hike that Congress
|> wrangled out of Bush.

Yea, right.  ...and an across the board 1% tax reduction will also
solve our problems.  The problems facing the US are much more complex
than that, and such gimmicks -- used by both candidates -- will do nothing.
What we need are fresh, comprehensive plans to deal with such things
as welfare reform, health care, etc.  Clinton has an established record
of experimenting with new approaches to such problems.  Not all have worked;
many have.  While trying these pilot programs in Arkansas, he has balanced
the budget 12 straight years.  Change can happen in a fiscally responsible
manner, but you have to be willing to trust that change can happen for
the good and not vote on fear.  If you simply lack any such trust, then
you should move.

How much bigger will
|> the deficit be in four years?

You seem to forget it was Reagan who tripled the national debt, not Carter
or even Bush.  In this decade of fiscal concern -- heightened by the S&L
debacle and the House Bank scandel that spurred a postwar record of incumbant
primary losses -- Clinton can kiss '96 goodbye and the Democrats can kiss the
next 20 years goodbye if he presides over foolish spending.  But this is a
party working to redefine itself from the Kennedy style of liberalism and
certainly it is led by a more moderate voice (witness, for instance, Clinton's
lukewarm reception of the labor union endorsement or his support of capital
punishment or his desire for welfare reform).  Your arguments against
Kennedy, Johnson and Carter are understandable yet show your ignorance of
Clinton's idealogy and record.

International affairs is the major province
|> of the President, and there Bush's record is much better.

Sure it is.  And Carter had much more international experience
than Reagan did in '80.  But that did not preclude Reagan from international
leadership.

 Do you
|> believe Clinton can do better than an experienced leader like Bush
|> with his military and spook experience?

I'm not sure what you mean by "spook experience."  If you are referring to
Clinton's opposition to the Vietnam War, I must say I think the bigger
coward was Quayle who *supported* the War but wouldn't subject himself to it.
As unethical at it may seem, history shows the US government subjectively preferred sending high school dropouts and minorities to the war before
Rhodes Scholars.  That is simply the bare truth of the matter.  As for
future leadership, every President surrounds himself with knowledgeable
professionals (incl. the Joint Chiefs of Staff) to help insure military
decisions are well thought out.  Obviously, armed service experience does not
ensure intelligent leadership, and certainly the lack of service does not
preclude it.  Did Margaret Thatcher serve in the Royal Armed Forces?
Was she an international leader?  Obviously.  Your argument here is weak.

For fun, you should read the current issue of Newsweek where Schwartzkopf (sp?).
Basically says that the Persian Gulf war would have been easier if Bush
had just handed over the task to the professional servicemen (and
women) and then stayed out of it.  Perhaps a little knowledge is the more
dangerous thing! :)

-Jeff

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

Date: Fri, 23 Oct 1992 05:34:48 GMT
From: Henry Spencer <[e-mail]>
Subject: DCX Status?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Simon E. Booth) writes:
>The DCX (Delta Clipper, right??) wouldn't neet government launch facilities,
>so what would the launch pads and servicing facilities for the DCX be like??

Well, DC-X is a demonstrator only.  The question is really, I assume, about
DC-Y or DC-1.

It will need a launch stand -- the landing gear can support the landing
(empty) weight but not the much larger takeoff (full) weight.  Some stuff
for noise suppression might be needed as part of that.  It will need
tank trucks for supplying it with fairly large amounts of liquid oxygen
and liquid hydrogen.  It will need whatever facilities the payloads want.
It will need a tow truck, and possibly a dolly of some kind, to move it
from its landing point to the launch stand.  It might need a special
truck or two with facilities for flushing out its tanks after landing.
It will need a special truck or two, vaguely similar to those used for
airliners, to provide access to its payload bay (well above the ground).
And it will need, probably, either noise-tolerant neighbors or an area
a couple of kilometers across (my guess) with no neighbors.

That's all it will *need*.  The biggest question regarding safety is
which rules will apply:  those appropriate to an airliner carrying a
similar amount of fuel, or those used for a missile carrying a similar
amount of fuel.

>And would it be limited to overwater launching as are done with existing
>facilities?? ...

Once testing has established safety and fault-tolerance of the basic design,
there is no fundamental reason to require over-water launching.  The big
question, again, is will sensible rules prevail, or will the ones developed
for ammunition be imposed on testable, fault-tolerant spaceships?
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 29 Oct 92 08:00:03 GMT
From: Ron Baalke <[e-mail]>
Subject: Galileo High Gain Antenna Update
Newsgroups: sci.space,sci.astro,alt.sci.planetary

From "The Galileo Messenger"
September 1992
By Bill O'Neil, Galileo Project Manager

     In just a few months, on December 8, 1992, Galileo will complete the VEEGA
(Venus-Earth-Earth gravity assist) phase of its trajectory to Jupiter.  EGA2,
(Earth Gravity Assist #2) on December 8, will boost Galileo into its three-year,
direct, Earth-to-Jupiter heliocentric transfer orbit.  EGA2 is a very
significant milestone.  And, once again, we are looking forward to some
spectacular observations of the Moon and Earth.

     We have not yet succeeded in freeing the stuck ribs of the High Gain
Antenna (HGA).  Fortunately, the most aggressive actions by far are still
ahead of us.  The thermal cycling of the HGA by warming and cooling turns
to "stroke" the HGA central tower to try to walk the stuck locating pins out
of their receptacles was abandoned in July after the seventh cycle.  Performing
seven cycles without even one rib releasing demonstrated that this technique
cannot free the ribs -- either the parameters are too adverse or the pin-
walking model does not adequately represent what is restraining the ribs.

     It is well to remember that, due to thermal contraction, the HGA was not
at assembly dimensions at the April 1991 deploy attempt [this was when the
first deployment of the HGA was attempted] or at any time since then.  Three
weeks after EGA2, in the last week of December, we will have the first
opportunity to restore the HGA to assembly dimensions.  Galileo will be 1.0
AU from the Sun, where a warming turn will expand the tower to assembly
length for the first time.  While considered unlikely, it is possible that
this action alone will free the ribs.

     "Hammering" the deployment system is our very best prospect to free the
ribs.  While performing investigative testing on the flight spare HGA at JPL
early this year, it was discovered that pulsing the deploy motors rotated
the deployment ballscrew substantially beyond its continuous run stall point.
Following the extension of the tower, we will hammer the ballscrew as far as
it will rotate by pulsing the motors.  During the April 1991 deploy attempt,
the ballscrew stalled at 5.1 turns.  Our recent ground tests and motor pulse
test on the spacecraft indicate we can advance the ballscrew 1.5 turns by
a combination of running the motors continuously at warm temperatures
(windup) followed by about 1000 pulses.  This will double the force in the
highest loaded rib deploy pushrod.  There is a good chance that before
reaching the new hammer stall point, the rising force in the pushrod will
overcome the rib restraint and pop the rib free.  The dynamic effect on the
deployment mechanism of this rib springing out could free the other ribs.
If this "zipper" action does not occur, then we will resume hammering the
now softer system.  This will increase the force in the remaining stuck rib
pushrods by several factors.  The hammering technique has the prospect of
actually yielding (permanently deforming) any stuck pins and receptacle
surfaces.

     While the prospects of freeing the HGA by the above method are good, we
must be prepared for the possibility that the ribs will remain stuck.  Earlier
this year, the Project, in conjunction with the Telecommunications and Data
Acquisition (TDA) organization at JPL, studied how to maximize the mission
return over the Low Gain Antenna (LGA).  We have always known we could perform
the atmospheric entry Probe mission and put the Orbiter into Jupiter orbit
without the HGA.  The challenge was to return Orbiter science, particularly
imaging, over the LGA.  The joint Galileo and TDA study determined that
improvements in the Deep Space Network (DSN) antennas and arraying of
antennas in conjunction with data compression onboard the Galileo spacecraft
would enable the return of a tape recorder load of data each Jupiter orbit.
Each tape load could contain 200 to 400 images, as well as data from all the
other lower rate instruments.  So, in our primary 10-orbit mission, we
could return 2000 to 4000 images.  Most of these would be the highest
resolution satellite images that have always been a very special feature
of the Galileo mission.  Field and particles data would be returned nearly
continuously at low rates.  Our overall estimated science return for the
LGA mission in percentages of the primary HGA mission breaks down as:
atmospheric science, 80%; satellite science, 70%; and magnetospheric
science, 60%.  NASA Headquarters has accepted our recommendation that we
proceed with the implementation of the LGA mission on March 1, 1993, if the
HGA is not deployed by then.  The implementation will include new DSN
hardware and software and major new flight software for the Galileo Command
and Data Subsystem (CDS) and Attitude and Articulation Control Subsystem
(AACS).  With or without the HGA, Galileo will be a spectacular mission
at Jupiter!

     Finally, I am very pleased that an excellent Jupiter satellite tour
was designed and selected on schedule, May 1, and, concomitant with the
selection, the Project recommended and NASA enthusiastically approved the
August 1993 asteroid Ida encounter.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | If God had wanted us to
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | have elections, he would
|_____|/  |_|/       |_____|/                     | have given us candidates.

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

Date: 23 Oct 92 02:40:58 GMT
From: Douglas R Fils <[e-mail]>
Subject: Info on Nasa X-20 project
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Mire) writes:
>Would like some info on X-20 project of late sixties if it is the basis for
>some of the developing projects in France, Japan and Germany for a winged
>spaceplane?
>
>----
>INET: [e-mail]      GEnie & America-Online: jmire

    I don't think the x-20 (built by Boeing and called the Dyna-Soar)
is the basis for either the HOPE or Sanger (sp) space planes that you
ask about.  However, if you are interested in the project the
best source bar none is the following:

The X-Planes X-1 to X-31
by Jay Miller
Orion Books
Published by Aerofax Inc. of Arlington Texas
published in 1988

Recall that the contract for the Dyna-Soar was in Dec 1959.  On a
personal note, I wish this had the path to orbit rather than the
mercury capsule.  Oh well.  I truely doubt you find a better source
for information on this (or most of the X-planes) than this book, it's
really that good.

take care
Doug

--

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

Date: Thu, 1 Oct 1992 01:21:35 GMT
From: Frank Crary <[e-mail]>
Subject: Mariner Mark II vs smaller missions
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>To be fair it should be noted that the failure of Galileo's antenna only
>jeopardizes part of the mission (the imaging which requires high bandwidth).

There are quite a few people here at CU Boulder involved in non-imaging
science on Galileo who would disagree. If NASA gave up on imaging
entirely, the rest of the mission could get by without problems. However,
they are going to record and slowly broadcast back as many images as
possible. This will have a substantial impact on non-imaging science.

(I'm saying this based on my interpertation of what others have said:
I haven't heard any official or public complaints about the lower
data rates available for non-imaging science, nor any suggestions
that NASA should dump imaging. Those are my own conclusions...)

>Also, if you didn't need a big antenna and a powerful battery on each
>sattelite for communications (because of the relay sattelite), you
>could conceiably make a sattelite much smallar and cheaper than the ones
>they are planning on flying by Pluto.

The Pluto mission isn't going to use a big antenna or a powerful transmitter:
They are planning on recording the flyby and playing the data back
slowly over a low-gain minimum-mass/power antenna.

                                                  Frank Crary
                                                  CU Boulder

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

Date: Wed, 28 Oct 92 22:01:25 EST
From: John Roberts <[e-mail]>
Subject: NASA shakeup rumor?

-From: [e-mail] (Allen W. Sherzer)
-Newsgroups: sci.space
-Subject: Re: nasa shake up rumor?
-Date: 26 Oct 92 19:31:42 GMT

-In article <1992Oct24.1604.15298@execnet> "tom betz" <[e-mail]> writes:
->To feed the rumor mill still further, rumor has it that Richard Truly is
->preparing, once Al Gore takes over for Dan Quayle, to take a White House
->position directing NASA.

-Which just goes to show that Gore has no interest in an effective space
-program.

The existence of a *rumor* proves this? This is an example of why sci.space
is an inappropriate format for detailed political analysis. Logic that's
considered quite satisfactory in politics doesn't come near the degree of
rigor that's expected for posts to sci.space. (Yes, I know illogic is

sometimes posted here, but it's generally promptly shot down in flaming
ruin.)

Speaking of NASA reorganization rumors, the author of a newspaper article
I read had the impression that Lennard Fisk has been taken off actual
science and put on technology transfer to industry. That's an important
job, and in theory the change is considered a promotion, but to me it seems
like somewhat of a waste of a scientist. A post here indicates that he's
been put on the design or administration of SSF. Any more substantial
rumors available? :-)

John Roberts
[e-mail]

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

Date: 1 Oct 92 02:40:38 GMT
From: Dave Tholen <[e-mail]>
Subject: PLANETLIKE OBJECT SPOTTED BEYOND PLUTO
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

> From "New Scientist", 26 September 1992:
> ICY OBJECT FOUND ORBITING BEYOND PLUTO
>   A long search for objects on the outer fringes of the Solar System
> has finally yielded results. American astronomers have found an object
> about 200 kilometres across beyond the most distant part of Pluto's
> orbit.

The most distant part of Pluto's orbit is about 49 AU.  1992 QB1's orbit
is currently computed to be about 41 AU in radius, with the eccentricity
indeterminate at this time.  I saw it last night, and it was about 1.2 arcsec
northwest of the ephemeris.  Not too bad.

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

Date: 1 Oct 92 06:31:52 GMT
From: frisbee <[e-mail]>
Subject: Seeking Correlation of Solar Activity to S/C Events
Newsgroups: sci.space

To Whom it May Concern,

    I am trying to correlate certain effects observed on an
active spacecraft with possible solar proton emissons. The events
occured at UTC 1992/274-02:54:31 and UTC 1992/275-03:33:22. Was there
a high degree of solar activity at these times?

        [e-mail]

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

Date: 28 Oct 92 22:50:08 GMT
From: Henry Spencer <[e-mail]>
Subject: Solar Sails
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brad Whitehurst) writes:
>    Well, I don't have any numbers, but don't forget the "solar
>wind" of particles streaming from the sun.  I would think it would
>have a significant contribution.

Usually trivial by comparison with the light pressure.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 1 Oct 92 03:48:43 GMT
From: Jay Denebeim <[e-mail]>
Subject: Space and Presidential Politics
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes:

> I also think Dan Goldin is possibly NASA's last hope. It would be the
> act of a low grade moron with the mental cabilities of an amoeba to
> replace him.

Oh no, isn't it Quayle who's the administration's pro-space person?
Does this mean Goldin is out?

> Which is why my (absentee) vote is for Marrou/Lord.
They'll get my vote too.

--

 |_o_o|\\
 |. o.| || The           Jay Denebeim
 | .  | ||  Software
 | o  | ||   Distillery
 |    |//        Address: UUCP:     duke!wolves!deepthot!jay
 ======                   Internet: [e-mail]
         If the above bounces try: uunet.uu.net!oichq!deepthot!jay
                 BBS:(919)-460-7430      VOICE:(919)-460-6934

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

Date: 29 Oct 92 00:01:33 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Swift-Tuttle Comet a threat to earth?
Newsgroups: sci.astro,sci.space

[e-mail] (Steinn Sigurdsson) writes:

>In article <[e-mail]> [e-mail] (Thorsten Altenkirch) writes:

>   I understand that it is pretty unlikely that Swift-Tuttle will hit
>   earth in 2126. However, I would like to know what would happen in the
>   case such a big object would collide with our planet? I am not sure

>You die, I die, Everybody dies!

Said in a monotone of course :-)

>   whether my memory is right but in the discussion about the
>   disappearance of the dinosaurs an object of a size like 200m was
>   mentioned. Now, Swift-Tuttle is supposed to be much bigger (10 km?)...

>Nah,  P/Swift-Tuttle is barely a dinosaur killer with
>worst case diameter estimates - if you assume low albedo
>it is 10 km across, likely it is a little smaller,
>not quite enough to kill 50%+ of species, more of
>a civilization killer and 10% extinction (of species,
>higher fraction of individuals would die).

You're the astronomer, so you may have taken this into account in your
estimates, but it's important to remeber that as a comet, S/T has a much lower
mass and is much more fragile than a similarly sized asteroid.  As such, it's
much less dangerous than an asteroid of the same size.
--
Josh Hopkins                                          [e-mail]

"We can lick gravity, but the paperwork's a bit tougher."  Wernher von Braun

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

Date: 1 Oct 92 02:36:04 GMT
From: Dave Tholen <[e-mail]>
Subject: Toutatis impact in 2000 AD? (was Re: Help !)
Newsgroups: sci.space

Bill Higgins writes:

> I am sure that by the time the Decmber 1992 encounter has happened,
> the uncertainties in Totatis's future position will shrink
> considerably.  Then we will know whether we should start panicking or
> forget about the whole thing.

Why wait?  We already know it isn't going to hit in 2000.  We do know it
will pass 0.011 AU in 2004.

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End of Space Digest Volume 15 : Issue 355
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