Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_342.TXT

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Subject: SPACE Digest V11 #342

SPACE Digest                                     Volume 11 : Issue 342

Today's Topics:
               Re: Galileo entry probe
            Re: Re: Fermi paradox
          Navstar GPS Status Reports on WWV and WWVH
               Re: Galileo entry probe
             I need an engineer.
        Re: Navstar GPS Status Reports on WWV and WWVH
             Re: Hubble Telescope
          Radiation Effects on Spacecraft Computers
          (How to get rid of) space garbage
           Satellite Dish Recommendations?
   Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow)
----------------------------------------------------------------------

Date: Tue  1 May 90 12:43:23-PST
From: Jay Glass <[e-mail]>
Subject: Re: Galileo entry probe
Mail-System-Version: <VAX-MM(228)+TOPSLIB(132)+PONY(228)@PLUTO.ARC.NASA.GOV>

>Does the Galileo probe that is going to enter the Jovian atmosphere
>have a camera on board? What other sensors are present?

The Galileo probe doesn't have a camera, but the orbiter does. There are
six instruments on board the probe, each with one or more sensors. Rather than
list pages of specifications on the net, interested parties can request
a technical brochure from:

Benny Chin, Manager, Galileo Probe Operations
Mail Stop 244-19, NASA-Ames Research Center, Moffett Field, CA 94035-1000

or email to [e-mail]  .

Incidentally, I couldn't find Mary Shafer *anywhere* Sunday morning...when
asked where the Usenet RDV was, her boss looked blank...

Jay Glass
[e-mail]
-------
-------


-------

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

Date: Tue, 1 May 90 20:16:33 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Re: Fermi paradox


>From: usc!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
>Subject: Re: Fermi paradox

>   No, I think you can say that the probability that there is exactly
>one life-bearing planet in the universe is no more than 1/e.
>   Assume that the probability that a given star will harbour one
>life-bearing planet is some value r where r << 1.
>   Now, what is the probability that out of N stars, exactly one will be
>life-bearing? It's:   P(1) = choose(N,1) * r * (1 -  r)^(N-1).
>   Apply the familiar calculus techniques to find the maximum value of
>this function for 0 <= r <= 1. It turns out that the critical value
>which maximizes P(1) is r = 1/N. For this value of r, P(1) = 1/e,
>assuming that N is very large. For any other value of r, P(1) < 1/e.
>Hence, the probability that there is exactly one life-bearing planet in
>the universe is no greater than 1/e, or about 37%.

I think at best you're overanalyzing the situation. The 1/N principle is
very common in probability analysis. (If you have three cows, of a breed in
which the chances of the animal being white are one in three, how many of
the cows would you expect to be white? - and so on.) What we're looking for
is a conditional probability - if we know A, B, and C, what is the probability
that D is true. For the presence of life on other planets, we know so little
about the conditions that trying to assign a probability at this point is
little more than number-pushing.

There are a number of logical fallacies or weaknesses in many of the estimates
of life elsewhere. One of the most common is the assumption that the earth is
representative of conditions elsewhere. We say, "Well, we're here, so it stands
to reason that that there must be other folks somewhere else." The problem
with this is that it makes no allowance for the calculated probability (as
seen at some point in the distant past) of our coming into existance. It
could have been only by a very slim chance that life developed on Earth. If
we were't here, we wouldn't be able to speculate. (This concept is very
difficult to express - maybe someone else can do a better job?)

Another fallacy is that the universe is large - it is by most standards, but
not by the laws of probability. One rough estimate is that the observable
universe has about a hundred billion galaxies of about a hundred billion
stars each. Which is greater - the number of stars in this volume, or the
number of possible ways to shuffle a deck of 52 cards? It's the cards. (In
fact, if every one of those stars had a planet with a billion people shuffling
cards for a billion years, it's still very unlikely that any specific sequence
would come up.) If the odds of life developing around an average star are
comparable to the odds of shuffling a deck of cards into a specific sequence,
then it's wildly improbable that life would develop anywhere. The fact that
we're here *could* be a case in which the wildly improbable happened (or it
could be due to divine intervention - there's currently no way to determine
this objectively :-).

It is often assumed that given the right environmental conditions, it is
highly probable that life will arise within a few billion years. That could
be correct - there's no way to tell with what we know now. While we're just
beginning to understand the mechanisms of life, there are at least two things
that can be said with considerable confidence - all the organisms we've looked
at which fully fit our definition of independent life are *extremely* complex,
and there is as yet *no* completely described sequence of events that would
lead to the spontaneous formation of living organisms as we know them from
nonliving matter. Thus we really can't say what the odds are. In fact, it has
been speculated that the chances could be so slim that that the unlikely
possibility that life came to Earth from somewhere else in the galaxy would
still give better odds than local development.

My opinion is that given our current level of knowledge, calculating the
probability of life elsewhere may provide useful insights, but that's about
all.
        John Roberts
        [e-mail]

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

Date:        Tue, 01 May 90 11:21:36 ADT
From: [e-mail]
Subject:     Navstar GPS Status Reports on WWV and WWVH

National Institute of Standards and Technology time signal radio        00000100
stations WWV and WWVH transmit brief reports on the status of the       00000110
Navstar Global Positioning System.  These reports are prepared by the   00000200
U.S. Coast Guard's Omega Navigation Systems Center (ONSCEN) in          00000300
Alexandria, VA.  The broadcast from WWV is at 15 minutes past each hour.00000400
A brief description of GPS is given in the preceding minute.  The       00000500
broadcast from WWVH is at 44 minutes past each hour with the            00000600
introduction during the preceding minute.  The broadcasts are updated   00000700
nominally once a day.                                                   00000800
                                                                        00000900
WWV, Fort Collins, CO, transmits continuously on 2.5, 5, 10, 15, and 20 00001000
MHz.  WWVH, Kauai, Hawaii, transmits continuously on 2.5, 5, 10, and 15 00001010
MHz.  Only a simple shortwave receiver is needed to pick up these       00001100
broadcasts.                                                             00001110
                                                                        00001200
Both stations also transmit solar activity and geomagnetic field reports00001300
as well as Omega navigation system status reports and weather.  The     00001400
"program" schedule for WWV and WWVH is as follows:                      00001500
                                                                        00001600
WWV                                                                     00001700
H:08  North Atlantic weather                                            00001800
H:09  North Atlantic weather cont'd.                                    00001900
H:10  East Pacific weather                                              00002000
H:14  GPS message introduction                                          00002100
H:15  GPS status report                                                 00002200
H:16  Omega status report                                               00002300
H:18  Solar activity / geomagnetic field report                         00002400
                                                                        00002500
WWVH                                                                    00002600
H:43  GPS message introduction                                          00002700
H:44  GPS status report                                                 00002800
H:45  Solar activity / geomagnetic field report                         00002900
H:47  Omega status report                                               00003000
H:48  Pacific weather                                                   00003100
H:49  Pacific weather cont'd.                                           00003200
H:50  Pacific weather cont'd.                                           00003300
H:51  Pacific weather cont'd.                                           00003400

================================================================================
 Richard B. Langley                            BITnet: [e-mail] or [e-mail]
 Geodetic Research Laboratory                  Phone:  [phone]
 Dept. of Surveying Engineering                Telex:  014-46202
 University of New Brunswick                   FAX:    [phone]
 Fredericton, N.B., Canada  E3B 5A3
================================================================================

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

Date: 1 May 90 16:17:13 GMT
From: news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Galileo entry probe

In article <[e-mail]> [e-mail] (alan pengelly) writes:
> Does the Galileo probe that is going to enter the Jovian atmosphere
>have a camera on board? What other sensors are present?

There's no camera on the probe, as I recall, just an assortment of
atmospheric instruments.  (Sorry, I don't have a list handy.)  Pity.
--
If OSI is the answer, what is |     Henry Spencer at U of Toronto Zoology
the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry [e-mail]

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

Date:       Tue, 01 May 90 13:10:31 EST
From: [e-mail]
Subject:    I need an engineer.

     I am doing some research for a program that I am going to write as a
(potential) graduate project in computer science. I am wrting a game
*blush* that takes place in the near future, and I want to make it as
realistic as possible. (within certain limits)

     I therefore would like to talk with an indulgent aero engineer about
various space-related topics. (esp. power sources, drive systems, and
weapons) I'd use our library for this, but all the books I can find are
either too simplistic, or are 4000 page journals written in technospeak
that I (as a poor helpless computer science student :) ) can't understand.

    If someone out there would like to help me, or could point me in the
direction of some good documentation, please respond to me E-mail.

ALSO: I need a starmap of the local area of the galaxy (local = nearest 50
stars or so) as seen from an observer from "above" (ie if the orbital plane
of the earth is on the x,y plane, with the sun at the origin, the observer
would be at the point (0,0,n) with n large enough to see about 50 stars or
so) I have never seen a map of this sort- all the maps I can find are of
the earthbound-observer variety.

Thanks in advance,
                       Dennis Grant
                       CMR, Quebec, Canada
                       Comp Sci 92
                       [e-mail]

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

Date: 1 May 90 07:11:35 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Navstar GPS Status Reports on WWV and WWVH

In article <[e-mail]> [e-mail] writes:
>National Institute of Standards and Technology time signal radio        000100
>stations WWV and WWVH transmit brief reports on the status of the       000110
>Navstar Global Positioning System.  These reports are prepared by the   000200
    . . .
>H:49  Pacific weather cont'd.                                           003200
>H:50  Pacific weather cont'd.                                           003300
>H:51  Pacific weather cont'd.                                           003400

On reading this, I had the most overwhelming urge to //PUNCH it out,
pick up the deck, drop it it on the floor, collect the cards, stick them
in the card sorter and admire the results!  Ahh, for the good old days!

I'll be back in my cave -- Hollerith you need anything.

--
The genius of you Americans is that you never make   **  Tom Neff
any clear-cut stupid moves, only complicated stupid  **  [e-mail]
moves that leave us scratching our heads wondering
if we might possibly have missed something. -- Gamel Abdel Nasser

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

Date: 1 May 90 18:08:43 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: Hubble Telescope

In article <[e-mail]> [e-mail] (Russ Tillman) writes:
>Viewing the 1969-70's lunar sites with the Hubble would be a great PR tool to
>display it capabilities to the common non-scientist person (aka taxpayer).
>Most people know how far the moon is from earth but not many can relate to the
>Hubble view the edge of the universe so hit em up on it capabilities with
>something they understand.  I remember back in the 70's, that while enroute to
>Jupiter, Pioneer took a picture of both the earth and the moon in the same
>frame.  A picture like that get's people thinking!
>

There are a couple of space movies planned mainly to be used for PR purposes.
When Galileo transmits back its Venus science data this November, the images
will be put together to form a movie of Venus.  In December, 1992, when
Galileo makes it 2nd earth flyby, it will takes pictures of the Earth/Moon
every 20 minutes, which also be put together to form a movie.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |    Go Lakers!

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

Date: 1 May 90 21:07:40 GMT
From: shlump.nac.dec.com!renoir.dec.com![e-mail]
Subject: Radiation Effects on Spacecraft Computers


        The following message is from Hema Murty, who is currently
    unable to post to USENET.  Please send all messages to her.
    Thank you. - Larry Klaes

                                #############

        Can anyone give me references or information on how radiation from
    the Van Allen Radiation belts surrounding Earth affects computers on
    spacecraft which spend a long time in that region of space?  There
    must have been studies done on previous missions, yet all I am able
    to find so far are the ALOUETTE results from the 1960s.

        Thank you very much for your help.

        Hema Sandhyarani Murty, Institute for Aerospace Studies,
                                University of Toronto

        Reply-To: [e-mail] (Hema Murty)
                  [e-mail]

        Organization: Engineering Computing Facility, University of Toronto

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

Date: 1 May 90 23:55:35 GMT
From: thorin!homer![e-mail]  (Jonathan Leech)
Subject: (How to get rid of) space garbage


    In light of the current 'life of HST' discussion, maybe we could
talk about ways to get rid of orbital debris.  First off the wall
suggestion: use high-powered lasers to accelerate decay from the
Poynting-Robinson effect.  If this thread takes off, I'll run some
numbers on this suggestion.
--
    Jon Leech ([e-mail])    __@/
    ``Thus Mathematics helps / our brains and hands and feet
      and can make / a race of supermen out of us.''
    - The Education of T. C. Mits

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

Date: 2 May 90 02:22:10 GMT
From: sam.cs.cmu.edu![e-mail]  (Vincent Cate)
Subject: Satellite Dish Recommendations?


Our cable TV costs us $21/month (no movie channels).  My personal line of
credit account only needs payments $23 for every $1,000 owed.  If I could
get a dish for $1,000 it would cost me about as much per month as cable.
I am willing to pay much more than this for a dish, since the payments
will not go on forever.  Also, I could turn around and sell the dish later
to get back some of this money.  Another thing is that cable will probably
cost me more than $21/month if I am still getting it next year.  Anyway,
I am very interested in buying a satellite dish to pick up TV signals.

What should I look for?

Can anyone recommend a good one?

Any that I should avoid?

Is Radio Shack's 9 foot dish for $2,000 a reasonable deal?  (it can move
from satellite to satellite)

Are there still plenty of unscrambled channels?  Is this going to
continue to be the case?  Is there something like HBO or Showtime
that is unscrambled?

Can I get plenty of channels with a dish that does not move or do I
need to get one that can switch from satellite to satellite?  What
are the price ranges for each?

Thanks for any info,

   -- Vince

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

Date: 2 May 90 02:39:17 GMT
From: zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!uluru6![e-mail]  (Daniel Ake CAROSONE)
Subject: Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow)

In article <[e-mail]>, [e-mail] (Clive Feather) writes:
> In article <[e-mail]> [e-mail] (Steven P Coltrin) writes:
[Talking about the inertialess drive being neutrino-reaction drive]
> >because the exhaust is thrown where it cannot be seen.  (Though in _The
> >Ringworld Engineers_ it is revealed that ships using thrusters can be tracked
> >by their neutrino exhaust.)

> But in "Flatlander" an Outsider ship accelerates Beowulf and Elephant to 0.9c
> in a matter of minutes. This can't be a simple reaction drive; it has to act
> on the occupants as well as the ship, or they'd be squashed.

Indeed. Having made the awful blunder recently of forgeting that drives need
a power supply, I am now qualified to say that the neutrino exhaust in question
would come from the fusion plant that powers the ship.

> I always assumed that man had reinvented the drive. Beowulf seemed to think
> that the price was too high, and anyway, knowing it can be done is 90% of the
> battle.

Interesting thought, It has been so long since I read most of the books that
I cannot remember the details at all.

I disagree that knowing it can be done makes the rest trivial. What happened
to "Success is 1% inspiration, 99% perspiration."?

Knowing it can be done makes it a hell of a lot easier to convince yourself
that it is not impossible (!!) but does not really help much more. Knowing
roughly *how* it is done is of much more use.

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

End of SPACE Digest V11 #342
*******************