Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V10_0/V10_014.ZIP/V10_014

Internet Message Format | 1991-07-08 | 17KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from corsica.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/oYztpPe00UkVIMIU50>;
          Sat,  2 Sep 89 05:29:00 -0400 (EDT)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Sat,  2 Sep 89 05:27:42 -0400 (EDT)
Subject: SPACE Digest V10 #14

SPACE Digest                                      Volume 10 : Issue 14

Today's Topics:
             Re: Books about Space Flight
          Spacecraft error in TIME magazine.
            Re: Voyager Color Pics
             Re: Voyager: Tape recorder?
               Voyager & Star Parallax
    Re: Voyager & Star Parallax (using for astro platform)
               Voyager Factoid
            Re: Direct Information
         NASA Headline News for 08/28/89 (Forwarded)
           Re: RTG's and nuclear reactors.
             Re: Neptune on the Boobtube
----------------------------------------------------------------------

Date: 28 Aug 89 17:13:01 GMT
From: [e-mail]  (Jon Jacky)
Subject: Re: Books about Space Flight

Nick Watkins ([e-mail]) asks:

> I am interested in hearing suggestions of books that have good critical
> examinations of manned Space Flight

I recommend THE HEAVENS AND THE EARTH: A POLITICAL HISTORY OF OUTER SPACE, by
James McDougal.  This book won the Pulitzer prize for history in 1986.

Its emphasis is not particularly on manned spaceflight, although of course
that is treated, too.  McDougal (or MacDougal - I don't have the book handy
at the moment) admits in the preface he isn't a space buff, he is an academic
historian  whose real interest seems to be the relations of science and
politics.  However, the book is certainly not a stuffy bit of scholarship, it
is beautifully written.  McDougal takes the long view, the story begins
with the assassination of a Czar in the late 19th century!  Also, the book
only goes up through Apollo - the events of the last 20 years are mentioned
only very briefly in a postscript.

MacDougal's theme is that the huge resources required by the space programs
in the US and USSR resulted in those nations building organizations of
unprecedented scale and complexity.   He notes that these large centrally-
controlled technology projects were actually better suited to the Soviet
political system than the Western, which is one reason why the Soviets got
their program off the ground rapidly while the Americans dithered through the
50's.

MacDougal provides much entertaining material about the post-Sputnik panic in
the US, in particular how the Democrats, especially Lyndon Johnson, used the
Sputniks to beat poor old Eisenhower about the head.  MacDougal is really more
sympathetic to Ike --- he agrees that the Democrats overemphasized the
significance of the Sputniks, and notes that the US space program
legitimatized large-scale federal technology projects, and federal influence
in science, technology, and education --- which Eisenhower tended to distrust.

MacDougal also discusses the almost mystic sense of transcendance with which
many people regard space exploration, a feeling MacDougal does not share.

Whether or not you agree with MacDougal, the book
is well worth reading.  It's crammed with history and anecdotes, particularly
about the Soviet space program, that are difficult to find elsewhere.

- Jon Jacky, University of Washington

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

Date: 28 Aug 89 20:38:50 GMT
From: wrksys.dec.com![e-mail]  (CUP/ASG, MLO5-2/G1 6A, 223-3283)
Subject: Spacecraft error in TIME magazine.


        The latest issue of TIME magazine made one glaring error in its
    article on the VOYAGER 2 encounter of Neptune:  The spacecraft model
    they showed is of the GALILEO probe to Jupiter, not VOYAGER.

        I also noted that NEWSWEEK made the VOYAGER encounter its cover
    story and devoted seven pages to the mission, whereas TIME has the
    Rolling Stones as their cover story, and only gave VOYAGER four pages.

        Larry Klaes  [e-mail]
             or - ...!decwrl!wrksys.dec.com!klaes
                 or - [e-mail]

        EJASA Editor, Astronomical Society of the Atlantic

             N = R*fgfpneflfifaL

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

Date: 29 Aug 89 01:37:46 GMT
From: [e-mail]  (RAMontante)
Subject: Re: Voyager Color Pics

[partial disclaimer:  my responses are second-hand from the astronomers
in our "audience"...]

[e-mail] (Phil R. Karn) <[e-mail]> :
-
-the wide angle camera. FILTER is self-explanatory; if you see the same
-scene taken several times with different filters, you can be reasonably
-sure that a color separation is being taken and you'll eventually be
-able to see this scene as a color image. EXP is the exposure time in

The different filters are not primarily to produce color separations;
they are used because different frequency bands carry qualitatively
different information.  Witness the filter named "methane", and "violet"
which is really near-uv.  Some of the information will eventually be
displayed in false-color, of course.  Real-color views are something of
a side-benefit, as they don't convey much hard information compared to
well-chosen narrow bands.  Although it is nice to see a pink moon...


-that the image compression software developed for Uranus is also being
-used here, so only 3 bits per pixel are actually required. At a 21.6 kb/s
-downlink rate it would therefore take about a minute and a half to send
-each compressed picture if the entire downlink capacity is used.

Somebody said that they thought only some images were being compressed,
as identified in one of the fields in the right bottom.  Why, I don't know.


-particularly interested in knowing the meaning of the IHA EMA and PHA
-figures; they appear to be pointing angles of various kinds.

(I don't think these are exactly the abbreviations, e.g. INA...)  INA
and EMA, or whatever they were, describe some angles between solar
illumination, target, and ???  PHA was the angle between Sun, target,
and camera (Voyager).  I.e., when PHA was 7.5, the Sun was almost
directly "behind" Voyager --- viz., most of the shots during the
approach.  The last shot of Neptune and Triton would've had a Phase
Angle of nearly 180; I remember a cross-system shot of some ring pieces
with a PHA of about 135.

I didn't get much out of the other two angles, (like "understanding"...)
but PHA helped me visualize more or less what was being photographed
much of the time.  It also helped that they threw a diagram of the
craft's path on an overhead next to the projection TV, for reference.

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

Date: 28 Aug 89 19:14:44 GMT
From: philmtl!philabs!briar.philips.com![e-mail]  (Robert Casey;6282;3.57;$0201)
Subject: Re: Voyager: Tape recorder?

In article <[e-mail]> [e-mail] writes:
>I keep hearing of data being spooled to the tape recorder for later
>transmission to earth.  Surely they don't use a conventional mag.
>tape drive.

From what I remember seeing, they *do* use magnetic tape to record and store
info.  Don't know how the spacecraft designers delt with problems related to
the very low temperatures that the spacecraft must find itself at (heaters?).
Or what to do when the heads get dirty.  Though these sorts of problems can't
be that hard to answer.

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

Date: 27 Aug 89 17:13:52 GMT
From: zephyr.ens.tek.com!tektronix!psueea!parsely!agora![e-mail]  (Rick Coates)
Subject: Voyager & Star Parallax

While watching the NASA feed at the 'time' of closest approach (it's kind
of fun to actually experience spacetime effects - what is 'simultaneous'?)
- good commentor, BTW, I never thought about the difficulties of navigating
something that far away - the chief navigator mentioned that by using
long exposures Voyager can image stars down to tenth magnitude (for
navigation purposes).

Now, just a little while ago someone asked about putting a telescope in
orbit way out to study star parallax.  Why not use images from Voyager?
It's not its primary mission, but they should work.  I realize that the
craft is in no way set up to do whole sky surveys, but even a few images
might be helpful.  The navigator also said that they could resolve images
to sub-pixel precision - would this be good enough?

If it worked, Voyager could spend part of its retirement taking pix of
stars - a nice, quiet occupation.

Just a thought -



Rick Coates
Consulting H/W - S/W engineer
(Graphics - Sun - Unix - ASIC design - imbedded systems)

...!tektronix!reed!percival!agora!rickc

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

Date: 28 Aug 89 17:39:38 GMT
From: [e-mail]  (Eugene Miya)
Subject: Re: Voyager & Star Parallax (using for astro platform)

There are several reasons why Voyager would not make a good
astronomy platform.

1) the spacecraft has a normal wobble which does not make it a stable
platform for astronomy.  You can see this on images of exposures
greater than 1 minute.  Stars not only blurr, but jump around.

2) There is nothing to be seen where Voyager 2 is which can't
already be seen from Earth using bigger instruments (better).
(Stellar distances, Earth-Voyager distances are trivial).

3) Even the simplest video observations would take resources
disproportionate to other projects.  Magellan (which I also worked on)
has huge communications bandwidth requirements.  The Deep Space Network
has to be configured for this mission.

Another gross generalization from

--eugene miya, NASA Ames Research Center, [e-mail]
  resident cynic at the Rock of Ages Home for Retired Hackers:
  "You trust the `reply' command with all those different mailers out there?"
  "If my mail does not reach you, please accept my apology."
  {ncar,decwrl,hplabs,uunet}!ames!eugene
                  Live free or die.

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

Date: 28 Aug 89 16:38:50 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Voyager Factoid

For the signature seekers among you:

    $10 million = 48.7 Voyager-days (Vd).

--
"We walked on the moon --    ((    Tom Neff
    you be polite"         ))     [e-mail]

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

Date: 29 Aug 89 01:02:40 GMT
From: [e-mail]  (RAMontante)
Subject: Re: Direct Information

[e-mail] (Tom Neff) <[e-mail]> :
-
-Actually the NRAO has a 1200bps dialup service transmitting Coordinated
-Universal Time (CUT) once per second.  That electronic service could be
-said to be uncolored by opinion.  Everything else is tainted. :-)

Considering how badly tainted my wristwatch, alarm clock, PC realtime
clock, and school wall clocks all are, I'd be very interested in knowing
the phone number of that dialup service.

Any help?  Usage instructions, etc.?  (I'd say "Thanks in advance", but
I can't get a consensus vote on when "advance" occurs.)

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

Date: 28 Aug 89 16:33:45 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 08/28/89 (Forwarded)


-----------------------------------------------------------------
                           NASA Headline News
Monday, August 28, 1989                       Audio: 202-755-1788
-----------------------------------------------------------------

This is NASA Headline News for Monday, August 28.......

Information gathered from Voyager 2 over the weekend indicates
that up to five rings may encircle Neptune.  The rings are seen
as thinly scattered dust particles.  Program scientists also
revealed that Uranus has a magnetic field whose poles tilt at
least fifty degrees relative to the axis around which it rotates,
rather than the thirty degrees reported earlier.   Other data
indicates that the planet's giant storm, "The Great Dark Spot,"
has winds up to 760 miles-per-hour.

Dr. Laurence Soderblom of the U.S. Geological Survey speculated
in a press conference yesterday that the dark spots and streaks
seen along the polar region of the Neptune moon, Triton, may be
active volanoes.  Dr. Soderblom suggested that these potential
volcanoes may be shooting plumes of liquid nitrogen twenty miles
into Triton's atmosphere.  If these findings are confirmed,
Triton will become only the third body in the solar system,
behind Earth and the Jupiter moon Io, known to have active
volcanoes.

The first commercial rocket to ever carry a satellite into Earth
orbit was launched from Cape Canaveral Air Force Station
yesterday at 6:59 p.m. Eastern time.  A British Broadcasting
satellite was lofted into orbit by a Delta rocket, which was
built and launched by the McDonnell Douglas Space Systems Company
of Huntington Beach, California.

Major portions of the STS-34 Shuttle interface test were
completed yesterday, and the Space Shuttle Atlantis is slated to
be moved from the Kennedy Space Center's vehicle assembly
Building to Launch Pad 39-B at midnight tonight.  The principal
payload of STS-34, the Jupiter-bound Galileo spacecraft, is
slated to be placed inside Atlantis' payload bay later this week.

                    *           *            *





---------------------------------------------------------------
Here's the broadcast schedule for public affairs events on NASA
Select TV. All times are Eastern.......
---------------------------------------------------------------

Monday, August 28 through Tuesday, August 29....


Comprehensive coverage of Voyager's encounter with Neptune
continues today with NASA Select coverage from noon to 9 P.M.  A
press conference is scheduled for 1 P.M. today.
NASA Select coverage for tuesday begins at 6:30 A.M. with the
rollout of atlantis to Launch Pad 39-B.  Rollout coverage will
end at 8 A.M.
Tuesday will also be the last day of coverage for the VOyager
encounter with Neptune.  Coverage begins at noon, and the
mission's final press conference is scheduled to begin at 1 P.M.
Voyager's coverage concludes at the end of the press conference.
Transponder 13 on Satcom F2R and Transponder 21 on Aurora 1.

All events and times are subject to change without notice.

---------------------------------------------------------------
These reports are filed daily Monday through Friday at 12 noon,
Eastern time.
---------------------------------------------------------------

A service of the Internal Communications Branch (LPC), NASA
Headquarters.

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

Date: 28 Aug 89 17:35:39 GMT
From: crdgw1!minerva![e-mail]  (B. S. Oplinger)
Subject: Re: RTG's and nuclear reactors.

In article <[e-mail]> [e-mail] (Rikhit Arora) writes:
>In response to my original queries regarding Galileo's RTG's, Henry
>mentioned that one should get rid of RTG's altogether and switch to
>nuclear reactors.  Well, what exactly is an RTG then?  It *is* called
>a Radioisotope Thermoelectric Generator.  How much different is it
>from a genuine nuclear reactor?  And what technical difficulty
>prevents NASA from using a real nuclear reactor for these deep space
>probes?
>

I just checked with a friend who does reactor work for US gov't.
The nuclear reactions, decay, produce heat. In a reactor the heat
makes water warm, the warm water runs a turbine, the turbine
produces electricity. Just like a deisel (sp?) engine. Engine
turns turbine, eletric motors run locomotive. RTG use
thermocouples to produce electricity directly. Take two pieces of
metal, each in a semicircle ( and ), now connect them at the ends
to produce a circle. Put a wire at each junction. Place one end
near atomic source of heat. Electricity flows between hot and
cold side. No moving parts, little chance of 'break-down' etc.
Drawback is low current produced, plus is no excess weight.

Hope this answers the questions a number of people have.

Brian

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

Date: 27 Aug 89 19:17:00 GMT
From: usc!csun!fedeva!premise!mirror!frog![e-mail]  (John Woods)
Subject: Re: Neptune on the Boobtube

In article <[e-mail]>, [e-mail] (John Sparks) writes:
T> In article <44600002@primerd> [e-mail] writes:
V> Well I watched it. Just who were the dweebs that they had commenting? For the
 > most part they didn't know their head from their A[steroids].
"> At one point a caller asked what will happen to Voyager, where will it go
n> when it leaves the system.
e> The answer was that in 8,000 years it will fly by Barnard's Star, in 20,000
w> or so it will pass Proxima Centauri, and then the Oort cloud.
s> GACK!!! How bass-ackwards can you get?!!!
">
No, they're right -- the space aliens from Sirius will pick it up, gas it up
and recharge the RTG, and then wing it around Barnard's Star (or is that
Valeyard's Star...) in a gravity assist to send it back to us.

                :-)        I hope this isn't needed...

--
John Woods, Charles River Data Systems, Framingham MA 508-626-1101
...!decvax!frog!john, [e-mail], ...!mit-eddie!jfw, [e-mail]

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

End of SPACE Digest V10 #14
*******************