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Subject: SPACE Digest V11 #424

SPACE Digest                                     Volume 11 : Issue 424

Today's Topics:
             Re: Surface of Venus
            Re: Terraforming Venus
  What Voyagers are up to (long)(was Re: Voyager Update - 05/08/90)
         Astronomical Image Processor[D[Ding
             Re: Shuttle Designs
            Re: Voyager Update - 05/08/90
----------------------------------------------------------------------

Date: 18 May 90 20:30:06 GMT
From: mcgill-vision!quiche!calvin![e-mail]  (Mark SOKOLOWSKI)
Subject: Re: Surface of Venus

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>Why do you assume the surface of Venus is free of impact craters? I agree the
>thick atmosphere would tend to stop the smaller meteors, but the really big
>ones (i.e. ~1km or more) that go through Earth's oceans pretty much as though
>there were nothing there should have even less trouble blasting the surface of
>Venus. Given the low wind speed, uniform temperatures, and lack of
>precipitation on the surface, I would assume that weathering is very slow
>at best.
>
>In any event, the beauty (if any) of the surface of Venus is the presence of
>bare, broken rock. If you make the surface rougher, you increase the surface
>area, so aren't you by definition increasing the beauty? :-)

Your assumptions are OK, but don't forget that there aren't so many large
meteorites. The Earth has eroded craters too, but they aren't overlapping
themselves. About the beauty of the surface, it should be obvious:
Impenetrable and mysterious cloud cover from which tens of lightnings
emerge each second, incredible sound levels, some wind which sustain some
dusty turbulences.
Some recent hypotheses stipulate that the surface is traversed by subtle
wave patterns analogous to the ones that can be seen on the floor of some
shallow pool. Isn't it beautiful??? And note too that in a photo contest
at McGill, a picture of a desert with the same kind of wave pattern (but
static, though) was chosen as the best one.

Mark S.
-------

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

Date: Fri, 18 May 90 17:30:54 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Terraforming Venus


>From: zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!sendai![e-mail]  (Matthew Yow Ming KWAN)
>Subject: Re: Terraforming Venus (was: Manned mission to Venus)

>How about putting a "rocket" like this on Venus. There are several
>advantages :

>Let's assume Venus' atmosphere makes up 1/10,000th of its total mass.
>If you can accelerate it to (say) 10% lightspeed you'll give Venus
>a delta V of ~3,000 m/s. Maybe that's unreasonable, but you could
>surely at least induce rotation.

>Now for the tricky bit - designing the rocket. I don't think it's
>feasible to build a rocket that stretches all the way from ground level
>into space

If you can afford everything else, a 1000-mile-long rocket is a trivial
expense.

>Powering the rocket. The only way I can think of is some kind of fusion
>ramjet,

That would be your major problem. I don't think fusing the heavier elements
would be useful, at least for the power density you need. I calculate that
the project would require about 2.1E35 Joules - equivalent to the total
power output of the sun for about 17 years (!)

(Even if you could tap all the solar output, somebody would probably complain
before the end of the first decade. :-)

>Personally I'd use Venus as a toxic waste dump or an environmental
>testbed (just what is the effect of a gigaton bomb on a planet? would
>a nuclear winter really occur? etc). Too much effort to terraform.

That's the problem. Anything you have that might help to terraform Venus
is much more useful for some other application. The planet might be handy
as a source of carbon. There's also a lot of thermal energy there that could
possibly be tapped.
               John Roberts
               [e-mail]

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

Date:     Fri, 18 May 90 05:50 CST
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject:  What Voyagers are up to (long)(was Re: Voyager Update - 05/08/90)
Original_To:  SPACE

(Sorry this is kinda long, but I hope some will find it worth reading.)
Lance Michel (rochester!rit!cci632![e-mail]) fumes:

>If there is still interest in specific objects or areas, why don't we know
>what's being looked at?  What bothers me the most is that once the fanfair
>of a big encounter is over everybody forgets about the whole project.
>Engineers stop talking, and Reporters stop reporting... It seems like
>a waste of good "PR" for NASA to stop talking.

Gee whiz, Lance, it's not a secret.  JPL's Public Information Office kicks out
Voyager status reports pretty regularly, and Ron Baalke is kind enough to post
'em to Space Digest/sci.space.  If you have been reading them, you know what's
been going on.  I'll bet any taxpayer who desparately needed to know what the
Voyagers were up to could request that these reports be mailed to him or her.
But, let's face it, most of these things are pretty dull if you're not involved
with the mission.  (I like 'em because they give a little feel for what
day-to-day operation of a spacecraft is like.)  It's clearly not true that the
engineers have "stopped talking."

Now that all the planets on the Voyagers' itinerary have been passed, some of
their instruments are essentially useless.  The imaging and infrared
spectroscopy gadgets have nothing close enough or bright enough to look at
anymore.  As a one-time stunt (I almost said "one-shot," but then remembered
it's a mosaic (-:), Voyager 1 snapped the "family portrait" showing the bodies
of the Solar System as little dots.  Data are back on the ground, and we oughta
see the result any week now.  The final frame of the portrait showed the Sun,
and in taking it solar heat may have damaged the shutter of one camera
permanently.  That's okay-- Voyager 1 will never need that camera again.
(Barring flying saucer visits.)  If there is a scientific purpose to the family
portrait, I'm not aware of it.  But it's a nice thing to have.

Other instruments aboard continue to gather interesting information, which is
what JPL means by "routine cruise science."  The particles-and-fields stuff
reports on the environment at the edge of the solar system; examples include
the Plasma Wave System, the Magnetometer, and Low Energy Charged Particle
instrument.  As the plutonium in the generators decays and power runs low in
the years to come, instruments and their heaters will be shut off, starting
with the cameras.  But the Voyager gang hopes to hit the heliopause-- the
boundary between the solar wind and the interstellar wind-- in the next decade
or two.  So they'll need as many of the P&F experiments  running as they can
manage.

One special case is the Ultraviolet Spectrometer (UVS), which sits on the scan
platform with the cameras and the infrared spectrometer.  Its primary purpose
is for looking at ultraviolet emission and absorption lines in the atmospheres
of planets.  It is sensitive to wavelengths in the "extreme ultraviolet,"
between 500 and 1700 angstroms.

Now, it happens that not much astronomy has been done in these wavelengths.
The galaxy has clouds of interstellar hydrogen.  A "Lyman alpha" photon (912
angstroms, 13.6 electron volts) has enough energy to ionize neutral hydrogen.
Any photon of wavelength *shorter* than this runs the risk of bumping into a
hydrogen atom and getting absorbed as it knocks the electron loose.  Now, there
is not much hydrogen in interstellar space.  There's a lot of room between
hydrogen atoms.  But over trillions upon trillions of kilometers, the hydrogen
adds up.  Beyond a few light-years, it's hard to see any light with really
short wavelengths, because it gets absorbed in the interstellar hydrogen before
it gets to us.

Consequently, the ultraviolet telescopes that have flown in space, such as the
International Ultraviolet Explorer, have not been given the capability to see
extreme ultraviolet (EUV) colors.  But the sky isn't as opaque as people
thought;  you can see *some* distance into space in the EUV, and there is
interesting physics going on in nearby stars, especially extremely hot ones.

The Voyager UVS instruments are the only currently flying which can make
measurements in the EUV.  They are small, and their spectral resolution is only
about 100 angstroms, but they have lots of leisure time to make long exposures
these days.  So there's an ongoing program to use the UVS to study a series of
stellar targets, which, I imagine, will continue as long as they have the power
to operate them.  I'd speculate that the Voyager studies are valuable
precursors for planning such missions as the STS-35 ASTRO observatory, carrying
the Hopkins Ultraviolet Telescope, and the Extreme Ultraviolet Explorer, which
will make an all-sky survey.

  In recent months, according to the Voyager status reports, the following
targets have been studies with the UVS instruments of the two spacecraft:

MU Centauri
HD 206165
EG165
PKS2155-304
Markarian 509
HD 212571
NGC 7027
HD 164284
HD 217675
HD 200120
HD 120324
HD 164284

(Maybe one of our astronomer friends can explain these catalog designations?)

So you see, Lance, NASA hasn't exactly clammed up about Voyager's activities
since the Neptune encounter.  You don't read about them in your local newspaper
because they're pretty technical and routine.  The same is true for Fermilab--
we only call a press conference when we've got something novel to announce, not
when we've completed the fifteenth week of a fixed-target run with 122 hours of
beam time...  You can be sure that if Voyager scientists come up with something
juicy from all this raw data, the JPL or NASA public-information people will be
quick to issue a press release on it.

                      ______meson   Bill Higgins
                   _-~
     ____________-~______neutrino   Fermi National Accelerator Laboratory
   -   -         ~-_
 /       \          ~----- proton   Bitnet: [e-mail]
 |       |
 \       /                          SPAN/Hepnet/Physnet: 43011::HIGGINS
   -   -
     ~                              Internet: [e-mail]

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

Date: 18 May 90 02:41:04 GMT
From: bywater!scifi!paladin![e-mail]  (Carmine Nicoletta)
Subject: Astronomical Image Processor[D[Ding

Sometime ago I found an article in BYTE magazine that described some
techniques for astronomical image processing.  It appeared on the DEC 1987
issue of BYTE.  There was an editor's note that the assembly source code was
available on BIX, on BYTEnet.  Does anybody have access to the referred
network??  I would be very interested in getting a copy of the source code
listing.  Please E-mail to [e-mail] (Carmine Nicoletta).

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

Date: Fri, 18 May 90 14:04:26 CDT
From: [e-mail]
Subject: Re: Shuttle Designs

> agate!agate![e-mail]  (William Baxter)

> In article <[e-mail]> [e-mail] writes:
>
> >> agate![e-mail]  (William Baxter)
>
> >> >Fact 1:  The Shuttle is significantly bigger and has much more
> >> >delta-v capacity than the original design.
>
> >> The original 'design' was not well defined.  It was, for the most
> >> part, a set of promises about performance. (e.g. $100/lb to LEO,
> >> fully reusable)
>
> >> Comparing apples and hypothetical oranges is irrelevant.  What's the
> >> total launch cost of the 'original design,' and what is the unit cost
> >> per kilo?  How much will it cost to build?  How does the maintenance
> >> schedule differ from that of the existing Shuttle?
>
> >I certainly don't have those figures handy, ...
> >but having some idea of what sort of
> >detail goes into any kind of proprosal to a government agency, I
> >have no doubt that there are at least first cut estimates of a lot of
> >those things.
>
> This is a statement of faith, not of fact, and doesn't address the
> questions.

I trust you're now willing to accept that such studies were done now
that people who have seen some of the wind-tunnel test articles have
spoken up and the detailed evolution from there to what we got has
bee posted?

Or do you prefer not to cloud the issue with facts?

[As I said, you should take your own advice about finding out the
facts before posting to the net.]

> >So is it your contention, Mr. Baxter, that nothing that was said
> >until after the first hardware was flying matters?  I thought that
> >the thing that everyone was so upset about was the difference
> >between "promises" and what got delivered.
>
> Had the promises been based on the detailed design which you claim
> existed, it is unlikely that they would have been so wildly inaccurate.

Really?  Why is it so unlikely, given that what they built wasn't
the same system that those initial promises were based on?

> >[Drivel about my perversion of his signature]
>
> Are you really unable to make a single posting without all the noise?

Are you?  You're like a man who starts raving into a canyon and then
gets upset at the echo and starts ranting about that.  The solution,
Mr. Baxter, isn't to try to shout down the echo or insist that the
canyon should be changed or is wrong.

The solution, if you don't like the echo, is to stop your raving and
shouting.  If you care to engage in reasonable and polite
conversation, that's what you'll get back.  If you choose to
continue to behave the way you have been, I'll continue to flame
you.  Actually, the latter is easier, since it requires much less
time and thought; perhaps why it seems to be your mode of choice.

[And if you're simply complaining about the *presence* of several
lines of signature, that's of a piece with your prior complaints
about grammar.  It's pretty obvious why you choose those kind of
things to snipe at, given that you apparently can't be bothered to
ascertain the facts of the issue and so can hardly argue against
that.]

> William Baxter
>
> ARPA: web@{garnet,brahms,math}.Berkeley.EDU
> UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web
> --
> William Baxter
>
> ARPA: web@{garnet,brahms,math}.Berkeley.EDU
> UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web
>

Hmm, seems like even if he only did it once it's not that much
shorter than mine, so I guess he couldn't have been complaining
about length.

==============================================================================
| Fred McCall  ([e-mail]) | "Insisting on perfect safety is for  |
| Advanced Systems Division           |  people who don't have the balls to  |
| Defense Systems & Electronics Group |  live in the real world."            |
| Texas Instruments, Inc.             |                     -- Mary Shafer   |
+-------------------------------------+--------------------------------------+
|  I speak for me.  I don't speak for others, and they don't speak for me.   |
==============================================================================

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

Date: 18 May 90 20:03:08 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: Voyager Update - 05/08/90

In article <[e-mail]> [e-mail] (Craig Milo Rogers) writes:
>
>    The sad part is, often these observations are not received
>on Earth due to insufficient Deep Space Network resources.  Who
>establishes the DSN schedule amd bumps low-priority observations?
>Any comments from JPL?
>
Some of the data is commanded to be sent back even though it is known well in
advance that there will be no DSN support to receive the data.  Keep in mind
that the data is recorded on Voyager's tape recorders and is not really lost,
and can be retrieved later.  Also, since the Voyagers are so far away, they
send the commands anyway on the remote chance that maybe the DSN time will
become available.
       _   _____    _
      | | |  __ \  | |       Ron Baalke           |  [e-mail]
      | | | |__) | | |       Jet Propulsion Lab   |  [e-mail]
   ___| | |  ___/  | |___    M/S 301-355          |
  |_____| |_|      |_____|   Pasadena, CA 91109   |

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

End of SPACE Digest V11 #424
*******************