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Date: Fri, 23 Jun 89 05:16:48 -0400 (EDT)
Subject: SPACE Digest V9 #506

SPACE Digest                                      Volume 9 : Issue 506

Today's Topics:
         HST update - from the horse's mouth
             Military and Civilian Space
      Re: Ozone depletion, atmospheric models, and public policy
               RE: SPACE Digest V9 #494
      Re: Ozone depletion, atmospheric models, and public policy
          How does one subscribe to this...
             Re: Orbital queries
              Re: Chaotic orbits
              Re: Outer Space Committee
                  subscribe
----------------------------------------------------------------------

Date:     Sat, 17 Jun 89 22:00 EST
From: <[e-mail]>
Subject:  HST update - from the horse's mouth

     The following is amalgamated from my notes taken at the recent
(last week) American Astronomical Society meeting.  The talk was given by
A. Boggess from NASA/Goddard, and was an update on everything that is going
on with the Hubble Space telescope at this time.  My notes of the talk are
chicken scratches, so forgive any errors.

     The HST is set to launch March 26, 1990, but is actually ready to go at
any time before that.  As mentioned earlier, it is currently at Lockheed in
California and will be moved via an Air Force C5-A to Cape Kennedy.  Certain
final checks still need to be done before moving (and are currently in
progress).  These are:

     -  The cataloguing and closing off of all boxes on the HST.  (I guess
        that these are the accessible compartments on the outside of the
        HST.)  These will then not be opened again until the HST is in
        space, and then only if repair work need be done.  When this is
        completed, the only opening will be the main mirror aperture.

     -  It will then be moved into a horizontal position to be ready for
        packaging (into a special box designed by the Air Force) and shipping.

     -  Three potentially loose bolts on the secondary mirror must be checked.
        These will be replaced, with the new bolts being affixed with epoxy.

     As of June 1, 1989, the schedule for the HST is the following:

     July 10-11     Turn horizontal - replace nuts/bolts.
     July 24-28     Optical tests.
                      - illuminate with white light to look for dust/clean
                      - turn on the instruments, flood with white light,
                        and do final instrument alignment
     October 7-12   Ship to launch site.
     October 26 onward
                    Functional tests at Kennedy Space Centre.
     March 10       Place in shuttle and move to launch site
     March 26       Launch
                      - deploy within 2 days (thank you, now go away :-) )
     2 months of turn on testing
        -  power, maneuvering capability, then instruments
     Next 5 months
        -  basic calibrations, simple basic science (3 months, 2 months
           respectively, but intermingled)
     7 months after launch
        -  telescope is `open' for business to the general observing public
        -  currently, there is a 10-1 oversubscription for the available
           observing times (first year)

     There were also some comments made with respect to questions from the
audience.  Even with the solar maximum expected in the next few years, NASA
figures that HST will only require about 1 reboost every 5 years.  Any reboost
would require a shuttle flight by itself (someone explain this to me - I
didn't get a chance to ask), with the first one tentatively set for about 5
years down the road.  However, if it turns out that reboosts are required
more often, the HST would become uneconomical.  In fact, the suggestion was
made to move back the launch date if newer simulations show this to be the
case.  Nothing much else was said about that matter.

     For those of you who dislike the idea of spending so much money on
space-based research, you should be glad to hear that the 8-meter ground-based
telescopes look like they have a good chance of getting the funding needed.
Currently, the US will build one of them, and Canada and Great Britain will
split the second.  One will go to Mauna Kea, the other to Chile, with a 2:1:1
subscription ratio for the two instruments going to the countries involved.
Cost is currently estimated at about $60 million for the Hawaiian telescope,
and about $48 million for the Chilean one.  Some of the difference is due to
the Chilean instrument being built second, the rest, I think, is due to the
difference in labour costs.  By the way, don't quote me on the numbers, I
didn't write them down - they are accurate within $10 million (a lot better
than the government is capable of doing!).  There are, of course, 4 other
telescopes of the 8-meter class being built - by the Keck group, ESO, and Japan.

                                         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Arnold Gill                             | If you don't complain to those who  |
Queen's University at Kingston          | implemented the problem, you have   |
BITNET:  gill@qucdnast                  | no right to complain at all !       |
                                         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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

Date: 17 Jun 89 17:24:17 GMT
From: agate![e-mail]  (William Baxter)
Subject: Military and Civilian Space

Should military and civilian space programs be separate in the US?  If
so, how can this be accomplished?  If not, what objections do you have?

Please e-mail replies to me.  I'll post a summary.

William Baxter

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

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

Date: 17 Jun 89 23:40:49 GMT
From: visdc![e-mail]  (John E Van Deusen III)
Subject: Re: Ozone depletion, atmospheric models, and public policy

In article <[e-mail]>
[e-mail] (John Roberts) writes:
>
> In article <[e-mail]> [e-mail] (Mike Van Pelt) writes:
>> I suspected from the beginning that the so-called 'ozone hole' was
>> just part of a natural cycle that we would have been seeing all along
>> if we had had satellites for decades.  It makes no sense whatsoever
>> that a fluorocarbon-induced hole would first appear over the south
>> pole.

According to the Jan 1988 issue of Scientific American, pg 32., the
decline in springtime ozone levels over Antarctica was first identified
by Joseph C. Farman and his colleagues at the British Antarctic Survey.
They have monitored ozone levels directly over Halley Bay since *1956*.
Their work continued until the results were published in 1985.
Satellite observations beginning in 1971 completely confirm their work.
The mean value of 300 Dobson Units declined precipitously starting in
1976 and reached a low of 160 in 1985.

> ... the proposed "fix" is to undertake a presumably expensive switch
> to alternate products, with us as consumers or taxpayers expected to
> foot the bill. ...

John Roberts seems to be in general agreement with Mike Van Pelt's
statements.

> - It is generally agreed that an increase in the short wavelength
> ultraviolet light reaching the surface is undesirable. This light can
> be blocked by O3 (ozone) or by O2 (regular oxygen). (The books don't
> really go into the relative effectiveness of the two.)

For much of the following see "The Astrophysics of Suntanning" by
Bradley E Schaefer, NASA-Goddard Spaceflight Center, in SKY and
TELESCOPE, June 1988, pg. 595.

The most destructive UV-C radiation has a wavelength shorter than
2800 Angstroms.  It is so strongly absorbed by the earth's atmosphere
that it is seldom observed on the surface.  The observation that O2
absorbs "short wavelength ultraviolet light" is not relevant, because
UV-C does not reach the earth.  The burns, skin cancer, wrinkles,
blotchy pigmentation, and leathery skin resulting from prolonged exposure
to Sun light are the result of UV-B rays, 2800-3200 angstroms.  Oxygen
does NOT block UV-B.  For a standard ozone layer, (300 Dobson Units or
3 mmm STP), UV-B is dimmed 4.6 magnitudes per air mass.  Other factors
include scattering by air molecules, 1.2 magnitudes, and scattering by
dust, 0.2 magnitudes.

> CFCs tend to break down very slowly, with an expected lifetime of
> 50-100 years. The free chlorine atoms last only a relatively short
> time, before combining with other substances and drifting back toward
> the troposphere.

CFCs are almost impervious to breakdown by normal atmospheric processes,
and they persist until they diffuse into the stratosphere.  CFCs break
apart when they absorb UV radiation. The result is the release of a free
Chlorine atom.  When the free Chlorine encounters ozone, Chlorine
monoxide and an oxygen molecule are formed.  Once Chlorine monoxide
encounters a free oxygen molecule, the Chlorine atom is released, and
another molecule of O2 forms.  The Chlorine atom thus acts as a
*catalyst* for the destruction of ozone.  The only interference reaction
that removes the Chlorine atom is the reaction of Chlorine monoxide with
Nitrogen dioxide to form Chlorine Nitrate.

> - Ozone depletion by chlorine is expected to be effective only in the
> upper atmosphere. If the current ozone layer were depleted, it is
> expected that more ozone would form lower down ...

Ozone forms when UV radiation cracks an Oxygen molecule.  If the Ozone
layer is depleted, then this process should occur at lower elevations.
As stated above, the production of free Chlorine from CFCs uses exactly
the same mechanism.

> - There is very little interest in measuring the short wavelength
> ultraviolet light at the surface.

Because it does not exist.  See above.

> Many (but not all) researchers seem to feel that depletion of the
> current ozone layer would be directly proportional to increase of
> ultraviolet at the surface.

The fraction of light reaching the ground is 10^-kM/2.5
    where k is the absorption coefficient, shown above to be about
    6.0, and M is the number of Air Masses, 1 at zenith.

A ten percent reduction in Ozone results in over *50* percent increase
in UV-B radiation reaching the earth.

> - I would assume that the winter holes in the ozone layer at the poles
>   are caused by depletion of the ozone when there is not much sunlight
>   present. The ozone builds back up in the spring when the sun reappears.

The Antarctic Ozone hole forms in the spring!
--
John E Van Deusen III, PO Box 9283, Boise, ID  83707, [phone]

uunet!visdc!jiii

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

Date: Sun, 18 Jun 89 03:43 CST
From: [e-mail]
Subject: RE: SPACE Digest V9 #494


Re: GANYMEDE

I am a writer working on a project that puts life on Ganymede, and I'm
trying to decide what kind of differences a Ganymedan would have to
have to live on a giant ice-covered moon with low density, no
atmosphere to speak of and a greatly distant sun.  It seems to me that
there could be underground oceans heated by Ganymede's core, and some
kind of life could exist there, but my lack of expertise is really
showing as I develop this.  Can anyone help?

Also, I'd like to know how I can find out if there are gold deposits
on Ganymede or any other body in our solar system.

Many thanks,
Rogers (IH04@NTSUVAXB)

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

Date: 17 Jun 89 23:19:49 GMT
From: amdahl!pacbell!ditka!bucket!loop![e-mail]  (Keith Lofstrom)
Subject: Re: Ozone depletion, atmospheric models, and public policy

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
> - There is very little interest in measuring the short wavelength ultraviolet
>   light at the surface. Many (but not all) researchers seem to feel that
>   depletion of the current ozone layer would be directly proportional to
>   increase of ultraviolet at the surface.

There was an article in *Science* last year or so (Ref?) about actual,
long term measurements of biologically active UV at various sites around
the US.  There has been a *slight decrease*. The sites included both
rural and urban measurements - the decrease is not due to local pollution.

Decreasing CFC use is still a good idea, as long as people show a little
perspective in what they replace it with, and how nasty they get about it.

Keith


--
Keith Lofstrom    keithl@loop    tektronix!tessi!qiclab!loop!keithl
Launch Loop, P.O. Box 1538, Portland, Oregon 97207   (503)-628-3645

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

Date: Sun, 18 Jun 89 12:01:47 MDT
From: [e-mail] (Ehud Gavron, MS H828 [phone])
To: GOV@"[e-mail]", [e-mail]
Subject: How does one subscribe to this...

subscribe
    How does one subscribe to this space digest?

    EG

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

Date: 17 Jun 89 23:49:00 GMT
From: ux1.cso.uiuc.edu!uxe.cso.uiuc.edu![e-mail]
Subject: Re: Orbital queries


From [e-mail]:

>   2)  Why do most space launches orbit west-to-east relative to the earth's
>    surface?  Obviously other possibilities exist (e.g., geosynchronous
>    and polar).  Nonetheless, I don't know of any that go east-to-west.
>    How come?

Many satellites *do* orbit in east-to-west (or retrograde) orbits.  Most are
in orbits which are just barely retrograde (i.e., an inclinations of just
greater than 90 degrees).

The only relatively equatorial retrograde satellite in my recent recollection
(and the most news worthy) is Ofek-1 launched by Israel last September using
a Shavit rocket.  If you consider Israel's geographic position relative to
the Mediterranean, it's fairly obvious why it was launched in this manner.

> Thanks in advance for any insights -

You're welcome.
--
 Andrew J. Higgins              |     Illini Space Development Society
 [e-mail]     |     a chapter of the National Space Society
 phone: [phone]            |     at the University of Illinois
          P.O. Box 2255 - Station A, Champaign, IL  61825
"We are all tired of being stuck on this cosmical speck with its monotonous
 ocean, leaden sky and single moon that is half useless....so it seems to me
 that the future glory of the human race lies in the exploration of at least
 the solar system!"                          - John Jacob Astor, 1894

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

Date: Sun, 18 Jun 1989 11:38-EDT
From: [e-mail]
Subject: Re: Chaotic orbits

> of the "new science of chaos" (of which I understand nothing) as opposed
> to the sense in which "chaos rules my desk" (which I understand far too

Look for the book by Gleick ("Chaos"). There is also a reasonably
stuffy "historical/philosophical" treatment by Ilya Prigogine himself. I
recommend them both.

A chaotic orbit is one that is bounded but never repeats exactly, ie it
is described by a strange attractor.

Normal orbits are just cases where the attractor has not bifurcated at
all. There is a series of bifurcations leading to chaotic regions. The
limits are still predictable and the object is well behaved, not
"random" in a gaussian sense. It is just impossible (in a
mathematically provable sense) to predict its future position at an
arbitrary time t in the future. The accuracy of the prediction is
sensitively dependant on the conditions at t0,  and two points
arbitrarily close together at t0 will be arbitrarily far apart at time
t sufficiently far in the future. You cannot measure better than
Heisenberg allows, therefore you cannot predict a chaotic orbit arbitrarily
far in the future.

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

Date: Sun, 18 Jun 89 14:34:47 EDT
From: "Keith F. Lynch" <[e-mail]>
Subject: Re: Outer Space Committee
To: ccnysci![e-mail]
Cc: [e-mail], [e-mail]

> The Committee on the Peaceful Uses of Outer Space ...

With China, the USSR Cuba, and other butchers as members.  Right.
I hope the US isn't involved.
                                ...Keith

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

Date: Sun, 18 Jun 89 22:34:29 MDT
From: [e-mail] (Ehud Gavron, MS H828 [phone])
To: GOV@"[e-mail]", [e-mail]
Subject: subscribe

subscribe space  Ehud Gavron
set ack
sub Ehud Gavron

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

End of SPACE Digest V9 #506
*******************