Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v09_4/v9_479.txt

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Subject: SPACE Digest V9 #479

SPACE Digest                                      Volume 9 : Issue 479

Today's Topics:
         Re: Venus & the Greenhouse effect..
           Re: Getting news about China from space
            Re: Amazon Forest Destruction
         Re: Venus & the Greenhouse effect..
          Re: Hang gliders and "bailing out"
              Re: Space telescope optics
          Re: Space Station computer system
         Re: Venus & the Greenhouse effect..
         Re: Venus & the Greenhouse effect..
            Re: Russians bomb U.S.
            Re: Terraforming Venus
                 Re: Magellan
Hartsfield to head Space Flight/Space Station Integration Office (Forwarded)
----------------------------------------------------------------------

Date: 6 Jun 89 19:14:29 GMT
From: china.uu.net![e-mail]  (Dan Williams)
Subject: Re: Venus & the Greenhouse effect..

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
> There are other problems in making Venus habitable too, like a grave shortage
> of water and an excessively long rotation period.


    Does Venus really have a lack of Water?  I know it has no liquid
H2O but doesn't the atmosphere still hold the balance?  Also what about
vulcanism releasing water and more in the rocks?
    If we manage to cool the planet would water begin to collect?
Now the rotation period is a problem of a different magnitude.

--

| Dan Williams (uunet!china!dan) | FRP: It's not just a game,        |
|       MCDONNELL DOUGLAS        |            it's an adventure!     |
|           Denver CO            | "Of course thats just my opinion" |

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

Date: 7 Jun 89 03:34:14 GMT
From: usc!merlin.usc.edu!nunki.usc.edu![e-mail]  (Dennis Kriz)
Subject: Re: Getting news about China from space


With the continuing crisis in China and with it for the most part being
played out far from Tienanmen square these days, probably outside of Beijing
even, I was wondering ... could satellite photos from spacecraft like Spot
make any difference.  I mean that's how the networks covered the Chernobyl
accident when it first broke.  I doubt that such a satellite could detect
individual tanks but perhaps it could detect masses of them.  Maybe it could
detect them deployed by bridges, intersections and the like.  Any comments?

Dennis

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

Date: 7 Jun 89 17:38:01 GMT
From: ncrlnk!ncrcce![e-mail]  (Wayne D. T. Johnson)
Subject: Re: Amazon Forest Destruction

In article <[e-mail]> [e-mail] (Tom Neff) writes:
>In article <[e-mail]> [e-mail] (Mike Van Pelt) writes:
>>In article <[e-mail]> [e-mail] (Wayne D. T. Johnson) writes:
>>>Article in the local news last night:
>>>ozone was being destroyed by electrons coming from the magnetosphere
>>>this causing 14% of the ozone loss since 1975...
>              ^^^^
>              note number

I must correct myself, the figure they said was 14% of the ozone.  That
is a significant amount since the ozone varies in thickness and is
thinest at the poles.

Wayne Johnson                 (Voice) 612-638-7665
NCR Comten, Inc.             (E-MAIL) [e-mail] or
Roseville MN 55113                    [e-mail]
These opinions (or spelling) do not necessarily reflect those of NCR Comten.

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

Date: 7 Jun 89 03:26:29 GMT
From: mailrus!jarvis.csri.toronto.edu!me!ecf![e-mail]  (Hema Sandhyarani Murty)
Subject: Re: Venus & the Greenhouse effect..

>     Does Venus really have a lack of Water?  I know it has no liquid
> H2O but doesn't the atmosphere still hold the balance?  Also what about
> vulcanism releasing water and more in the rocks?

A recent New Scientist article says the Venus may have had water at one
time.  Apparently, a measure of deuterium to hydrogen in the atmosphere
of Venus gives them the indication that at one time there was more
water.  When temperatures were lower, I suppose not all the water was
boiled away. They even suggest that at one time there may have been
large oceans of water on the surface of Venus.  Magellan is supposed to
look for signs of dried up river beds etc.

Hema Murty
Institute for Aerospace Studies, University of Toronto,
Downsview, Ontario, M2M 3V8 Canada

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

Date: 7 Jun 89 01:45:03 GMT
From: aeras![e-mail]  (Tom Neale)
Subject: Re: Hang gliders and "bailing out"

In article <[e-mail]> [e-mail] (Jeff Berkowitz) writes:

>Henry's analysis of the difference is (as usual :-) correct.  Parafoil-
>like designs, however, are in use both as kites and as human-carrying
>gliders; the latter are popular especially in Europe.  Their advantage
>over hang gliders is that the lack of airframe makes them easy to fold
>into a backpack and carry; they have a relatively poor glide, however,
>and appear to be difficult for humans to flare (and therefore land) safely.

On the contrary, ram air (squares as we call them) parachutes are quite
the norm in sport parachuting today.  Their glide is a respectible
3:1 or better (great when compared to a round parachute at <0.4:1).
Forward speeds are 20-30 MPH for most models.

Further, they are quite easy to flare and land safely. I have over
1300 square jumps with no problems and landings are normally tippy-toe
soft. :-)

This is no longer shuttle related but I felt compelled to clear
up any mis-information about a subject near and dear to my heart.
--
Blue skies,    | ...sun!aeras!tneale    |
        | in flight:     N2103Q    |         The hurrieder I go
Tom Neale    | in freefall:   D8049    |         the behinder I get.
        | via the ether: WA1YUB    |

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

Date: 7 Jun 89 17:43:33 GMT
From: frooz![e-mail]  (Steve Willner)
Subject: Re: Space telescope optics

In article <[e-mail]>
[e-mail] (John Roberts) wrote:
> Several people have posted to the net stating that the Hubble Space
> Telescope could not focus on an object as close as the earth. I
> tend to be somewhat skeptical of this claim, because of the
> phenomenon known as depth of field.
> ....
> but a few guesses and application of the formulas used for cameras
> suggest that the hyperfocal distance may be only a few miles. Does
> anyone have any better numbers?

Then in article <[e-mail]>,
[e-mail] (David Palmer) replied:
> It is easy to see that when you focus an optical system at
> infinity, the circle of confusion of an image at a finite distance
> is the size of the aperture at that distance.
> ...
> This means that the HST cannot see objects smaller than its 2.4 m
> mirror, compared to the pie-plate size of a Spy-sat.

My initial reaction was that Mr. Roberts was right, but a calculation
leads to the opposite conclusion.  (Thanks to Mr. Palmer for further
explication.)

If an optical system focused at infinity observes an object at
finite distance, the position of the image will be shifted.  The
amount of shift (for an object at distance d >> focal length) is
  s = (F D)^2 / d ,
where F is the focal ratio of the system, and D is the diameter.
(Note that FD is the focal length.)

For HST observing the ground, the numbers (very roughly) are F=20,
D=2.4 m, and d=2E5 m.  Thus the focal shift is of order 12 mm.  The
blur circle produced by the focal shift (assuming we do not refocus
the telescope) is just s/F or about 0.6 mm in this case.  For
comparison, the diffraction blur circle is approximately 2.4 Fw,
where w is the wavelength.  This amounts to about 24 microns for HST
in visible light, so the Earth would not be observable by HST without
either refocusing or losing resolution.

In general, for a diffraction-limited optical system focused at
infinity, objects must be more distant than D^2/w to be effectively
"in-focus."  This is about 1E4 km for HST.

My guess is that the amount of focal shift is within the range of
adjustment for HST; if so, Mr. Palmers last statement needs the
qualifier "without refocusing."  Other forms of image blurring,
notably spacecraft motion, would also be important.  And the HST
instruments are not really designed for ground observations.
However, it's not hard to imagine an instrument very similar to HST
but designed specifically for ground observations.  Rumor has it that
some have been built.
Steve Willner            Phone [phone]         Bitnet:   willner@cfa
60 Garden St.            FTS:      830-7123           UUCP:   willner@cfa
Cambridge, MA 02138 USA                 Internet: [e-mail]

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

Date: 7 Jun 89 18:48:51 GMT
From: vsi1!daver!lynx![e-mail]  (Neal Woodall)
Subject: Re: Space Station computer system

In article <[e-mail]> [e-mail] (Rick Francis Golembiewski) writes:

>> highlights:  they're talking about thirty to forty IBM PS/2 model 80's

>EEEK  This sounds really frightening MS-DOS in space,
>now I KNOW that the space program is in trouble...

Who said that the computers had to run MS-DOS? Why not
some other operating system?

Neal

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

Date: 7 Jun 89 15:53:49 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Venus & the Greenhouse effect..

In article <[e-mail]> [e-mail] (Dan Williams) writes:
>    Does Venus really have a lack of Water?  I know it has no liquid
>H2O but doesn't the atmosphere still hold the balance?

Unfortunately, no:  when Venus's greenhouse effect ran away and the water
ended up in the atmosphere, at high altitudes solar radiation cracked it
to hydrogen and oxygen, and the hydrogen escaped into space.  Not a fast
process, but over time most of it went.  What little hydrogen is left is
noticeably deuterium-enriched because deuterium is twice as massive and
doesn't escape nearly as easily; this is the definitive evidence of what
happened.

> Also what about
>vulcanism releasing water and more in the rocks?

Not significant over time scales that humans care about.

>    If we manage to cool the planet would water begin to collect?

No, since there's none to collect.  We'd have to import it, perhaps from
the outer solar system.
--
You *can* understand sendmail, |     Henry Spencer at U of Toronto Zoology
but it's not worth it. -Collyer| uunet!attcan!utzoo!henry [e-mail]

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

Date: 7 Jun 89 21:08:06 GMT
From: concertina![e-mail]  (Steve Hix)
Subject: Re: Venus & the Greenhouse effect..

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
> In article <[e-mail]> [e-mail] (Dan Williams) writes:
> >    Does Venus really have a lack of Water?  I know it has no liquid
> >H2O but doesn't the atmosphere still hold the balance?
>
> >    If we manage to cool the planet would water begin to collect?
>
> No, since there's none to collect.  We'd have to import it, perhaps from
> the outer solar system.

Say, if we throw enough comets and other iceballs at Venus to get the
water back, and if they're placed correctly, maybe we could get the
planet's spin rate up some.

Probably not enough comets, huh?

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

Date: 7 Jun 89 14:05:20 GMT
From: prism![e-mail]  (Matthew DeLuca)
Subject: Re: Russians bomb U.S.

In article <[e-mail]> [e-mail] (Wayne D. T. Johnson) writes:
>
>Upper stage from Proton booster crashs in U.S. near Canadian border.
>
>Any one have any details?
>--

According to the local paper (Atlanta Constitution, from AP report) the
stage did *not* crash, rather, its re-entry was visible from northern
Minnesota.  According to the report, the booster had launched three
satellites into orbit.

ARPA: [e-mail]      :

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

ReSent-Message-ID: <[e-mail]>
ReSent-Date: Wed,  7 Jun 89 09:33:20 -0400 (EDT)
ReSent-From: Ted Anderson <[e-mail]>
ReSent-To: Resend this message to: Space <[e-mail]>,
    [e-mail];
Date: 6 Jun 1989 16:17-CDT
Sender: [e-mail]
Subject: Re: Terraforming Venus
From: [e-mail]

Concerning the questions on planetary cooling caused by clouds vs
CO2 'Greenhouse' effect.  If I remeber correctly in one of my classes
years ago the discussion came up about clouds of water-vapour being
highly reflective to near infrared and visible light and less reflective
(Note: not transparent) to far infrared while CO2 is more reflective
to far infrared than to near thus accounting for CO2 being better at
trapping the longer wave-length far infrared which is generated when
sunlight strikes a planetary surface.

Please if I have this information incorrect or backwards, be gentle
with the flames as this is really out of my area, I have spent the past
21 years as a para-professional in Aerospace Medicine.

Al Holecek
<[e-mail]>

Disclaimer - the above is my own ramblings, but my bosses are welcome to 'em

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

Date: 7 Jun 89 17:18:33 GMT
From: ncrlnk!ncrcce![e-mail]  (Wayne D. T. Johnson)
Subject: Re: Magellan

In article <[e-mail]> [e-mail] (Peter Scott) writes:
>
>In other words, if something sticks, give it a kick.
>

Rube Goldberg's law (my patrion saint):

If it dosn't work, use a bigger hammer.

An IUS is just about the biggest hammer I've seen yet.
--
Wayne Johnson                 (Voice) 612-638-7665
NCR Comten, Inc.             (E-MAIL) [e-mail] or
Roseville MN 55113                    [e-mail]
These opinions (or spelling) do not necessarily reflect those of NCR Comten.

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

Date: 7 Jun 89 23:10:56 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Hartsfield to head Space Flight/Space Station Integration Office (Forwarded)

Barbara E. Selby
Headquarters, Washington, D.C.                       June 7, 1989

Billie A. Deason
Johnson Space Center, Houston, Texas

RELEASE:  89-88

HARTSFIELD TO HEAD SPACE FLIGHT/SPACE STATION INTEGRATION OFFICE

     Veteran astronaut Henry Hartsfield has been assigned
temporary duty in the Office of Space Flight, NASA Headquarters,
Washington, D.C., effective immediately.

     Hartsfield will serve as director of the Space Flight/Space
Station Integration Office, reporting directly to the associate
administrator for space flight.

     Hartsfield replaces astronaut Robert Parker who has returned
to the Johnson Space Center to begin training for his mission
specialist assignment on Space Shuttle mission STS-35, scheduled
for launch in the spring of 1990.

     The Space Flight/Space Station Integration Office was
established in 1987 to facilitate integration of the Space
Station and its unique requirements into the Space Transportation
System.  The office coordinates the exchange of information
between the two programs and serves as a forum for resolving
technical and programmatic issues.

     Hartsfield began his Air Force career in 1955 and is a
graduate of the USAF Test Pilot School at Edwards Air Force Base,
Calif.  He was an instructor there prior to his assignment in
1966 to the USAF Manned Orbiting Laboratory (MOL) program as an
astronaut.  After cancellation of the MOL program in June 1969,
he was reassigned to NASA.  Hartsfield retired from the Air Force
in August 1977 and remained in the astronaut corps.  He was pilot
for STS-4 in June/July 1982 and commanded Shuttle missions STS
41-D in September 1984 and STS 61-A in November 1985.  His most
recent assignment was deputy director for flight crew operations
at the Johnson Space Center.

     In addition to other awards, he has received the NASA
Distinguished Service Medals in 1982 and 1988 and the NASA
Exceptional Service Medal in 1988.

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

End of SPACE Digest V9 #479
*******************