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Subject: SPACE Digest V10 #282

SPACE Digest                                     Volume 10 : Issue 282

Today's Topics:
         space news from Oct 9 AW&ST, part 1
             Re: shuttle question
           Re: Why NASA wants to go to Mars
          Incredible Shrinking Space Station
             Re: Viewing Earth w/the HST
              Re: HST resolution
             Re: Viewing Earth w/the HST
           Re: Why NASA wants to go to Mars
----------------------------------------------------------------------

Date: 27 Nov 89 07:03:27 GMT
From: cs.utexas.edu!jarvis.csri.toronto.edu!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: space news from Oct 9 AW&ST, part 1

[Yes, you read that correctly -- "part 1".  This is a planetary-missions
issue, with lots of coverage in anticipation of the Galileo launch, so
I'm doing it in (at least) two parts.]

The cover is an artist's conception of Galileo approaching Jupiter.

Security at KSC tightened for the Galileo launch, against the possibility
of the Christics et al attempting disruptive tactics.

Hubble telescope smuggled from Lockheed Sunnyvale to KSC Oct 4, using a
USAF C-5 modified for heavy spysats.  NASA wanted to make it a public
event, but the USAF said the shape of the shipping container used --
the same one that will be used for a new large imaging spysat -- is
secret!  One NASA manager comments that "it doesn't take a rocket
scientist" to figure out that the new spysat must be shaped rather like
the Hubble telescope...

Initial NASA assessments indicate that using the space station as a
staging base for lunar operations would have "a significant impact".
The estimated cost of design changes is about $1G; they would include
more power, more heat radiators, upgrades to life support to handle
14-16 astronauts temporarily, and construction of the lower part of
the old "dual keel" design to accommodate docking facilities for
Shuttle-C and a servicing facility for a lunar transfer vehicle.
The extra hardware would have to go up pretty much immediately on
completion of the basic station if lunar activity starts on the
schedules some are projecting, circa 2000.  There is debate about
whether using the same platform for lunar operations and microgravity
research is really a good idea.  ESA is uneasy about whether lunar
support will divert NASA attention and money away from research work.
Lenoir says NASA has rather mixed feelings about simultaneous requests
to save money on the space station and to expand it to support lunar
exploration; he says one or the other will have to give.

Amateur astronomers report that the spysat launched in summer by
Columbia is tumbling rapidly, circa 30 RPM, suggesting that it is out
of control.  "Intelligence community" sources say that although the
bird had problems initially, it is now functioning normally.  [More
recently, it has apparently maneuvered, lending support to this.]
To add to the mystery, apparently Columbia deployed *two* satellites
on that mission; outside analysts think the big one was an uprated
KH-11 optical spysat, but nobody has any ideas about the other one.

First Amroc launch attempt fails Oct 5 with a fire destroying much of
the vehicle on the pad at Vandenberg.

Hipparcos's scientific mission is underway, everything working fine
despite the undesired orbit.

Analysis of Voyager 2 images turns up a geyser-like volcanic (?) plume
on Triton, with a cloud drifting 90mi downwind.

[Lots of coverage of US planetary-mission plans, much of it fairly
familiar.  I will just hit high spots...]

A graph of US scientific launch activity in the last 30 years is somewhat
striking.  From 1958 to 1978, the longest gap between major exploration
missions was one year.  Between Pioneer Venus in 1978 and Magellan this
May... nothing.

JPL will start CRAF/Cassini construction work in 1991, the first major
spacecraft start at JPL since Galileo over a decade ago.  There is some
concern about the loss of crucial skills in the hiatus.

Galileo launch prepations include four heavy transports standing by at
KSC with emergency teams.  One is fairly mundane, an orbiter-return team
in case of an emergency landing downrange.  The others are a little less
common:  a two-aircraft team with cooling equipment to deal with Galileo's
RTGs in the event of an emergency landing, and a DOE radiation-spill team
in case of a crash.

Atlantis will carry an assortment of small experiments along with Galileo.
The only one of note is a gravity-gradient experiment, to assess whether
the orbiter's attitude can be stabilized simply by positioning it with
nose toward Earth and one wing facing into the direction of flight.
This could save fuel for later long-duration flights.

Galileo will attempt various experiments during its Earth encounters.
Plans are not yet fixed, but among the ideas are:

    - A high-speed movie of the Earth approach, starting from 20Mmi
    with Earth as a small crescent and moving in to encounter (with
    a resolution of 50ft or so).  The two encounters will pass over
    Egypt and South Africa respectively.

    - Detailed examination of the Moon with modern instruments.
    About 2/3 of the Moon has not been seen well for two decades.
    Galileo will get good views of areas that have never been
    mapped at high resolution.

    - Examine lunar polar craters for evidence of frozen volatiles.
    Galileo's instruments are not ideal for this but could give
    some information.

    - Look for evidence of the swarms of mini-comets that some think
    contribute a significant amount of water to Earth.  Lunar impacts
    should result in a considerable cloud of hydrogen around the
    Earth-Moon system, which could be detectable from deep space.

    - Use Galileo's dust detector to look for a "dust belt" in the
    vicinity of Earth's orbit; one theory holds that dust falling
    inward towards the Sun from the asteroid belt could be delayed
    near Earth, forming a thin belt.

Galileo's second asteroid encounter is probably off the agenda unless
cruise fuel consumption is significantly lower than predicted.  Even
the first encounter will be endangered if consumption is worse than
expected.  Nothing will be decided until after Venus encounter in Feb.
--
That's not a joke, that's      |     Henry Spencer at U of Toronto Zoology
NASA.  -Nick Szabo             | uunet!attcan!utzoo!henry [e-mail]

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

Date: 27 Nov 89 14:08:34 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: shuttle question

In article <[e-mail]> [e-mail] (Robert Johnson) writes:
>In article <[e-mail]> [e-mail] writes:
>>
>>What's all that sparks that fly around under the shuttle before it launches?
>>They seem to get all excited just before the real launch and fizzle around
>>the next. isn't it dangerous to have open flames near the gas nozzles? what
>>if rocket fuel leaks out?

>Well, actually, they are there to ignite the engines.
>...  The shuttle engines are not
>able to ignite themselves (there is a word for this, can't remember
>it though), so they need these pyrotechnics.

Ack!

The space shuttle main engines have internal spark igniters, built
into the main injector assemblies.  For a picture, see Sutton's
Rocket Propulsion Elements (5th ed.), page 191.

Lighting a liquid fueled rocket by (essentially) holding a match
to the nozzle is an excellent way to cause an explosion.

The *real* reason for the pyrotechnics is to ignite any hydrogen
gas escaping after a launch abort.  If it were not ignited, it
might accumulate and explode.

    Paul F. Dietz
    [e-mail]

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

Date: 27 Nov 89 20:53:10 GMT
From: [e-mail]  (JOHNSON RICHARD J)
Subject: Re: Why NASA wants to go to Mars

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

]Franklin D. Martin, NASA's associate administrator for exploration, has a
]host of reasons for sending humans to Mars.
]...
]"Hey, Frank, you left off science," A. Thomas
]Young, the president of Martin Marietta Electronics and Missiles Group,
]said.  "Yeah, maybe so.  Yeah," Martin acknowledged.  But he quickly
]brushed Young's comment aside, remarking offhandedly that "science is
]one of the reasons you do these things, but it's not the driver." '

]Personal Editorial Begins:

]Am I the only one who nearly became physically ill after reading this?
]Is this truly what our space program has become, a bunch of administrators
]who are no longer aware that space exploration is meant for science?

Huh?  Wherever did you get the idea that space exploration was meant for
science?  Space exploration was meant for geo-political muscle-flexing from
the start.  "Science" was just tacked on to make the launching of rockets
more palatable from a propaganda point of view (and more acceptable to a
peace-loving public).

Then what did those silly scientists do?  They believed the justification,
found they could do good science from rockets, and wanted to do more.

Now, space exploration is still about geo-political muscle-flexing, but
this time we're trying to look like the most peaceful and helpful nation
instead of showing off our missile capabilities.  So why isn't science
high on the list?

I don't really know, but my guess is space, like all human activities, is
bigger than just scientific research.  (So why am I getting a PhD? :-)


| Richard Johnson                           [e-mail] |
|    CSC doesn't necessarily share my opinions, but is welcome to.     |
|  Power Tower...Dual Keel...Phase One...Allison/bertha/Colleen...?... |
|   Space Station Freedom is Dead.  Long Live Space Station Freedom!   |

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

Date: Mon, 27 Nov 89 23:35 EST
From: [e-mail]
Subject: Incredible Shrinking Space Station

I am a great advocate of our space program, but I think I've finally
had it with our "incredible shrinking space station." I NEVER thought
I'd hear myself say this, but I'm ready to scrap it. Let's design
a completely different space station.

We were able to put men on the Moon in a decade's notice, using 1960's
technology. If we can't build a measly (by comparison) space station
in the same span of time with 1980's technology, something is wrong

If we don't change course radically, we're going to have a space station
that'll do no more than Spacelab on the shuttle.

I'm just really fed up.

                                      Craig Cole   V071PZP4@UBVM
                                      University at Buffalo

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

Date: 27 Nov 89 09:36:29 GMT
From: portal!cup.portal.com![e-mail]  (Martin J Brown-Jr)
Subject: Re: Viewing Earth w/the HST

I would've thought that since the HST was designed to look at the stars, that
the earth or moon would be too close to be focused. What is the minimum
focusing distance of the HST.
                                        - MJB -

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

Date: Mon, 27 Nov 89 20:19:23 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: HST resolution


>From: mailrus!shadooby!terminator!ronin![e-mail]  (Allan M. Bjorklund)
>Subject: HST resolution

>>>From: John Roberts <[e-mail]>
>>>>From: cs.utexas.edu!samsung!aplcen!haven!uvaarpa!hudson!astsun9.astro.Virginia.EDU![e-mail]  (Greg S. Hennessy)
>>>>The resolution of HST is [roughly] 20 milliarcseconds. Let us consider
>>>>Alpha centuri. It is about 1.3 parsecs away, this 1 arcsecond will be
>>>>1.3 AU or about 130 million miles. 20 mas will be about 26 million miles.

>>>>>, [e-mail] (Allan M. Bjorklund) writes:
>>>>> I redid the calculations, and came up with the HST being able
>>>>> to resolve a 3000 mile wide object at 39 AU

>>>With 60 seconds of arc in an arcminute, 60 minutes in a degree, and 360
>>degrees in a full circle, an angle of 20 milliarcseconds makes up
>>1/10800000 of a full circle.
>>...Thus, by both of these methods,
>>...
>>becomes width = d * 9.696E-8. For 1.3 parsecs and 39 AU, this gives about
>>2.4 million miles and 350 miles. The original calculations by Hennessy
>>and Bjorklund are therefore off by a factor of about 8-10.
>>
>>Does it look right now? (This shows why engineers like to have someone else

>No, it doesn't.  You using just basic trigonometry, and ignoring
>the diameter of the mirror and some basic optics.

>[derivation for diffraction-limited resolution of a telescope]

>theta = 1.22 * (lambda/d) * 206265  [with theta in arcseconds]

>...Another way is to take W (the width of the
>object) and divide it by R (the distance to it) and note that it is also a
>radian value.  Thus we can obtain 1.22*(lambda/d) = (W/R).  A little rearranging
>gives 1.22*R*(lambda/d) = W.  Putting in .88m for d, 6*10^-7m for lambda, and
>5.83*10^12m (39AU) for R, we get W = 4.8*10^6m which equals 3007 miles.

>Doing it the trigonometric way, we obtain theta = 1.7*10^-1 arc seconds.
>(How was the 20 milliarcseconds previously quoted determined?  That would
>apply only if the HST were looking in the extreme ultraviolet/Xray region.)
>Take the sine of that, multiply by 39AU, convert to miles and the answer
>comes out to be 3009 miles.

>So I stand at my previous estimate of 3000 miles at 39AU.

>Allan Bjorklund                   Co Administrator of the
>[e-mail]      University of Michigan's
>[e-mail]     MsDos Archives.
>[e-mail]          terminator.cc.umich.edu 35.1.33.8

The use of basic trigonometry has nothing to do with the difference in the
answers. I did not calculate the angular resolution of HST - I just used the
value theta = 20 milliarcseconds, which had been posted, and I used the
working assumption (since you did not question the value) that you had used
the same number. In fact, you used theta = 170 milliarcseconds, derived
from your own calculations. If that value is plugged into my basic
trigonometry, it produces the same result that you got. (Thanks for the
formula for theta.)

By the way, how did you get .88m for the diameter of the HST primary? I don't
know what it is, but I'm *sure* it's more than .88m. I seem to recall something
in the range of 80-90 inches. (Could it be 88 inches?) Also, I imagine HST
could manage a lambda of at least 4*10E-7m.
                                     John Roberts
                                     [e-mail]

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

Date: 27 Nov 89 18:52:07 GMT
From: philmtl!philabs!briar.philips.com![e-mail]  (Robert Casey;6282;3.57;$0201)
Subject: Re: Viewing Earth w/the HST

In article <[e-mail]> [e-mail] (I Like Hike!) writes:
        The info I received (and subsequently lost) stated that the sensors
        would burn out if the HST was used on objects with magnitudes too
        bright.  I'm sure there must be a way to turn these sensors off

        The question this raises in my mind is, "Wouldn't observing the
        Earth with the HST damage its optical sensors?"  If this is the
        case, then the HST resolution power @ the surface of the Earth
       is purely academic.  Please correct me if any of my info is in error.

It seems to me that this means that you shouldn't look at the Earth's dayside,
but looking at the Earth's nightside should be OK.  Not sure what all you
could see, other than lots of streetlight lit roads and parking lots.  Maybe
more stuff during full moon.  But let's stick to looking at stuff in the sky.
That's HST's main job, anyway.

-----------------------------------------------------------------------------
communism sucks

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

Date: 28 Nov 89 05:35:20 GMT
From: uhccux![e-mail]  (Jeff Goldader)
Subject: Re: Why NASA wants to go to Mars

In article <[e-mail]> [e-mail] (Kieran A. Carroll) writes:
>[e-mail] (Jeff Goldader) writes:
>
>> >Space exploration was meant for geo-political muscle-flexing from
>> >the start.  "Science" was just tacked on [...]
>>
>> Well, I've gotten many replies to this effect.  I guess that was just the
>> last of my youthful idealism being washed down the drain.
>
>Yes, Jeff, but you've also gotten replies to the effect that "there's
>more to human endeavor than just science, so maybe there should be more
>to space than jsut science".  Is that such a bad thing to contemplate?

No, certainly not!  I hope I didn't imply that as strongly as it appears
even to me (reading my posting again).  I absolutely agree we should
be in space, even if "just to be there," if you know what I mean.
But we shouldn't spend that kind of money just to put someone on Mars!
My argument is: if the science budget is to be zapped for space endeavors,
let it be zapped only for the scientific ones.  Let the DoD and State Dept.
pay for muscle-flexing, and let foreign aid pay for those great "let's
join hands with our brothers/sisters" missions (sarcasm intended).

I see how physics is going to be hurt by the SSC; I can see how shuttle
and now station have, are, and will be hurting the space science budget;
I do not wish to see the havoc this wasteful trip to Mars will wreak.
If there were good, sound reasons to send people to Mars to do science,
I would not complain- however, even the strongest supporters of the Mars
mission say it's mainly for "international cooperation," whatever that
means (no, I don't think Apollo-Soyuz did much to help end the Cold War).
Notice that the biggest space-cheerleading club, the Planetary Society,
was against the space station--- until they saw it to be a stepping-stone
to Mars.  They were then all for it, all $20-$40 billion of it.  And it
wasn't for science, it was for politics.  Congress, however, doesn't see it
that way.  When they point to NSF budget increases, they neglect to point
out that most of it went to the SSC, leaving most other areas just
meeting inflation.  In their eyes, all of science reaped benefits from the
increases.  Who doubts that the 10-year hiatus in US planetary
launches was not caused by the shuttle's expense?

I do not know of anything people could do better on Mars than robots could;
for those $400 billion, we could send ~600 probes to Mars.  Does anyone
out there really think four people are going to do better than that many
robots?

Putting people on Mars is just a waste of money, that's all.

Jeff Goldader                        University of Hawaii
[e-mail]      Institute for Astronomy

"So, Lonestar, now you see that Evil will always win- because Good is stupid."
-The Dark Lord Dark Helmet, _SPACEBALLS_

Disclaimer: The University of Hawaii and the Institute for Astronomy neither
support nor are in *any way* responsible for these opinions.

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

End of SPACE Digest V10 #282
*******************