Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V13_7/V13_784.ZIP/V13_784

Internet Message Format | 1991-07-05 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/8cR1cgS00WBwQGsE58>;
          Fri,  5 Jul 91 03:05:16 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Fri,  5 Jul 91 03:05:11 -0400 (EDT)
Subject: SPACE Digest V13 #784

SPACE Digest                                     Volume 13 : Issue 784

Today's Topics:
             Galileo status report 6/6/91
            Need LA GIFs by Modem!
  Re: Platinum-group metal concentrations in earth-crossing objects
            Re: microsat tracking
            Re: RFD:  talk.politics.space
      Re: What is the Cheapest Import from Outer Space?
               Re: NASA Budget
          Re: USF International Space Agency
           Re: Solar sails and Belt mining
               Re: Launch failure today

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 22 Jun 91 23:59:38 GMT
From: att!linac!mp.cs.niu.edu!ux1.cso.uiuc.edu!rs6000.cmp.ilstu.edu![e-mail]  (Eric Behr)
Subject: Galileo status report 6/6/91


GALILEO MISSION STATUS June 6, 1991

     The Galileo spacecraft is 68 million miles from Earth, making
the round-trip communication time 12 minutes, 9 seconds.  Speed in
orbit is down to 50,300 miles per hour, and the solar distance is
now 155 million miles.

     This week the sun moved to such an angle that Galileo's sun-
gate sensor once again could see the shadow of one of the antenna
ribs sweeping by as the spacecraft rotates.  This is how spacecraft
analysts originally estimated the position of the partially
deployed high-gain antenna; with indications from radio-signal and
other tests, this provides additional confirmation that the warming
maneuver conducted two weeks ago did not change the antenna's
position.  A greater degree of warming will be available in about
15 months; in the meantime, Galileo will cool gradually as it
recedes from the Sun.

     Otherwise, Galileo's health and performance are excellent. The
spacecraft is spinning at a little less than 3 revolutions per
minute and transmitting engineering telemetry data at 40 bits per
second.

--
Eric Behr, Illinois State University, Mathematics Department
Internet: [e-mail]    Bitnet: ebehr@ilstu

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

Date: 21 Jun 91 10:38:28 GMT
From: dev8c.mdcbbs.com![e-mail]
Subject: Need LA GIFs by Modem!


Anybody know of some Los Angeles sites where NASA gif files can be accessed
via modem? This site does not support remote ftp operations.

Thanks in advance

Michael



--
==========================================================================
\\\\    Michael Rivero      | "I drank WHAT!" |"When MARRIAGE is illegal,|
  (.    [e-mail] | Socrates  -------------------  Only        |
   )>   DISCLAIMER:::       |-----------| "How come I'm   | OUTLAWS will |
  ==    "Hey man, I wasn't  |Looking4luv|taxed by the guy | have INLAWS! |
---/    even here then!"    |Settle4sex!|I voted AGAINST!"|              |
++++++++++++++++++++++++++++++++++++++++-------------------+++++++++++++++

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

Date: 21 Jun 91 06:52:05 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: Platinum-group metal concentrations in earth-crossing objects

In article <[e-mail]> [e-mail] writes:
>
>This is why the ice mining industry needs to be self-supporting outside
>of platinum mining.  Indeed, this is a general principle that central
>planners usually miss out on -- the technology needs to evolve in such a
>way that each step is self-sufficient.  Grand schemes to mine the platinum
>right now, without having first done the exploration and developed the
>simpler industries, would likely end in financial disaster.

Actually, intermediate industries are rarely profitable without the
captive market supplied by their primary end user. This is one of
the major forces leading to vertical integration in an industry.

>Ice can provide reaction mass, fuel, shielding, and heat sinks for
>Earth orbiting spacecraft, so that ice mining, if undertaken with
>sufficiently low costs, can pay for itself with current markets.
>How soon this will become possible depends on whether or not, and how
>soon, we discover earth-crossing ice, or as a second choice high
>concentrations of water of hydration, in good trajectories.  It also
>depends on our ability to reduce the cost of automated missions on the
>order of complexity of CRAF and Phobos.   Currently CRAF is in sad shape,
>using 70's-era computer chips and having to drop the penetrator.  We all
>know what happened to Phobos.  :-(  We need to be a generation or two
>beyond that.

Indeed, the current budget fight may be a blessing in disguise if it
results in the scrapping of CRAF and a later startup with a clean
sheet of paper that can incorporate twenty or thirty years of technical
improvements. After all, there's no hurry, the comets will still be
out there.

Gary

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

Date: 21 Jun 91 07:05:28 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: microsat tracking

In article <[e-mail]> Ian Stirling <[e-mail]> writes:
>>>retrofitting standard,$5,000 satellite dishes.Can somebody comment
>>>on what it takes to get a standard TV satellite dish to track a
>>>low-earth-orbiting satellite?
>>
>>Basically a new mount and more powerful motors and realtime tracking
>>software running on a personal computer. The polar mount used
>>on home dishes gives limited continous sky coverage in a tracking
>
>Why would it need more powerful motors? Arn't most mounts designed
>for reasonably rapid change between different satelites ,surely all
>that would be needed is a cleverer or re-programmed driver?

The problem occurs during near overhead passes. The satellite's
relative bearing changes quite rapidly during this time with a
traverse of nearly 60 degrees in under 4 minutes.  Our 5 meter
dish requires 4 plus minutes to traverse 60 degrees in azimuth.
A change in gearing is needed to reduce the traverse time and
consequently a more powerful motor is needed to turn the
higher speed gears. I haven't closely timed some of the smaller
home dishes, perhaps they can handle this as is. Anyone with a
home dish care to post their 60 degree traverse timings?

Gary

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

Date: Sat, 22 Jun 91 08:51:36 PDT
From: [e-mail] (Jim Bowery)
To: crash![e-mail]
Subject: Re: RFD:  talk.politics.space

sci.politics would be a better classification in my opinion since
the current debate over big science vs little science is at the root
of the rancor over space as well as SSC, HGP, NREN, Tokomak, etc...
and virtually all scientific areas have become subject to the big
science ideology over the last 2 to 3 decades.  The politics can't
be decoupled in discussion without favoring the status quo which is
overtly political in nature, particularly in space.

If not sci.politics then at least talk.politics.science.
-----------------------------------------------------------------------------
Jim Bowery      619/295-3164               The Coalition for
PO Box 1981                                   Science and
La Jolla, CA 92038                             Commerce
-----------------------------------------------------------------------------

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

Date: 23 Jun 91 00:36:17 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!hela![e-mail]  (Allen W. Sherzer)
Subject: Re: What is the Cheapest Import from Outer Space?

In article <[e-mail]> [e-mail] (Loren Petrich) writes:

>    I was discussing the question of suitable space projects not
>too long ago, and I was told that a study had revealed that the
>cheapest import from outer space was information(!).

More precisely the cheapest import is photons. This is important because
output from solar power satellites would be just a cheap.

>It is significant that the most successful space
>applications so far have involved sending back information.

Given the current state of the infrastructure this comes as no suprise.

>    If one wishes to return physical objects, then it is
>appropriate to have ones with high value per unit mass, to get around
>launch costs.

Another way is to reduce launch costs. History has shown reducing
cost to be far more effective in growing markets than focusing on
high value per pound. In the case of avation for example it took
large well focused subsidies to produce the aerospace industry we
have today. Had we focused back then on value per pound there would
be no large aerospace industry since there where very very few
things worth moving by air.

>This has been the philosophy of most space manufacturing
>schemes so far, which have tried to utilize microgravity...

With a spectacular lack of success so far. There just aren't many
things worth $8,000+ per pound. Now if we used the methods which
have worked in the past, we could see prices drop rapidly which
would make a lot more things worthwhile.

>    It is evident here that sending people up into space is
>something of a loser.

In the recent past we have seen two approaches for building a
crewed station for satellite repair. Both are very close to
viable operations. These approaches will also enlarge the market
size and provide huge incentive to lower costs.

Humans in space are not 'something of a loser'; rather they are key
to the development of a viable self sustaining space industry.

>Big prestige projects with
>central supporters are impressive, but VERY vulnerable to political
>whim and charges of benefiting some select group of fat cats. Smaller
>scale projects with less centralized support have much greater
>longevity, and are less dependent on any individual success or
>failure.

Given the large number in infrastructure projects which where 'big
prestige projects' which produced useful outputs it is hard to
justify this statement.

If your theory where true we could have no interstate highways, airports,
ports, and a host of others.

  Allen
--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |   DETROIT: Where the weak are killed and eaten.         |
|   [e-mail]   |                                                         |
+---------------------------------------------------------------------------+

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

Date: 22 Jun 91 08:55:08 GMT
From: mips!ptimtc!nntp-server.caltech.edu![e-mail]  (Todd A. Brun)
Subject: Re: NASA Budget

In article <[e-mail]> [e-mail] (Craig E. Ward) writes:
>
>/* Sorry of the delay of this follow-up.  I actually have to do some real
>work around here, from time-to-time ;-) */
>
>In article <[e-mail]> [e-mail] (Joe Cain) writes:
>>3) Last year's budget agreement effectively gave NASA a cap. As a
>>result, NASA will not significantly expand in the future. It's now a
>>zero sum game. As the Space Station Budget grows, the Space Science
>>budget will not grow but shrink. NASA is at a crossroads and
>>scientists need to be heard.
>
>This is not true.  The agreement is that any increases in domestic spending
>programs will need to be matched decreases in other domestic programs.  This
>gives a lot of room to maneuver.  This goes to the point I made earlier about
>space supporters forming coalitions.  (An area completely ignored by
>Meredith's statements.)
>
>Furthermore, the OMB gets to interpret the rules.  Noting that President Bush
>threatened to veto any appropriations bill that lacked station funding, you
>can figure that OMB will bend the rules as much as it can to increase funding
>at NASA.
>
>This is not a zero sum game.
>
Well, technically no, but practically yes.  The budget agreement was that
domestic spending as a whole was a zero-sum game.  So, in principle, funds
for the Space Station could be taken from any combination of domestic
programs.  However, given the committee system in Congress, no committee is
likely to let funding for their projects be swiped by programs in another
committee, and much the same is true on the level of subcommittees.  So
practically speaking, funding for SSF has to come from other programs in the
same subcommittee.  Well, those programs are NASA, NSF, Housing and Urban
Development, Veterans benefits, and a few others.  If you think Congressthings
are going to take money from veterans and give it to the Space Station, you're
crazy.  So actually, within NASA it is pretty much a zero sum game.

Anyway, the point is moot.  The fact is, the funding that was scraped up for
the Space Station *did* come largely from space science.  Sobering reality,
which cuts through all manner of theory.

    -- Todd Brun
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Physics Department, California Institute of Technology
"Feezeeks?  Ve don't need no lousy feezeeks!"

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

Date: 21 Jun 91 21:55:59 GMT
From: van-bc!rsoft!mindlink![e-mail]  (Nick Janow)
Subject: Re: USF International Space Agency

I think that a private organization dedicated to presenting a project (Mars
Mission, Robotic Lunar Mining, Solar Sail to an Asteroid, whatever) could be
worthwhile.  It could provide its supporters with a focal point and support
services.  Whether or not the project gets government funding depends on the
value of the project's goals and on how well it gets presented.

The USF sounds more like: "Give us total control over space development and
we'll work on projects we decide are best.  ...Trust us!"
--

[e-mail]

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

Date: 21 Jun 91 08:34:51 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: Solar sails and Belt mining

In article <[e-mail]> Ian Stirling <[e-mail]> writes:
>If you can make a workable solar sail how much more difficult is it
>to make a large parabolic mirror for melting large boulder size
>chunks of rock? Could you mine a asteroid my melting it and allowing
>the vapour that comes off to condense on nearby cooled surfaces,using
>a sort of fractional distilation to seperate the metals.Also could
>you get higher temperatures than the surface of the sun by filtering
>the incoming light at the mirror(diffraction grating ?)to leave only the
>higher energy photons,this does not seem to violate any laws as you
>are only able to use a small fraction of the incoming light to heat
>the object but most of the light goes past at lower overall energy.

In principle, there is little difference between a solar sail and
a solar mirror. Both can be light foil structures. The control
problems are somewhat different, but not seriously so. Using filters
on the mirror would have a negative effect on the amount of focused
energy. Assuming a near perfect black body as the absorber, any
photon will contribute energy to the heating process. The concentration
ratio of the mirror will allow temperatures much higher than the
surface of the sun at the focal point. The amount of heat delivered
less the amount reradiated, not just the temperature, determines whether
rock, or anything else, can be melted. Somewhat less than a kilowatt-sec
of energy is delivered to each square meter at Earth orbital distance
from the sun. A mirror with 10,000 square meters surface area focused
on a 1 square meter target would deliver 10,000 kilowatt-sec or 143,300
kilogram calories per minute. This would raise the temperature of one
kilogram of water from 0 Celsus to 143,300 degrees in one minute, if
you could contain the steam! That ought to be enough to melt any rock.
This is strictly back of envelope, anyone who wants to consult the
steam tables, check the solar constant, and do an exact calculation is
welcome to do so.

Gary

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

Date: 22 Jun 91 03:09:32 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss![e-mail]  (Bev Freed)
Subject: Re: Launch failure today


 > From: [e-mail] (Paul Carroll)
 > Message-ID: <[e-mail]>
Re: Joust 1

 > Does it look like a failure in the nozzle?  I tried to get some
 > video later in the day, but CNN only showed the rocket before
 > and after the failure, not during.


I have all the raw footage on tape from all the cameras -- including long range.  It looked like a failure in the nozzle to me and I've looked at it several times.  If you'd like the footage, e-mail me and I'll see about getting it to you.


--- Opus-CBCS 1.20.18
 * Origin: NSS BBS - Ad Astra! [phone] *HST* (1:129/104.0)
--
Bev Freed - via FidoNet node 1:129/104
UUCP: ...!pitt!nss!freed
INTERNET: [e-mail]

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

End of SPACE Digest V13 #784
*******************