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Subject: SPACE Digest V11 #162

SPACE Digest                                     Volume 11 : Issue 162

Today's Topics:
             Spectra of Venus Atmosphere
     Re: Coilgun on a 747 - supplies to orbit at $20/lb?
           Re: Coilgun on a 747 - supplies to orbi
             Any HST-Schedule out there?
        Re: What was Challenger really up to?
            Re: Microgravity Research Drop
               Shuttle Escapes
       Use of HST guide-star sensor data for astrometry
              Challenger Report question
        Re: Resolving Power of Hubble Space Telescope
----------------------------------------------------------------------

Date: 17 Mar 90 19:11:45 GMT
From: stretch.cs.mun.ca![e-mail]  (Chris Paulse)
Subject: Spectra of Venus Atmosphere

I'm a neophite when it comes to astronomy and astrophysics.  Can
anyone direct me towards a comprehensive introduction to the planetary
atmospheres, particularly that of Venus.  To be more specific, I'm
looking for any available libraries of measured spectra of clouds on
this planet (IR or UV).  Any help would be appreciated.

Chris Paulse
Memorial U

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

Date: 18 Mar 90 07:56:58 GMT
From: deimos.cis.ksu.edu!uafhp!uafcseg![e-mail]  (Patrick Spinler)
Subject: Re: Coilgun on a 747 - supplies to orbit at $20/lb?




I'm not a physicist or engineer (yet!) so some of my concepts may be frayed,
but:

A mass driver accelerates an armature + payload, then decelerates the armature,
correct ?  In this case (231ft length limitation) why bother deccelerating and
saving the amature ?  Simply eject it with the payload, and seperate them in
flight.  it would give you several more feet to accelerate your payload, and
at a guess, the armature is cheap enough to waste, at least for a proof of
concept.

-- Pat

Just a student            [e-mail]
engineer in training        [e-mail] [134.29.1.1]

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

Date: 18 Mar 90 17:39:59 GMT
From: elroy.jpl.nasa.gov!usc!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!suna5![e-mail]
Subject: Re: Coilgun on a 747 - supplies to orbi


/* Written  5:12 pm  Mar 16, 1990 by [e-mail] in suna5:sci.space */
In article <[e-mail]> [e-mail] (Vincent Cate) writes:
>Sounds like a coilgun on a high flying 747 should be a cheap way to
...
>What are the hard parts of this type of approach?

My guesses would be recoil and  muzzle aerodynamics.  Some of the momentum of
the aircraft gets transfered to the projectile.  Your projectile mass is
limitted by the need to keep flying.

There is a minimum size payload that will be useful, and multi-shot
groups will be spread out over a whole lot of orbit.  Fuel, for instance,
really wants to be launched in large batches for a decent payload/container
mass ratio and handling costs.

And a 747 really doesn't fly that high.  Maybe you could reengine
one for operation where the air is rare, but in any case you'd start
running out of lift and have to derate your mass calculations.
You could get above a lot of atmosphere but you'd still be shooting
through a lot, and now you'd have it shearing past your muzzle at
450 kts or whatever.

I do know that the energy storage problem has a solution.  A group
at Texas A&M (if memory serves) has a railgun power supply "the
size of a garbage can", using some kind of magnetic/electromechanical
principle.  The primary generators in the engines or your APUs place
one limit on the firing rate, but once you charge the secondary
generator you can pull megawatts out of it for the duration of the
shot.

A 747 is what, 200 ft long?  Calculate the accelleration required
to reach orbital velocity from, say, 1200 kts (air speed plus
rotation, fudged for inclination and wind) in 200 ft.  It won't
be as kind to your payload as a longer ground based gun would
be, but you may make it up in reduced heating for some payloads.

Interesting idea, but I think you need a high-altitude, hypersonic
aircraft for your first stage.  A 747 just isn't enough better than
a ground station to justify the cramped quarters, increased operation
risk, and weight limits.

One advantage it does have over a ground station is the ease with
which it can match launch to window.  Just fly to where the window
is and yank the cord.
--
Steve Nuchia          South Coast Computing Services      [phone]
"You have no scars on your face, and you cannot handle pressure." - Billy Joel
/* End of text from suna5:sci.space */

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

Date: 15 Mar 90 23:00:00 GMT
From: snorkelwacker!ira.uka.de!smurf!gopnbg!altger!doitcr!nadia!delos![e-mail]  (Bernd Ebach)
Subject: Any HST-Schedule out there?


Is there anybody out there knowing the schedule for the Hubble-Space-
Tele-scope-Projects? I think there are about 100 People/Institutions
waiting for their 'timeslice'.

My special interest is about the 'Search-For-An-Extrasolar-Planetary-
System-Projekt'. I heared, HST is meant to take a closer look at 53
Lightyears far 'Beta Pictoris' (where the hell can I find it this in-
significant Star, which constellation?). I think responsible for this
Project is Robert Brown. (Hi there, Rob, can you read me? Correct me
if I'm wrong... ;^>)

So, does anybody know how long I'm supposed to wait for the results of
this event? Besides, the dates for the other Projects would be also
nice to know.

In gratitude for every hint...

                                        Bernd

---
.signature (long)
---

           - believing in  -
         /                   \
 ...still                     extraterristrial live...
         \                   /
           - searching for -


                  |         |             |
 ...may it be   - C -  ,  - Si -  or  - WTHE* -   based...
                  |         |             |


 * (WTHE = What The Hell Ever)

---

Disclaimer: Everything said above is my very own insignificant opinion.
                                                 -------------
___

Benediction:  ...May this Message be seen by every host...

---

  Bernd Ebach, Blarerstr.1, 7ooo Stuttgart 5o
-----------------------------------------------
 [e-mail] ...{uunet;mcvax}!unido!nadia!be

---

The End

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

Date: 18 Mar 90 19:28:07 GMT
From: news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (Brian or James)
Subject: Re: What was Challenger really up to?


 Actually, the Challenger explosion was caused by a secret Canadian Death Ray
satellite hidden in the SRB prelaunch (Thus the similarty to O-Ring failure).
The True purpose of this satellite is, of course, classified, although it
either pertains to defending our North West Passage from foreign invasion,
or the Final Slution for our Grand Banks fishing difficulties. No counter
evidence exists because, of course, They covered everything up perfectly, as
They always do. In fact, this thread was *started* as the most recent step in
the conspiracy, but Their funding just got cut, so it's ok to talk about it
now. Sorry for the inconvinience.
                        On behalf of The Men In Black,
                                JDN

PS: Your Vice President was Their doing, too.

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

Date: 18 Mar 90 20:29:09 GMT
From: csusac![e-mail]  (David Brock)
Subject: Re: Microgravity Research Drop

JP Aerospace is developing a Microgravity research vehicle.  The vehicle
is to be dropped from 10,000' and will be soft-landed.  All interested
parties are encouraged to contact:
    JP Aerospace, Inc.
    P.O. Box 2165
    Fair Oaks, CA 95628

Free experiment space will be availible during testing drops for
academic use.

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

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From: [e-mail]
Subject:  Shuttle Escapes

   As a fan of single seater autoracing (Formula One, Indy and the like) I have
seen plently of incidents involving high speed collisions and fire.  The vast
majority of these incidents involve no, or little, injury to the driver.
  Modern racing cars have carbon fibre tub in which the drivers sit.  This tub
provides a great deal of protection.  It seems to me that if the Shuttle
cockpit was designed in a similar fashion, it wouldn't matter if the rest of
the shuttle had disintegrated, as long as the section containing the
astronauts was relatively intact.  A small drogue 'chute could prevent the
cockpit section from tumbling wildly and slow it sufficiently to enable a
survivable impact with the sea.  If this approach was used, then you wouldn't
need an array of fancy explosive bolts and associated equipment that could
go off when you didn't need it.
  It seems that everyone wants to spend tremendous amounts of cash on massively
difficult projects that have a miniscule chance of being useful.  Why not try
something simple for a change.

Andy Greenshields [[e-mail]]

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

Date: 18 Mar 90 19:15:56 GMT
From: mephisto!eedsp!chara![e-mail]  (Donald J. Barry)
Subject: Use of HST guide-star sensor data for astrometry

Henry Spencer wrote that the guide-star tracking data from the HST
was probably to be used for astrometry.

It is -- the results will be of finer dimension than Hipparcos.  The
principal investigator is Otto Franz of Lowell Observatories, who
is a collaborator with us in our Speckle Interferometry program.  The
guide-star lock data will be part of the "engineering science stream"
relayed to earth, and will be archived and used to update and refine
positions and precessional motion on the guide-stars, and also to
search for duplicity among these objects.

It's interesting to note that it was a major political battle just to
ensure that the "engineering science" was separated from the "image
science", so that the guide-star tracking data would not be held back
for a year as part of an investigator's privileged datasets.  There
wasn't antipathy -- only bureaucratic inertia to overcome in making sure
this data was separated and archived separately as part of a coherent
record.

--
Donald J. Barry       [phone]         | [e-mail]
Center for High Angular Resolution Astronomy | President, Astronomical
Georgia State University, Atlanta, GA 30303  | Society of the Atlantic

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

Date: Sun, 18 Mar 1990 22:17:30 PST
From: "Mike Hewett" <[e-mail]>
Subject: Challenger Report question

I understand that Feynman wrote an addendum to the report that
put stronger blame on the parties involved.  I recently checked
the Challenger Commission report out of the library and Feynman's
addendum was not in it.  Does anyone know where I could find it?

If you haven't done it yet, I highly recommend reading the report.
It has all the pertinent information, great pictures, and absolutely
the best writing on a scientific subject that I have ever read
(apologies to Stephen J. Gould, who formerly held the top spot
on my list).  I expected to spend a week wading through semi-coherent
writing.  In fact, I finished it in one evening and was spellbound
the entire way through.

Mike Hewett
([e-mail])

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

Date: 18 Mar 90 19:08:58 GMT
From: mephisto!eedsp!chara![e-mail]  (Donald J. Barry)
Subject: Re: Resolving Power of Hubble Space Telescope

Dan Briggs-  Your point is well taken; I suppose we all are proud of
our achievements in the field, and sometimes our claims take on
a tone of superiority.

Dan Fischer -- we are not studying stellar diameters -- I think
you are confusing our speckle work with that of John Davis, et al.
and the Narrabri Stellar Interferometer of the early 70's.  The
current speckle interferometry work is that of binary surveying -- we
have spent some 150 observing nights on 4-m class instruments over
the last ten years, making some 11,000 measures of binary stars.  We
are determining visual orbits to integrate with spectroscopic orbits
to study mass functions, distance scales, and stellar evolution.  The
data is not processed with true imaging techniques, but rather limited
imaging techniques that make use of the knowledge of the source as a
collection of points.  We have done true imaging, using modifications
of "Shift and Add" (Bates, 1978), but have avoided to date Knox-Thomson
because our camera is probably too noisy to give us good convergence.
Until we have better reproducibility in this realm of processing,
though, we won't publish -- we've got enough stellar papers in the
works, anyway.  (Do you feel as I do that too many people are publishing
imaging results with poor reproducibility?)

The array interferometer we consider likely to be funded within this
year -- if so, we'll have first light through it by the beginning of
1994.  The magnitude limits will not be so impressive as those you
claim for the VLT and its cousins, but those numbers also assume
workable development of adaptive technology which is still in its
infancy.  We are trying to be conservative until this exciting
technology is better known.  In any events, the instruments will
complement one another -- the VLT array in light grasp, and the
CHARA array in resolution.  John Davis' proposed array in Sydney
will yield yet greater resolution, but at lower (magnitude 8) limit.

Although speckle masking permits easier phase identification, and
makes reconstruction algorithms much more robust, it's good to
remember that Fienup showed that almost every type of source can
be reconstructed unambiguously from intensity information alone.

I'll wait expectantly to hear the progress of the interferometric
capability on ESO's new telescopes.  This is an exciting, growing
field for all of us.  Best of luck with your progress.

--
Donald J. Barry       [phone]         | [e-mail]
Center for High Angular Resolution Astronomy | President, Astronomical
Georgia State University, Atlanta, GA 30303  | Society of the Atlantic

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

End of SPACE Digest V11 #162
*******************