Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_1/V11_153.TXT

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Subject: SPACE Digest V11 #153

SPACE Digest                                     Volume 11 : Issue 153

Today's Topics:
               Re: NASA SR-71's
       Re: Shuttle escape systems, was Challenger's Last Words
            U.S. Coast Guard GPS Broadcast
        Re: Resolving Power of Hubble Space Telescope
     Re: SPS cost-effectiveness (was Re: Large vs. Small scale.)
                Sandia Railgun
      What happened to the satellites retrieved by the Shuttle?
----------------------------------------------------------------------

Date: 15 Mar 90 15:46:27 GMT
From: zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!IDA.ORG!pbs![e-mail]
Subject: Re: NASA SR-71's

In article <[e-mail]>, [e-mail] (Mary Shafer (OFV)) writes:
> In article <[e-mail]> [e-mail] writes:
>
>>It is my understanding NASA will be receiving three SR-71's for high
>>altitude research.  With the proper sensors installed and aided by inflight
>>refueling, could one of these make a nonstop flight around the world, passing
>>over the North and South Poles to study the holes in the ozone layer?  This
>>would be an aviation first.  It would also tie in with NASA's Mission to Planet
>> Earth.
>
> Not "high altitude research" in the sense of research into the higher
> altitudes, but rather in high-altitude _flight_ research.  The
> aircraft are at the Ames-Dryden Flight Research Facility, which is
> involved in research in the behavior/dynamics/etc of aircraft.
> Atmospheric research is based at Ames-Moffet, using slower aircraft.
> They're doing a good job, so why use something as expensive as the
> SR-71, just for "an aviation first"?
>
> I wouldn't rule out atmospheric sampling, but running a hot Mach-3
> airplane through your sample space may distort the results you're
> looking for.
>
> We're probably going to be hesitant to modify the airplanes enough
> to do this, too.
>
>> As another possible use for these Blackbirds, why not launch Pegasus from
>>them at 80,000 feet plus instead of from a B-52 at only 40,000 feet?
>
> Because Orbital Science Corp. can't afford to pay for the required
> analysis, wind-tunnel testing, aircraft modification, envelope
> expansion, and operational costs.  We're talking about _really_
> expensive here.  You don't just hang Pegasus on the SR-71 (to begin
> with, there's nowhere to hang it), take off, and launch.


I agree there IS nowhere to hang it, but I had in mind carrying it piggyback
like a recon drone.  However, some postings in the military newsgroup suggest
this may not be such a hot idea either.   (PStinson)

>

> The B-52 is available, already configured and tested, and cheap.  OSC
> is using it because they can't afford to modify and clear any
> aircraft, even a third-hand one, so there's no way they'd be able to
> afford the SR-71.  We won't do it; it's not our problem.  Besides, we
> can't afford it either.
>
> Look, all you purists don't want NASA involved in space anyway.  You
> can't suddenly decide to include us, just because we just got a nifty
> airplane that you think would be neat to use.  :-)  (Jealousy, pure
> jealousy.)
>

I am not one of those purists.  I believe NASA should be involved in space.  I
hope that NASA will not loose the spirit of imagination that lead to such
innovative ideas as Lunar Orbit Rendezvous which was against the conventional
wisdom of its day.  Sombody came up with a bold idea and made it work.
(PStinson)

> --
>
> Mary Shafer  [e-mail] or ames!skipper.dfrf.nasa.gov!shafer
>          NASA Ames Dryden Flight Research Facility, Edwards, CA
>                    Of course I don't speak for NASA

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

Date: 12 Mar 90 18:05:05 GMT
From: nisca.ircc.ohio-state.edu!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!nic.MR.NET!jhereg!orbit!pnet51![e-mail]  (S Schaper)
Subject: Re: Shuttle escape systems, was Challenger's Last Words

From the footage of the disaster, it seemed to me that there was a significant
period of time that the errant exhaust plume could be seen before the
explosion.
 So: Might it not be, that with sufficient sensors to moniter this sort of
accident, the shuttle could be programmed to sep from the stack, with escape
rockets of some sort and do an RTLS? We might unnecessarily loose a few
missions that way and have to recycle, but might'nt it be worth it?
 Or are the dynamic pressures on the shuttle during the SRB ascent phase too
high for an RTLS to work?

UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
ARPA: crash!orbit!pnet51![e-mail]
INET: [e-mail]

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

Date:        Fri, 16 Mar 90 00:19:04 AST
To: [e-mail],
        "Space Digest" <[e-mail]>,
        "NTP List" <[e-mail]>
From: [e-mail]
Subject:     U.S. Coast Guard GPS Broadcast


U.S. COAST GUARD TO START GPS OPERATIONAL ADVISORY BROADCAST
------------------------------------------------------------
The U.S. Coast Guard will begin providing a GPS Operational Advisory Broadcast
(OAB) on a "test and evaluation" basis beginning 20 March 1990.  The broadcast
will originate from the Coast Guard Omega Navigation Systems Center (ONSCEN)
located in Alexandria, VA.  The ONSCEN will receive GPS status messages from the
U.S. Air Force's 2nd Satellite Control Squadron (2SCS) located in Colorado
Springs, CO, and disseminate this information on many existing and new
radionavigation advisory services.  Initially, the advisory services will be
updated on "business days" (Monday through Friday, except Federal holidays)
only.  The hours of live operation will be 08:00 to 16:00 Eastern Time, but the
dial-in services can be accessed 24 hours a day, 7 days a week.

Initially, the OAB will consist of
o  current constellation status (satellites health/unhealthy)
o  future scheduled outages
o  an almanac suitable for making GPS coverage and satellite visibility
   predictions.

Among other methods of distributing the OAB, the following will be used:
o  WWV/WWVH worldwide HF radio broadcasts
o  ONSCEN Computer Bulletin Board: [phone]
o  ONSCEN Voice Telephone Recording: [phone]
The WWV/WWVH broadcasts and the telephone recording do not include almanacs.
These services are scheduled to begin on 20 March 1990, but the computer
bulletin board appears to be available already.

For further information, contact:

Commandant (G-NRN-2)
U.S. Coast Guard
2100 2nd St. S.W.
Washington, DC  20593
Voice: [phone]  Fax: [phone]

(Source: U.S. Coast Guard release)

========================================================================
Richard B. Langley                  BITnet:  [e-mail] or [e-mail]
Geodetic Research Laboratory        Phone:   [phone]
Dept. of Surveying Engineering      Telex:   014-46202
University of New Brunswick         FAX:     [phone]
Fredericton, N.B., Canada  E3B 5A3
========================================================================

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

Date: 14 Mar 90 18:11:54 GMT
From: unmvax!nmtsun![e-mail]  (Daniel Briggs)
Subject: Re: Resolving Power of Hubble Space Telescope

>Daniel Fischer writes an informative and concise article about the
>Faint Object Camera, the current state of speckle techniques, and
>several new telescopes under development by the European Southern
>Observatory.

I have a couple of reactions to what Daniel Fischer just wrote.
Probably the first is, "Whoops!"  I must admit that I completely
forgot about the f/288 mode of the Faint Object Camera, and the plans
to attempt diffraction limited deconvolution there with.  Mea culpa.
(It's been a couple of years since I last read a NASA poop sheet.)

Second point: I freely admit that the VLT is an extremely exciting
development in optical astronomy, and is potentially the most powerful
intrument extant that has assured funding.  But does anyone else but
me feel that the level of discussion is dropping just a bit?  I'm
starting to feel like a kid arguing the merits of his bubble gum card
collection with his rival down the street.  A certain amount of
rivalry is almost certainly a positive motivating factor in science,
but let's not forget that we _are_ all working together, after all.
(No one has been particularly obnoxious about it, but this "my
resolution is better than your resolution" theme is beginning to wear
a bit thin for me.  I couldn't resist twitting Don Barry just a bit
about his resolution claims, myself.  I am at least at culpable as any
of us.)  This shouldn't be taken to imply that instrumental specs
aren't interesting, either.  Just maybe the tone of some of our
postings should be taken down a peg or two.

Enough of that.  Dan Fischer mentioned something that caught my
interest.  He mentions the stationary speckle pattern of the FOC, and
then talks about a roll deconvolution.  Could we get a few more
specifics on this technique?  It is two images, one rotated by some
angle with respect to the other?  Is there a particular angle that
optimizes the deconvolution process?  Does one deconvolve by using the
rotated images as contraints in some sort of Maximum Entropy style
process, or does one solve for the PSF first?  If the optics of the
telescope are as stable as we are lead to believe, shouldn't the Point
Spread Function of the scope be a measurable quantity?  I am certain
that ground based scopes routinely measure this prior to
deconvolution.  Once this is in hand, then deconvolution is downright
easy.  (You can take your pick of methods, but even a Hogbom CLEAN
works pretty well.)  There must be a good reason why HST doesn't plan
to do it, "the simple way".  Here are a few thoughts on why not.  1)
Difficulty in finding a calibrator source.  I should think that any
reasonably strong star would do it, other than our closest neighbors.
Field stars shouldn't be too much of a problem, given the 7.5 arc
second field of view.  (Besides, look out of the plane to minimize it
further.)  2) The optics are stable (if irregular on this scale), but
the mechanical structure isn't?  Does the PSF change dramatically as a
function of pointing.  (Ie., any gross motion of the telescope).
Change badly, or change somewhat?  3) There are dominant components to
the PSF that come from the the filter wheels, so one would need a
different PSF for each for each filter combination.  This could get
expensive in observing time.  (Doesn't strike me as really likely, but
I dunno.)  4) The PSF changes every time that the high resolution
apodizer is switched out of the beam and back.  5) None of the above.
Does anyone know the answer, or care to speculate?

BTW.  No flames were intended in this post, so I apologize if I have hurt
any feelings.

-----
This is a shared guest account, please send replies to
[e-mail] (Internet)
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)

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

Date: 15 Mar 90 14:29:21 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!sunybcs!uhura.cc.rochester.edu!rochester![e-mail]  (Paul Dietz)
Subject: Re: SPS cost-effectiveness (was Re: Large vs. Small scale.)

I wrote:
>>This isn't obvious to me, Russ.  Yes, you won't need big vacuum
>>chambers (although one would still need a gas-tight vessel for some
>>processes, like deposition of a-Si:H from a plasma),

Russ Cage wrote:
>I doubt that such processing would be used.  It would be much simpler
>to vaporize elemental silicon with a solar furnace and deposit it on
>a substrate.  It could be doped either while being deposited or
>afterward, by ion implantation.  No pressure chambers required.

But this doesn't work very well.  Amorphous silicon cells contain
significant amounts of hydrogen to terminate "dangling bonds".  If
these bonds are not passivated they act as centers for the
recombination of electrons and holes, which reduces cell efficiency.

>>but other costs
>>will be much higher than for ground-based manufacturing.
>
>Some of them will be.  Some will be exactly the opposite.  For instance,
>process heat will be INCREDIBLY cheaper.
...
>lunar samples ran about 20% FeO by weight.  Assuming 1 MT/yr of regolith
>into orbit, I calculated how much power it would take to break down 200
>kT of FeO into Fe and O each year.  I got a figure of about 24 megawatts.
>If the objective is to produce multi-GW powersats, making 24 MW of power

Manufacturing is only as strong as its weakest link.  The cheap parts
will not dominate the cost.  In PV cell manufacture energy is not the
dominant cost.  In space, I think other costs will dominate.  Even at
current electricity prices (for example), 24 megawatt-years is only
about $18 M, or about $.16/pound of iron (to use your example).

>>The cost of
>>keeping people in orbit is currently on the rough order of $100K *per
>>hour*.  Even if you drop that by a factor of 100, space-based labor
>>will still be extremely expensive.
>
>I think I know where you got that number:
>
>($100K/crewmember-hr)*(24 hrs/day)*(11 days)*(7 crewmembers) = ~$185,000,000
>
>or on the rough order of the price of a Shuttle launch, with the
>capacity of a Shuttle crew and the length of a Shuttle orbital stay.

I think a shuttle launch is more expensive than that, if you add
in all the overhead.  If I recall correctly, the part of the NASA
budget devoted to operating the shuttle comes out to something like
$3 B/year, or $300M per flight at 10 flights/year.

I also question the assumption that a person can work 24 hours a day
for 11 days straight.

With those two corrections, it's more like $300 M / (12 x 7 x 11)
or about $320 K per hour.   EVA is even more expensive.

>Guess what?  You're comparing apples and oranges.  Having people work
>a 3-year hitch, with NO OTHER CHANGES, drops the cost by two orders
>of magnitude right there.  They will go up on cheaper vehicles or in
>bigger groups; a 50-seat Spacelab-style "Shuttle Bus" module could
>certainly be built, and would cut personnel launch costs by nearly
>another order of magnitude.  We're already down to investment banker
>wage costs, without yet replacing Shuttle as the launcher.

But -- these people will have to work in high orbit, not in low earth
orbit.  So double this cost to bring up the fuel needed to get them
and the nonrecycled consumables to high orbit, and shield their living
quarters so they aren't over-irradiated.  A 3-year hitch could require
a rotating structure.  Yes, eventually ET resouces let you do that
more cheaply, but didn't that Rockwell study show that lunar
propellant production only broke even after some very large amount of
LOX had been produced?

>Without looking at all the angles and opportunities for economies,
>you can't make realistic projections of the cost of SPS.  I lean
>toward the L5/SSI/LLNL-type thinkers on this one, they are more
>often right about the technical details and possibilities.

Paper is a wonderful construction material.

I think we will see massive space industry, some day.  But I think
you seriously underestimate the problems and the investment required.

    Paul F. Dietz
    [e-mail]

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

Date: 15 Mar 90 19:40:16 GMT
From: MATHOM.GANDALF.CS.CMU.EDU![e-mail]  (Donald Lindsay)
Subject: Sandia Railgun


Seen in a recent magazine:
------------
Sandia National Laboratories is testing a prototype of an
electromagnetic gun, a full sized version of which could be used to
launch vehicles into orbit for a fraction the cost of current
rockets. The device, a staple of SF for years, has been proven
feasible using a new computer program, ironically called Warp-10,
which has proven the validity of the design principles, and the
arrival of a new generation of electrical capacitors.

Current prototypes hurl 10 pound projectiles half a mile at the speed
of an artillery shell. Sandia has applied for funding for a 10-stage
launcher to accelerate an 850 pound projectile behond the atmosphere,
at which point a rocket engine would fire to push it into orbit.

The Sandia prototype solves the problem of wear on the launcher by
eliminating contact between the system and the projectile. Set to
spinning at 100 rotations per second, the projectile floats through
the system's rings using a girdle of metal. For a full-size launcher
a heat shield will be needed because of the intense heat generated
when the vehicle is accelerated to a speed of 2.8 miles per second.

Finally, although the projectile will experience an initial force of
1,000 to 2,000 G's, this is mild compared to the 30,000 G's an
artillery shell is subjected to when fired from a cannon.
------------

If anyone out there knows more, please post. What is this "girdle"
trick? How do you build a multistage gun? - And like that.
--
Don        D.C.Lindsay     Carnegie Mellon Computer Science

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

Date: 16 Mar 90 00:52:57 GMT
From: cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!mips!rapid.Berkeley.EDU![e-mail]  (Greg Shippen)
Subject: What happened to the satellites retrieved by the Shuttle?

Whatever happened to the satellites that at least one pre-Challenger
shuttle mission retrieved from orbit?  As I recall at least two were
retrieved.  At the time, this was touted as an opportunity to reuse
these satellites.  Did this really happen?  Were they returned in
working order
or did they end up being damaged during launch and/or retrieval?

Gregory B. Shippen
MIPS Computer Systems, Inc.                    {ames,decwrl,pyramid}!mips!greg
928 Arques Ave.                                [e-mail]
Sunnyvale, CA  94086 [phone]

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

End of SPACE Digest V11 #153
*******************