Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V13_3/V13_362.ZIP/V13_362

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Subject: SPACE Digest V13 #362

SPACE Digest                                     Volume 13 : Issue 362

Today's Topics:
              Re: SPACE Digest V13 #344
     New GIFs available in the SPACE archive on ames.arc.nasa.gov
        Unofficial Ariane Launch Manifest (April 1991)
                SIGN ME OFF!!
                flares
                Re: Mt. Venus
         Why does every SAR have another resolution?
         Re: Air Force small launch contract
       Re: Why does every SAR have another resolution?
       Another Dinosaur Barfs (Was Re: How 'bout them Titans?)
           Re: Advancing Launch Technology

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: 4 Apr 91 21:17:59 GMT
From: orca!bambam![e-mail]  (Bob Pendleton)
Subject: Re: SPACE Digest V13 #344

In article <[e-mail]>, [e-mail] (Bob Pendleton) writes:

> One of the reasons I don't think chemical rockets have topped out is
> that ideas like this one have been around, and practical, since the
> 1930s and know one has even tried them.
            ^^^^^^^^

Of course this was supposed to be "no one." I'm not sure if this is
the worst typo I ever came up with or if it is some sort of a
Freudian slip.

--
              Bob Pendleton, speaking only for myself.
   [e-mail] or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet

                         Tools, not rules.

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

Date: 5 Apr 91 05:51:16 GMT
From: [e-mail]  (Peter E. Yee)
Subject: New GIFs available in the SPACE archive on ames.arc.nasa.gov

Ever wanted to touch the Space Shuttle?  Walk around it and look at different
parts in minute detail?  Well, here's your chance.  I've just completed
scanning in various photos of the Shuttle (interior and engines) that were
provided to me by Ken Hollis down at KSC.  These photos go into the gory
details of the switch panels and engine parts.  In addition to these
photos, I've also scanned in a couple of photos from the Hubble Space Telescope
deployment and a couple of Atlantis landing at Edward AFB.  All of these
scans are in GIF format and may be obtained via anonymous ftp to
ames.arc.nasa.gov, directory /pub/SPACE/GIF.  All photos are named by their
label numbers, with the shuttle parts being named ksc*, the HST photos are
s31*, and the landing photos are ec*.  Descriptions of the photos (not always
useful) are found in corresponding files with a .txt extension.

Problems with archive operations or access should be sent to me.

                            -Peter Yee
                            [e-mail]
                            ames!yee

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

Date: 3 Apr 91 22:31:34 GMT
From: agate!bionet!uwm.edu!spool.mu.edu!munnari.oz.au!yoyo.aarnet.edu.au!sirius.ucs.adelaide.edu.au!levels![e-mail]
Subject: Unofficial Ariane Launch Manifest (April 1991)


Here is the Ariane launch manifest that was published in the October 1990
issue of Spaceflight. Since V42 was delayed V43 was shifted into April.
I am guessing that V44 will shift into May and that the rest of the manifest
remains the same.

Flight    Date       Vehicle   Payload
-------------------------------------------------------------------------
 V40    20 Nov. 90   Ar 44P    Satcom C1, Gstar 4
-------------------------------------------------------------------------
 V41    15 Jan. 91   Ar 44L    Eutelsat II-F2, Italsat 1
 V42    18?Mar. 91   Ar 44LP   Astra 1B, MOP-2
 V43       Apr. 91   Ar 44P    Anik E1
 V44       May  91   Ar 40     ERS-1, Datasat X, Tubsat, Uosat F, SARA
 V45       Jun. 91   Ar 44L    Intelsat VI-F5
 V46       Jul. 91   Ar 44LP   Eutelsat II-F3, Inmarsat II-F3
 V47       Sep. 91   Ar 44P    Anik E2
 V48       Oct. 91   Ar 44L    Intelsat VI-F1
 V49       Nov. 91   Ar 44L    Superbird E, Inmarsat II-F4
-------------------------------------------------------------------------

Notes:
1) The payloads for V46 and V47 may swap.
2) In V49, Superbird E has a relaunch priority. Telecom 2A may
   substitute for the V49 payload.

--
Steven Pietrobon, Australian Space Centre for Signal Processing
School of Electronic Engineering, University of South Australia
The Levels, SA 5095, Australia.          [e-mail]

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

Date: Thu, 04 Apr 91 11:01:08 CST
From: [e-mail]
 (<[e-mail]>)
Subject: SIGN ME OFF!!

     I have tried and tried to get signed off of this listserv.  I REALLY like
the space-request listserv, but I have NO time for it now....maybe later.  I
have been trying to get taken off of it for almost a MONTH and still nothing.
PLEASE take me off of the list.
     THANK YOU.

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

Date: 4 Apr 91 17:40:48 GMT
From: agate!stanford.edu!snorkelwacker.mit.edu!usc!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: flares

In article <[e-mail]> [e-mail] (Kent P. Iler) writes:
>... It was that a major flare could cause serious injury-even death-
>to any astronauts in orbit at the time of the resulting storm.

Soviet cosmonauts have been aloft during all the major flares of the last
few years, and at least one shuttle mission happened to be up at the time
of one too.  They did get more radiation than usual, but I don't believe
there is major risk, unless perhaps we got the great-granddaddy of all
flares.
--
"The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 are all true."  -D. Harrison|  [e-mail]  utzoo!henry

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

Date: 5 Apr 91 04:58:24 GMT
From: theory.tn.cornell.edu![e-mail]  (Paul Schinder)
Subject: Re: Mt. Venus

In article <[e-mail]> [e-mail] (Christopher Neufeld) writes:
>   So, putting my hand to these equations, using the adiabatic model for
>atmosphes, as recommended in an undergraduate course I once took, I get,
>using P0 = 9E+6 Pa, T0 = 800K, g = 8.87 m/s^2, molecular weight = 44,
>gamma = 7/5:
>P(h=914m) = 85 atm
>T(h=914m) = 787K
>
>   Something looks funny about this, but the equation does say that the
>atmosphere ought essentially to disappear at 50km altitude, and that
>doesn't seem completely unreasonable. Maybe somebody could check my
>numbers, just to be on the safe side.

The numbers are:

        at 0 km:  P = 93.0 bar, T = 731K
    at 10 km: P = 47.5 bar, T = 650K
    at 50 km: P = 0.97 bar, T = 346K

The sensible atmosphere extends to about 100 km.  These numbers were
computed using a mean fit by Young et al. (J. Atmos. Sci., 44, 2628)
to actual spacecraft measurements of the atmosphere.  The atmosphere
is not quite adiabatic because of the sun and it's own thermal
radiation (simple radiative equilibrium models give good agreement
with what's observed), and has at least one planetary scale convective
region.  This probably accounts for the failure of the simple
adiabatic model.

>--
> Christopher Neufeld....Just a graduate student  | Flash: morning star seen
--
Paul J. Schinder
Department of Astronomy, Cornell University
[e-mail]

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

Date: 4 Apr 91 13:05:35 GMT
From: math.fu-berlin.de!fauern!unido!mpirbn![e-mail]  (Daniel Fischer)
Subject: Why does every SAR have another resolution?

From NASA NEWS RELEASE 91-34 of February 27, 1991 on the RADARSAT spacecraft:
> The satellite's synthetic aperture radar (SAR) will be ... scanning the
> Earth in swaths varying from 50 to 500 km. The SAR will produce high-resolu=
> tion (10 to 100 meters pixel size) images of the Earth's surface...

Now we all know that the Magellan in its orbit around Venus produces swaths
some 25km wide, with a resolution of approx. 120 meters. Why can the resolution
of RADARSAT's SAR be so much better, about a factor of 10? This can't be due
to a lower orbit alone, I presume. Also, why can RADARSAT have many more
pixels across the swath's width (according to this article 5000) compared to
Magellan (200)? Does that depend on their antennas or on the data processing?

Furthermore, there are rumors that the Lacrosse satellite's SAR can resolve
features down to 1 meter in size (how official is that?).

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

Date: 4 Apr 91 16:18:30 GMT
From: agate!bionet!uwm.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Air Force small launch contract

In article <[e-mail]> [e-mail] (Vincent Cate) writes:
>Assuming this is true, does anyone know why?  It seems there are a
>number of companies bidding on the Motorola replacement launches and
>I would think these same companies would be interested in the Air Force
>contract too.

Maybe OSC is the only one that can stomach the government paperwork... :-)
--
"The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 are all true."  -D. Harrison|  [e-mail]  utzoo!henry

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

Date: 4 Apr 91 17:38:32 GMT
From: rex!samsung!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Why does every SAR have another resolution?

In article <[e-mail]> [e-mail] (Daniel Fischer) writes:
>Now we all know that the Magellan in its orbit around Venus produces swaths
>some 25km wide, with a resolution of approx. 120 meters. Why can the resolution
>of RADARSAT's SAR be so much better, about a factor of 10? This can't be due
>to a lower orbit alone, I presume. Also, why can RADARSAT have many more
>pixels across the swath's width (according to this article 5000) compared to
>Magellan (200)? Does that depend on their antennas or on the data processing?

Radarsat's main advantage is a much bigger, and custom-built, antenna.
Magellan is SAR on the cheap, using hardware out of NASA's junkbox.  An
important secondary issue is the ten years or so that separates their
design efforts.

I also wouldn't be surprised if Radarsat is quite a bit heavier, although
I don't have numbers handy.

>Furthermore, there are rumors that the Lacrosse satellite's SAR can resolve
>features down to 1 meter in size (how official is that?).

The official word is "Lacrosse?  What's that?".
--
"The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 are all true."  -D. Harrison|  [e-mail]  utzoo!henry

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

Date: 3 Apr 91 02:29:34 GMT
From: unisoft!fai!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Another Dinosaur Barfs (Was Re: How 'bout them Titans?)

In article <[e-mail]> [e-mail] (Mary Shafer) writes:

>[Titan IV looks pretty]

How about those Dinosaurs (oops, I mean Titans)?  Yes, $300+ million in a
ball of smoke sure looks pretty, if you are into expensive fireworks
shows, and don't care too much about reliable transporation.  Titan IV
costs will now rise to Shuttle levels, and we will be lucky if Titan
IV can catch up to Shuttle's reliability %.  So much for the "expendable
vs. reusable" debate.  In the long run, they are both losers, and those
of us who want to get our payloads into orbit are the biggest losers of
all.

It's time for USAF to go to smaller, more redundant payloads and launchers,
and start looking at the alternatives to chem rockets.  These dinosaurs
are history.


>Before everyone gets excited and blames the wound casing,
>[metal fails too]

Wound casing or metal, they both fail far too frequently for reliable
transportation.  No, I'm blaming $tens of billions down the tubes for
chemical rocket research, money that could have been much better spent on
the basic science behind superconductors, gas guns, lasers, et. al.  Well,
that's all water under the bridge, but the future lies ahead -- let's
do it right this time!


--
Nick Szabo            [e-mail]
"If you want oil, drill lots of wells" -- J. Paul Getty
The above opinions are my own and not related to those of any
organization I may be affiliated with.

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

Date: 2 Apr 91 18:09:55 GMT
From: unisoft!fai!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: Advancing Launch Technology

In article <[e-mail]> [e-mail] (Walt Leipold) writes:

>What *are* the absolute minimum costs of a a *practical* EML system? ....

[a reasonable analysis]


>For
>the sake of discussion, let's assume a modest 500g acceleration in a purely
>horizontal launcher....

We can actually get much more than this right now in the lab, but
perhaps this is a good number for a system with low materials
costs.


>Energy: [$1/lb.]

Reasonable for EML.  Depending on the fuel used, a light gas gun might
lower this by a factor of 5, since electricity is a fairly inefficient form
of energy.


>Hardware:
>
>How much does a linear foot of high-capacity, reliable, maintainable,
>weatherproof railgun cost?  Ten thousand dollars?  If so, your 26-km
>railgun will cost $850 million dollars.

To avoid wear, a coilgun is probably a better option than railgun.
The above estimate is also pretty good for a first generation
coilgun; Sandia projects $1,0000 million for the whole first-generation
project.  At least two possible technical advances, if they pan out, could
greatly reduce this cost for subsequent projects:

* Building practical systems at >500g
* Mass-produced warm superconductors

Given these, we could go down to 10 km and $1,000/foot, or $32 million.
But currently, $850 million is pretty good estimate for the first-generation
system.


>Real estate:
>...I'll assume that this piece of land will cost about $100 million

The best thing to do might be to bridge the gun across several used
oil tankers or platforms, hundreds of miles away from inhabited areas, to
avoid noise pollution.  This could also cost up to $100 million.


>Management:
>
>We'll assume a revolution in management styles gives us an administration
>cost of only $4 million/month....

This doesn't take any management revolution, since many smaller airports,
handling much larger amounts of cargo, operate at an overhead of $4
million per _year_.   However, $4 million/month sounds reasonable for
the first generation project.


>Liability insurance is a big unknown....

Not necessarily.  Insurance costs are based on reliability, which
in guns is typically 2-3 orders of magnitude greater than for rockets.

>[total cost of] $9/lbm doesn't sound like a lot, but remember that this
>kind of rough estimate was used to predict $100/lbm for the Shuttle a
>couple of decades ago....

Well, if you want to doom _any_ attempt to lower launch costs based
on one NASA chem rocket project, there's not much to say about that....

But there are many, many differences between EML and yet another chemical
launcher like the Shuttle:

* Even your projection, which contains several pessimistic assumptions,
  is 10 times lower than any chemical rocket launch projection, and is
  500 times lower than realistic rocket launch cost projections and
  actual rocket launch practice.

* A totally different technology: fuel is not stored on board.
  Shuttle is, when all is said and done, another chemical rocket,
  which follows the curve of costs for internally chemical powered
  vehicles.

* The first EML is to be designed be Sandia, not NASA, and subsequent
  EML's should be designed, owned and operated privately.  Therefore, we
  will avoid aerospace/chem rocket world concepts of launch cost and
  operation.

The choice is between large ($4-5 billion) chemical rocket
projects, which are proven incapable of significantly lowering launch
costs, or smaller ($100-$500 million) R&D/prototyping projects to
demonstrate a whole suite of new technologies (gas gun, EML, laser
launch, etc.).  If EML passes this phase, we would go to a $1 billion
first-generation system, which would dramatically and quickly lower launch
costs.  We can introduce a greatly superior technology for less than
the cost of building yet another chemical rocket.  This is a whole new
ballgame.


--
Nick Szabo            [e-mail]
"If you want oil, drill lots of wells" -- J. Paul Getty
The above opinions are my own and not related to those of any
organization I may be affiliated with.

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

End of SPACE Digest V13 #362
*******************