Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_1/v11_178.txt

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Subject: SPACE Digest V11 #178

SPACE Digest                                     Volume 11 : Issue 178

Today's Topics:
  Supercapacitors?? (was Re: The Amazing technicolour flying coilgun
       Re: Shuttle escape systems, was Challenger's Last Words
              Re: Strange flash of light
               Re: Spacecraft on Venus
          heard about the Challenger Center?
      Re: NASA Finds Major Flaw in Space Station Design
           Payload Status for 03/22/90 (Forwarded)
             Re: Intelsat / Titan failure
----------------------------------------------------------------------

Date: 22 Mar 90 05:20:44 GMT
From: sam.cs.cmu.edu![e-mail]  (Vincent Cate)
Subject: Supercapacitors?? (was Re: The Amazing technicolour flying coilgun


Brian Ross:
>I have been following this discussion about the use of a coil gun on a 747 or
>similar aircraft with interest.  However many have disparaged the idea because
>of the inability of most (if not all) present aircraft to either fly
>high enough or fast enough and be able to absorb the recoil of the gun when
>it fired.  I would have thought the obvious solution would have been to
>design and build a brand new aircraft, which *uses* the coil gun as a major
>structural member.

The recoil is not a problem.  A 747 can weight 1,000,000 lbs.  The
projectile we are talking about is in the 20 lbs to 200 lbs range.
With a gun of reasonable mas that can recoil, the plane will not
have much stress at all (can keep it under 1/10G without even
letting the gun move very far).  When a 747 accelerates on takeoff,
or slows down after landing, it is doing well over 1/10G.

If you are willing to live with 50,000 Gs, the gun need only be 100 feet
long (i.e. it fits in a 747).  For a number of payloads these high Gs should
be fine.

The height a 747 can get to is really above most of the air.  There will
be less and less benefit from going higher.

All of that said, yes a brand new aircraft could make things easier.
The reason not to is simply that it would add to the cost, risk, and
time to usable system.  If a 747 (or C5, or ...) works we are much
better off using it.  If all we need to do it put a coilgun on a 747
we could do this in a couple of years.  If we need to design and build
a blimp or new super plane we will have to wait for some time to get
the $20/lb.  If we have to, we could make a new plane, but...

The big question right now is how heavy is a device to store the energy
coming out of the generator.  Since this energy needs to be used by the gun
in only a few milliseconds the device must act like a capacitor.  The
only ones I have found are so heavy that we would be limited
to about 20 lb projectiles.  This is large enough to be encouraging but it
would be much nicer at 200 lbs.  Someone said they thought the energy
storage problem was solved.  Does anyone have any details of things
like how many J/kg or kw-hours/kg these storage devices have?

The number to beat is 20 kJ/kg  (a WIMPY 5 watt-hours/kilogram!!!!)
Anyone know of anything better?

   -- Vince

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

Date: 22 Mar 90 00:18:12 GMT
From: hp-pcd!hpcvia![e-mail]  (ken_scofield)
Subject: Re: Shuttle escape systems, was Challenger's Last Words


>If you are interested in how the parachute aspect of the shuttle escape
>system works, I recommend finding an isuue of Parachutist magazine for
>March '90.  The lead article is on this subject! Has some interesting
>pictures of people testing the system on a Mock-up build into a c-141.
>
> ...
>
>Barry Brumitt
>"Who is John Galt?"
>[e-mail]

  Darn, ya beat me to it -- I was just gonna post this same info ;-).

  However, I decided to post anyway, to bring up an interesting and confusing
  comment made in the aforementioned article.

  To quote a brief passage of the article:
       "Realistically, opportunities to survive an emergency exit from the
    shuttle only present themselves twice during the normal flight profile,
    during liftoff or during landing..."

  And another (longer) passage further on in the article, where a launch-phase
  separation is being discussed:
       "To make the environment outside the crew escape hatch a little
    friendlier, you first separate the orbiter from the two SRB's and the
    fuel tank, a task easier discussed than done.  (In early tests
    conducted by NASA, it was determined that the shock wave formed by the
    nose of the fuel tank, or the [SRB] exhaust plume ... would destroy
    the orbiter the instant the escape process began.)"

       "It has only been during recent tests that a fly-away escape profile
    for the launch phase has been developed by NASA's staffers at Langley
    Research Center in Virginia, to make this kind of separation a
    possibility.  But it's sort of like letting go of the tiger's tail: it
    has to be done carefully."

  And finally:
       "...The escape 'profile' is all done through an on-board computer..."

  So, all you NASA types and other shuttle experts, what do you make of this?
  Was the author of this article somehow woefully mislead, or has someone
  actually devised a workable [albeit difficult] plan for orbiter separation
  during SRB burn?  I've excerpted all the pertinent info given in the article;
  can someone fill in any more detail of how it would be done?

             *
            / \
       |---/---\---|            Ken Scofield    C-9355  SSI #453890085
       |   Gone    |            Hewlett-Packard, ICO
       | Divin' or |            1020 NE Circle Blvd.
       |  Jumpin'  |            Corvallis, OR  97330
       |-----------|            Phone:  [phone]
            ucbvax!hplabs!hp-pcd!kas
                        [e-mail]

Cute Disclaimer:  Nobody ever listened to me before, so why start now?

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

Date: 21 Mar 90 09:32:41 GMT
From: zaphod.mps.ohio-state.edu!uwm.edu!lakesys![e-mail]  (Joseph T. Klein)
Subject: Re: Strange flash of light

In article <[e-mail]> [e-mail] (Will Martin) writes:
>I and a couple of my guests saw the same flash of light Saturday night
>(Mar 17, approx 9:30 PM CST).  However, we saw it through windows and were
>not looking directly at the sky or the source, so only had a brief
>flicker of impression.  The color appeared to me to be *blue-white*,
UPI reported that a white flash was seen over a three state area. This
strange event has not been discussed by the space/astronomy word, yet is
has is being eaten up by the UFO nuts. Check out cross listing from people
who carry clarinet (they have the UPI story.)
This is an odd event. Why do the space/astro people shy away from talking
about these events? The silence lets the whackos think the scientific community
is covering things up.


--
 "The place of the deity seems to be           Joseph T. Klein
  taken by the wholeness of man." -- Jung      [e-mail]
Riverwest Milwaukee  {uunet!marque,uwvax!uwm}  !lakesys!rwmke!jtk

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

Date: Wed, 21 Mar 90 15:04:03 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Spacecraft on Venus


>Date: 21 Mar 90 00:44:23 GMT
>From: sco![e-mail]  (John DuBois)
>Subject: Re: Spacecraft on Venus

>     How about a thermoelectric generator that uses the temp. diff. between
>Venus surface ambient and and a cold source?  I seem to recall that some
>Venus landers (Soviet?) boil off their remaining thruster fuel just before
>atmosphere entry to cool down the spacecraft to extend its life on the
>surface.  A "hot" lander wouldn't need it for that purpose; perhaps the
>remaining cryogenic fuel (of course, you'd need to ensure that plenty remained)
>could be used as a cold reservoir.  Probably not too efficient, but at least
>you could be sure that your power source wouldn't *add* heat to the lander.

I don't think it would work too well for the application described in the
original message, which was building a Venus lander capable of running for
a long time. Like the flashlight that projects a beam of darkness, a method
of storing or producing large amounts of "coldness" has not been found.

Landers that have been used to date *do* use a cold source (or thermal
inertia) to keep the electronics cool, but they only work for a few hours
at best. Over that period it's much more efficient to use batteries for power,
and reserve the "cold source" for keeping the system cool. (Thermocouples are
not very efficient.)

The point of the design approaches several of us have been proposing is that
landers which run *hotter* than ambient temperature could in principle last
for months or years. Sources that put out heat over a very long period of
time (i.e. RTGs) are already in existence. Unless you build electronics that
can operate at ambient temperature, you're going to have to actively cool
anyway - it's pretty silly to worry that the power source might cause the
lander to be heated to 800K, instead of staying at a nice, comfortable 750K.
The only major concern is whether it is practical to build a heat engine that
will operate under these conditions, and whether it would be worth the trouble.

The concept of using a heat source to provide cooling is not new. Kitchen
refrigerators have been built and used that are powered by the burning
of natural gas.

  John Roberts                 "The idiotic we do right away. The merely
 [e-mail]      ill-advised takes a little longer."

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

Date: 22 Mar 90 04:42:38 GMT
From: a.gp.cs.cmu.edu![e-mail]  (Mark Maimone)
Subject: heard about the Challenger Center?


    Can anyone post any information about the Challenger Center?  It's a
proposal to set up a network of buildings across the US, dedicated to
teaching schoolkids about space.  I received a six page invitation to become
a "Founding Sponsor" from Senator Jake Garn, thanks to membership in the
Planetary Society.  Those six pages are long on hype, short on content.  I'd
appreciate hearing from anyone who has solid information about the proposal,
like what the existing "Mission Sites" in Texas and Maryland are doing.

--
----------------------------------------------------------------------
Mark Maimone                phone: (412) 268 - 7698
Carnegie Mellon Computer Science    email: [e-mail]
grad student, vocal jazz and PDQ Bach enthusiast

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

Date: 22 Mar 90 17:36:01 GMT
From: idacrd![e-mail]  (Robert McGwier)
Subject: Re: NASA Finds Major Flaw in Space Station Design

From article <[e-mail]>, by [e-mail] (Herman Rubin):
>
> What can anybody expect?  We know very little about the problems of
> space station construction and maintenance.  We will have to learn much
> of it up there.  True, we do have some information from the American
> and Russian small stations, but these have been small enough to have
> been sent up as a unit.
>


This is incorrect.  The KVANT modules, etc. are being brought up one
at a time as they are too large to be boosted all at once.

They are facing EXACTLY the same problems we  will be.  I hope some
data sharing will happen.

Bob

--
____________________________________________________________________________
    My opinions are my own no matter    |    Robert W. McGwier, N4HY
    who I work for! ;-)            |    CCR, AMSAT, etc.
----------------------------------------------------------------------------

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

Date: 22 Mar 90 20:46:30 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 03/22/90 (Forwarded)


    Daily Status/KSC Payload Management and Operations 03-22-90.


    - STS-31R HST (at VPF) -

    Preps for transferring HST into the west cell VPHD were
    completed yesterday.  The actual transfer will occur today.


    - STS-32R SYNCOM/LDEF (at SAEF-2) -

    LDEF deintegration continues.


    - STS-35 ASTRO-1 (at OPF) -

    Payload to orbiter electrical and freon connections were
    worked yesterday and will continue today.


    - STS-40 SLS-1 (at O&C) -

    Systems test post operations and preparations for rack and
    floor installation into the module were worked yesterday and
    will continue today.  Fire suppression bottle installation
    will also continue today during second shift.


    - STS-42 IML-1 (at O&C) -

    Staging activities on racks 7, 10, 11, and 12 were worked
    yesterday.  Staging activities on racks 3, 4, 5, 7, 8, 9,
    10, 11, and 12 are scheduled for today.


    - STS-45 Atlas-1 (at O&C) -

    Pallet joint kit installation on frame 4 was active
    yesterday and will continue today.


    - HST M&R (at O&C)

    ORUC cable installation will continue today.


    - STS-55 SL-D2 (at O&C)

    A Spacelab single rack will be unloaded today.

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

Date: 22 Mar 90 21:51:35 GMT
From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Intelsat / Titan failure

In article <[e-mail]> [e-mail] (Will Martin) writes:
>... The obvious thing that comes to
>mind is the upcoming HST launch. Here's a shuttle going up full and
>coming back empty -- what an opportunity! But is it possible?

Probably not.  The shuttle will be coming back empty, yes, but the "empty"
part includes the fuel tanks as well as the payload bay -- they're going
to be using every drop of fuel they've got to get HST up as high as possible.
Extra maneuvering and carrying a heavy payload cradle are not on the agenda.

>1) So, the shuttle carrying HST into orbit has fittings installed to
>support HST. Would those same fittings interfere with or be usable for
>loading the Intelsat into the payload bay after the HST was out? Will
>the Intelsat fit in the payload bay? Have antennae and solar panels,
>etc., already deployed on the Intelsat that make it too big or too
>awkward to be put into the Shuttle, or can such things be refurled or
>disconnected and discarded in a reasonable fashion?

The Intelsat is probably still tucked up tight for maneuvering; they
don't normally deploy antennas and such until the heavy engine firings
are over.  I'd be very surprised if it wouldn't fit the payload bay.
However, it was not designed for shuttle launch, so supporting it in
the payload bay would not be a simple problem.  (For one thing, a
shuttle payload has to be supported for horizontal flight, not just
vertical flight.)  At the very least you'd need a custom cradle of
some kind.

>2) Is it possible for the shuttle that releases HST to get to the
>location of the Intelsat at correct relative speeds, or are we talking
>"apples and oranges" in terms of orbits here? ...

Unless there is some subtlety I haven't heard about, the orbits should
be broadly compatible.  Both Intelsat and HST want a minimum-inclination
launch from KSC for best fuel economy, which should make the resulting
orbits similar.  Constraints on sun angles and eclipse timings can be
complicated, though, and the orbits may well be similar but 90 degrees
out of phase.

>3) Is it safe to get the Intelsat? I gather from news stories that all
>the onboard fuel is used up...

"Safe" is a relative term.  I think Palapa and Wester retained some
maneuvering fuel, the last time this was tried.  There is also the
question of whether you want to bring it back down or tack a fresh upper
stage onto it and send it on its way.  I very strongly suspect the latter.

>should be a fairly safe inert body to retrieve. But can it be retrieved?
>Does it have handles or hooks the arm can latch onto? Is it rotating?

It will probably be rotating for temperature control.  It has no grapple
points for the shuttle arm, since it was never supposed to be involved
with the shuttle.

>Even if it is physically possible, and the astronauts say "We want to do
>it", and Bush says "Do it" for national-prestige reasons, could it be done?

NASA may be interested in flying the mission, but they're not going to
compromise the HST launch in any way for it.  Given the practical problems,
it's much too late to get it onto that mission.

>As a side issue, a philosophical query -- do we want this capability? Do
>we want to make a space program that can DO things on short notice and
>respond to emergency situations or sudden requirements? ...

Emphatically yes, because emergencies and sudden requirements *do* arise,
and the next one may be more significant than just a stranded comsat.
The notion that you can plan things well enough to eliminate such problems
is a myth, and always has been.

>... Maybe NASA should go get the
>Intelsat as salvage, and sell it back to them and make a profit?

If it is done, almost certainly it will be done because NASA has its own
motives for doing it.  Even combining it with some other normal flight,
the mission is too expensive to make a profit at current satellite prices.
--
US space station:  8 years    |     Henry Spencer at U of Toronto Zoology
and still no hardware built.  | uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V11 #178
*******************