Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO460.TXT

Internet Message Format | 1993-07-13 | 32KB

Date: Thu, 26 Nov 92 05:06:07
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #460
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 26 Nov 92       Volume 15 : Issue 460

Today's Topics:
                         Dante on "Nightline"
                   GPS handheld receivers (2 msgs)
            hypergolics (was Re: Pumpless Liquid Rocket?)
                   manned vs. unmanned spaceflight
Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded)) (2 msgs)
                    Shuttle replacement (10 msgs)

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

Date: 25 Nov 92 17:36:18
From: Steinn Sigurdsson <[e-mail]>
Subject: Dante on "Nightline"
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Thompson Reynolds) writes:

   Just out of curiosity, is there any valid Science being done by this NASA
   "mission" to Antartica, or is this just showboating to get some network
   coverage?  Assuming that science is in fact being done, what does it have

Why science? Is NASA now forbidden from doing engineering development
and testing?

   to do with Aeronautics and Space?  Why is NASA getting involved in
   oceanography?  I can see them supporting other organizations such as NOA,
   but I can't see why they would be "stealing the limelight".

Because they're paying for it?

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Tue, 24 Nov 92 21:58:39 EST
From: Dan Shoop <[e-mail]>
Subject: GPS handheld receivers
Newsgroups: sci.space

[e-mail] (Dave Hopkins) writes:

> Is the market for GPS handheld receivers is really as big as we've been
> lead to believe? What use will long, lat and alt be to anyone unless it
> it is fully integrated into a navigation system?

The New York - New Jersey Trail Conference uses them for mapping trails.




FARSEF | The                                  Dan Shoop
       | Far Side                             [e-mail]
       | Expeditionary                        ATTnet:          201.612.0895
       | Force                                PagerNet: 800.225.0256 #92664
                                              Snail:   127 E Prospect 07463

                Give your child mental blocks for Christmas.

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

Date: 26 Nov 92 04:05:00 GMT
From: Philip Young <[e-mail]>
Subject: GPS handheld receivers
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Dave Hopkins) writes:
>Is the market for GPS handheld receivers is really as big as we've been
>lead to believe? What use will long, lat and alt be to anyone unless it
>it is fully integrated into a navigation system?

On Tuesday night (22nd NoV) "Beyond 2000" (*) showed a segment on smart cars
which had GPS receivers mounted as a navigation aid.  Evidently the folks
who are test driving the vehicles are wrapped.  Not exactly hand-held, but
small & mobile, and could conceivably become ubiquitous.

* Science and technology show in Australia, on channel 7. Best show on TV,
IMHO.

--
Philip R. Young
Data General Australia Pty. Ltd.


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

Date: 26 Nov 92 02:32:23 GMT
From: "Charles R. Martin" <[e-mail]>
Subject: hypergolics (was Re: Pumpless Liquid Rocket?)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:


   If you're willing to settle for a hybrid liquid/solid combination, water
   and aluminum foil work once you get them started.  Aluminum is difficult
   to ignite but is a *ferocious* fuel, enough so to rip oxygen out of water
   molecules.

Oooh, I like the sound of this.  I have this image of Our Hero
improvising a rocket out of materials available in the USS Enterprize's
kitchen.  (Old Generation, of course.  NG people would just use the
replicator.)

What would it take to light it off?  Would thermite be sufficient?
--
        Charles R. Martin/(Charlie)/[e-mail]
     Dept. of Computer Science/CB #3175 UNC-CH/Chapel Hill, NC 27599-3175
        3611 University Dr #13M/Durham, NC 27707/[phone]
     "Oh God, please help me be civil in tongue, pure in thought, and able
      to resist the temptation to laugh uncontrollably.  Amen." -- Rob T

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

Date: Thu, 26 Nov 1992 03:05:23 GMT
From: Robert W Murphree <[e-mail]>
Subject: manned vs. unmanned spaceflight
Newsgroups: sci.astro,sci.space

[e-mail] (John David Regehr) writes:

>Sorry if this is a dead subject, but I've only been reading this group for a
>week or so.  I'm writing a paper contrasting manned and unmanned spaceflight.
>I'm in the middle of a couple of books, but I haven't been able to come up
>with a good thesis statement yet.  I would appreciate hearing from people who
>have opinions on the subject, or who can suggest some good reference material.
>I am trying to approach this from a practical and philosophical standpoint,
>rather than detailing the historical controversy on whether the focus of space
>exploration should be on manned or unmanned flights.  Thanks.

Your really going to get overwhelming pro-manned space from these groups.
Nick Szabo sometimes posts antimanned stuff.

Have you read "and the heavans and the earth" by Walter Mcdougall,
Bruce Murray's new memior Journey to the Planets and his old book, before
he became a politician, navigating the future, there's a new book by
somebody burrows who wrote "deep black" on the politics of satellite
reconaissance.  The burrows book, whose title excapes me, is probably the
best single peice.  If you haven't read "the right stuff" by Toma
Tom Wolfe on how astonauts became somebody instead of nobody you should
either read it or watch the movie.  I have an extensive anti-manned
bibliography that I would be willing to share if you'll give me
your address.  Since your in Kansas you might call me, I',m in
oklahoma my number is (405)-447-7590.

I have shared my bibliography with others who have written policy
statements on men vs machines, here at OU.  Also, I lobbies against
the space station in 1991.

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

Date: 25 Nov 92 19:50:35 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded))
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Peter Yee) writes:
> Daily                 News
> Tuesday, November 24, 1992  24-hour audio service at 202/755-1788
>  % Fourth Town Meeting to take place in Pasadena Thursday, Dec. 3;


Urk! This may not be true.

> The fourth in NASA's series of Town Meetings will take place next
> Thursday, Dec. 3, on the Pasadena campus of the California Institute of
> Technology in the Ramo Auditorium.  The Town Meetings include
> presentations by top NASA officials and invited individuals from
> universities and industry in the region of the meeting.  Members of the
> audience have several opportunities during the 4 1/2-hour long events
> to raise questions or comment on the presentations.  As with the
> previous three meetings, the Pasadena Town Meeting will be covered live
> on NASA Select television.

At the Indianapolis town meeting on Friday, Goldin mentioned that they
had moved it from Caltech to another campus.  Sorry, my notes don't
show just where.   I think somebody forgot to inform the PAO apparatus
at NASA HQ.

If you intend to go to the LA-area meeting (I encourage it, it was
more interesting than I thought it would be, and I think NASA should
hear from Our Kind Of People), check with the Town Meeting Office at
[phone], or fax a request to [phone].  Of course, they'll
be closed Thursday, and I'm not sure about the rest of the weekend.
But you can get them Monday.

Also, beware of location info in these Daily News reports.  They
got the location wrong on the Indianapolis meetings, too.

Bill Higgins, Beam Jockey         | "I'm gonna keep on writing songs
Fermilab                          | until I write the song
Bitnet:      [e-mail]  | that makes the guys in Detroit
Internet:  [e-mail]  | who draw the cars
SPAN/Hepnet:      43011::HIGGINS  | put tailfins on 'em again."
                                            --John Prine

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

Date: Thu, 26 Nov 1992 10:19:13 GMT
From: Ron Baalke <[e-mail]>
Subject: Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded))
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Bill Higgins-- Beam Jockey) writes...
>In article <[e-mail]>, [e-mail] (Peter Yee) writes:
>> Daily                 News
>> Tuesday, November 24, 1992  24-hour audio service at 202/755-1788
>>  % Fourth Town Meeting to take place in Pasadena Thursday, Dec. 3;
>
>
>Urk! This may not be true.
>

The location for the Dec. 3 Town Meeting has been changed to
Cal State Dominquez Hills.  I've already informed Charles
Redmond who puts out the NASA Daily News.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Learn to recognize the
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | inconsequential, then
|_____|/  |_|/       |_____|/                     | ignore it.

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

Date: 25 Nov 92 17:47:43
From: Steinn Sigurdsson <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

   In article <[e-mail]> [e-mail] writes:

   >>To date it has never been done. Shuttle flights are so expensive
   >>that it isn't likely it can ever be done. You would need to return
   >>at least five or so satellites.

   >I seem to remember several satellites that were returned and later launched
   >on other vehicles.

   You are referring to the two Palpa communication satellites. It was about
   all the Shuttle could do and it cost the taxpayers hundreds of millions
   in launch subsidies.

   We spent half a billion $$ to recover $75 million worth of satellites. Only
   a NASA employee could consider that a good deal.

Come on Allen, you can't charge the whole cost of the flight to
the rescue, this has been hashed out a dozen times -

   >Also there was LDEF that is contributing greatly to
   >lowering the cost of all of the other spaceflight missions due to the
   >information gathered

   ERROR: You are assuming LDEF as is was the one and only way to get this
   infromation. This is incorrect.

True, but just exactly who was doing it a different way? As LDEF is it
as of now should not all the benefit derived from it be credited to
the shuttle program? Irrespective of whether it would have been
better&cheaper some mythical other way?

   >>Would you consider a pickup truck which only worked one day a week and
   >>cost $200 per mile to operate 'working hardware'? I wouldn't which is
   >>why I don't consider Shuttle working hardware.

   >We are not talking about pickup trucks

   It's called an analogy. If you don't know what that is or can't deal with
   it, then remove this part of the thread. Otherwise tell us all if you
   think the truck works.

Ooh, I love analogies: so, Allen, would you argue that an Aircraft
carrier is best left anchored in mid-ocean and the planes flown in?
After all, it seems silly to sail the thing back and forth all the
time when what you really want is a launch platform for aircraft
(somewhere) in the ocean, no?

   Delta Clipper is fully reusable. That means it isn't likely the
   controller was miswired. If it was miswired, the DC couldn't have
   flown to the spaceport.

Maybe we should wait for the thing to fly before making these claims?

   +----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Mon, 23 Nov 92 17:42:47 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

>By the way Henry, I found out some interesting stuff there are three versions
>of  the Saturn V first Stage. These are as follows
>
>S1C-T                   Test Stage for Manufacturing and Ground firings
>                        This is the one at the Alabama Space & Rocket Center
>
>S1C-D                   Dynamic Test model. Was later scrapped at the end of
>                        the program.
>
>S1C-1,2,3....           Flight Saturn S1 C stages.
>

I don't know the true designations, but I think that the S1C-D that you said
was scrapped is presently on display near the VAB at Kennedy Space Center.
It was part of the AS-500F vehicle used to test the Kennedy facilities in
1966. At least, I'm pretty sure that AS-500F is on display at the Cape.

-Brian

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

Date: Tue, 24 Nov 92 18:05:51 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>>Shuttle certainly does not have 'twice the lift capacity' of Titan IV as
>>an earlier poster contended, but it does have about one-third more, I
>>believe.
>
>The new Titan SRMs will close most if not all of that gap.

>  Allen

As long as we're talking about future upgrades (the new Titan SRMs) then
we can also consider the Space Shuttle's Advnaced Solid Rocket Motors.

Titan IV / IUS maximum payload: 49,000 lbs.
Space Shuttle maximum payload: 55,000 lbs.

Titan IV / Solid Rocket Motor Update maximum payload: 55,000 lbs.
Space Shuttle / Advanced Solid Rocket Motor maximum payload: 65,000 lbs.

I won't argue with you other points, but this one is more than "most if not
all of the gap".

-Brian

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

Date: Tue, 24 Nov 92 21:17:20 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>I think (USSR?) Shuttle is only rocket to have killed crew during
>the boost phase.  We've got to replace it before it happens
>again.  Get rid of those damn SRBs.  If they're no good on a titan
>then they're no good on the shuttle.  Everytime I watch a launch
>I find myself holding my breath for the 2 minutes it takes to
>expend the SRBs.
>
>--
>Thomas Clarke

Oh, now stop harping on the SRBs. It wasn't the Solid Rocket Booster which
led to the loss of Challenger, it was those ninnies in NASA and Thiokol
management. They're the ones that said "37 degrees? Sure, let's go ahead
and launch it..."

On a related topic, why on Earth didn't NASA just put those joint heaters
on the SRB back in '86 and start flying again, fixing the other problems
one at a time through a reduced flight rate? Ah... politics.

-Brian

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

Date: Tue, 24 Nov 92 21:18:43 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>In article <[e-mail]> [e-mail] (Gary Coffman) w
r
>ites:
>Notice NASA is funding the 4 great
>observatories.  if ASTRO was so great, they'd fly it more.
>
  Actually, the AXAF has been broken down into two missions, with a
  third, (X-ray Timing Explorer) now being planned, too. It's a "Good
  Observatory" now, but not "Great". :-)
  Meanwhile, the Space Infrared Telescope Facility in unfunded.

>judging how often
>LDEF, ASTRO and SPacelab have flown over the last 12 years,  i dont think
>people are dying for those missiions.
>
     Spacelab has flown ten times, in it's various configurations.
     That's about one flight per year the Shuttle has been flying.
     Shuttle has been flying eleven years. By the time the 12th
     anniversary comes around next April, we'll have added two
     more Spacelab missions. (D-2 and ATLAS-2)  Hopefully.
     We can do better, of course, but that's not so bad.

>>wasteful. Might as well bring down a satellite or two at the marginal
>>cost of a little maneuvering fuel.
>
>I think this is easier said then done.  Henry, Alan????
>
    See my previous post. STS-41C sort-of did that, STS-51A really did.


>Nonsense.  a booster destroyed by the RSO is part of a planned process.
>All previous manned missions had emergency escape provisions for the
>crew during boost.  I cant remember wether apollo used a escape rocket
>or the SM engines,  but the crew could get clear.  certainly not fun,
>but probably no worse then ejection seats.  certainly any manned vehicle
>would have this capacity.  Henry,  does the Soyuz have an escape rocket????
>
>>>>the idea of a powered descent and vertical
>>>>landing gives me the willies...
>>>
>>>Much safer than airplanes for most people. A DC crash will only affect the
>>>Spaceport. When aircraft crash they tend to kill people on the ground.
>>
>>And a Shuttle crash landing is that of a glider, no boom, and perhaps
>>survivable by the crew. Plus who says the SSTO will crash on the Spaceport
>>grounds, few aircraft do. If they have a guidance failure, it might be
>>downtown Disney World. All those kids, consumed in flaming rocket fuel,
>>I can see the headlines now.
>>
>remember it is a piloted
>powered vehicle.  if the ILS screws, the crew is still able to visualy
>guide as well as get instructions from ground control.

     At Mach 24, it doesn't take long for things to get out of hand.
     Remember that Scott Carpenter missed his landing zone by so much
     that Walter Cronkite was about to pronounce him gone. There are
     many incidences of off-target returns in the Russian space
     program too. What would that do to Delta Clipper? ("Ah! Set her
     down in Golden Gate Park! Everybody remember where we parked!")

>Besides, a DC flies on LOX/LH.  coming in it should be low fuel and
>LOX/LH does not really explode effficiently.

      Actually, I'd rather it have enough fuel to buzz around in search
      of a clearing. We don't want a repeat of Apollo 11's 20-seconds-of-
      fuel-left when they're are populations down here!

      Besides, most of that explosion we saw on 28 January 1986 was
      the result of uncontrolled burning of LH2/LOX. I watched that from
      my back yard, and I wouldn't want one of those on top of Orlando.

      -Brian

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

Date: Tue, 24 Nov 92 21:17:58 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>In article <[e-mail]> [e-mail] (Gary Coffman) w
r
>ites:

>>Deadheading is never cost effective. But that's a management problem,
>>not a Shuttle problem per se. If you have to charge an entire Shuttle
>>mission against a satellite return, then it is expensive,
>
>To date it has never been done. Shuttle flights are so expensive
>that it isn't likely it can ever be done. You would need to return
>at least five or so satellites.

   Not exactly, Allen. The Solar Max repair mission came pretty close to
   this in 1984. If the STS-41C crew had been unable to repair Max, they
   would have brought it home. This flight had carried the LDEF satellite
   into orbit and then gone on to repair Solar Maximum Mission.

   And then there is the STS-51A mission in November, 1984 which did
   EXACTLY that. STS-51A launched the Anik D-2 and Syncom IV-1 satellites
   for commercial organizations. A couple of days later, the crew captured
   and stowed Westar VI in the payload bay. Then they captured and stowed
   Palapa B-2 in the payload bay. Both were returned to Earth.
   By the way, both satellites were relaunched in 1990 by a Long March III
   and a Delta.

>So? When a Titan goes boom the crew has a very good chance of surviving.
>There hasn't been a Titan failure which would have resulted in loss of
>crew for at least 10 and more likely 20 years.
>
    Oh, PLEASE! Do you HONESTLY believe a crew would have survived the
    April, 1986 Titan 34-D launch failure? Like Challenger, there was
    no warning... only close scrutiny of the telemetry indicated a
    problem (well after the fact). I doubt even an Apollo LES would
    have been able to fire before that cataclysm enveloped the spacecraft,
    assuming, of course that a crew would have known to pull the lever.
    This failure occured so close to the ground, that the Vandenberg
    launch pad was wrecked.

>If your in Shuttle, true enough. On the other hand if your in a Delta
>Clipper made of much simpler components (less likely to fail) and with
>abort modes throughout the entire flight envelope it is a great deal
>of comfort.
>
>   Allen

Except of course, the RL-10 engine, which has now failed in flight twice
in the past eighteen months. Remember what I said about 'rocket engines
having a way of conking-out at innoportune times?'

 -Brian

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

Date: Thu, 26 Nov 1992 03:29:17 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:

>As long as we're talking about future upgrades (the new Titan SRMs) then
>we can also consider the Space Shuttle's Advnaced Solid Rocket Motors.


Not quite what was said.

>Titan IV / IUS maximum payload: 49,000 lbs.
>Space Shuttle maximum payload: 55,000 lbs....

Both configurations are fairly close in terms of weight especially considering
that Titan today can launch almost anything. How about this comparison:

Shuttle cost: ~10,000 per pound
Titan cost:   ~ 3,000 per pound

Now if YOU where paying the bills (and as a taxpayer, you are) which do
you consider the better buy?

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 26 Nov 1992 03:46:44 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:

>   Not exactly, Allen. The Solar Max repair mission came pretty close to
>   this in 1984. If the STS-41C crew had been unable to repair Max, they
>   would have brought it home.

I'm not sure but I doubt they could have returned Solar Max that mission.
I don't see how they could have put both LDEF and the fixtures for Solar
Max in the payload bay.

>   This flight had carried the LDEF satellite
>   into orbit and then gone on to repair Solar Maximum Mission.

Fine. Split the costs 50% each way. Your still only breaking even (and to
do that you had to ignore billions in shuttle costs).

But even if you did show a small profit, it was the only time in 10
years of operation. Does that justify the $50 billion of so Shuttle has
cost us?

>   And then there is the STS-51A mission in November, 1984 which did
>   EXACTLY that...

Sure but at great cost to the taxpayers. We spent half a billion $$ to
recover $75 million worth of satellites. Does that sound like a wise way
to spend the taxpayers money?

>   By the way, both satellites were relaunched in 1990 by a Long March III
>   and a Delta.

FYI, both those launches put together cost less than 20% of the cost of
ONE shuttle flight.

>    Oh, PLEASE! Do you HONESTLY believe a crew would have survived the
>    April, 1986 Titan 34-D launch failure?

Yes I think they would have had a 50/50 chance. When they take off one
guy always has his finger on the abort button. Less than 1/5 a second would
have been enough.

>Except of course, the RL-10 engine, which has now failed in flight twice
>in the past eighteen months.

As has already been pointed out, similar failures on a DC1 would not have
resulted in loss of either spacecraft or crew.

> Remember what I said about 'rocket engines
>having a way of conking-out at innoportune times?'

Not the same thing. Reused components don't fail as often as re-used
components. The fact that the spacecraft survives malfunction so
problems can be repaired adds to reliability.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 26 Nov 1992 03:18:50 GMT
From: Rich Kolker <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>[e-mail] (Gary Coffman) writes:
>
>(Henry Spencer) writes:
>(Allen W. Sherzer) writes:
>>>>>the idea of a powered descent and vertical
>>>>>landing gives me the willies...
>>>>
>>>>Much safer than airplanes for most people. A DC crash will only affect the
>>>>Spaceport. When aircraft crash they tend to kill people on the ground.
>>>
>>>And as any Harrier pilot will tell you, a vertical powered landing is
>>>safer than a horizontal powered landing.  And either one is *much* safer
>>>than a Shuttle-style horizontal landing *without* power.
>
>>As any glider pilot will tell you, gliders don't burn on impact. Nor
>>do they pinwheel across the sky when a thrust diverter fails.
>
>The only thing a shuttle landing has in common with a standard glider landing
>is that neither uses engines.  I've heard astronauts describe the shuttle
>while it's landing as performing like a greased brick.  If I recall correctly,
>a 747 with engines off can glide better than a shuttle.

To make a Gulfstream fly like ths huttle (to act as Shuttle Training Aircraft)
they drop the gear, drip the flaps (make that drop), and...
run the Engines in REVERSE!

Needless to say, the orbiter aint much of a glider!

++rich
-------------------------------------------------------------------
   rich kolker       [e-mail]
                          It's been a long, long time
--------------------------------------------------------------------

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

Date: Wed, 25 Nov 92 20:55:50 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>Most gliders have no fuel on board. The shuttle, however has a considerable
>amount of hypergolic fuels on board for the OMS and RCS thrusters.
>Which means a big explosion w/toxic gas clouds, as well as the loss of the
>crew.

I think that most of the OMS/RCS fuel is dumped after the de-orbit burn,
leaving just enough for the maneuvering during re-entry. By the time
the Shuttle touches down, it'c close to bone dry.

The STS-45 landing last April test-dumped the remaining fuel in the tanks
to see if it adversely effected Shuttle control. It didn't.

-Brian

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


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From: Henry Spencer <[e-mail]>
Subject: Re: What comes after DC-1
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In article <deanr.722718879@sco> [e-mail] (Dean Reece) writes:
>How long can the DC-1 stay on orbit?  Will the Cryo fuels boil off?

It's hard to answer detailed questions about DC-1, because it's a
design concept rather than a finished design.  The current notion is
for a stay time of a few days.  Some boiloff will occur, but the problem
is not disastrous.  Not a lot of fuel is needed for retrofire and landing,
and modern insulation works pretty well.  (IRAS and COBE were both cooled
by liquid *helium*, with orbital lifetimes measured in *months*.)

>How hard (how many mods) would need to be made to re-fuel a DC-1 on
>orbit?  Assume the fuel is there for starters.

At least some of the people involved would like to see this part of the
specs from the start.  There is limited experience in moving large amounts
of cryogenic fuels around in orbit, but it shouldn't be that hard to do.

>What is the highest (circular) orbit that the DC-1 can attain if it
>doesn't need to worry about fuel for landing? GEO?

Not a prayer.  The fuel requirement for retrofire and landing is nowhere
near what's needed for that.  A slightly higher LEO would be all you'd get.

>Is there any technical reason that a DC-1 couldn't make it to the moon
>if it could be fully re-fueled at this (maximum) orbit?  Hard radiation,
>Too much thermal stress...?

Refuel it in (low) orbit and it should be feasible, modulo issues of
in-space stay time and the details of the landing.

>Assuming fuel stores (or production) on the moon, could the DC-1 support
>its own weight fully fueled on luna, or would a launch cradle need to be
>constructed there?

At 1/6 G, it should be able to support its weight with something close to
full tanks, and they won't be full after the landing.

>Would it be able to return to Earth on a single
>fillup, or would it need to attain Earth orbit and refuel again?

The only real question is whether its thermal protection is adequate for
a lunar reentry.  Making Earth orbit is *more* expensive than going into
the atmosphere and landing, because the atmosphere does all the braking
for the landing.

>Again, assuming high orbit refueling, could DC-1 make Mars?  Could it
>return? (a 1 way trip might still be plenty useful if the DC-1 is in
>mass production and fairly cheap, compared to a custom Mars lander)

For this I'd have to check numbers in more detail.  I suspect you'd need
some fairly serious work on stay times and the like to make this viable.
Not ridiculous but not obviously practical.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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End of Space Digest Volume 15 : Issue 460
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