Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO531.TXT

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Date: Fri, 11 Dec 92 05:18:55
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #531
To: Space Digest Readers
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Space Digest                Fri, 11 Dec 92       Volume 15 : Issue 531

Today's Topics:
                               DC info
                 DC vs Shuttle capabilities (2 msgs)
                           DoD launcher use
                         Earth Movie (2 msgs)
                             pop in space
                        Range Safety and DC-X

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Date: Thu, 10 Dec 1992 15:03:55 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DC info
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael F. Santangelo) writes:

>  I'm real foggy from this description as to what the RL200 engine is
>going to be.

It is a separate engine which will be used for DC-Y if built. Some of the
RL-200 engines will have extendable nozzles and will be sustainer engines
for DCY and others will have non-extandable ones and will be used as
boosters. Except for the nozzles, they will be the same.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------135 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 10 Dec 1992 04:56:16 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: DC vs Shuttle capabilities
Newsgroups: sci.space

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


>In article <[e-mail]> [e-mail] (Gary Coffman) writes:

>>... A more intelligently designed
>>spacecraft is badly needed to replace Shuttle, but the DC program
>>isn't it. It may be *part* of a fleet of specialized vehicles that
>>replace Shuttle, but it can't do many of the things that Shuttle
>>is capable of doing, lifting large payloads, carrying large crews,
>>support Canadarm, return large objects, etc...

In principle, I agree with Gary.  Delta Clipper will not by itself replace
the Shuttle.

>Large payloads can go up in pieces for in-orbit assembly.

The in-orbit assembly of the Space Station was scaled way back because
in-orbit assembly was judged to be tougher than originally thought.  The
Intelsat mission reinforced that line of thought.  However, if SSF is in
orbit by the time Delta Clipper becomes operational (and I really hope it
is), in-orbit assembly becomes much easier.

>The Canadarm is nice, but I'm sure Spar would be delighted to supply a
>cut-down version to fit on DC-1.

That is one option.  Another is building an Orbital Maneuvering Vehicle.
Spar is already building a dandy arm for the Space Station.

Like Gary said, DC won't replace the Shuttle.  But DC + SSF + OMV + new EMUs
would come pretty damn close.  And when you get that close, you have to ask
whether the remaining unique capability of the Shuttle is worth $2.94 billion
per year.

>There appears to be no significant requirement to return large payloads.
>I can't think of anything larger than a Spacelab experiment rack that
>has to come down in one piece.

I'd like to keep flying LDEF and EURECA (I know there are no plans for the
former, but is the structure still intact enough to refly, or did they
dissect it?).

Here's a question that just popped into my head:  Would a modified Spacehab
(note the "h") module fit in the cargo bay of the Delta Clipper?

Mike

--
Michael Kent                                   [e-mail]
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!

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

Date: Thu, 10 Dec 1992 15:12:10 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DC vs Shuttle capabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael V. Kent) writes:

>>Large payloads can go up in pieces for in-orbit assembly.

>The in-orbit assembly of the Space Station was scaled way back because
>in-orbit assembly was judged to be tougher than originally thought.

That is true for now but only because we only work on it for a few hours
every couple of years. With DC and routine access (assuming it works) then
we will quickly learn how to do it.

>However, if SSF is in orbit by the time Delta Clipper becomes operational
>(and I really hope it is),

Check out this weeks space news. Don't hold your breath.

>>The Canadarm is nice, but I'm sure Spar would be delighted to supply a
>>cut-down version to fit on DC-1.

>That is one option.  Another is building an Orbital Maneuvering Vehicle.
>Spar is already building a dandy arm for the Space Station.

The OMV is a DC with a bolt-on Spar arm.

>I'd like to keep flying LDEF and EURECA (I know there are no plans for the
>former, but is the structure still intact enough to refly, or did they
>dissect it?).

No problem. Cut it in half and stick it in the DC cargo bay. Sure you only
fly half the experiments but you fly them a thousand times more often.

>Here's a question that just popped into my head:  Would a modified Spacehab
>(note the "h") module fit in the cargo bay of the Delta Clipper?

Why not just make it a module on the space station?

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------135 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 10 Dec 1992 15:00:04 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DoD launcher use
Newsgroups: sci.space

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

>The immediate concern is making DC-X work and getting DC-Y funded.  But
>the military would most assuredly be interested in easier and cheaper
>access to space.

The USAF Space Command is being briefed on DC and they are very interested.
The current head of Space Command ran the air war against Iraq and was
hampered by lack of access to satellite images. A vehicle with DC's
turnaround time is just what he needs.

Equally important, DC is a real kick-the-tires kind of vehicle which
has appeal for the ex-fighter types who run the Air Force.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------135 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 10 Dec 1992 10:11:15 GMT
From: "Hugh D.R. Evans (ESA/ESTEC/WMA Netherlands" <[e-mail]>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

In article <[e-mail]>, [e-mail]
(David Toland) writes:
|>In article <[e-mail]>,
|>[e-mail]
|> (Thomas E. Smith [LORAL]) writes...
|>>I have another question that maybe Ron Baalke can answer. Is Galileo
|>going to
|>>take any footage of the lunar eclipse tomorrow? I think that would be
|>an awesome
|>>short movie, and a once in a lifetime chance.
|>
|>Too bad it's not a solar eclipse.  Footage of the moon's shadow
|>crossing
|>the earth's surface would really be striking!
|>
|>--
|>----------------------------------------------------------------------
|>-----
|>All opinions are MINE MINE MINE, and not necessarily anyone else's.
|>[e-mail]   |  "Laddie, you'll be needin' something to
|>wash
|>                           |  that doon with."
|>

Here at ESTEC there is a poster containing a series of
publicity photos of a solar eclipse as the shadow traverses the Earth
(taken by MeteoSat).

Unfortunately, it is a bit of a disappointment - the shadow is not
terribly obvious.
If I can find a copy of it (mine was lost when we moved to the new
building)
I could post it.

Hugh.

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

Date: 10 Dec 1992 09:54:29 GMT
From: Thomas Rauber <[e-mail]>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

Note that the volcanism of the last year
around the earth may have caused some
improvements in contrast.
(Provided that you observe from down here.)
Unfortunately, my observation area was clouded,
so I don`t know the results yet.

Does anyone have more information about
these effects??

Frank Schulz
Saarbrucken, Germany

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

Date: 10 Dec 92 19:30 -0600
From: Brad Thompson <[e-mail]>
Subject: pop in space

I have drank pop quite a few times on the KC135 that flies out of JSC. If
you put a blob of it in the air in front of you during a free fall portion
of a parabola, you can see bubbles forming in the blob as the carbon dioxide
outgasses from the pop. The bubles just hang around inside the blob, and
the blob volume increases. Its kind of tough to say much other than that;
after all you only get 20s of free fall per parabola.

For the record it was diet coke, no special can.

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

Date: 10 Dec 92 04:07:44 GMT
From: Charles Frank Radley <[e-mail]>
Subject: Range Safety and DC-X
Newsgroups: sci.space

Why no destruct system on DC-X ?   I do not know the official reason, but
it might be like this :-

The first hazard I can think of is losing thrust mid-flight, causing
the vehicle to descend rapdily, and explode on impact with the ground.

DC-X has a multiple engines and multiple propellant valves.  To lose
all engines would be incredible, multiple plumbing failures,
unless there is some kind of common cause failure in the control system.
They could get around this by having a redundant control system.

The normal groundule is that a system which is still sufficiently
operational after two failures is acceptable from a safety point of
view.    If the DC-X engineering team has succesfully demonstrated
by failure modes and effects analysis ( a standard aerospace technique )
that no two failures will result in a situation where the DC-X thrust
is no longer capable of sustaining controlled flight, then I could
believe that Range Safety would accept this as an adequately safe
system not requiring in flight destruct capability.

Another hazard would be sudden inflight explosion of the DC-X resulting
from in flight instability.   This would create a lot of debris.  This
hazard could be controlled by making sure that the flight path of the
debris cannot intrude beyond the range perimeter, where debris falling
is accceptable.

Another hazard is the DC-X control system causing the vehicle to deviate
from its planned trajectory, and begin to overfly habitable areas.  If
it can be shown that it is not physically possible for the DC-X to reach
the vicinity of non-controlled airspace, then there would be no need
for a destruct system.

I do not know how big the range perimeter is at White Sands, but if it
is big enough, then the above arguments would be valid.



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End of Space Digest Volume 15 : Issue 531
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