Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO519.TXT

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Date: Tue,  8 Dec 92 05:02:44
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #519
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  8 Dec 92       Volume 15 : Issue 519

Today's Topics:
                        Another Orbit Question
                            Cryogen costs
       Detonavion vs Deflagration (was Re: Shuttle replacement)
                           Galileo GIFs ? ?
              Japanese Solar Mission_Yokoh:comparisons?
                        lunar flight (2 msgs)
                              Mass ratio
                        NSSDC Datata on CD-ROM
                            Orbit Question
                        Range Safety and DC-X
                     Rush Limb., Hubble, and UFOs
         Rush Limbaugh says problems with HST are a DoD hoax!
                         Shuttle replacement
                STS-48 and "SDI": Oberg vs. Hoagland
           Terminal Velocity of DCX? (was Re: Shuttle ...)
                          unpowered landings
                            Weather images

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

Date: 7 Dec 92 17:37:42 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Another Orbit Question
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>In light of the fact that a geostationary orbit above only one pole is
>not possible, I have another question that concerns an idea that I have been
>working on for the past few months. Is it possible to keep a body at
>relatively the same point say about 20000 or so miles above the north pole
>or south pole of the earth? I assume that it would require some type of
>thrusting to keep it from orbiting around the earth in normal fashion. If
>you could give some insight on this question such as the relative amount of
>thrust this would require and whether it would have to be continuous or not
>I would appreciate it.

It would require exactly as much continous thrust as it weighs. Thus it
would run out of fuel quickly. Being stationary over the Earth, and at
only 20,000 miles, it would weigh almost the same as it weighs on the
surface. Things in space aren't "weightless", only things in *orbit*
are "weightless."

Gary

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

Date: Mon, 7 Dec 92 22:18:28 EST
From: John Roberts <[e-mail]>
Subject: Cryogen costs

-From: [e-mail] (Gary Coffman)
-Subject: Re: Shuttle replacement
-Date: 6 Dec 92 17:06:16 GMT
-Organization: Gannett Technologies Group

-Well yes, I've seen such tankers. The dewars are pretty good, but
-I think they only carry something like 1000 gallons in one of them.
-The proposed DC-1 will need something like 270,000 pounds of cryogenics
-from what I've seen here. That's 15 to 20 tanker truck loads per launch.
-If the plant is in Florida, and the launch from John Wayne, the trucking
-costs are going to exceed flight costs(!). Liquid air plants are pretty
-common, but how many liquid hydrogen plants are there in the US? For
-such high tonnage uses, I'd think an onsite plant would be a real
-advantage.

I'm inclined to agree - for any really high-volume use, it appears best
to aim for on-site production. That doesn't apply so much during testing,
of course.

I finally picked up a cost figure from a press conference on NASA Select -
the marginal cost of taking a Shuttle to shortly before launch and then
cancelling (i.e. for next-day launch) is about half a million dollars.
That's a large enough fraction of total launch cost that they don't like
to make a launch attempt unless there's at least a fairly good chance of
launch, or unless there's a scheduling problem such as a narrow launch
opportunity (i.e. planetary probe launch) or interference with the next
scheduled launch.

That cost includes the price of the cryogenic fuels (presumably not
reused), and also many other costs such as labor. I've never been able
to find out where NASA gets the fuel (they have big spherical tanks, but that
doesn't necessarily mean it's produced on-site), or what they do with the
stuff that's drained out of the tanks when a launch attempt is cancelled.

NASA's had very good luck with launching on the first attempt this year
(at least for the Shuttle fleet).

John Roberts
[e-mail]

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

Date: Mon, 7 Dec 1992 16:28:59 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Detonavion vs Deflagration (was Re: Shuttle replacement)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>[e-mail] (Gary Coffman) writes:
>
>>In article <[e-mail]> [e-mail] (Pat) writes:
>>>Gary has been going on
>>>and on about Flaming rockets crashing into disneyworld. a vehicle
>>>crashing with deflagrating fuels is much less damaging then a SCUD
>>>missile with a TNT warhead.
>
>>A SCUD warhead leaves a crater a few dozen feet across at the impact
>>site.
>
>I recall film of early US V-2 tests in which the 1 ton instrument packages left
>80 foot craters in the ground.  Since the Scud is a derivative of the V-2, I
>would expect a ton of TNT on a roughly similar vehicle to do more damage.  What
>am I assuming wrong?  Are you perhaps taking your info from Israeli Scud hits?

7 is a few dozen. That yields an 84 foot crater. One city house
lot.

>>Of course ordinary airliners present this fire risk too, but they
>>have a proven track record of reliability that makes the odds of
>>such a crash tolerable. No rocket has that kind of track record
>>yet, and it will take many thousands of takeoffs and landings to
>>develop one.
>
>And rest aussured that human beings are smart enough to be careful.  They
>aren't launching DC-X from O'Hare or LAX and they won't.   Allen optimistically
>assumes a time in the future when SSTO designs have lived up to predictions
>they may deserve.  Chill folks.

As Mary noted, DC-X isn't an SSTO, maximum altitude is 30,000 feet. Later,
not yet funded, prototypes may be SSTO, and a DC-1 may be derived from
them. It's a long way off, and airliner style spacecraft won't be giving
Shuttle competition any time in the near future.

Now, given that such a SSTO is developed, and that it turns out to be
both safe and relatively inexpensive *for a space launcher*, it still
seems ludicrous to ship dozens of 18 wheel tanker truck loads of
cryogenic fuels into Podunk airport to support the launch of a payload
that could easily be carried in *one* six wheel truck to a central
launch facility.

Gary

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

Date: Mon, 7 Dec 1992 18:41:28 GMT
From: Douglas R Fils <[e-mail]>
Subject: Galileo GIFs ? ?
Newsgroups: sci.space

sci.space,
    It's my understanding that Galileo is to transmitt back
images for Gaspra that it has stored on tape, and (more exciting)
images from the lunar pole taken by Galileo sensors.

    If it's possible, I would love to see some of these images,
especially the lunar ones, in GIF format.  If they exist, could
someone direct to where they are (or will be if they are yet to
be done) or post them to alt.binaries.pictures.


Thanks much.
Doug

(I know this post is a bit early, with Dec 8th still a day away,
but might as well get a head start)

--

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

Date: 7 Dec 92 18:44:09 GMT
From: "John W. Cobb" <[e-mail]>
Subject: Japanese Solar Mission_Yokoh:comparisons?
Newsgroups: sci.astro,sci.space,sci.physics

In article <[e-mail]>,
[e-mail] (Robert W Murphree) writes:
|>The Japanese Space agency, ISAS, launched its newest Solar observation
|>satellite a year ago.  It has soft and hard x-ray imaging devices with
|>resolution around 6-7 arc seconds(I think I remember that).  And it
|>has two x-ray spectrometers.  How does this compare to the U.S. satellite
|>Solar Max?  Is it any improvement over Solar Max?
I don't remember the numbers, but I have looked at some photographs from
Yokoh and from previous sateliite and ground based solar observatories.
I was very impressed at Yokoh's resolution. You can really began to see the
structure of solar events in detail. They are no longer just bright flashes,
but they are flashes with contrast, shape and other detail. I can't say I
completely understood what I saw, but it seems clear to me that at least
some of the outstanding theoretical questions can be addressed with the new
data.

|>Does it lack capacities
|>that Solar Max had?
I don't know. I think Solar Max was sone of these "let's do it all on
one platform" observatories, but perhaps my memory is failing here.

|>I know it weighs a lot less.  The U.S. has
|>cancelled its follow-up to Solar Max.  How would that follow-up US
|>satellite have compared to Yokoh?
You get me hanging on that one.

-john w. cobb

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

Date: Mon, 7 Dec 92 20:27:29 EST
From: John Roberts <[e-mail]>
Subject: lunar flight

-From: [e-mail] (Henry Spencer)
-Subject: Re: lunar flight
-Date: 6 Dec 92 23:33:56 GMT

-In article <[e-mail]> [e-mail] (John Roberts) writes:
-[Henry:]
->-Except that Clinton & Co have already came out as opposed to any resumption
->-of manned space exploration, or any preliminary steps towards it, no matter
->-how cheap.
->
->Wrong.

-Wrong?  Really?  Details, please.  As I recall, the Clinton/Gore position
-on SEI is quite explicitly "we cannot afford to do anything about this now".

First of all, by "manned space exploration", I presume you mean travel by
humans beyond LEO - astronauts sitting in SSF wouldn't count, for instance.

You recall fairly well, except that what you recall is not the official
position, but the Henry Spencer Official Translation of a Clinton position
statement, which you posted on July 24:

# Translation:  we're not going to spend any money on them or start
# any serious efforts toward them.

Now that does sound quite definitive and explicit, but as highly as I
respect the author, I can not view the words posted as being an actual
explicit statement by Clinton.

What you were responding to was this excerpt:

#From: [e-mail] (Robert Bunge)
#Subject: Clinton Space Position
#Date: 22 Jul 92 21:05:17 GMT

#The following was passed on to me.  I'm told it came from the Clinton
#Headquarters (I don't have any reason to doubt that):

#Bill Clinton on America's Space Program
...
#Aim to establish a permanent human presence on the Moon and to send
#humans to Mars. Although we cannot yet commit major resources to
#these goals, they should be among the considerations that guide our
#science and engineering.

Of course you can quibble over the level of support implied by this
statement, but I don't think you can reasonably expect to show that
the above statement represents total opposition to any manned spaceflight
beyond LEO, "or any preliminary steps towards it, no matter how cheap".
You interpreted "cannot yet commit major resources" as "cannot commit
*any* resources, period". I mentioned at the time that it appeared to me
that the main target of the platform element was genuinely *major*
expenditures such as a multi-hundred-billion-dollar crash-priority manned
mission to Mars - and later comments released by the campaign team appear
to me to support this view. Opposing these enormously expensive, current-
technology approaches does not rule out the longer-term goals of coming up
with a more affordable and sustainable approach, such as developing cheaper
launch systems, increasing the knowledge base of the life sciences through
continued microgravity research (Spacelab and SSF), and sending preliminary
unmanned probes thoughout the solar system - Clinton has spoken in favor
of all of these, as well as the general goal of manned bases on the moon
and exploration of Mars:

#From: [e-mail] (Robert Bunge)
#Subject: Space Activists to Rally at Democatic Convention
#Date: 10 Jul 92 01:35:52 GMT

#Gov. Clinton has stated several times that he supports SEI and
#that he considers it critical to the Nation's future.  Responding
#to a telephone call-in question asking if he supported SEI on
#NBC's Today Show (June 30), Gov. Clinton responded, "I have been
#a consistent supporter of the space program including manned
#space exploration and I would do it through recommending
#appropriations in Congress".  Today Show host Bryant Gumble
#asked, "Can we afford it?",  Governor Clinton responded, "We
#can't afford not to do it".

#Earlier in the campaign, in response to an Associated Press
#question, "Should the government pursue President Bush's space
#exploration initiative to colonize the moon and send a manned
#expedition to Mars?"  the Clinton campaign responded that the
#candidate "supports efforts to colonize the moon and the long-
#term goal of a manned expedition to Mars."

So I don't think that it can be categorically stated that Clinton has
established his position as being in opposition to manned space exploration
on general principles, or in opposition to the preliminary steps that we
have the technology to do and can afford to do now.

As I mentioned before, I suspect the *name* "SEI" may go away pretty soon,
but the name doesn't seem to have been politically useful anyway. What's
important is that the basic goals be maintained. (I'm not talking about the
original timetables - those were obsolete even before the election.)

So much for the platform. As far as actual performance in office is concerned,
I think your statistician would once again say "not enough data points". But
that's hardly surprising - after all, the man is not even President yet. :-)

I think the comments by Administrator Goldin may be relevant here. He
appears to be sufficiently interested in his vision of NASA that he would
like to keep his job and see it through. He impresses me as a person who's
pretty good at keeping his ear to the ground - careful listeners may have
noticed a change in his statements after the election, not so much in his
basic message (which is pretty much compatible with Clinton's anyway) as
in his choice of words and what he chooses to emphasize. (He's been making
some really spectacular statements at the Town Meetings, covering many of
the topics that have been discussed in sci.space. I hope to eventually post
at least some summaries - transcripts are a real nuisance to type in. :-)
Anyway, I managed to get part of the latest Town Meeting in California.
A young person in the audience expressed dismay over the long timelines
projected for the manned exploration of Mars, and wanted to know when NASA
would send people to Mars. Goldin replied that right now NASA has some
serious credibility problems regarding technical ability to do ambitious
projects, to meet timelines, and to stay within budget. He said that before
NASA can effectively sell new ambitious projects, these problems must be
addressed convincingly, and he projects that it will take perhaps five
years to do so. So what Goldin apparently sees is about five years of
NASA cleaning up its act, continuing with existing programs, developing
new technologies needed for the more ambitious projects, and initiating
some ("smaller , faster, cheaper") projects such as the Pluto flyby.
Then when NASA has restored its reputation and better technology is
available, the big projects such as manned exploration of the moon and Mars
(and space resource exploitation, to make Nick happy :-) can be tackled,
and hopefully can proceed fairly quickly.

John Roberts
[e-mail]

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

Date: Mon, 7 Dec 1992 17:10:55 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Lunar flight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>Inquiring minds want to know:
>
>A Soyuz capsule costs about $7 million, and has a mass of 7 tons.
>
>The new Proton KM launcher (due in 1995) will cost about $30 million,
>and be able to  send 7.5 tons in a lunar trajectory.

Watch these ex-Soviet cost figures. The Russians are going to have to
start paying their people a living wage and get rid of all the hidden
subsidies that currently permeate their system. Cheaper than us, yes,
as cheap as the above prices, not likely after the fire sale.

>Why isn't there talk of a circumlunar flight, paid for by the USA, and crewed
>with US astronauts? We could send US astronauts around the poles of the moon
>during the Clinton Administrations' first term......
>
>The enhanced Proton KM, the one with a LH2 escape stage should be able to send
>10 tons to the Moon, perhaps enough to put the Soyuz in lunar orbit.
>With a little ingenuity, we might be able to develop a lunar landing mission
>architecture with this system, for an extremely small amount of money.

Why bother? We've already circled the Moon several times. We've even
landed and driven around in a rover. While I'd like to see us go back
to the Moon, doing a subscale rehash of Apollo isn't the way to do it.
Let's do a Lunar resources mapper, or three, first.

Gary

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

Date: Mon, 7 Dec 92 22:23:04 EST
From: John Roberts <[e-mail]>
Subject: Mass ratio

-From: [e-mail] (Gary Coffman)
-Subject: Re: Terminal Velocity of DCX? (was Re: Shuttle ...)
-Date: 7 Dec 92 17:33:21 GMT
-Organization: Gannett Technologies Group

-That's what they said about Shuttle at a similar point in it's development.
-A space truck. As a *beefy* version of a spaceship, DC-X would qualify
-with a mass ratio of 2:1, but it's only intended to reach 30,000 feet,
-not orbit. DC-Y has a mass ratio of 100:1. That doesn't leave much
-room for "beefy".

Where did you get that number? I thought the mass ratio was supposed to
be around 10 or 20.

John Roberts
[e-mail]

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

Date: Mon, 7 Dec 1992 16:45:36 GMT
From: Martin Connors <[e-mail]>
Subject: NSSDC Datata on CD-ROM
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (Ryan Korniloff) writes:
> Also, there is a program for the IBM PC called Vista Pro. To be as short
> as possible in explaining this, it is a 3D landscaping gernerator that
> accepts the U.S. Geological Survey's Digital Elivation Model images. You
> can also creat liniar flybys with it. Can I do this with the Magellan
> images or any other that are available? And if so, what other images are
> available??? And, where can I get them?

In advertising in -Earth- magazine, the VistaPro folks say they can do
Magellan images. I am not sure whether this means you can translate
Magellan altimetry to DEM (Digital Elivation Model) and look at it or
whether it can handle the altimetry files directly. Looks like a neat
product and I am keen to see a demo of it.
--
Martin Connors         |
Space Research         | [e-mail]  [phone]
University of Alberta  |
Disclaimer: NO connection with any company making/selling Vista Pro.

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

Date: Mon, 7 Dec 92 16:05:12 PST
From: "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov
Subject: Orbit Question

In Space Digest V15 #516,
[e-mail] writes:
>I have a question concerning geosyncrenous (please excuse my spelling, my
>dictionary was  printed before space exploration got started) orbits. It is
>my understanding that a body in geosyncronous orbit remains over the same
>point on the earth and has the same rotational period as the Earth. My
>question is what happens to a body that is in geosyncronous orbit at either
>the north or south pole. Does it remain stationary above the pole?
>If you can help me with this question please mail me.
>Thanks.
>
>[e-mail]

A spacecraft in a circular orbit at 35786 km altitude will have an orbital
period equal to the Earth's rotational period.  If the inclination of the
orbital plane is 0 degrees, the spacecraft will appear to remain stationary
above a point on the Earth.

At higher inclinations, the spacecraft will appear to execute a figure 8
trajectory centered over a point on the equator.  For half a day the
groundtrack will be over the northern hemisphere and for the other half over
the southern hemisphere, but how far north or south is determined by the
inclination.  The lobes of the 8 become wider as the inclination increases,
until at 90 degrees inclination, the groundtrack spans 90 degrees in the
East-West direction and 180 in the North-South direction.

The groundtrack of any synchronous orbit appears as a circle when viewed
from the pole.  A 90 degree synchronous orbit appears as a circle of
diameter equal to the Earth's radius when viewed from the pole.

There is a 12 hour orbit developed by the Russians which I believe is called
the Molniya orbit, after their Molniya [Lightning] communications satellites.
This is a high inclination (around 53 degrees, I think), highly elliptical
orbit.  Here my memory fails me: I'm thinking the apogee is 22000 km and
the perigee is 1100 km, but this could be way off.

But the point of the orbit is that because of its ellipticity, the spacecraft
spends a lot of time near apogee and not much time at all near perigee: that's
just the way orbital mechanics works. So if you have two or three of these in
the same orbit, it serves almost the same purpose for high latitude countries
that a synchronous orbit serves for low to mid latitude countries.

_____________
Dale M. Greer, whose opinions are not to be confused with those of the
Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER
"Pave Paradise, put up a parking lot." -- Joni Mitchell

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

Date: Mon, 7 Dec 1992 16:45:41 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Range Safety and DC-X
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>I just got back from the NSS Policy Committee. There I was told the
>following interesting tidbit:  The DC-X will NOT have destruct charges
>when it flies. They convinced the range safety people that they
>simply wheren't needed.

With the glide characteristics of a bullet, and a max altitude of 30,000
feet, and White Sands being a *big* empty place, I can see why. 50 cal
machinegun bullets can travel higher, and they don't use destruct charges
on them either. It's the ones that can climb a 100 miles you've got to
watch.

Let's hope it flies like a Pheonix, rising gracefully out of it's own flames.
It certainly can't soar like an Eagle. :-)

Gary

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

Date: Tue, 8 Dec 92 02:10 GMT
From: Daniel Burstein <[e-mail]>
Subject: Rush Limb., Hubble, and UFOs

Like all good dis-information campaigns, the
story Rush has picked up on regarding the HST being
used to view messages from extra-terrestrials
has a -bit- of truth in it, but just enough
to have people believe it, rather than the reality.

Which is.... the REAL proble "they"'ve had with
chatting with et's is NOT in the Earth-based listening
post.  The problem facing our super secret agencies
is in how to talk TO the et's without anyone noticing.

A ground based radio array powerful (and directional) enough
to reach "out there" would be far too visible and
insecure.  Similarly, an orbital based radio transmitter
would have too much "scatter" and could be detected.

The solution (as described way back when in an Arthur C. Clarke
story), is to use a visible light TELESCOPE as a transmitter.

Now I'm not quite sure what the range of the HST would be,
but if you use a monochromatic modulated beam, and you have
a large reciever at the other end, I'm sure there would
be an absolutely secure and reliable channel going out
for quite a few AUs, and perhaps even a couple of parsecs.

Please do NOT use my real name here.... you never know
who is watching!

Yours in paranoia,
Danny Burstein  <[e-mail]>

ps:  Just to make sure everyone understands,
this is a SATIRE.  (or is it????)

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

Date: 7 Dec 92 18:52:48 GMT
From: [e-mail]
Subject: Rush Limbaugh says problems with HST are a DoD hoax!
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Dean Adams) writes:
>
>  >The popular American radio personality Rush Limbaugh
> "popular"?  That doesn't say too much for the population...  :->
>
>  >stated today that the problems with HSTs mirror are a Department of
>  >Defense hoax.
> Oh, brother!  What a load of bull...
>
>  >Rush has over 13 million listeners and has may connections into the
>  >goings ons of many behind-the-scenes happenings.
> Apparently not.
>
>  >I don't think that he would make such a statment without a
>  >reason to believe it is true.
> This guy is a lunatic!  He "believes" all kinds of ridiculous nonsense.
>
>  >This is a rather radical statement.
> Considering the *source*, i'd say that is a perfect description.  :->
>
>  >it's time!? This can't be and with 13 million listeners how come nobody
>  >else said anything about this??
>
> Because nobody takes him seriously.  He's just a nut mouthing off.
>

The problem here is that people do take him seriously.  There are 100 people
out there in the world who think that science is magic for every one of us that
happens to know how a toaster works.  If Rush Limbaugh says it, then it must
be true.  (After all, he has more credibility than the national enquirer, and
I bet we all know at least one person who belives in it!!!)

It would be interesting to see where he got this impression, and if there isn't
some spark of reality to it.  (did DoD do >ANY< imaging with hubble recently?)

And it will be interesting to see how this rumor percolates through society...

Education of our soiled masses is the best and only defense against this kind
of (dis)-information.

            John Stevens-Schlick

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

Date: 7 Dec 92 15:11:16 GMT
From: Peter Jarvis <phred!petej>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Rich Kolker) writes:
>
>..... The Saturn V at MSFC is the Engineering
>test model, not a flight article.
>-------------------------------------------------------------------
>   rich kolker       [e-mail]
>                          It's been a long, long time
>--------------------------------------------------------------------

Rich, I assume you mean the one at the Space and Rocket Center. There
isn't one at MSFC. :-)

Peter..........

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

Date: Mon, 7 Dec 1992 16:42:05 GMT
From: Steve Gamble x3293 <[e-mail]>
Subject: STS-48 and "SDI": Oberg vs. Hoagland
Newsgroups: sci.skeptic,sci.astro,sci.space,alt.alien.visitors

In article <[e-mail]>, [e-mail] writes:
> James Oberg will _of course_ have an explanation.  He is a member of
> PSICOP and works with Philip Klass, THE well-known skeptic "nothing-
> is-real" other famous member of PSICOP.  I've been seeing more and
> more things from Oberg lately, and I *never* see this connection
> mentioned, only his NASA ties.
>
> Robert Sheaffer may be "Skepticus Maximus", but for the rest of us
> with open minds, please consider the source.
>
> Barb

Does the fact that Robert Sheaffer is a member of CSICOP and James Oberg
is a friend of his and they both know Phil Klass mean that their solution
to the video is incorrect?

I saw this video when I visited MUFON Headquarters during the summer. I have
made a special study of UFO photos over the last fifteen years, during which

time I have been a photoanalyst for the British UFO Research Association, the
UK equivalent of MUFON. I am happy that Oberg's explanation fits with what is
shown on the video. The UFOs and the missile which shoots them down are nothing
other than small debris close to the camera, probably ice crystals. The change
in motion is caused by the firing of a thruster just out of camera shot.

Continuing myths does not help the serious study of UFOs. I am supposed to be
a believer (although what I believe could be another long discussion!) and
I am convinced of the same solution as the non-believers.

These are of course my own views, not those of my employer or BUFORA.

Steve.
--
(Disclaimer: These are not my employer's opinions, they may not even be mine!)
Steve Gamble, Computing Services, Clinical Research Centre and Human Genome
Mapping Project Resource Centre, Watford Road, Harrow, Middlesex, HA1 3UJ, UK.
Phone: [phone]  JANET: [e-mail] INTERNET: [e-mail]

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

Date: 7 Dec 92 17:33:21 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>
>>I'm an EE not a PE, but I know enough to figure out that if your
>>mass margins are extremely thin you don't add extra mass if you
>>can trim it out. In structures and in engines, beefier parts almost
>>always mean higher reliability. A truck engine is usually good for
>>a million miles while a formula one engine may last 100. They both
>>put out roughly the same amount of power, but one masses a lot more
>>than the other.
>>
>
>I think formula one race engines are good for about 1,000 miles.
>they need to be able to do the Daytona 500;-).

NASCAR stock cars do the Daytona 500, USAC Indy cars do Indy, Formula
One races are much shorter, and twisty.

>But you see.  you are proving my point.  The DC will be a beefy
>version of a spaceship.  it will be the model-T of space, not a
>Daimler Roadster.  A truck compared to a racecar.

That's what they said about Shuttle at a similar point in it's development.
A space truck. As a *beefy* version of a spaceship, DC-X would qualify
with a mass ratio of 2:1, but it's only intended to reach 30,000 feet,
not orbit. DC-Y has a mass ratio of 100:1. That doesn't leave much
room for "beefy".

>Gary,  you have hit the point of the argument.  It's religious.
>You believe certain things about spacecraft, and not your mind
>or your senses will alter it.  People used to believe the same thing
>about aircraft.  Would you want to commute on a wright flyer?
>how about on a COmet.  People used to say Aircraft have to push the margins.
>Well, somebody found away to increase the envelope.
>Sure. early rockets were very marginal,  but if you scale back your
>expectations, you can increase reliability.

Mass ratio is a very good measure of margin, and DC-Y's will be very
very much pushing the envelope.

>>Look, I'm not trying to be dense here, but in circuit design we know
>>that the more parts you have in a circuit, and the harder you push
>>them, the more likely you'll have a failure. So you try to simplify,
>>and beef up what remains to stand the maximum expected stress. Redundant
>>power supplies tend to fail redundantly into a shorted load. Add protective
>>circuits, and the protective circuits will fail in such a way as to take
>>the system off line at the most critical moment. Simplicity, two wires
>>make a light, the lever and the inclined plane, strict quality control,
>>extensive testing, never depend on an active system when a passive system
>>will do, never have two critical systems with a common failure point, always
>>have a totally separate backup system, these are the routes to reliability
>>in my business.
>>
>Exactly Gary.  Your complaints are the shuttle.  Your solutions are the DC.
>The shuttle has 4 engine types, separate engines for each mode of flight,
>three different heat protections, 8 cargo bay doors, .

Yes, *totally* separate systems, completely different backup systems,
*exactly* what I'm calling for above.

>DC,x,y,1  will have one common set of engines.  the RCS i think uses
>LH2/LOX.  The same engines will do orbital manuevers, landing, takeoff.

Single point failure. One system must do everything.

>Gary.  If the DC-X can pull off 100 flights in 1 year of testing, and no
>major problems show up, will you stop complaining that it's unreliable?

Absolutely. If anyone wants a craft with *no* payload capacity, a max
altitude of 30,000 feet, and $10 million per flight, after 100 flights
I'd concede that DC-X is just the ticket. Now if *DC-1* can deliver
10 kilopounds to *orbit* 100 times in a year with no failures, I'd
be much more impressed. I'd even consider buying a ticket. But there
are many *giant* steps between DC-X and DC-1.

Gary

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

Date: 7 Dec 92 17:50:11 GMT
From: Ed Faught <[e-mail]>
Subject: unpowered landings
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer)
writes:
>Total power loss is extremely rare in multi-engine turbine aircraft.

Unfortunately not rare enough! A leading cause of general aviation accidents (
excluding major airlines ) is still "fuel mismanagement" or just plain running
out. It doesn't matter how many engines you have when this problem occurs!
--
Ed Faught  WA9WDM  [e-mail]
 Superconducting Super Collider Laboratory

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

Date: Mon, 7 Dec 1992 16:19:56 GMT
From: James Whitfield <[e-mail]>
Subject: Weather images
Newsgroups: sci.space

I often get gif images of the western US, but is their a server where I can
get images of Europe?  Many of my friends here at work are from their and
would like to know the weather back home.

Thanks
Jim Whitfield

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

End of Space Digest Volume 15 : Issue 519
------------------------------