Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_0/v16no037.txt

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Date: Tue, 12 Jan 93 05:02:41
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #037
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 12 Jan 93       Volume 16 : Issue 037

Today's Topics:
            Cheap Mars Rocks (was Re: Moon Dust For Sale)
                      Cheap Mars Rock Sources...
                    DC-1 and the $23M NASA Toilet
                          fiber optic cable
      Let's be more specific (was: Stupid Shut Cost arguements)
                                LRDPA
                      Magellan Update - 01/11/93
        One Small Step for a Space Activist... (Vol. 4 No. 1)
                   Railgun in Southwest US (2 msgs)
                          Re; Shuttle Toilet
                    Saving an overweight SSTO....
                Shameless Hucksterism to Plague STS-54
                            Shuttle tiles
                   What was NASA thinking? (2 msgs)

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

Date: Mon, 11 Jan 1993 20:26:04 GMT
From: Henry Spencer <[e-mail]>
Subject: Cheap Mars Rocks (was Re: Moon Dust For Sale)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] (David Hinz ([e-mail])) writes:
>By what mechanism do these rocks get here?  Volcanic action & random launching?
>How do they acheive escape velocity?

Probably by complex phenomena associated with large impacts.  One of the
sticking points on declaring the SNC meteorites to be definitely Martian
has been the difficulty in explaining precisely how they got off the planet.
Getting shrapnel from a large impact off the Moon is not hard, but Mars's
escape velocity is rather high for this kind of thing.

>Why do they end up so often in
>Antarctica?  Or are they just more  visible there? ...

This one's just a sampling effect.  Antarctica is a great place for
meteorite hunters, because any rock found sitting on the ice *must* be
a meteorite -- there's no other way it could get there.  Elsewhere, it
is hard to tell whether a random rock belongs where it's sitting or not.

In particular, if memory serves, there are a few areas of Antarctica
where ice flows just sort of terminate, gradually eroded away by wind
rather than flowing into the ocean.  A meteorite which falls on ice that
is heading that way will end up on the surface in the termination area.
This concentrates meteorites from large areas over long periods of time.

A bonus is that the Antarctic environment is very cold and virtually
sterile, preserving the meteorites in very nearly their pristine state.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Mon, 11 Jan 1993 20:51:59 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Cheap Mars Rock Sources...

In article <[e-mail]> <[e-mail]> writes:
>Nobody knows for sure how the SNC came from Mars to Earth,

Shed spore pod shells, maybe?

--
Phil Fraering         |"...Who in the valley shed the poison tear
318/365-5418          |no one knows...
[e-mail]|An old myth of a mythical hero..."

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

Date: 11 Jan 93 01:32:01 EDT
From: Ethan Dicks <[e-mail]>
Subject: DC-1 and the $23M NASA Toilet
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Richard A. Schumacher) writes:

>Uhhh... why didn't NASA just reuse the Skylab toilet on Shuttle?

Because the Skylab toilet was just a large outhouse in orbit.  The system
was a very low tech, based on the astronauts filling up plastic bags and
chucking them into the waste storage area.

The Skylab living quarters were built into the area of the Saturn V normally
used for the hydrogen tank in the second stage.  The oxygen tank area was
where the garbage was stowed.  Skylab was never intended to be used enough
to fill the entire waste disposal area with waste.

The toilet on the shuttle was supposed to be a major breakthrough in
orbital waste management.  The collected human byproducts were supposed
to be dessicated in the vacuum of LEO and (devoid of significant volume)
discharged into orbit.

You think the STS toilet is expensive?  Take a look at the head aboard
Fred.  Last I heard, there were two competing designs; NASA was not
expected to endorse either, but rather combine both designs.

BTW, does anyone have the text of the toilet instructions on _2001_?  I
recall that a still was reproduced in the book of the movie.

-ethan

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

Date: Mon, 11 Jan 1993 16:33:11 GMT
From: Brad Whitehurst <[e-mail]>
Subject: fiber optic cable
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>-From: [e-mail]
>-Subject: Fiber optic umbilical
>-Date: 4 Jan 93 15:30:14 GMT
>
>-Putting a fiber optic umbilical on a remote sensing platform designed to
>-traverse rough terrain seems very odd to me.  Can someone explain to me why
>-this was done?  A few things come to mind such as eliminating the weight
>-required for a radio and associated power supply.  Also the fiber optic does
>-allow for high reliability and high speed data transfer.
>
>-I'm *not* throwing stones at the Dante folks.  I'm just doing some head
>-scratching and hoping someone will explain this to me.
>
>Well, one thing for sure - plans for an Earth-Mars fiber optic link
>will have to be scrapped. :-)
>
>I can imagine the Dante team trying to straighten out the cable by hand,
>and that tiny, heartbreaking "snap" (or maybe they didn't hear anything
>at all). Commercial fiber optic cable is great in stationary applications,
>but it's too easy to stretch it or bend it beyond the radius of curvature
>limits. The people who install our fiber optic links put up warning signs
>with a drawing of a hangman's noose, implying what will happen to anybody
>who tries to move the equipment. :-)
>
>Does anybody (the phone companies or the military, for instance) use
>fiber optic cable that's stiff enough to reduce the risk of breaking?
>
    Speaking to a friend in Pittsburgh who is apparently
acquainted with one of the students on the Dante team this weekend,
she commented that they had apparently had an intermittent glitch in
the fiber cable before they went to Antarctica (N.B., while likely,
this is still 2nd hand quasi-rumor).  The cable supplier apparently
tested the assembly and claimed to find no problem.  So, the flaw may
have existed all along, and progressed to a complete break in field
condition.
    Actually, fibers can be quite rugged.  Isn't there a new
version of one of the wire-guided anti-tank missiles that uses a fiber
instead of copper, to reduce weight and increase range?  Is it
operational?  The key is to make a cable that is not stiff, I would
guess.

--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

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

Date: Mon, 11 Jan 1993 18:19:49 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Let's be more specific (was: Stupid Shut Cost arguements)
Newsgroups: sci.space

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

>A warhead re-entry vehicle is not a good model for a lander. A warhead
>doesn't attempt to do atmospheric braking. It's shaped like a long narrow
>cone, or hypersonic bullet.... A lander presents a blunt surface to the
>atmosphere and tries to shed as much velocity as possible by atmospheric
>braking.

Ah, which lander are you talking about.  The Delta Clipper *is* shaped
like a bullet.  It does not present its blunt surface (base) on entry.
It makes a nose-first, high-angle-of-attack entry modelled after an
ICBM-warhead trajectory.  This was chosen because of the large amount
of data available from computer modelling of missile warheads.

It seems rather presumptuous to claim you know more than McDonnell
Douglas engineers working on the project about what is and isn't
possible when you are uninformed on such basic facts as this.


>Shuttle designers originally
>considered a titanium skin for the Orbiter, but even a metal as refractory
>as titanium wasn't up to the job

Yet Another Historical Error.  Refractory metals were up to the
job until NASA doubled the size of the Shuttle orbiter to meet
military payload demands.  (And some engineers at Rockwell still
felt that refractory metals were viable, given sufficient ingenuity.
Langley, and possibly other NASA centers have since come up with
refractory metals which they believe can do the job.  Some of these
were considered for use on the fifth orbiter.)

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

Date: 11 Jan 93  09:47:52
From: [e-mail]
Subject: LRDPA
Newsgroups: sci.space

Back to the Moon Bill to Be Unveiled in San Diego during January
-
        San Diego L5, a chapter of the National Space Society, will
publicly release a draft version of the Lunar Resources Data
Purchase Act on Thursday, January 28 in Tierrasanta, San Diego.
The event will begin at 7 pm at the Tierrasanta Public Library,
located at 4985 La Cuenta Drive, and is open to the general
public.
        This legislation, also known as the Back to the Moon bill,
would authorize the U.S. government to purchase lunar science data
from private vendors. This new cost-saving approach to
exploration of the Moon would jump start the long dormant U.S.
lunar program, and provide scientists with a more complete
understanding of the potentially valuable mineral and elemental
resources on the lunar surface.
      The Lunar Resources Data Purchase Act is planned to be
introduced in the 103rd Congress, once comments on the draft
bill to be released in January are considered.
      San Diego L5, founded in 1982, promotes the development and
exploration of space through public education, communication
with other special interest groups, and political activity. San
Diego L5 played a major role in the enactment of the Launch
Services Purchase Act, a Federal law that prohibits NASA from
launching most space satellites.
      For more information, please contact Gregory Nemitz, San
Diego L5 Publicity Coordinator, at 619/295-3690.

--- Maximus 2.01wb

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

Date: 11 Jan 1993 18:51 UT
From: Ron Baalke <[e-mail]>
Subject: Magellan Update - 01/11/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Doug Griffith, Magellan Project Manager

                         MAGELLAN STATUS REPORT
                            January 11, 1993

1.  The Magellan spacecraft continues to operate normally, orbiting
Venus 50 times per week and transmitting a carrier signal (plus X-band
telemetry) which is precisely tracked by the DSN (Deep Space Network)
stations to extract gravity data.

2.  Temperatures remain in the expected range.  Bay 7 which contains
the CDS (Command Data Subsystem), is at 46 degrees C with a cycle depth
of 4 degrees.  Transmitter B is at 49.2 degrees with a variation of 0.7
degrees.

3.  Attitude control continues to be precise.  All starcals (star
calibrations) over the weekend were successful with only one partial scan.

4.  Magellan has completed 6523 orbits; 887 so far in Cycle-4 which
will end on May 25, 1993.

5.  Following the end of Cycle-4, the Magellan mission will begin a
"Transition Experiment" in which the periapsis will be intentionally
lowered to allow the atmospheric drag to slow the spacecraft's
velocity.  This aerobraking maneuver will enable the mission planners
to circularize the orbit and gather high-resolution gravity data
closer to the poles of Venus.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: Mon, 11 Jan 1993 19:33:16 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: One Small Step for a Space Activist... (Vol. 4 No. 1)
Newsgroups: sci.space,talk.politics.space

           One Small Step for a Space Activist...
                 Vol. 4 No. 1 - January 1993
                             By
                  Allen Sherzer & Tim Kyger

The San Diego L5 Chapter and David Anderman have come up with a
good idea on how to get Lunar probes back to the Moon. The
idea is encapsulated in the Lunar Data Purchase Act (LDPA) which
has been circulating and which will hopefully be introduced soon.

The LDPA would authorize the Administrator of NASA to
purchase from the private sector maps of the Moon (chemical,
terrain, or gravity). The requirements are simple enough
that a 'smaller, faster, cheaper' probe can accomplish the
task, which means that the NASA Administrator can fund LDPA
activities by simply reprogramming the small amounts of money
needed. Note that the bill is an authorization, NOT an
appropriation. LDPA may also specify resolution and
other details. This approach is far more likely to gain
us our goals then the course we have taken in
recent years for three reasons.

First, by emphasizing commercial procurement of data and not
hardware the way is left open for more creative solutions. In
addition, those solutions will not be bogged down by the NASA
requirements process. Second, a vendor doesn't get paid unless
they provide the data; there will be no incentives for dragging
out the effort.

Third, and most important, is that the bill gets the job
done by using our strengths and not our weaknesses. To
understand how this is so, one must understand the
difference between an Authorization and an Appropriation.

Like the rest of the government, there are a series of
checks and balances which apply to getting money from the
Feds. Each house has Budget Committee which sets overall
guidelines for outyear spending. Each year the budget
committees pass a budget (usually) early in spring
to guide Congressional spending.

Next comes Authorization Committees. These committees are
where the experts live. Their main function is to be
knowledgeable about their area and judge which programs are
worth funding and which aren't worth funding. They pass on
the merits of projects, both blessing for funding and
providing guidelines on how much can be spent.

Finally, the Appropriations Committees. They decide
how much money the government will spend each year and
allocate it to subcommittees who appropriate funds among
various projects. They are guided by the Authorization Bill;
they cannot appropriate funds to projects not authorized or
appropriate more than authorized. Authorization is a work
order, Appropriations is the check.

That, of course, is the theory. In practice it doesn't work
that way. In many cases, authorization bills are passed very
late; usually too late to do any good. This makes appropriation
bills de facto authorization bills. Thus, the House Appropriations
Committees a very powerful place and its chair arguably the most
powerful person in the government.

Because of their power, space activists have spent a lot of effort
trying to pressure Appropriators to do what we want. Several times
we have even shut down the office phone of the Subcommittees responsible
for funding NASA with calls to fund SEI. These efforts have, to quote
the bard, been full of sound and fury, signifying nothing. This is because
we have no power. We are out-spent and out-classed by the older
Veterans and Housing interest groups which compete with us for funds.

So where are we strong? Where have we actually made a difference? The
answer is in the House Subcommittee on Space and in the full Science
and Technology Committee. Here activists have been instrumental in
getting bills passed covering areas from commercial launch service
purchase to patent protection for space research. Twice the Committee
Chair (Rep. Brown (D-CA)) has received important election help from space
activists, and many members on the Committee share our agenda.

This brings us back to the LDPA. By AUTHORIZING the program
and keeping costs down, we can do the precursor work which
the Appropriations Committee to date refuse to fund. The
thing to remember is that LDPA accomplishes it by using our
strengths, not our weaknesses. This is an example of working
faster, better, cheaper; smarter, not harder.

                     Legislative Roundup

                          SSTO/SSRT
Freshmen Orientation is taking off. Among others Rep.
Torkelson will soon be visited by the Boston chapter. Several
other chapters are sending out letters and making initial
contacts. If you want to help, contact Tim Kyger at [phone].

On the inside, Clinton's new Science Advisor is John Gribbin who was
at the Office of Technology Assessment. He is neutral about SSTO but
most of his staff are strong supporters. Gore will likely be calling
the shots but this is good news.

                      Commercial Space
The start of the 103RD Congress is near. Time again to
continue the process of chipping away at government
impediments to commercial space activity. Expect to see some
of the tax provisions which didn't make it into last year's
NASA bill to be re-introduced. If Clinton is serious about
targeted tax cuts to promote investment then odds of
passage, even if only as an amendment may be pretty good.

Thing to do:
1. Do you have any ideas on what would be good to include in
future commercial space legislation? If so, drop a note to
Barry Berringer, Care Of Rep. Robert Walker.
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------103 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Mon, 11 Jan 1993 17:06:00 GMT
From: PETER YASUDA <peipyy@robots>
Subject: Railgun in Southwest US
Newsgroups: sci.space

In article <[e-mail]>, ssi![e-mail] ("Louis F. Adornato") writes...
>uunet!eros.calpoly.edu!jgreen writes:
>> I've heard a rumor that some organization (SSI?) has actually
>> built a large railgun somewhere in the SW USA.  It's apparently
>> supposed to be big enough to put small payloads (>5 kg) into
>> orbit, though I don't know if they've done that yet.
>>
>> Is this a rumor or is there some truth to it?

It's not a rail gun; it's some kind of gas gun.  It's being built
by one of the Energy Dept labs.  It uses a really big piston to
compress hydrogen gas which drives the projectile out the launch
tube, which is mounted at a right angle to the piston.  Gas is
fed into the launch tube as the projectile passes by.

The first attempt will be a test with a light projectile.  If
successful, the plan is to scale it up.

Sorry, that's all I recall.  I don't even remember where the
article appeared.

pyy

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

Date: Mon, 11 Jan 1993 20:24:52 GMT
From: [e-mail]
Subject: Railgun in Southwest US
Newsgroups: sci.space

In article <[e-mail]> ssi![e-mail] ("Louis F. Adornato") writes:
>Personally, I don't know that a railgun is going to be worth much for
>anything other than ASAT and ABM applications.  The problem is that a
>ground launched body can't attain orbit (at least, not an orbit that
>doesn't intersect the surface) without a circularizing burn at
>periapsis.  This means that you have to carry propulsion (motor and
>fuel), GNC hardware (star trackers or a gyro/accelerometer platform,
>momentum wheels or an RCS, guidance computer and control hardware),
>power and cooling, a shroud capable of protecting the whole shebang
>when it exits the launcher in sea level air at better than 17,000 mph
>(orbital velocity at 150 mi), aerosurfaces to prevent tumbling, and
>probably active control of same, and still retain enough mass
>capability for a payload.

You also has to survive the launch.  With accellerations up to 5
million G, temperatures in the 1000's C range, and some of the most
serious electrical and magnetic fields you can find anywhere, you
wouldn't want to be fired out of a rail gun.  Nor would you want to
try to design a payload which could be fired out of a rail gun.

But for those of you who don't know what a railgun is, I'll give you a
brief intro.  This is a VERY high level description, greatly
simplified.  A rail gun works because of the interaction between an
electrical field with a magnetic field called the Lorentz force.  If I
recall correctly, the basic equation is f = E x B.  So you want great
big E (electrical) fields and hefty B (magnetic) fields so you get a
whole lot of f = mA.

Let's see if I can explain using ASCII sketches:


         NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN    <- North end of
         NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN        magnetic field

        +++++++++++++++++++++++++++++++++++++++++P++++++++  <- Positive rail
<- Velocity vector <-                            P
        -----------------------------------------P--------  <- Negative rail

         SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS    <- South end of
         SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS        magnetic field

Where "PPP" marks the payload or payload carrier, which is a conducting
bar touching both rails.  A great big current flows through the rails,
passing through PPP.  This electrical field is perpendicular to the
magnetic field, so the PPP is subject to the Lorentz force, f = E x B.
Assuming there's little or no friction with the rails (which is very
difficult to arrange), the PPP scoots down the rails in a heckuva
hurry, accellerating as it goes.  Because there is friction with the
rails, they erode quickly and have to be replaced after every N
launches, where N varies with the friction and wear properties.

Since you need to reach orbital velocity in a short distance, you need
to have BIG accellerations.  This implies the big E fields (hence hefty
current along the rails and PPP), big B fields (hence hefty magnets),
and low mass (f = mA).

We now return you to discussions about the PEACEFUL use of space.

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "...Development of the space station is as inevitable as
      the rising of the sun." -- Wernher von Braun

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

Date: Mon, 11 Jan 1993 20:33:23 GMT
From: Henry Spencer <[e-mail]>
Subject: Re; Shuttle Toilet
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>>>Uhhh... why didn't NASA just reuse the Skylab toilet on Shuttle?
>>Good question.  I haven't seen a detailed explanation...
>
>    Actually, I think the primary reason was because the Skylab
>toilet used the old empty Saturn tank to dump the wastes into (like
>the Skylab trash disposal did)...

Nope, the Skylab toilet captured and bagged the solid wastes, because
some of the biomedical experimenters wanted them.

I don't remember exactly what was done with the urine; I know there was
a long squabble about the best approach during Skylab's development.

>Skylab toilet was rather large and heavy, and on shuttle they tried
>to reduce it down into a "closet" size...

There wasn't any particular reason why the Skylab toilet needed to be
big or heavy; are you sure?  Unlike the original shuttle toilet, it
wasn't a mechanical contraption with moving parts.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 11 Jan 93 12:27:25 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Saving an overweight SSTO....
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Gregory N. Bond) writes:
> Suppose DC-X works more-or-less as planned, and they go ahead and
> attempt to build a DC-Y/DC-1.  And suppose the pollyannas are right
> and it bloats and the dry mass goes up.        ^^^^^^^^^^

Cassandras?

> There are a couple of scenarios here:
[...]
> 3) The mass overrun is much larger than that.  At this point, the
> project is lost; however I suspect that (given the findings of the
> various reports into the general feasability) this is much less likely
> than the previous cases.
>
> And in any case, you know a lot more than when you started, and you
> can do it right next time!

If DC-Y flops, there won't BE a next time for SSTO.  Not before our
teeth fall out.

What a Pollyanna.  (-:

"Read my lips, Hal:          Bill Higgins
Open the Pod Bay doors!"     Fermi National Accelerator Laboratory
                             Bitnet:     [e-mail]
(Happy 1st, or -4th, birth-  SPAN/Hepnet: 43011::HIGGINS
day to Hal 9000 on 12 Jan!)  Internet:  [e-mail]

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

Date: Mon, 11 Jan 93 15:44:08 PST
From: "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov
Subject: Shameless Hucksterism to Plague STS-54

Here is a report on the upcoming Shuttle mission from Francis
Slakey of The American Physical Society.  Is it just me, or does
anyone else think that NASA's Shuttle people engage in a little
too much hucksterism?  I especially find the wake-up calls to
raucous music annoying - do those people really find that amusing?
Do they do their Christmas shopping at Spencer's Gifts?

______

WHAT'S NEW (in my opinion), Friday, 8 Jan 93       Washington, DC

3. SHUTTLE MISSION STS-54 WILL ADVANCE THE FRONTIERS OF SCIENCE.
The seven-day $843M mission is scheduled for a 13 Jan 93 launch.
In the "Application Specific Preprogrammed Experiment Culture
System Physics of Toys" test, Mission Specialist Susan Helms will
play with a "flipping mouse," Mario Runco with "klacker balls",
Greg Harbaugh with a basketball, and pilot Don McMonagle with a
"balloon helicopter".  After recess they can relieve themselves
in a test of the new $30M Hamilton Standard Space Toilet.  Then,
it's on to the Extravehicular Activity test.  The Intravehicular
Crew Member (Helms) will observe as Extravehicular Crew Member 1
(Harbaugh) and Extravehicular Crew Member 2 (Runco) manipulate
each other in the cargo bay.  As explained by NASA: "To simulate
carrying a large object, the astronauts will carry one another;
to simulate how well they can align an object, they will attempt
to place each other into brackets in Endeavor's airlock."

Francis Slakey  [phone]      The American Physical Society
_______

_____________
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
"Let machines multiply, doing the work of many,
                     But let the people have no use for them." - Lao Tzu

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

Date: Mon, 11 Jan 93 21:14:50 EST
From: John Roberts <[e-mail]>
Subject: Shuttle tiles

-From: [e-mail] (Gary Coffman)
-Subject: Re: Let's be more specific (was: Stupid Shut Cost arguements)
-Date: 11 Jan 93 15:48:12 GMT

-Shuttle designers... chose to use refractory silicates in the form of
-tiles. These are very poor conductors of heat, you can place your bare
-hand against one side of the tile while playing an oxy-acetylene torch
-on the other and not notice a temperature rise.

I think perhaps you mean a propane torch, or butane torch like Mary described.
Pulling some numbers from the Rogers report and elsewhere, the leading
edges of the Shuttle wings have to withstand heating up to 2750 F, and are
made of layers of graphite cloth in a carbon matrix, with the outer layers
chemically converted to silicon carbide. The upper fuselage, the coolest
portion during reentry, is only heated to about 600 F. The Shuttle has
high-temperature and low-temperature ceramic tiles, which are described in
this report as being "nearly pure glass" (I had thought they were silica),
with nearly 90% of the volume being "air". The low-temperature ceramic tiles
are are rated to 1200 F, and the high-temperature tiles to a higher value,
but something below wing leading-edge temperatures.

While such temperature resistance is admirable, a properly-designed
acetylene torch can heat a thermally isolated object to 6000 F (~ 3300 C).
I wouldn't expect any trouble melting most ceramics - I've accidentally
melted fire bricks that I was using as a backstop for acetylene welding.

>From the 1961 CRC handbook, here are some temperature ratings for ceramics
and other materials:

  SAFE CONTINUOUS OPERATING TEMPERATURE / MELTING POINT
     Material          C         F      /    C        F
     --------        ----      ----        ----     ----
     Porcelain       1195      2185     /  ....     ....
     Alumina (84%)   1400      2550     /  ....     ....
     Zircon          1455      2650     /  2500     4530
     Silicon carbide 1510      2750     /  2295     4160 (volatilizes)
     Silica          1620      2950     /  1670     3038
     Alumina (96%)   1700      3100     /  ....     ....
     Alumina (100%)  1950      3540     /  2050     3720
     Zirconia        2316      4200     /  2680     4850
     Magnesia        ....      ....     /  2800     5072
     Titanium boride ....      ....     /  2900     5250
     Thoria           ...      ....     /  3110     5630
     Titanium carbide ...      ....     /  3125     5660
     Tantalum nitride ...      ....     /  3440     6050
     Tungsten         ...      ....     /  3370     6100
     Zirconium carbide ..      ....     /  3520     6370
     Graphite         ...      ....     /  3800     6870
     Tantalum carbide ...      ....     /  3850     7025
     Hafnium carbide  ...      ....     /  4160     7520

John Roberts
[e-mail]

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

Date: 09 Jan 93 17:10:08 GMT
From: Ralph Buttigieg <[e-mail]>
Subject: What was NASA thinking?
Newsgroups: sci.space

Original to: [e-mail]
 c> Hence the question in the title of my post:  What was NASA
 c> thinking about?  Apparently the Saturn engines could have
 c> been used to build the shuttle vehicle.  Why weren't they?
 c>
 c> A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable
 c> boosters would have taken advantage of a history of literally
 c> dozens of successful flight firings.  Plus there would
 c> have been a much wider range of abort modes.
 c>

 But how reusable were the Saturn engines? Then again, how reusable are
 the SSME...

 ta

 Ralph Buttigieg

--- Maximus 2.01wb
 * Origin: Vulcan's World-Sydney Australia 02 635-1204 (3:713/635)

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

Date: Mon, 11 Jan 1993 20:27:56 GMT
From: Henry Spencer <[e-mail]>
Subject: What was NASA thinking?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ralph Buttigieg) writes:
> c> A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable
> c> boosters would have taken advantage of a history of literally
> c> dozens of successful flight firings.  Plus there would
> c> have been a much wider range of abort modes.
>
> But how reusable were the Saturn engines? Then again, how reusable are
> the SSME...

Any regeneratively-cooled liquid-fueled engine ought to be reusable almost
indefinitely, if it's mounted on a reusable vehicle.  Test-stand experience
certainly supports this.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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


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From: Joe Cain <[e-mail]>
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    Following the recent posting I asked my congressman's
assistant if he knew of any new information as to a possible new
adminstrator for NASA. His response was that the only two names he has
seen floated around DC have been Bill Nelson and Sally Ride. He
specifically had not heard anything new, nor that there was any action
on replacing Goldin. He said that these have been discussed since the
election.

    It sounds like some trial balloons are in the air, likely
comments or opinions should be directed to the new administration.

Joseph Cain        [e-mail]
[e-mail]        scri::cain
[phone]        FAX [phone] or -0098

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End of Space Digest Volume 16 : Issue 037
------------------------------