Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_3/v16no374.txt

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Date: Sat, 27 Mar 93 05:20:27
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #374
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 27 Mar 93       Volume 16 : Issue 374

Today's Topics:
          25 kg. to Venus, how much would it cost? (2 msgs)
                          Artificial Gravity
                          How to cool Venus
                            Idle Question
                 In what craft did Glenn orbit the E
                    JPL Instruments Set for STS-56
                          Life in the Galaxy
                          Luddites in space
                      Magellan Update - 03/22/93
           Meteorites on Earth...where did they come from?
         Predicting gravity wave quantization & Cosmic Noise
                Space Posters, and where to get them?
                       Space Ship - Outer Space
Speculation: the extension of TCP/IP and DNS into large light lag enviroments
                STS-55 (Columbia) abort (was Aurora?)
                  Why use AC at 20kHz for SSF Power?

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: Fri, 26 Mar 1993 17:05:52 GMT
From: Frank Crary <[e-mail]>
Subject: 25 kg. to Venus, how much would it cost?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Jeff Bytof) writes:
>Using existing technology and launch vehicles, what would be the
>cheapest way to deliver a 25 kg. payload to the upper Venusian
>atmosphere?

Putting an aeroentry/heat shield and related equipment would
drive the mass up to 40-50 kg. A minimum energy transfer from
Earth would require (overall) a 4.5 km/s delta-v for an
object in Low Earth Orbit. Allowing another 50 kg or so for
the rocket and fuel tankage, and assuming a rocket with about
300 seconds of impulse (typical for a good, small rocket), you'd
need perhaps 500 kg of fuel. So, adding it all up, a 25 kg
package to Venus would require about 600 kg IMLEO. The cheap
way to launch that would be either Pegasus or a Scout. With a
Scout, you would be well under the vehicle's capacity: You'd be
more efficient if you sent a larger (~50kg) package, or sent two...

                                                    Frank Crary
                                                    CU Boulder

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

Date: Fri, 26 Mar 1993 17:19:13 GMT
From: Keith Mancus <[e-mail]>
Subject: 25 kg. to Venus, how much would it cost?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
> For maybe $15M you can get Pegasus plus a spin-stabilized kick motor,
> which will give you about 75kg to Earth escape...

> For not a lot more, maybe $20M, you should still be able to buy a
> Molniya launch from the Russians:  1700kg (!) to Earth escape...

  Sounds to me like there is a LOT of room for cost improvement on the
low-mass end, unless the $20M figure is really a loss to the Russians
and they just don't know it (quite possible).  20E6 / 1.7E3 = 11.8E3,
or 11.8K $/lb.  15E6 / 75 = 2E5, or $200K/lb.  At $12K/lb, the Molniya
price, the 75 kg would cost $900K.
  It seems to me that a cost of < $1M per launch would have a great effect
on the viability of this type of mission.  Granted, there are some benefits
to scale here, but I don't believe that decreases cost by a factor of 10.
I wonder what a Russian-built Pegasus-class launcher would cost?

--
| Keith Mancus    <[e-mail]>                           |
|                 N5WVR                                                 |
| "Black powder and alcohol, when your states and cities fall,          |
|  when your back's against the wall...." -Leslie Fish                  |

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

Date: Fri, 26 Mar 1993 13:56:32 GMT
From: Nick Szabo <[e-mail]>
Subject: Artificial Gravity
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>You've missed a point:  where is the *requirement* for it?
> [artificial gravity]

You've missed a point: where is the *requirement* for astronauts?
Most of the astronaut program is justified by "life sciences"
research, which is predicated on an alleged major need for astronauts
in the future.

What will they be necessary for in the future, if anything?  If
the answer to this includes the moon or Mars, then there is
probably a need for artificial gravity to test out long-duration
adaptation of mammals to these gravity levels, as well as the
concern about long durations on flights to the Mars, asteroids,
etc.


--
Nick Szabo                     [e-mail]

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

Date: Fri, 26 Mar 1993 17:17:28 GMT
From: Michael Robert Williams <[e-mail]>
Subject: How to cool Venus
Newsgroups: sci.space

Some of the topics getting tossed back and forth are quite interesting;
I especially liked the idea of making it *snow* on Venus.

But, to the point, several people have been talking about using large
nuclear bombs (should that be "tools"?) to blast a large fraction of Venus's
atmosphere away. I read a really fascinating book a few years back called
"ThPhysical Principles of Thermonuclear Explosive Devices" that had a
chapter called "On Creating Thermonuclear Explosives of Arbitrarily Large
Size." It seemed pretty easy, at least conceptually; the author even says
something about blowing most of the atmosphere of the Earth away with a
suprisingly small bomb.

Does anybody with more experience in the field than I have (i.e. any at all)
have any idea if this sort of thing is truly possible, or was the author
improperly scaling his results?

In Real Life:Mike Williams     | Perpetual Grad Student
e-mail      :[e-mail]|   - It's not just a job, it's an indenture
---------------------------------------------------------------------------
"If you ever have a world of your own, plan ahead- don't eat it." ST:TNG

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

Date: Fri, 26 Mar 1993 16:08:58 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Idle Question
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] ("F.Baube[tm]") writes:
>>How much weight would I get to lob into LEO ?
>
>My copy of the Scout user manual is at home, but typically it's a few
>hundred pounds, as I recall.

Scout is rated at 475 pounds to a 300 km orbit. It has lofted as much
as 522 pounds to LEO.

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: Fri, 26 Mar 1993 16:45:58 GMT
From: Henry Spencer <[e-mail]>
Subject: In what craft did Glenn orbit the E
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Doug Loss) writes:
>Sorry, Tom, Glenn's capsule was called Friendship 7.  That was an
>official NASA name; they stopped using names for spacecraft with Gemini.
>The names for all the Apollo command and lunar modules were in fact
>radio call signs, non-official designations to make communications
>easier.

Not quite right.  All the Mercury capsules had names.  The first Gemini
capsule had a name too, but it's not mentioned much because NASA did not
like it *at all*:  Grissom dubbed it "The Unsinkable Molly Brown", in
reference to the way his Mercury capsule sank.  The next Gemini crew had
pencilled in "American Eagle" for their capsule, but at that point NASA
decided "no more names".

However, they were forced to reverse this during Apollo, when they were
maneuvering two spacecraft and needed radio callsigns.  The Apollo 9
names, Gumdrop and Spider, were unofficial inventions of the astronauts,
but after that the names were official again (mostly because NASA decided
that it could at least exercise some control over official names).
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: 26 Mar 1993 17:23 UT
From: Ron Baalke <[e-mail]>
Subject: JPL Instruments Set for STS-56
Newsgroups: sci.space,sci.space.shuttle,sci.geo.meteorology

From the "JPL Universe"
March 26, 1993

ACRIM, ATMOS set for shuttle flight
By Karre Marino

     As part of NASA's Mission to Planet Earth series, JPL's
Atmospheric Trace Molecule Spectroscopy (ATMOS) and the Active
Cavity Radiometer Irradiance Monitor (ACRIM) will be on board the
Space Shuttle Discovery, when it is launched sometime during the
early part of April. The two instruments will study the chemical
composition of the atmosphere and how it is changing, and will
measure solar variations and their impact on the earth's climate,
respectively.
     ATMOS, which is intended to fly aboard the shuttle about
once every year, uses a technique called infrared solar
occultation spectroscopy, which Mike Gunson, ATMOS' principal
investigator, described as "taking sunlight -- and particularly
sunlight at infrared wavelengths -- to create a spectrum.
     "As the sun's rays pass through the earth's atmosphere at
sunset or sunrise, the sunlight is absorbed by gases in the
atmosphere," Gunson said. "If you can produce a spectrum, you can
see how much of that infrared sunlight is absorbed at different
wavelengths and characterize which trace gases and how much of
these gases is present in the atmosphere."
     Gunson, from the Atmospheric and Oceanographic Sciences
Section 322, indicated that the window of opportunity is small.
"During each orbital sunrise or sunset, ATMOS must take a very
rapid series of observations. Since the sun's rays begin well
above the Earth, and take just a few minutes to go behind the
Earth," he explained, "we try to get about 100 measurements in
two to three minutes." Even in such a constrained time period,
Gunson said the team gathers "a huge volume of data."
     Each of these measurements is a high-resolution infrared
spectrum containing some million points of data. And through each
mission, Gunson said tens of gigabytes of data are accumulated.
     ATMOS will focus on the middle atmosphere ("from a few
kilometers above us up to 150 kilometers") to discern how its
composition is changing. "We want to measure as many different
gases as we can," he said. "The trace gases -- those over and
above nitrogen and oxygen -- include chlorofluorocarbons;
measuring these will enable us to learn what processes in the
stratosphere turn them into inorganic chlorine and how exactly
this happens."
     While ATMOS does not measure chlorine monoxide, the gas
directly involved in ozone destruction, it does measure the other
forms of chlorine-containing gases.
     "So what we have from an experiment like ATMOS is a snapshot
inventory of what's in the stratosphere. We can use these
vertical-distribution profiles for each of these gases to help
modelers to predict how the atmosphere will change."
     Gunson said that gathering the information creates a
reference point for future comparisons, "which tells us how the
atmosphere is changing."
     ATMOS first flew in 1985 aboard Spacelab 3 and flew in a
second mission in March 1992 aboard Atlas I. Important data were
gathered during both flights. "Looking at these measurements, we
have seen distinct changes in the atmosphere's composition."
     Those changes are not always a result of man. Gunson
described last year's eruption of Mt. Pinatubo in the Philippines
as providing the perfect opportunity to study how such natural
occurrences affect the atmosphere. "Nine months after the volcano
blew -- the biggest eruption of the century -- it was still
spewing bits of material into the environment," he said. "The
volcanic residue created an aerosol layer of fine droplets of
sulfuric acid and water in the lower atmosphere. Of course, it
was purely serendipitous that the volcano erupted, and we're able
to measure its effects."
     Gunson said history has shown that large volcanic eruptions
have an effect on climate; why is only partially understood.
"Pinatubo caused changes in the mean temperature worldwide," he
explained, noting that a National Oceanographic and Atmosphere
Administration analysis indicated a slight cooling trend. The
aerosol layer will last a year to 18 months, then will
precipitate out. However, he expects some longer-term effects.
     In the future, Gunson and his team would like to launch
during the fall, which allows them to look at the Antarctic,
"where we know we'll find some very interesting chemistry going
on."
     He said the importance of ATMOS is seen in repeating these
measurements over a decade or longer. "We provide measurements

that the scientific community at large can pull together and make
sense of. Our overall goal is to gather data with all these
different settings -- solar output, the state of the atmosphere.
This is part of NASA's large-scale program to which we all make
our own small contribution."
     Making its own contribution is the ACRIM instrument, which
will monitor and verify total solar irradiance (TSI) variability,
providing reference comparisons with other solar monitors on
satellites that are required to understand the sun's long-term
behavior.
     According to Dr. Richard Willson, principal investigator of
the ACRIM experiments, the earth's climatological mean is
determined solely by how much of the sun's radiant energy -- our
only source of heat and light -- falls on the planet's surface,
oceans and atmosphere.
     The Atlas/ACRIM results, he said, will assist researchers in
understanding the role of TSI variability in climate change.
While JPL currently has the ACRIM II instrument on the Upper
Atmosphere Research Satellite (UARS), "instruments on other
satellites and/or the shuttle are required for comparisons with
the results of ACRIM II to provide backup observations," Willson
said.
     This comparative/backup role played by ACRIM's upcoming
shuttle mission is helpful in several ways, Willson said. Most
importantly, if the currently operating UARS/ACRIM II should
cease functioning before ACRIM III is launched (projected for
2002), the shuttle ACRIM results would be used to compare
UARS/ACRIM II and ACRIM III.
     "The ACRIM instrumentation," Willson said, "although state
of the art in the solar-measurement field, is not sufficiently
accurate to sustain the required long-term precision in the TSI
database should an interruption in the train of succeeding
satellite monitors occur."
     Willson said sustained changes in TSI of "as small as 0.5
percent per century" could cause all the climate variability
known to have occurred in the past, and to detect solar
variability at that small rate requires that the long-term TSI
variability database be constructed with a precision equal to the
in-orbit precision of the monitoring instrumentation. The only
way to obtain this precision, he said, is to compare succeeding
satellite solar monitors directly or compare both of them with an
experiment like ACRIM.
     Willson, who works in the Atmospheric and Oceanographic
Science Section 324, and his team are interested in the shuttle
ACRIM observations, which he termed as "third-party experiments
that can relate one satellite's of results to another's at the
level of precision defined by all three instruments."
     Willson said the ATLAS/ ACRIM instrument's results, although
just snapshots of TSI during week-long missions once per year,
will thereby contribute to an understanding of the long-term
database.
     "Solar monitoring by the first ACRIM experiment on the Solar
Maximum Mission from 1980-89 showed that there is a solar cycle
component of variability: TSI is directly proportional to solar
magnetic activity, demonstrating an 0.1 percent peak-to-peak
variation over solar cycles 21 and 22 (the last sun spot cycle).
That in itself may be too small to have an observable effect on
climate," he said, "but we're interested in whether this little
0.1 percent `wiggle' over a solar cycle is superposed on
longer-term, larger-amplitude variability. Periods of 80 to
several hundred years are suspected to exist with amplitudes of 1
percent or more. TSI variability is suspected to have caused
known past climate changes on these time scales."
     Willson noted, however, that such subtle changes in TSI will
be very difficult to detect since the results of many satellites'
instruments must be used over many decades or even centuries to
prove definitively that solar variability causes climate change.
     The only hope of providing a sufficiently precise TSI
database over these time scales, he said, is to relate the
results of solar-monitoring experiments at the level of
instrument precision, which is orders of magnitude smaller than
instrument accuracy. While this is ACRIM's third shuttle flight,
Willson said that they have yet to determine whether the shuttle
experimental environment will be adequate for the task of
providing "third-party" observations.
     "We have had our share of problems trying to make good
measurements aboard the shuttle," he said. "The first attempt was
as part of the Spacelab 1 Mission in 1983, and the large array of
experiments on board overwhelmed shuttle resources. Additionally,
some of the untested, new shuttle instrumentation experienced
mechanical and electrical problems.
     "Our ACRIM experiment functioned flawlessly, but it was
attached to an ESA-provided command/data interface that ceased
functioning when it was warmed by the sun. This resulted in our
getting only an hour's worth of data when we'd been expecting
about 25 hours," he added.
     Willson said that on ACRIM's second flight, aboard Atlas I,
the shuttle systems functioned well, as did ACRIM, and a full set
of results was acquired. "We made real-time comparisons with the
UARS/ACRIM II experiment, providing a potentially useful
reference point for the future."
     The upcoming Atlas II mission "should help us tie down the
quality of observations we can expect from ACRIM in the shuttle
environment." Willson said data will be received in real time, as
they "pull it straight off the downlink, crunch the numbers and
offer feedback to the Marshall Space Flight Center in Huntsville,
Ala. We will have results within minutes of the actual
measurement," he said.
     "Both climatologists and solar physicists are keenly
interested in variations of TSI. Those monitoring the impact of
increasing `greenhouse gases' on the earth are especially
concerned."
                              ###
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't ever take a fence
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/  |_|/       |_____|/                     | reason it was put up.

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

Date: Fri, 26 Mar 1993 17:03:10 GMT
From: Michael Robert Williams <[e-mail]>
Subject: Life in the Galaxy
Newsgroups: sci.space,alt.sci.planetary

It's fortunate that Mars isn't in the so-called "life zone" of our Sun;
didn't any of you see/read/hear "The War of the Worlds"?

It's unfortunate that Venus isn't in the life zone of the Sun;
didn't any of you see "Half-Naked Amazons from Venus"?

In Real Life:Mike Williams     | Perpetual Grad Student
e-mail      :[e-mail]|   - It's not just a job, it's an indenture
---------------------------------------------------------------------------
"If you ever have a world of your own, plan ahead- don't eat it." ST:TNG

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

Date: 26 Mar 1993 12:27:58 -0500
From: Pat <[e-mail]>
Subject: Luddites in space
Newsgroups: sci.space,talk.politics.space

In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
>I hardly ever 'ignore economics', since I went to the trouble and
>effort to get a degree in the subject so I would understand things
>that to you are apparently beyond comprehension.  Perhaps you should

And DOug Mohney in a previous Post
   How much do I know about Economics, I have a degree in the subject.

SO who else has a degree in economics?

Pat

    Who didn't bother, because i already know the field.

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

Date: 26 Mar 1993 12:36:42 -0500
From: Pat <[e-mail]>
Subject: Magellan Update - 03/22/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

I have never studied the magellan design data, so I am operating blindly,
But if the Radar emitter is separate from the x-Band downlink
transmitters,  I thought they were the same devices,  Then is there
some way of coding into the Radar emission, and using that to transmit
back data, when the Last transmitter goes?

Evena simple morse-pulsing.  Certainly, low rate, but good for filling
in some of those remaining blank spaces that magellan never imaged.

That's only about 1% of the the surface.

pat

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

Date: 26 Mar 93 17:51:24 GMT
From: David Lai <[e-mail]>
Subject: Meteorites on Earth...where did they come from?
Newsgroups: sci.space

Hi netters,

    I know that there're some meteorites which were found in the
South Pole area has been identified as Moon and Mars rocks.  My question
is how do they know that they are from Moon and Mars?  I think they
compare the rock samples that carried back from Moon/Mars and the mete-
orities found on Earth.  But, did we ever bring back any rock samples
from Mars????

                        David.

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

Date: Fri, 26 Mar 1993 16:19:38 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

In article <[e-mail]> [e-mail] (Matt McIrvin) writes:
>[e-mail] (Gary Coffman) writes:
>
>>Why would there be an amplitude change? The EM wave is transverse,
>>the G wave is compressive.
>
>Compressive?  I thought gravitational waves were transverse quadrupole
>oscillations.  The oscillating tidal forces are transverse to the
>direction of motion of the wave.

I could write a book on what I don't know about gravity waves. I'm
taking a classical approach to the problem, which may be all wet.
If your description is accurate, then a G wave perpendicular to
the line of flight of the EM wave would have the largest effect,
and a wave along the line of flight would be undetectable. In any
event, I'm suggesting that the oscillating force alternately
stretches and compresses the ether (fabric of spacetime, whatever).

Gary
--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: 26 Mar 93 11:23:38 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Space Posters, and where to get them?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes:
> Wiers question, where is a good place to get Space Posters??? I know that many
> people seem to like posters of movie stars and such, beer (sexy girls okay),
> and other such things, I was wondering if someone has any Space Posters and
> where to get them?

Check the sci.space FAQ for sources to start with.

You can buy some nice space posters from the U.S. Government Printing
Office bookstore.  Voyager images and the Shuttle figure heavily.
Aaarrggh!  We don't have a USGPO address in the FAQ, though we refer
to it several times! They have local bookstores in many cities, though
none in Alaska (sorry, Mike).  Ask them for specialized catalogues of
space and astronomy stuff as well as their general catalogue.

U.S. Government Printing Office
MAin Office
710 N. Capitol St.
Washington, D.C. 20402
[phone]

Public Affairs Offices at NASA centers may send you a poster or two if
you ask politely.  Addresses are in the FAQ file.

The SEDS people have made some delightful posters for their
conferences.  Mail a message to [e-mail] asking them to
e-mail information.  Ask about the California 1989 "Space Surfing"
poster!

I've gotten nice posters from ESA at conferences, but I haven't seen a
catalogue.  Try the U.S. office first, but also write to their
Publications Office in the Netherlands.

EUROPEAN SPACE AGENCY (ESA)
    955 L'Enfant Plaza S.W.
    Washington, D.C. 20024
    (202)-488-4158

         Distribution Office
         ESA Publications Division
         ESTEC
         Kelplerlaan 1
         2200 AG Noordwijk
         The Netherlands

Most space companies have posters publicizing their projects.  Boeing, TRW,
Martin  Marrietta, Lockheed, etc.  Check a magazine or directory for their
addresses.

Check ads in *Ad Astra*, *Space Frontier*, *Astronomy*, and *Sky & Telescope*.

PlanSoc has some items for sale.

         Planetary Society
         65 North Catalina Avenue
         Pasadena, California 91106

And if you find one with a sexy girl movie star drinking beer in
front of a spacecraft, let me know!

--
     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
 /       \                          (_) (_)                    / | \
 |       |     Bill Higgins   Fermi National Accelerator Laboratory
 \       /     Bitnet:     [e-mail]
   -   -       Internet:  [e-mail]
     ~         SPAN/Hepnet:      43011::HIGGINS

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

Date: 26 Mar 93 17:57:25 GMT
From: David Lai <[e-mail]>
Subject: Space Ship - Outer Space
Newsgroups: sci.space

Hi netters,

    I remember that a spacecraft was around the nineth planet some
years ago.  Is there any spacecraft travelling beyond the nineth planet
now?  If so, what discovery has it make?  Can it still communicate with
the Earth?

                            David.

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

Date: 26 Mar 1993 18:23:47 GMT
From: "M. Sean Bennett" <[e-mail]>
Subject: Speculation: the extension of TCP/IP and DNS into large light lag enviroments
Newsgroups: alt.internet.services,sci.space

As man moves outward into space it will become essential to provide an information
structure for communication of data.

    The current set of protocols make no alowance for light 'lag' between
targets of wide divergence. (Mars-Earth). The current DSN is expensive to
use for continous data flow. If however we could use a series of store and
forward systems for data - we have no mechanism to ensure that the data is
delivered securely (Appart from ad-hoc protocols constructed by NASA).

    We need some form of ISO standard (I know they are hard to set,
but if NASA/GlavCosmos publish a protocol it will be the defacto standard)

    How are we to devide the domains to deal with other worlds?

        (yes I know this sounds mad - but if we have not made some
    form of descision we will have moonbase.nasa.gov - implictly
    making that instalation part of the USA..a dangerous precedent)

These are just my random thoughts. I make no claims that they hold great
thought or meaning.

    [e-mail]

Sean

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

Date: Fri, 26 Mar 1993 16:03:51 GMT
From: Gary Coffman <ke4zv!gary>
Subject: STS-55 (Columbia) abort (was Aurora?)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>... So liquid or solid, once you light the
>>boosters, you're committed to getting enough altitude to do a RTLS. The
>>holddowns can't keep the Shuttle on the pad against both main engines and
>>boosters.
>
>There's no good reason why they couldn't.  The Saturn V holddowns could,
>and did.  And they didn't even use pyrotechnic release -- they were 100%
>mechanical.

Yeah, but how much re-engineering would be involved, not just to the
pad, but to the Shuttle structure as well? Beefing the pad is relatively
easy, and I guess the new holddowns could be on the boosters rather than
the Shuttle structure, but it would be a nasty problem.

On the other hand, if liquid boosters were used (in your dreams), the
extra holddowns would be *necessary*. Unlike the solids, liquid boosters
could suffer the same kinds of problem that caused the SSME shutdown.
Having a booster shutdown during liftoff would be too much to handle.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: 26 Mar 1993 12:42:33 -0500
From: Pat <[e-mail]>
Subject: Why use AC at 20kHz for SSF Power?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
>
>But not nearly as weight conscious as spacecraft have to be.  In
>addition, needs are somewhat different between an aircraft and a space

Yeah,fred.  The difference is that aircraft have to fly.


>station.  Personally, I think 20kHz was a bad idea, but I also think
>that this insistence of yours that if it was good enough for the
>Wright brothers it's good enough for SSF is just a bit silly.


Don't try to misrepresent my position, fred.  It's intellectually
dishonest.  I am all for 20KHz power as part of a engineering
research and developement test bed.  TO make it the defined
Prime power on an OPERATIONAL station is absolutely  stupid.

You just can't believe that someone wwants to see proven trackrecord
before commiting a 40Billion dollar program.

pat

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End of Space Digest Volume 16 : Issue 374
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