Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_0/V15NO090.TXT

Internet Message Format | 1993-07-13 | 33KB

Date: Mon, 10 Aug 92 05:00:03
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #090
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon, 10 Aug 92       Volume 15 : Issue 090

Today's Topics:
               basic electrodynamic tether description
                            Comments, Misc
           Energiya's role in Space Station assem (3 msgs)
                           Fermi's Paradox
                      Home made rockets (2 msgs)
                                 HST
              Hubble used for spying? + other neat info
                      Magellan Update - 08/05/92
                   Meteor Soaks Datona FL (2 msgs)
                                 MIR
                        Seeding Mars with life
                        SPS fouling astronomy
                    SSF, Energia, Shuttle (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 9 Aug 92 19:53:48 GMT
From: SCOTT I CHASE <[e-mail]>
Subject: basic electrodynamic tether description
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Leigh Palmer) writes...
>In article <[e-mail]> [e-mail] (SCOTT I CHASE) writes:
>
>>Yeah.  Webster's is wrong.  They are only the same in a uniform gravitational
>>field, to which the Earth is an approximation *if you stay at or near the
>>surface*.
>
>That's terribly misleading. The Earth's gravitational field becomes
>more  nearly uniform as one gets farther from the surface. The reason
>the approximation of uniform field does not hold is because the
>structure in question is large, not because it is far from Earth's
>surface.

Sorry.  Quite true.   I should have said "*if you stay at or near the same
distance from the surface*.  In this usage, "near the same distance" means
fractionally near.  So actually, the further you are from the Earth's
surface, the more closely the field approximates a uniform field for a probe
of given height.

-Scott
--------------------
Scott I. Chase            "The question seems to be of such a character
[e-mail]        that if I should come to life after my death
                and some mathematician were to tell me that it
                had been definitely settled, I think I would
                immediately drop dead again."      - Vandiver

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

Date: 9 Aug 92 20:41:25 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Comments, Misc
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (George Hastings) writes:
>There is NO WAY you could fit four in a SOYUZ-TM. I've run
>RENDEZVOUS/DOCKING SIMS in them, and three in flight suits is
>TIGHT!

Is that three in the entire vehicle or three in the Return Module? If
the latter, the fourth person rides in the Orbital Module.

Remember the scenario: a failure which requires station evacuation but
the crew is cut off from one of the Soyuz vehicle. With ACRV they would
all die since there is only one. With two Soyuz, they would have a
chance.

If four can't fit in, two or three could go, get the other Soyuz, dock
at the safe port, and return that way.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------257 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 9 Aug 92 12:07:06 EDT
From: Chris Jones <[e-mail]>
Subject: Energiya's role in Space Station assem
Newsgroups: sci.space

In article <[e-mail]>, henry@zoo (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] writes:
>>Considering the operational record of Energia and its Cyclone Boosters I would
>>have grave misgivings about putting a fourth of the space station on Energia.
>
>Energia (two stages) and its strap-ons (one stage) have a flawless record
>as far as I know.  The one Energia failure was a payload engine failure.
>Unless I've missed one, all the Tsyklon failures have been upper stages.

As I recall (having myself made this identical mistake in the past), Energiya's
boosters are Zenit first stages, not Tsiklon (both are Ukraine-manufactured, I
believ).  One Zenit failure caused extensive pad damage, so it must have been a
first stage.
--
Chris Jones    [e-mail]

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

Date: 9 Aug 92 12:09:43 EDT
From: Chris Jones <[e-mail]>
Subject: Energiya's role in Space Station assem
Newsgroups: sci.space

In article <[e-mail]>, cecil@physics (Gerald Cecil) writes:
>In an earlier posting I misquoted the payload of a fully fueled Energiya: it is
>153 metric tons to LEO (not 103) with 4 strap-ons and 238 metric tons with 6.
>(GEO figures are increased accordingly.) Compare this with the 30 or so of the
>Shuttle.  Only the 4 strap-on variant has flown.

To date, all (both) flights of the Energiya used two strap-on boosters, I
believe.
--
Chris Jones    [e-mail]

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

Date: 9 Aug 92 19:16:00 GMT
From: [e-mail]
Subject: Energiya's role in Space Station assem
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Henry Spencer) writes...
>In article <[e-mail]> [e-mail] writes:
>>Considering the operational record of Energia and its Cyclone Boosters I would
>>have grave misgivings about putting a fourth of the space station on Energia.
>
>Energia (two stages) and its strap-ons (one stage) have a flawless record
>as far as I know.  The one Energia failure was a payload engine failure.
>Unless I've missed one, all the Tsyklon failures have been upper stages.
>
>>Much better would it be to put it on the Saturn which was a zero failure
>>system...
>
>High though my opinion of the Saturn V is, anyone who calls the first
>Energia launch a failure would have to work real hard to call the second
>Saturn V launch a success.
>--
Care to elaborate on that Henry? I don't recall a failure or even near failure
of the system.  The worst problem that I ever read about was the one where one
engine on the SII developed a fuel leak and the command to shut it down was
miswired to the center engine, which caused the controllers to shut two engines
down because they were afraid to restart in the middle of a burn. It sill made
orbit on three engines which they simply let burn longer. Pogo was a heck of
a problem and still is, but what failure are you talking about?

Dennis, University of Alabama in Huntsville

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

Date: Sun, 09 Aug 92 14:46:16 EDT
From: Tom <[e-mail]>
Subject: Fermi's Paradox

>> How fast do inter-stellar colonizers move? (No data)

>No data... but reaching 10-15% of the speed of light doesn't look impossibly
>hard.  We'll be able to do that ourselves within a century or two.  At that
>speed, the galaxy is only a million years across.

Be generous.  Say 50%.  But since that is the top speed, while traveling, it's
reasonable to conclude that their avearge speed across the galaxy will be far
lower, as they will be colonizing, not just zooming through.

>> How soon did life-bearing conditions arrive, galaxy-wide? (Other galaxies?)

>You can probably write off the first billion or two years of the galaxy's
>life due to shortage of heavy elements.  After that, it should be okay in
>the outer arms, where things aren't too noisy.  The center is probably a
>fairly inhospitable place even today.

But that still leaves the actual age of the galaxy open.  Maybe the question
should actually be: How long ago did the first life-bearing conditions
arise?

-Tommy Mac                     .  "                  +
.------------------------  +                      *       +
|   Tom McWilliams; scrub       ,     .                        "        +
|  astronomy undergrad, at     *       +;.     .  '             There is
| Michigan State University   '                      .    "   no Gosh!
|   [e-mail]                        '      ,   *
|       [phone]       ;  +  '                                 *
'-----------------------

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

Date: 9 Aug 92 09:58:48 GMT
From: "Frederick A. Ringwald" <[e-mail]>
Subject: Home made rockets
Newsgroups: sci.space

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

> or innocent bystanders (awful damn serious, especially in a country like
> the US that has let its liability lawyers go berserk)

The primary concern here is human life and safety, not lawsuits. Some
fool had the audacity to e-mail me and say "Thank God Robert Goddard
didn't listen to people like you." Well, Robert Goddard was a professor
of physics, and more importantly, *knew what he was doing*, because he
had the brains to find out, and to pay attention to safety. It does NOT
further the cause of space flight to get people killed or injured - it
sets it back, look at Challenger.

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

Date: 9 Aug 92 16:04:27 GMT
From: John Roberts <[e-mail]>
Subject: Home made rockets
Newsgroups: sci.space

-From: [e-mail] (Frederick A. Ringwald)
-Subject: Re: Home made rockets
-Date: 9 Aug 92 09:58:48 GMT
-Organization: Dartmouth College, Hanover, NH

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

-> or innocent bystanders (awful damn serious, especially in a country like
-> the US that has let its liability lawyers go berserk)

-The primary concern here is human life and safety, not lawsuits.

Well, someone whose rocket has caused a very minor injury (i.e. a burned
finger) to a bystander and is hit with a $30 million lawsuit might feel
differently. People are actually getting awards like that for injuries
about that minor. The lawsuit lawyers say this is a good thing, because
after all, it was your duty to hire 50 security guards to keep little kids
from picking up the spent rocket engine while it was still hot. The millions
they make on the deal is merely the reward they deserve as humble public
servants, for their thankless task of going about doing good. :-)

-Some fool had the audacity to e-mail me and say "Thank God Robert Goddard
-didn't listen to people like you." Well, Robert Goddard was a professor
-of physics, and more importantly, *knew what he was doing*, because he
-had the brains to find out, and to pay attention to safety.

Actually, Goddard almost blew up some of his neighbors until they chased
him out into the desert. (I'm exaggerating, but it *could* have happened -
he didn't have anywhere near the range safety he needed, and at least one
of his rockets came down where it definitely wasn't supposed to.)

By the way, to those who doubt - even a fairly small model rocket is
capable of flying right through a person - it's happened. So be especially
careful with stability tests, fins, launch rod and guide rings, etc.

-It does NOT
-further the cause of space flight to get people killed or injured - it
-sets it back, look at Challenger.

True. But I'd be happy to sign a liability release if it would let me watch
a Shuttle launch from a mile or two away.

John Roberts
[e-mail]

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

Date: 9 Aug 92 16:14:54 GMT
From: John Roberts <[e-mail]>
Subject: HST
Newsgroups: sci.space

-From: [e-mail] (Chuck Forsberg WA7KGX)
-Subject: Re: Hubble used for spying? + other neat info
-Date: 9 Aug 92 03:45:00 GMT
-Organization: Omen Technology INC, Portland Rain Forest

-In article <[e-mail]> [e-mail] writes:
->was also a mention of the backup mirror made by Kodak (which was not flawed).
->It is currently sealed inside a big box and no-one is allowed to look inside

-How many more things have to go wrong with Hubble before it becomes preferable
-to make a second unit around the good mirror, and replace the current satellite
-as a unit?

A *lot* would have to go wrong. With one big space telescope working fairly
well, it makes more sense to spend the money on ground-based astronomy, until
it's possible to put up a space telescope with greatly increased capabilities.
Remember that much of HST is designed to be repairable in orbit. I get the
impression that with so many delicate components, HST was lucky to get through
the launch with so much of it working correctly.

Also, I believe the Kodak mirror isn't really ready for use. It has the
correct basic shape, but I don't think it's been through the final polishing
stages or been coated. (And before anyone else asks, the primary mirror
can't be replaced in orbit.)

John Roberts
[e-mail]

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

Date: 9 Aug 92 17:26:43 GMT
From: [e-mail]
Subject: Hubble used for spying? + other neat info
Newsgroups: sci.space,sci.astro

> Unfortunately, the COSTAR was designed so that it could replace only the HSP.
> If one of the other instruments were to fail, the astronauts could end up
> pulling a perfectly good HSP to correct for a failed instrument! The Goddard

While perfectly good, the HSP has not been the most productive instrument.
It takes almost 30 minutes to ramp up the potential for observing but
it has to be shut down for earth crossings - somthing that happens frequently
in a low earth orbit.

> High Resolution Spectrograph is having power supply problems and that's
> another job for the astronauts to fix! What is worrying the scientists is that

Well they are not actually going to fix it.  There are to sides to the
HRS called side 1 and side 2.  As of right now side 1 cannot b used.
This si the really short UV side so this is very frustrating.  The
repair will ensure that side 2 will continue to function but side 1
will still be broken.  The HRS grating carousel is also acting up,
failing to lock into the right position on a regular basis.  I doubt
this could be fixed in the repari mission os lets hope it hangs in there.


> the astronauts won't have enough time to fix all of Hubbles problems. Only
> four 6 hour EVA's are planned, with one EVA left as reserve!
>

Also they will be upgrading the onboard computer system to something
approaching a real computer including a 386 processor.  That will be a big
help.



Now if we could just get a repair mission to fix the tedious, burdensome
and flawed proposal process we would be in great shape!

------------------------------------------------------------------------------
Robert Dempsey
Joint Institute for Laboratory Astrophysics
Boulder, CO

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

Date: 9 Aug 92 04:26:40 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Magellan Update - 08/05/92
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Martin Connors) writes:
>In article <[e-mail]>
>[e-mail] (Ron Baalke) writes:
>> Forwarded from:
>> PUBLIC INFORMATION OFFICE
>> JET PROPULSION LABORATORY
>>      Two tests were conducted on Magellan's transmitter B last
>> week at its minimum temperature of 23.4 C (74 F) to see if high
>> rate data could be received.  Both tests showed a continuing
>> noise spur at various temperatures
>        ^^^^
>Please explain! What is a noise spur? How does it differ from 'noise'?
>
>Puzzled in Canada

'Spur' is communications engineer slang for "spurious emission" it's
a signal at an unexpected frequency being radiated by the transmitter.
There are many causes of spurs, but the most common is operating the
PA stage out of it's design parameters. For a space based transmitter like
this, it's unlikely some alien has been tinkering with the tuning. More
likely is that the active device has degraded under radiation and now
has a different set of S parameters than it had when the circuit was
designed and tuned on Earth. So now it's effectively mistuned and
oscillating at a frequency where it doesn't belong as well as amplifying
the signal it's supposed to be amplifying. The oscillation will be
"noisey" because the stage was designed to be a power amplifier, not
an oscillator. Thus it will be very low Q. It's significant that the
problem is temperature sensitive. That points even more strongly to
the active amplifying element. Component specs vary with temperature.

Gary

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

Date: 9 Aug 92 04:15:47 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Meteor Soaks Datona FL
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>From article <[e-mail]>, by [e-mail] (FRANK NEY):
>>
>> -----I quote-----
>> A giant wave that drenched Datona FL and caused a lot of damage
>> in July turns out to have probably been caused by a 1 meter
>> meteor!
>>
>IS there any source on this <alleged> meteor event other than a TV news report?

Hey! I work for TV news, we reported it. Don't you trust me? :-)

Actually, we pirated it off an NBC feed, who knows where they got it.

Gary

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

Date: 9 Aug 92 05:11:17 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Meteor Soaks Datona FL
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Rusty Whitman) writes:
>In article <[e-mail]>, [e-mail] writes...
>>From article <[e-mail]>, by [e-mail] (FRANK NEY):
>>>
>>> -----I quote-----
>>> A giant wave that drenched Datona FL and caused a lot of damage
>>> in July turns out to have probably been caused by a 1 meter
>>> meteor!
>>>
>>IS there any source on this <alleged> meteor event other than a TV news report?
>>
>
>I heard this was caused by an underwater landslide (Washington Post I think).
>This sounds much more plausible than a meteor strike.  If a 1 meter meteor
>had hit the Atlantic just off Datona Beach there would have been some
>atmospheric effects along with the wave.  Also, I would hope that some
>Defense radar would have picked it up.  One meter objects falling from space
>are things they look for.  Of course, most of the radars look north and west.

Well, according to TV news, NBC in this case, the underwater landslide
theory was the first attempt at an explanation of the event. But, there
were no confirming seismic readings. According to NBC, a commercial
fishing boat reported seeing a meteor trail followed by a large explosion
in the water. They likened it to a nuclear blast. They didn't report it
at the time, but when they returned to port and heard about the Daytona
tidal wave on the same night, they put two and two together and reported
the incident. I don't know where the 1 meter figure came from, probably
somebody's calculation of the required size given the size of the wave
and the distance of the strike from shore.

I expect the local Daytona Beach newspaper has much more complete
details. A call to their metro desk would probably be in order if you
are really interested.

Gary

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

Date: Sun, 9 Aug 92 16:05:32 GMT
From: Brett Kollar <[e-mail]>
Subject: MIR
Newsgroups: sci.space

I am looking for the MIR space station orbital elements, can I
find them here????

IF so, can someone forward them to me, or at least point me in the
right direction...
--

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

Date: Sun, 9 Aug 1992 15:37:30 GMT
From: David Knapp <[e-mail]>
Subject: Seeding Mars with life
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Kenneth Tolman) writes:
>
> It appears that with today's technology an attempt to begin terraforming
>Mars could begin now.
>
>  Terraforming Mars could be begun by flying in a landing craft which
>carried on board a diverse spectrum of biological entities.  The biological
>entities would include:
>  Bacteria which currently lives in the ice pack
>  Genetically engineered bacteria for the conditions which exist on Mars
>  Bacteria which lives in extreme conditions currently, such as from thermal
>    vents, deep in rock strata
>
> The landing craft would not have to be too terribly sophisticated, but
>presumably would have some sort of MIRV like entry for multiple dispersion
>over a wide area (perhaps targeting specific temperate regions).
>  The colonization bacteria would have ZERO competition for resources,
>and if any of it survived it would begin mutation and development.
>Presumably, aneorobic bacteria would be best to start, with plenty of
>photosynthesizers going along.  At the very worst, this project would fail
>to implant life.  At the worst of the best, life would exist elsewhere in
>our solar system even if it took billions of years to evolve further, and
>at the best of the best life could begin to raise the temperature and free
>up oxygen for eventual multi species colonization.
>
> What do you think?


I think you should put that idea out of your head immediately.

If we *do* allow for even a non-sterilized craft to enter Mars atmosphere,
we endanger the ability to detect any previous life that may have existed there.
We also have no idea whatsoever what Earth's life forms (mostly bacterias
and funguses I'm guessing) would do to Mars.

I think introducing *any* life, intentionally or nonintentionally, to the
Martian system would be a *huge* mistake, until we have studied the hell out
of Mars.

And I haven't even touched on the moral or technological issues.

There is a reason that Mars has such a pitiful atmosphere and no (surface)
water. Do you know what that reason is?  Nobody is perfectly certain. Do you
want to try to *supply* that to a planet that should already have it and
probably did at one time?  I think that would be *extremely* egocentric and
irresponsible.

Luckily, the world's space agencies have decided on an agreement that forbids
the introduction of nonsterilized spacecraft until into the next century, when
we will perhaps have done more exploration.

--
David Knapp                                      University of Colorado, Boulder
Highly Opinionated, Aging  and                      [e-mail]
Perpetual Student of Chemistry and Physics.
            Write me for an argument on your favorite subject.

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

Date: Sun, 9 Aug 1992 19:10:00 GMT
From: [e-mail]
Subject: SPS fouling astronomy
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Frederick A. Ringwald) writes...
>In article <[e-mail]>
>[e-mail] (Tom) writes:
>
>> >(My biggest problem with SPS still is: do you really think you can make
>> >a living at it? Seems to me that ground-based Solar would be amazingly
>> >cheaper and less trouble. Wind is making surprisingly good progress,
>> >too. And these contraptions are made of native materials, too: from
>> >Earth.)
>>
>> About the resource-value.  Earth can't provide as much solar energy as is
>> available in space, as you know.  And even if you could get decent
>> solar power despite clouds, etc., you still have competing uses of the
>> land invloved.
>[...]
>>  From muscles, to wood, to coal, to
>> oil, we've seen living standards increase with energy use.  SPS can
>> continue that trend.  France is reaching the limits of fission, fusion
>> is still ellusive, if not illusive, and I don't know of anything that can
>> provide more total energy than SPS.
>
>Let's see some numbers. Until we do, SPS remains speculation. Having
>more power available in space may not offset the orders-of-magnitude
>increase in cost, and cost per unit; somehow, it doesn't seem likely.
>Ground-based Solar is becoming competitive now - and as little as a
>halving of costs would make it very competitive. Also, what about
>maintenance costs? Also, have you forgotten that the rectenna array
>will occupy a great deal of land, as will the fenced-off safety area
>around it? You know you are going to have problems convincing people
>that beaming all that energy through the atmosphere is safe - I'm not
>so sure, myself. What about interference with telecommunications? Also,
>if you do like astronomy, the static that will come with gigawatts of
>beamed power, even if far off-band, could easily mean the extinction of
>radio astronomy (see the 1991 November Physics Today, p. 41, for more
>on this).
>
Most of the ideas that are current are considering Lasers as the power beaming
transfer mechanisim.  This mechanism with a fifty sun output at the ground is
much more feasable than the microwave power beaming schemes for the reasons
that you state above. So scratch those arguments.  No it cant be used as a
weapon either due to the low power per square meter compared to what a laser
weapon would need to be useful.  These studies are current and involve the
use of the moon as the platform for the power beaming eliminating yet another
of the astronomers fears, although to carry your analogy to its logical
conclusion we must turn off all of our lights at night and quit buring
fossil fuels due to the degradation it causes to astronomy.

>Do increased living standards really require increased energy use?
>Compare Europe and Japan with the U.S. Most energy is used for heating
>or motion: the most modern conveniences, such as consumer electronics,
>don't use much energy. Besides, how much more waste heat can the
>biosphere tolerate? If this isn't a problem, what makes SPS superior to
>geothermal power? Don't say feasibility and expect me to believe it
>readily, as sticking two pipes into the ground seems a lot simpler than
>constructing some gigantic contraption in an alien environment it takes
>heroic efforts to conduct even the simplest of operations in, where it
>costs half a billion dollars just to get to.
>
Yes it will mean a greatly increased standard of living for a variety of reasons.
These reasons include the fact that if we increase the availability of
electrical energy by  a factor of ten as is envisioned in the SPS scheme and
implement more efficient batteries as we already are doing with nickel metal
hydride technology, we can finally have electric cars whose performance matches
that of fossil fueled vehicles.  When that occurs you just solved the problem
of hydrocarbon pollution of the biosphere, not a bad thing to achieve. In
addition, the alternatives that you suggest, especially geothermal, are
polluting in the extreme with heavy metals and other nice things that are
deep within the earth. Wind energy is ok but only available in limited areas.
Ever been out in the Mojave where Cal Edision has its wind farms? The destruction
of the biosphere of the desert is complete out there with all of the maintenence
roads. Hydroelectric? Not hardly, the environmentalist go orbital when the
word dam is even mentioned.  There is not even that many places we can even
put dams today that would help very much. Earth based solar tech. Not. All
development of solar tech in the U.S. is carried out by SDIO and they just got
their throat cut by congress critters pushing bread and circuses at the expense
of the future.

>(Sure, you folks say the cost will come down - that's what you said
>last time, too!)

No we say that we must finally open up the last frontier to development. No
single technology or service from space will justify the expense BUT, taken
together, the development of the resources of the solar system, whether it be
solar energy from space, materials from the Moon, asteroids, and other planets
will raise the planetary standard of living to a height that will make today
look like the abode of dirt dwellers.

PS I did not mention that the laser based SPS system could be used in Africa
to bring electical power to areas that do not nor will not have an electrical
power generating infrastructure unless it is from SPS.  This will allow the
Ethopians, our perennial starving masses to irrigate there land and finally
grow enough food to be taken off the planetary welfare roll.  This goes for
hundreds of uses of energy in all of the third and fourth world.  This will
have the benefit of saving lives and bringing political stability to areas
of the world that sorely need it.

Just a few thoughts

Dennis, University of Alabama in Huntsville

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

Date: 9 Aug 92 16:45:09 GMT
From: John Roberts <[e-mail]>
Subject: SSF, Energia, Shuttle
Newsgroups: sci.space

-From: [e-mail] (Gerald Cecil)
-Subject: Re: Energiya's role in Space Station assem
-Date: 9 Aug 92 01:24:19 GMT
-Organization: University of North Carolina at Chapel Hill.

-The full Energiya stack has flown twice.  On the first flight the core (2nd)
-stage was not fully fueled.  The 3rd (kick) stage failed, and the unspecified
-payload burned up. The ascent profile indicated that performance of the first
-2 stages was nominal. The first stage (liquid stap-ons) boosters have been
-used independently several times for satellite launches (another advantage of
-Energiya components over the Shuttle), before and after the 1st Energiya launch.
-They appear to be as reliable as other liquid boosters.

I had thought that several of them blew up in the last year or two, but Henry
says no, so it must have been some other Russian booster.

-Presumably NASA has realized that the Shuttle CANNOT POSSIBLY deliver all the
-Station components without loss of a vehicle.

That's extremely sloppy calculation of the probabilities. The closest estimates
of post-Challenger STS reliability that I've heard put the orbiter recovery
rate somewhere around 98.8% - 99% per launch. (Sure you can find worse numbers
if you look around, but I mistrust the assumptions that went into those
lower numbers.) The number of launches for assembly has dropped in recent
designs, but I don't know the current number (anybody?). I gather that it's
less than 30, perhaps a good deal less.

So I get the rough result that the probability of an orbiter loss on an
assembly launch is 20% or less. That's a significant risk, equivalent to
risking several hundred million dollars plus crew, and it definitely needs
to be factored into the design, but it's hardly the 100% that you claim.

The more relevant questions for use of Energia are cost (including the cost
of switching this late in the design), availability, politics, and whether
just two launches have demonstrated the reliability of Energia to the point
that switching to it would actually improve the odds.

John Roberts
[e-mail]

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

Date: Sun, 9 Aug 1992 20:03:10 GMT
From: Gerald Cecil <[e-mail]>
Subject: SSF, Energia, Shuttle
Newsgroups: sci.space

In article [e-mail], [e-mail] (John Roberts) writes:
>>-From: [e-mail] (Gerald Cecil)
>>-Presumably NASA has realized that the Shuttle CANNOT POSSIBLY deliver all the
>>-Station components without loss of a vehicle.
>
>That's extremely sloppy calculation of the probabilities. The closest estimates
>of post-Challenger STS reliability that I've heard put the orbiter recovery
>rate somewhere around 98.8% - 99% per launch. The number of launches for assembly
>has dropped in recent designs, but I don't know the current number (anybody?). I
>gather that it's less than 30, perhaps a good deal less.
>So I get the rough result that the probability of an orbiter loss on an
>assembly launch is 20% or less. That's a significant risk, equivalent to
>risking several hundred million dollars plus crew, and it definitely needs
>to be factored into the design, but it's hardly the 100% that you claim.

Yeah, I was being a grumbling pessimist. Thanks for the probabilities.
I'm not pointing this out to be morbid, simply restating one of the lessons of
Challenger: don't fly people to transport hardware.  The station assembly is still
years away, and there are quite a few missions in the queue.  Maybe 50 till the end
of assembly, so 0.988^50 = 45% chance of an orbiter loss.
---
Gerald Cecil 919-962-7169  Dept. Physics & Astronomy
U of North Carolina, Chapel Hill, NC 27599-3255 USA
-- Intelligence is believing only half of what you read; brilliance is
   knowing which half. ** Be terse: each line on the Net costs $10 **

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

End of Space Digest Volume 15 : Issue 090
------------------------------