Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO496.TXT

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Date: Thu,  3 Dec 92 05:34:09
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #496
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu,  3 Dec 92       Volume 15 : Issue 496

Today's Topics:
                  Comparative Launcher Reliabilities
                    DC-1 & landing in bad weather
                             DC-X status?
       Detonavion vs Deflagration (was Re: Shuttle replacement)
                         Gunpowder in vacuum
                           shuttle downtime
                     Shuttle replacement (6 msgs)
       Terminal Velocity of DCX? (was Re: Shuttle ...) (2 msgs)
         Voyager's "message"... What did it *say*?!? (2 msgs)
                What is the SSTO enabling technology?

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

Date: 2 Dec 92 23:36:00 GMT
From: Henry Spencer <[e-mail]>
Subject: Comparative Launcher Reliabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John S. Neff) writes:
>What is the formal definition of a manned rated spacecraft? I thought that
>it meant that the booster was liquid fueled and could be turned off if
>necessary. Obviously that is not the case, because the shuttle uses SRBs.

In theory, "man rated" means that the vehicle has passed a fairly elaborate
safety review, which often requires adding things like redundant systems to
reduce -- in theory -- the chances of failure.

In practice, the added reliability appears to be minimal, and the value of
the "man-rating" process has been questioned.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 21:49:04 GMT
From: Henry Spencer <[e-mail]>
Subject: DC-1 & landing in bad weather
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("ZALBAR DELPHI, MAIL::GOD") writes:
>    What effect would a wind shear have on a taildown
>    landing of a DC-1...

Not a lot, since it doesn't rely on aerodynamic lift.  There will be limits,
of course.

>    How about cross winds...

Not much of an issue for a vertical landing.  Just requires a trim adjustment
when you start getting close.  Again, there are limits.

>    but if the DC-1 comes in on empty tanks (or nearly so),
>    what if the craft has to divert to an alternate site...

How late is the diversion?  Even after retrofire, DC-1 can choose a landing
site anywhere within a circle a few hundred km across (I don't remember the
exact number).  Of course, the closer you get, the more the choices narrow
down.  At 1000ft with the engines lit, you're pretty much committed.  This
will require slightly conservative weather forecasting, so diversions can
be made early.

>    Could (being realistic now) the DC-1 set down on ANY
>    more or less flat surface, like a cornfield...
>    Or would that result in a forest fire (er popcorn...).

The exact extent of the problem would have to be settled by experiment,
probably -- Harriers have landed on carriers with wooden decks, but the
Harrier exhaust jets are a lot cooler -- but in general you'd like the
landing area to be relatively firm and free of combustible material.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 21:28:00 GMT
From: Henry Spencer <[e-mail]>
Subject: DC-X status?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Matthew Kaiser) writes:
>what's the status on the DC-X and Y?

DC-X:  under construction for flight in spring.

DC-Y:  proposed but unfunded.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 21:27:02 GMT
From: Henry Spencer <[e-mail]>
Subject: Detonavion vs Deflagration (was Re: Shuttle replacement)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John D. Boggs) writes:
>> At least in the language of supernovae research, a detonation involves
>> a flame front that propogates supersonically, whereas a deflagration has
>> a subsonically propogating flame front...
>
>Hmm.  And just how fast *does* sound move in space?

In vacuum, there is no sound.  In space, there is, because space is not a
perfect vacuum.  (Admittedly, in most regions of space you need pretty
sensitive instruments to notice the difference.)

In any case, either detonation or deflagration involves propagation of
a flame front *through a combustible medium*, so the point is moot.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: Wed, 2 Dec 92 22:19:08 EST
From: John Roberts <[e-mail]>
Subject: Gunpowder in vacuum

-From: [e-mail] (Patrick Draper)
-Subject: Re: NASA has 5 hand grenades still on the moon from Apollo missions
-Date: 2 Dec 92 06:15:45 GMT
-Organization: UMCC

-In article <[e-mail]> [e-mail] writes:
->
->Ordinary firearms wouldn't work in a vacuum anyhow.
->The gunpowder couldn't burn.
->*(==) Ken Barnes, LifeSci Bldg.                                      *
->*(-)**Memphis,TN********75320,[e-mail]**********************

-Of course ordinary firearms will work in a vacuum. Gunpowder carries its own
-oxidant, but even if you didn't know that, you could deduce it if you knew
-just how much gas volume of oxygen that combustion requires.

-| Patrick Draper           Disclaimer:  I can't control my fingers,        |
-| University of Michigan Computer Club                                     |

To amplify on the comments of Mike Moroney:

Black powder is not a chemical compound, but a physical mixture of oxidizer
and fuel. Combustion is propagated by a flame front, which requires the
presence of gases. As a result, the rate of combustion is *highly* dependent
on ambient pressure. At atmospheric pressure, black powder burns very
slowly. I'm not sure about the characteristics of modern smokeless powder,
but it also burns slowly at atmospheric pressure - I believe the main
functional difference is that at increased pressures, the rate of combustion
of smokeless powder increases much more rapidly.

I've read that in a vacuum, black powder basically will not burn. The same
may be true of smokeless powder. However, the conditions in a gun barrel
*do not* count as vacuum. Modern firearms use a percussion cap, which is
not dependent on ambient pressure for burning, and the firing of the
percussion cap fills the interior of the cartridge with very hot gas -
so when the powder is ignited, it's not in a vacuum. Once combustion of
the powder has started, pressure and rate of combustion both increase
rapidly, and normal firing takes place.

You might have a lot of trouble firing a flintlock gun in a vacuum, since
the firing process starts with ambient-pressure burning in the flashpan
and the touchhole.

Since some of this also applies to SRMs, I assume that the design of
solid boosters for use in vacuum (such as the one that put Magellan in
orbit around Venus) have to take the phenomenon into account. (As Henry
has pointed out, some solid rocket fuels won't burn even at 1ATM pressure -
it takes a shotgun primer or equivalent to get them going by causing
localized heating and increase in pressure.)

John Roberts
[e-mail]

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

Date: 2 Dec 92 23:32:14 GMT
From: Henry Spencer <[e-mail]>
Subject: shuttle downtime
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>I believe that once they lost one shuttle they suddenly discovered that the
>shuttle had a significantly high risk of loss due to any of a number of
>problems many of which were fixed at the same time...

The accident focussed quite a bit of attention on safety issues, and got
some action taken on several worrisome problems.  The paranoia ultimately
escalated, mind you, well beyond reasonable levels.  Had the shuttle been
an aircraft, it probably would have resumed flying -- subject to some
restrictions and precautions -- after a considerably shorter downtime.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 21:58:09 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>In article <[e-mail]> [e-mail] writes:

>>So than now as the system has matured and the probabiltiy of launching when
>>they say they will has been reached, you want to kill the system. [Shuttle]

>Since it is still three times more expensive than the alternative it does
>seem a good thing to do.

There IS NO alternative!  The Shuttle is the only manned vehicle we have.  It
is the only vehicle that can return payloads.  It is the only vehicle with a
robot arm.  It is our only space station.  And it is cheaper per pound than
a Titan IV to boot.  If you think your paper airplanes can beat the Shuttle
then PROVE it!  (In the aerospace industry, that means FLY it.)

>>Intelsat was willing to pay the big bucks to NASA to retrieve I VI
>
>Hold on there! They paid what amounts to the scrap value of the satellite.
>You and I paid the bulk of the rescue costs. They did it to get out of
>the cost of a new satellite and luancher. All in all an excellent deal
>for them but only because they got some suckers to pay the actual costs.

And I'm awfully glad we did, too, because now we know enough (maybe) about
satellite servicing that next year's Hubble servicing mission may actually be
successful.  The first thing we learned was that we need more practice.

>Had Intelsat been forced to pay the
>actual costs, they would have found it cheaper to wait for the new
>satellite and launch it themselves.

They DID pay actual costs, or close to it.  The rescue was only about a
fourth of the mission.  The rest other objectives were to practice servicing
techniques, test space station construction techniques, check out Endeavour,
and a few other minor things.  Why do you insist on "charging" Intelsat for
a full mission when they only used a fraction of it?

>>>One reason Hubble is unique is that Shuttle eats almost a third of
>>>NASA's budget. I hope you consider this when measuring Shuttle utility.

Closer to a fifth, but who's counting?

>>No Allan if you remember no commercial sats are going up on the Shuttle.
>>Where is this government competition?
>
>Does the word 'Airiane' ring a bell?

So if Ariane is the competition you're referring to, what does this have to
do with the Shuttle?  Go bother France and get off of NASA's back.

>The fact that the largest user of launch services refuses to use cheaper
>commercial services just makes it worse. Of course, the free world sure
>was lucky recently when a half billion dollar Shuttle flight was used
>to launch a 400 pound satellite!

LAGEOS was ONE payload aboard STS-52, among about a dozen more.  Considering
the development cost of integrating IRIS with another booster, paying for
about 1/12 of a Shuttle flight was almost certainly a bargain.

>Sure we could have used a Pagasus which would have been 50 times cheaper
>and helped reduce costs. But then it's good we had those people on board
>to do, well, stuff to support the luanch.

I'd like to see you try to run the Space Vision System with a Pegasus.  Or
just wear a Lower Body Negative Pressure apparatus.

>NASA hasn't reduced the cost of access to
>space in 30 years.

Maybe not, but it did make it 8 times more reliable and an order of magnitude
more frequent.  Guess you have to walk before you can run.

Mike

--
Michael Kent              [e-mail]        Rensselaer Polytechnic Institute
"Interviewing during a recession is a lot like faking an orgasm.  You have to
pretend you're interested all the while getting badly screwed." - Anonymous
Tute-Screwed Aero, Class of '92                               Apple II Forever!

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

Date: 2 Dec 92 22:21:46 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>No, Spacelab and Astor are two payloads that we want very much to keep
>in orbit so they can be used. Building multi-billion $$ payloads and then
>flying them for a few days every two years isn't cost effective.

Ah, what good is Spacelab if it isn't attached to an orbiter?  (Answer: None)
Where is the power to run the experiments going to come from?  Where is the
heat rejection system?  Where is the life support system?  Where is the
emergency return system?  Spacelab has none of these without an orbiter
attached.

>>If you have to charge an entire Shuttle
>>mission against a satellite return, then it is expensive,
>
>To date it has never been done. Shuttle flights are so expensive
>that it isn't likely it can ever be done. You would need to return
>at least five or so satellites.

Never been done?  Do you know anything about the Shuttles you hate so much?
STS-32 returned LDEF from orbit in January, 1990.  It also launched Leasat 5,
grew protein crystals for about a dozen firms, studied the diurnal cycles of
mold to learn more about biological clocks, performed floating zone crystal
growth experiments, tested optical trackers, performed medical research on
the astronauts, did lightning storm research, and filmed part of a motion
picture.  It (combining missions) has been done.

>Would you consider a pickup truck which only worked one day a week and
>cost $200 per mile to operate 'working hardware'? I wouldn't which is
>why I don't consider Shuttle working hardware.

I would if I needed a pickup truck and it was the only operating pickup
truck in the world.

>A range safety officer can blow up a Shuttle, not so with Delta Clipper.

Of course not, since there is no Delta Clipper.

Mike

--
Michael Kent              [e-mail]        Rensselaer Polytechnic Institute
"Interviewing during a recession is a lot like faking an orgasm.  You have to
pretend you're interested all the while getting badly screwed." - Anonymous
Tute-Screwed Aero, Class of '92                               Apple II Forever!

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

Date: 2 Dec 92 22:53:08 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <james.723012567@menaik> [e-mail] (James Borynec; AGT Researcher) writes:
>This brings up an interesting point.  What happens if you run out of
>fuel?   I would guess that it would happen occasionaly.  It happens
>with Airlines (can you say Gimli).  There is no redundancy when there
>is no fuel...

There isn't much for airliners, either, unless they get lucky (as happened
at Gimli).  The glide range of an airliner, from typical airliner altitude,
is maybe a couple of hundred miles if we're generous.  At any time, day or
night, there are hundreds of airliners farther than that from the nearest
airfield (in many cases, farther than that from any solid land at all).
The fact that no widebody has ever had to ditch at sea shows just how rare
total power loss is.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 22:59:32 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>... will have to be built to keep the probability of such failures low.
>>That means, as with airliners, careful analysis of fatigue lives of parts
>>and inspection/replacement schedules set up to avoid problems.  (It also
>>means, as with airliners, that there will probably be an occasional crash
>>due to unanticipated problems.)
>
>Yes, I agree with this. My question is whether any space launch system
>can accumulate enough flight hours to make any of this analysis meaningful.

If a jet fighter can, it should be possible with a DC-1.

>It seems to me that the launch requirement for something of the DC class
>is small enough that there will only be a few built, and those flown
>fairly infrequently...

If you use a DC as a straight replacement for existing launchers, sure.
But there is no real requirement to replace existing launchers.  The whole
point of building something radically different, e.g. the DCs, is to try
to open up new markets.  Given this, it's difficult to predict numbers and
flight rate... but it could be large.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 23:48:01 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>Please shut up about gliders, Gary, they aren't relevant.
>
>They *are* relevant since that's the Shuttle's landing style...

I thought we were talking about reasonably safe systems.  The shuttle's
landing style does not qualify by any sane standard.

>>>... Wind gusts are the worst.
>>For vehicles relying on aerodynamic lift (wings or rotors), that is.
>
>Even for a bullet. I don't see any magic that makes DC immune to
>gusts.

Not immune, just much less bothered by them, because it doesn't have sails
(aka wings, stabilizers, etc.) spread out to catch them, and it doesn't
rely on a nice smooth predictable flow of air over lifting surfaces to
hold it up.

>>>... That all takes fuel margin.
>>Certainly, which is why VTOLs need (and have) fuel margins.  As we've
>>been telling you.
>
>Of course you said that the DC lands on nearly empty tanks.

And as I also said, "nearly empty" is relative to a vehicle that is 9/10ths
fuel at takeoff.  You can't have it both ways, claiming that a DC would
be simultaneously a tremendous fire hazard and desperately short of fuel.

>... I was questioning this margin. How many
>minutes of hover, or retreat to higher altitude, are available in
>those nearly empty tanks? Five minutes? Ten? Airliners declare low
>fuel emergencies when they're down to those kinds of margins...

I don't have numbers on hand.  But remember that DC doesn't have to spend
five minutes making a wide circle and lining up again for a fresh approach.
It will need to have the way cleared for it in advance, so it can come
straight in for a landing without unnecessary delays... foreshadowing the
sort of traffic-control procedures that will be needed for supersonic
airliners (and were already needed for the SR-71).
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 3 Dec 92 00:35:07 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

Before I respond to Allen I want to make clear that I do agree with many of the
things he says and thank him for his work with DC-X.  If DC works it will do
incredible good for the country just by killing this immortal topic.  :-)

[e-mail] (Allen W. Sherzer) writes:
...That Dennis wrote...

>>>Largely because they are forced to compete with government subsidized
>>>competition.

>>No Allan if you remember no commercial sats are going up on the Shuttle.
>>Where is this government competition?

>Does the word 'Airiane' ring a bell?

>The fact that the largest user of launch services refuses to use cheaper
>commercial services just makes it worse. Of course, the free world sure
>was lucky recently when a half billion dollar Shuttle flight was used
>to launch a 400 pound satellite!

Allen, there isn't a rocket on the planet that would be operating today if it
weren't for government funded development and launch contracts.  That's not
good, it's not convenient, but it's a fact.  Delta and Atlas can call Ariane
unfair, but it sure reminds me of a story involving glass houses and stones.
While I'm not satisfied with Uncle Sam's privatization either I think it
deserves much more credit than you give it.  Is there a nation on the planet
that has done better?  It's not Japan or the CIS.  It's not China or India.
It's not ESA or Israel.

Your shuttle accounting ignores the difference between marginal and average
costs as well as the economic issues involved in shutting down.  Because
shuttle was a mistake fifteen years ago does not mean that eliminating it now
is the best thing to do.

In addition you are either very skillful at editing details to fit your
desires or you just plain don't understand the manned space program.  If you
honestly think that the launch of Lageos 2 or the repair of Intelsat VI were
the only things accomplished on those missions then you clearly weren't paying
attention.

--
Josh Hopkins                                          [e-mail]

    "Why put off 'til tomorrow what you're never going to do anyway?"

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

Date: 2 Dec 92 21:23:44 GMT
From: Henry Spencer <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>... It's not an airliner, and it likely can never be an airliner....

The FAA, which legally defines "airliner" for purposes of US aviation,
reportedly disagrees.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 2 Dec 92 23:52:44 GMT
From: Pat <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Pat) writes:
>>
>>Now i know this would make gary coffman happy, no more blazing balls of
>>ROCKET FUEL crashing into DISNEYLAND!!!!!!  so maybe we should compromise
>>system design, throw away the manueverability to SHUT UP GARY.
>
>Chutes add mass for the chute, suspension, and hard points. They aren't
>cheap. And they aren't 100% reliable (but then what is?). To shut me
>up, all you need to do is agree to launch and land this thing away from
>major population centers. It's not an airliner, and it likely can never be
>an airliner. If it's a cheap launcher that ocasionally crashes or goes
>boom in an uninhabited spot, that's good enough for me.
>
>Gary

glad you recognize nothing is 100%.  Henry and alan and myself believe
that the DC architecture is the best posited approach for manned space
transit  given cost and safety guidelines with current technologies.

We dont specify where the DC will be landing.  we hope that it will be
safe and reliable enough to use without test pilots and with airline
operating procedures.  If the FAA likes the concept and the implementation
they will agree on where this thing gets landed.

You are right.  the DC is not an airliner.  its a paper prototype until it
flies.  once it starts flying,  then start talking.  Henry and alan
think it will fly and can fly as safely as 747's.  I'll be happy
if the damn thing cuts launch costs by 1/3 and only blows up every 100
flights.  The only thing to do. is wait and hope and lobby to keep the
research program flying.  When the DC-1 is ready for routine ops i'll
be glad if it runs once/week out of edwards.  if it can,  people will
beat their way to the door.

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

Date: Wed, 2 Dec 92 23:14:15 GMT
From: "Bradford B. Behr" <[e-mail]>
Subject: Voyager's "message"... What did it *say*?!?
Newsgroups: sci.astro,sci.space

(Rick Miller, Linux Device Registrar) writes:
>Does anyone know (or know who knows, or where to find out) what the heck
>the "message" on Voyager's gold plate was supposed to 'mean'?  In case I'm
>naming the wrong vehicle, I'm talking about a rectangular plate on which
>is inscribed a man, a woman, a simplification of the vehicle itself, a
>chart of our solar system showing the vehicle's flight-plan, and a couple
>other things.
>What bothers me is that I, a *native* of the world it came from, can't
>decipher what the crazy 'code' is that everything is written in.  For
>example, here's the labling for our nine planets:
>
>    Mercury:    |-|-
>    Venus:        |--||
>    Earth:        ||-|-
>    Mars:        |--||
>    Jupiter:    |----||
>    Saturn:        ||-||
>    Uranus:        ||-||
>    Neptune:    ||-- -||-
>    Pluto:        ||-||

For a full explanation, go see one of Sagan's books -- the Voyager
(Pioneer?) plaque is explained in either _Cosmos_ or _Murmurs of
Earth_, or perhaps both.

But, for those of you who just can't wait that long to find out,
here's what I remember off the top of my head.

Those |--|-||-||| markings are binary (- and | instead of 1 and 0)
measurements of distance and time, in
units specified by the two side-by-side circles, which represent the
spin-flip transition of hydrogen (the 21-cm line). Hence, one length
unit = 21 cm, and one time unit = 21 cm / 3e10 cm/s. This was chosen
as a standard b/c it was thought to be a "universally" known reference
and easily depicted via cartoon. As verification, the diameter of the
spacecraft's radio dish is shown on the plaque; if the dish survives
until (if ever) it is picked up, the aliens can check their math. The
markings for the planets as given above are orbital radii? masses?
sizes? dunno.

The starburst shows positions of strong pulsars (I think) in our
galaxy. From the distances gioven to each, the aliens should be able
to "triangulate" and find Earth, at the center of the starburst. Keep
the front porch light on...   :)

If anyone's got a copy of those Sagan books handy, you might want to
check all this and verify (or not) my recollections...

Brad
--
----------------------------------------------------------------------
  Bradford B. Behr                   [e-mail]
     Sacramento Peak National Solar Observatory, Sunspot NM 88349
----------------------------------------------------------------------

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

Date: 2 Dec 92 12:13:03 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Voyager's "message"... What did it *say*?!?
Newsgroups: sci.astro,sci.space

In article <[e-mail]>, [e-mail] (Rick Miller, Linux Device Registrar) writes:
> Does anyone know (or know who knows, or where to find out) what the heck
> the "message" on Voyager's gold plate was supposed to 'mean'?  In case I'm
> naming the wrong vehicle, I'm talking about a rectangular plate on which
> is inscribed a man, a woman, a simplification of the vehicle itself, a
> chart of our solar system showing the vehicle's flight-plan, and a couple
> other things.

Rick, your facts are distorted and a trip to the library will answer
your questions.

First, the plaque you describe was attached to the Pioneer 10 and 11
probes, not the Voyagers.  Voyager 1 and 2 had a *different* plaque,
along with a disc containing audio and video recordings.

Carl Sagan describes the Pioneer plaques, and humanity's reaction to
them, in one of his books.  I think it's *The Cosmic Connection.*  The
picture on the plaque was drawn by Linda Sagan, his wife at the
time.

The story of the Voyager records is told in *Murmurs of Earth*, by
Sagan and his friends (Ann Druyan, Tim Ferris, Jon Lomberg, Frank
Drake, Linda Sagan, et al).  It's an awfully good read, and it also
discusses the Pioneer plaque and Drake's binary message transmitted
from Arecibo.

The Voyager record is now available on CD from Warner New Media for
about sixty bucks.  I went to the release party in Washington's Hard
Rock Cafe, a pretty entertaining evening.  The first track of the CD
encodes a bunch of still pictures chosen to give aliens a good idea of
mankind and our activities.

> What bothers me is that I, a *native* of the world it came from, can't
> decipher what the crazy 'code' is that everything is written in.  For
> example, here's the labling for our nine planets:
[obscure scratches deleted]

I forget what this is supposed to mean, but it is a binary notation (|
= 1, - = 0, most significant figure on the left-- note that there is
never a leading "-" in these numbers) and it encodes some value like
the size of the planet or its distance from the Sun or something.

Whether or not the code is appropriate is a matter you'll have to
debate with Sagan and Drake.  I'm not going to defend them here.
Their best answer will be, "well, smart guy, can you propose a
*better* system?"  And maybe you can.

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

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

Date: 2 Dec 92 21:40:59 GMT
From: Henry Spencer <[e-mail]>
Subject: What is the SSTO enabling technology?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>... Look at the
>Japanese experience in "slight" improvments or even re-inventing current
>LOX/H2 engines...

That's because they *aren't* making "slight" improvements -- they're building
a brand new engine, and they made the dreadful mistake of copying the staged-
combustion cycle of the SSME.  It doesn't surprise me that the resulting
engine is having lots of trouble and is far behind schedule; I predicted it.

The Vulcain LOX/LH2 engine for Ariane 5, by contrast, is on schedule and
having no serious problems.  *They* didn't use staged combustion.

>How many
>hours are the engines supposed to run befor a rebuild? currently with the
>SSME's that is only about twenty minutes.

It's over three times that for the RL10 (4000 seconds, as I recall).
Actually, that's the rated firing time between maintenance attention of
any kind, not just between rebuilds.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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


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From: Henry Spencer <[e-mail]>
Newsgroups: sci.space
Subject: Re: What is the SSTO enabling technology?
Message-Id: <[e-mail]>
Date: 2 Dec 92 21:21:08 GMT
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In article <[e-mail]> [e-mail] (Brad Whitehurst) writes:
>>>big problems keeping any kind of reusablility of the engines.
>>RL-10s seem to do just fine.
>>
>    But are they reused? ...

There's no reusable vehicle to carry one for re-use, so they can't be.
DC-X will be the first actual re-use of RL10s.  But they're routinely
fired several times in Centaur missions, and test firings likewise say
there should be no problem with re-use.

Most any regeneratively-cooled rocket engine should be reusable, actually.
The F-1 was rated to be fired 50 times, as I recall, and a modified Saturn V
first stage -- winged, manned, reusable -- came within a hairsbreadth of
being used instead of SRBs for the shuttle.

The maintenance headaches of the SSME are the exception, not the rule.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

End of Space Digest Volume 15 : Issue 496
------------------------------