Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_6/V15NO627.TXT

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Date: Sun,  3 Jan 93 05:05:42
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #627
To: Space Digest Readers
Precedence: bulk


Space Digest                Sun,  3 Jan 93       Volume 15 : Issue 627

Today's Topics:
                  Aluminum as Rocket Fuel? (3 msgs)
                      Clueless Shuttle Questions
           Galileo's high-gain antenna still stuck (2 msgs)
             Justification for the Space Program (5 msgs)
       Let's be more specific (was: Stupid Shut Cost arguement
                     Moon Dust For Sale (2 msgs)
               Orbital elements of junk in space wanted
                           SSTO vs 2 stage

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

Date: 3 Jan 93 03:42:07 GMT
From: Anthony J Stieber <[e-mail]>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

No one has mentioned using a cylinder of aluminum with perhaps a star
shaped core and spraying LOX down it.  The aluminum is both the fuel
and structure.  Running it until much before burn through is probably a
bad idea, but it may be cheaper than importing steel shells from earth.

Doing casting in an unknown enviroment with bulky molds could be a
problem.  Instead it might be possible to build up a cylinder from
a lightweight aluminum frame on the moon in layers by either aluminum
liquid or vapor.  Oxygen tanks might be made this way as well.

I guess this would be a solid/liquid hybrid motor of which I have heard
little about.  Are there serious problems with hybrid motors or with
what I've outlined above?
--
<-:(= Anthony Stieber    [e-mail]   uwm!uwmcsd4!anthony

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

Date: 3 Jan 93 05:53:56 GMT
From: Bruce Dunn <[e-mail]>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

> Karl Dishaw writes:
>
> --the injector plate is going to need an internal heater to keep the LAl
> from solidifying as it passes through and to keep it clean for restarts.


        I would think that the easiest configuration would be for the
combusion chamber to thermally coupled to the tank of molten aluminum, with
only enough of an intermediate flow passage to insert a valve.  When the
aluminum is melted in the tank, the fuel line, valve, and injector will all
be heated to above the melting point of aluminum.





--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 3 Jan 93 07:31:44 GMT
From: George William Herbert <[e-mail]>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Anthony J Stieber) writes:
>No one has mentioned using a cylinder of aluminum with perhaps a star
>shaped core and spraying LOX down it.  The aluminum is both the fuel
>and structure.  Running it until much before burn through is probably a
>bad idea, but it may be cheaper than importing steel shells from earth.

I'm posting this because Tony bothered me into catching up on sci.space
by talking about this post for a while 8-)

Solid aluminum burns just fine, but it has a really poor regression
rate (it burns very very slowly).  The best way to do this would be to
bunlde aluminum wire in a combustion chamber to increase the surface
area so that you get decent thrust.

The primary problem of a steel combustion chamber is that combustion
will be hot enough that LOX will definitely be burning with steel
as well as aluminum.  I don't know what I'd do, perhaps a ceramics
lining.

And, as much as you people hate to have reality dropped on a conversation,
aluminum is the wrong fuel to use if it's an earth based application.
A General Dynamics report on Hybrid replacements for the Space Shuttle SRBs
indicates that Zinc  is a better solid to burn; it's a whole lot more
dense, a lot cheaper, and it's Isp is nearly the same (density Isp is
a whole lot better). (NASA Contract NAS8-37777)

-george william herbert
Retro Aerospace
2240 Blake #101
Berkeley CA 94704

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

Date: 3 Jan 93 00:33:21 GMT
From: Henry Spencer <[e-mail]>
Subject: Clueless Shuttle Questions
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Lawrence Curcio) writes:
>1) Why is the tank so blunt? Isn't the shuttle a super-sonic vehicle?
>Shouldn't this be sharper, say one of theose secant ogive numbers?

These things are complex compromises.  A more pointed shape would have

lower drag, but also would be heavier for the same internal volume...
and the shuttle does most of its accelerating at extremely high altitude,
where air drag is negligible and weight is all-important.

>2) Why is the tank so rough? Not only is the texture less than smooth,
>but there are a number of grooves near the front as well.

The surface is relatively smooth, but surface smoothness doesn't matter
that much on such a large object, which will inevitably have a turbulent
boundary layer over most of its length anyway.  The grooves you see near
the front are actually ridges, external reinforcements for the intertank
ring; they add some drag but moving them inside or doing without would
add weight.

>3) The struts that hold the shuttle to the tank are apparently naked
>cylenders. Shouldn't these be streamlined in some way?

They're in pretty turbulent air anyway, and it doesn't matter that much.
Again, streamlining would add weight.  Even more conventional supersonic
aircraft have a strong tendency to rely on brute-force engine power rather
than aerodynamic elegance, as a close inspection of most any jet fighter
will reveal!

>4)On the side od each SRB, there is a piece of metal running lengthwise.
>Is this a strap to hold the segments together?

No, they're held together by pins at the joints themselves.  What you're
seeing is probably the wiring tunnel that runs the length of each SRB,
carrying cables and the linear destruct charge.

>5) Wouldn't the SRB segments mate more reliably if the propellant grain
>from an upper segment extended into the next lower segment? That way,
>the propellant segments wouldn't coincide with the chamber segments and
>the infamous O-rings wouldn't take as direct a blast. No?

So long as the propellant grain has a joint in it, there's always the
possibility that gas will get through that joint to reach the casing
joint.  It wouldn't help much, and it would complicate handling and
transport.  The post-Challenger joints do have a number of features
to reduce the amount of gas reaching the O-rings.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 3 Jan 93 00:17:20 GMT
From: Henry Spencer <[e-mail]>
Subject: Galileo's high-gain antenna still stuck
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Joshua Bell) writes:
>... If the HGA is freed, allowing the high speed
>transmission, will the compression still be used (hopefully with
>'a higher Q value') so that even _more_ data than anticipated in
>the original mission plan be returned?

The on-board computers don't have the horsepower to do serious compression
at 100-odd kbps.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 2 Jan 93 23:42:35 GMT
From: Dave Michelson <[e-mail]>
Subject: Galileo's high-gain antenna still stuck
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>The hammering sessions will continue all the way through the entire month
>of January, if necessary.  Even though the first hammering attempt didn't
>open up the antenna all the way, it did have a postive effect.

!!  It did?  I sure don't remember seeing reference to that in the last
report but I'm glad to hear it.

What was the "positive effect"?  How was it determined or measured?

Like everybody else, I'm *really* looking forward to seeing the HGA
deploy -- if only because I'm an antennas and propagation person who
would hate to see a problem with the antenna spoil the mission :-)

--
Dave Michelson
[e-mail]

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

Date: 3 Jan 93 01:42:40 GMT
From: Graydon <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

A functioning economy (a whole one - heavy manufacturing, food growing,
service sector, the whole nine yards) on the Moon is in a what military
position with respect to the earth?

Sounds like a justification to me....

Graydon

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

Date: 3 Jan 93 04:05:47 GMT
From: Henry Spencer <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

In article <[e-mail]> Graydon <[e-mail]> writes:
>A functioning economy (a whole one - heavy manufacturing, food growing,
>service sector, the whole nine yards) on the Moon is in a what military
>position with respect to the earth?

"Largely insignificant" is the description you are looking for.

Despite a lot of science-fiction plots pivoting on the Moon's supposed
strategic importance, the fact is that it's not in an especially good
position to exert military control over Earth.  Most of those plots
stack the deck for dramatic effect.

The Moon's fundamental military defect is simple:  it's *too far away*.
Missiles launched from the Moon would take days to reach Earth, as
opposed to minutes from an Earthly launch site, giving lots of time
for warnings, countermeasures, interceptions.  Beam weapons would be
nearly useless at that distance due to diffraction, unless they were
truly enormous.

The one significant asset of the Moon is its position at the top of
Earth's gravity well.  But even this is much exaggerated in SF.  The
Moon has a noticeable gravity well of its own, which must be overcome
before you can launch kinetic-energy weapons at Earth.  The physics
of the situation amplify the energy provided by your launch system,
but by no means infinitely -- the advantage is about a factor of 25.
The only good way to exploit this is to build some sort of catapult
system capable of catapulting large masses... but such a catapult
is a big fixed target, not enormously difficult to locate and bomb.
If you want kiloton- or megaton-range weapons, nuclear-tipped missiles
are less vulnerable and much cheaper.  If you're really thinking big,
you want mass you don't have to launch, e.g. an Earth-approaching
asteroid or comet.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Sun, 3 Jan 1993 00:02:01 EST
From: Graydon <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

Yep, stuff launched from the Moon is a bad idea.

However, if you want to fill near earth space with weapons platforms,
or just decide that you're going to have a comsat monoploy, a lunar
economy might (who can say? they might need to import all their K
vitamins or something) very well have a significant advantage.

And the 'lots of time to smack it' works both ways, generally in
the Moon's favour.

Not a justification I am fond of; not one I'd really like to see
pushed, either, but it's there.

Graydon

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

Date: 3 Jan 93 05:39:34 GMT
From: "James Borynec; AGT Researcher" <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>In article <[e-mail]> Graydon <[e-mail]> writes:
>>A functioning economy (a whole one - heavy manufacturing, food growing,
>>service sector, the whole nine yards) on the Moon is in a what military
>>position with respect to the earth?

>"Largely insignificant" is the description you are looking for.

I disagree.  I submit that a functioning moon colony will be
able to dominate Earth orbit.  The depth of the gravity well is just too
big of an advantage.  It would form the orbiting equivalent of the
fabled "unsinkable aircraft carrier"

j.b.

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

Date: 3 Jan 93 07:03:41 GMT
From: Henry Spencer <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

In article <james.726039574@menaik> [e-mail] (James Borynec; AGT Researcher) writes:
>I disagree.  I submit that a functioning moon colony will be
>able to dominate Earth orbit.

How?  Earth-based antisatellite weapons are simple and cheap; anything
in Earth orbit can easily be destroyed from Earth.  Unless you assume
a major technology difference -- again, stacking the deck to make the
plot work -- *Earth* dominates Earth orbit, beyond all doubt.

>The depth of the gravity well is just too
>big of an advantage...

Why?  Please explain, in detail.  Remember that a large-scale moon colony
is most unlikely to come into existence without fairly cheap transport
from Earth to low orbit.  Not as cheap as from the Moon, true... but it's
not *that* big a difference if we're talking about military control.

There is a big difference between being the preferred supplier of goods
and services and being the military power in the area.  Delivering a
kiloton of explosive power is a *whole lot* easier, nowadays, than
delivering a kiloton of freight.

>It would form the orbiting equivalent of the
>fabled "unsinkable aircraft carrier"

Remember the numbers.  The "unsinkable aircraft carrier" was a few hours
from the area of operations; the Moon is *days* away from Earth, the
equivalent of North America, not England.

And if you're going to draw WW2 analogies, do bear in mind that the
"unsinkable aircraft carrier" was in grave danger of being invaded
and conquered throughout the summer of 1940.  In particular, if the
Germans had mounted a maximum-effort crash-priority offensive starting
immediately after Dunkirk, it would probably have succeeded (in the
opinion of, among others, the British general staff at the time).
Even with the way they dilly-dallied until midsummer in reality,
they'd have had a good chance if they'd had better intelligence and
target planning:  a few days of determined raids on radar stations
and crucial aircraft plants could easily have changed Britain's
air-defence situation from bad to impossible.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 3 Jan 93 02:15:42 GMT
From: Brian Stuart Thorn <[e-mail]>
Subject: Let's be more specific (was: Stupid Shut Cost arguement
Newsgroups: sci.space

>        Shuttle could have lower costs then  NASA currently has,
>        but it still needs a tremendous infrastructure.  The OPF,
>        the VAB, Tilting bay,  the crawler/transporter.  Launch towers.
>
>        The DC  will not need much more infrastructure, then a
>        airline hangar.  Henry, alan and I all believe that eliminating
>        all this structure and cost  will make up for any lower
>        vehicle lift capacity.
>pat

         Pat, the SLC-6 facility at Vandenberg did not have a VAB,
         "tilting bay" (that's ths same as the VAB, though) or a Crawler.
         SLC-6 reversed the action at the Cape's Complex 39. At 39,
         the Shuttle moves from facility to facility to pad. At SLC-6
         the Shuttle was to move from OPF straight to pad, eliminating
         the VAB. Orbiter, ET, and SRBs were to be stacked on the pad.

         Apparently, somebody said that NASA could save money on the
         Shuttle if they used the Saturn 5 facilities. Another blunder.

         -Brian


-------------------------------------------------------------------------
Brian S. Thorn                                    "If ignorance is bliss,
[e-mail]                               this must be heaven."
                                                -Diane Chambers, "Cheers"
-------------------------------------------------------------------------

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

Date: 3 Jan 93 02:20:54 GMT
From: Brian Stuart Thorn <[e-mail]>
Subject: Moon Dust For Sale
Newsgroups: sci.space,sci.astro

>I heard on Paul Harvey radio two days ago that former Gemini and Apollo 15
>astronaut David Scott had been charged with fraud.  No further information
>was presented.  Does this auction of the piece of tape have something to
>do with the story report on P.H./ABC News?

   It might have something to do with the Apollo 15 stamped-covers
   scandal of 1971. Don't know if Scott, Worden, and Irwin were ever
   charged with any legal violations, though.

   -Brian

-------------------------------------------------------------------------
Brian S. Thorn                                    "If ignorance is bliss,
[e-mail]                               this must be heaven."
                                                -Diane Chambers, "Cheers"
-------------------------------------------------------------------------

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

Date: 3 Jan 93 05:33:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Moon Dust For Sale
Newsgroups: sci.space,sci.astro

>I heard on Paul Harvey radio two days ago that former Gemini and Apollo 15
>astronaut David Scott had been charged with fraud.  No further information
>was presented.  Does this auction of the piece of tape have something to
>do with the story report on P.H./ABC News?

INo. it has something to do with a business partnership that was formed in
1980, and is unrelated to the Moon dust.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 3 Jan 93 03:43:18 GMT
From: Joachim Paganus <[e-mail]>
Subject: Orbital elements of junk in space wanted
Newsgroups: sci.space

I'm looking for a '2-line orbital elements list' of junk, i.e. deceased
satellites, rocket-bodies and other debris that is still in orbit.
I have one very old list, but where could I get a list that is up to
date? (I don't know from where I got the list I have)

--
Joachim Paganus
[e-mail]
[e-mail]

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

Date: Sat, 2 Jan 1993 22:02:35 EST
From: Graydon <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

Ed, having opinions about as tractable as an iridium lump does
not help convince people, you know.

What I understood Bruce to be proposing/discussing was the idea of
building a bottom stage for a DC-1 for those occaisons when a 'heavy'
payload needed launch.  (Heavy - either something that grosses out
long before it bulks out the cargo bay, or something that is going
higher than LEO on one launch (for whatever reason)).

This would seem to make a lot of sense; I did *not* understand him
to be advocating *all* launches as being two stage, just those that
would benefit from it.  (Or are you arguing that there will never
be any payloads that weigh too much for a DC-1?)

Graydon

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

End of Space Digest Volume 15 : Issue 627
------------------------------