Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_6/v15no621.txt

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Date: Fri,  1 Jan 93 05:05:02
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #621
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri,  1 Jan 93       Volume 15 : Issue 621

Today's Topics:
               "Moonraker" -- fact or fiction? (2 msgs)
                  Aluminum as rocket fuel? (6 msgs)
                            averting doom
                          DC cost estimates
                Government-run programs  Was: Re: Just
                           January 3, 1993
      Let's be more specific (was: Stupid Shut Cost arguements)
                 Public support for the space program
           Sea floor Planetary Protection really. (2 msgs)
                           SSTO vs 2 stage
        Stupid Shut Cost arguements (was Re: Terminal Velocity

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

Date: 1 Jan 93 01:58:01 GMT
From: Tim Smith <[e-mail]>
Subject: "Moonraker" -- fact or fiction?
Newsgroups: alt.conspiracy,talk.politics.misc,sci.space.shuttle,sci.space,sci.astro

>story readable.  For that reason Fleming completed a new James
>Bond novel only about once a year.  If it had all been
>imagination, as many people believe, he would have been capable
>of producing a new book every few months, making himself far
>richer.

Hmmm...Zahn's "Star Wars" novels are coming out once a year.  Does this
mean that they are not fiction?  And Asimov spent a lot of time between
the original Foundation trilogy and the last few novels.  Hmmm...

Dr. Beter is an idiot.

--Tim Smith

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

Date: 1 Jan 93 03:20:57 GMT
From: "Robert J. Granvin" <[e-mail]>
Subject: "Moonraker" -- fact or fiction?
Newsgroups: alt.conspiracy,talk.politics.misc,sci.space.shuttle,sci.space,sci.astro

In article <[e-mail]> [e-mail] (Tim Smith) writes:
>>story readable.  For that reason Fleming completed a new James
>>Bond novel only about once a year.  If it had all been
>>imagination, as many people believe, he would have been capable
>>of producing a new book every few months, making himself far
>>richer.
>
>Hmmm...Zahn's "Star Wars" novels are coming out once a year.  Does this
>mean that they are not fiction?  And Asimov spent a lot of time between
>the original Foundation trilogy and the last few novels.  Hmmm...
>
>Dr. Beter is an idiot.

Hmmmm... I edit a small (12 page) newsletter which usually takes me about
two weeks to assemble - much more if I have to write much of it.  I have
also had a number of articles published.  Writing something for print is
a lot more intense than writing it for the sake of only a few people, a
specified group or yourself.  It took several months to correctly put
together an article (and this is fact, not fiction - with a fully documented
history) which numbered only a few pages.

Putting together a novel in less than 12 months is a herculean feat no
matter what the focus.  If the words and story comes easily, the editing
and preparation take enormous amounts of time.

Most full-lenth books that are written, edited and published on the order
of weeks or very few months tend to be fluff - and they're usually intended
to be that when it's started.

Anyone who thinks the writing process, even for a literary genius, is not
time consuming at the least is fooling themselves.

--
\\ Robert J. Granvin                                 User Services Specialist
// School of Statistics - University of Minnesota            [e-mail]

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

Date: 31 Dec 92 22:58:12 GMT
From: Henry Spencer <[e-mail]>
Subject: Aluminum as rocket fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
>... have the molten aluminum stored in a spherical steel
>tank pressurized by injecting liquid nitrogen into the tank (which because of
>the heat will immediately vaporize).  Is nitrogen available from the moon?

There's no significant amount of nitrogen on the Moon unless there are
frozen polar volatiles.  You can recover a very little bit from the
regolith, if you're willing to process a lot of regolith.

A note of caution:  you're assuming that nitrogen is an inert gas.  This
isn't necessarily true when hot metals are involved.  I'm not sure about
aluminum, but I know titanium will burn fiercely in nitrogen (in fact,
the ash from titanium burning in air is about 80% titanium nitride).
Without an ignition source, the combination might be stable enough.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Fri, 1 Jan 1993 00:12:52 GMT
From: Paul Dietz <[e-mail]>
Subject: Aluminum as rocket fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:

> density of about 2700 kg/m^3 will require small tanks.  The tanks are very
> hot, meaning that little mass of pressurization gas will be needed.  A useful
> technique might be to have the molten aluminum stored in a spherical steel
> tank pressurized by injecting liquid nitrogen into the tank (which because of
> the heat will immediately vaporize).  Is nitrogen available from the moon?


Hydrogen or helium could work.  If the tank is at 1000 K, and the tank
pressure is 2 MPa, one needs about 1 gram of hydrogen for every 5000
grams of aluminum.  Producing a gram of aluminum requires the
processing of about 10 grams of anorthite.  So, if the anorthite has
at least 20 ppm hydrogen (implanted from the solar wind) , this
byproduct would be sufficient to provide pressurizing gas (actually,
since there will be an excess of oxygen in the rocket, still more
regolith would have to be processed, so still more hydrogen would be
produced).  No need to liquify it, just store at high pressure.

Water might be more convenient, although I expect steam would react
with the aluminum (not necessarily a problem, unless the aluminum
oxide byproduct clogged things).

    Paul F. Dietz
    [e-mail]

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

Date: Fri, 1 Jan 1993 00:49:01 GMT
From: Bruce Dunn <[e-mail]>
Subject: Aluminum as rocket fuel?
Newsgroups: sci.space

Regarding using nitrogen to pressurize molten aluminum

> Henry Spencer writes:
>
> There's no significant amount of nitrogen on the Moon unless there are
> frozen polar volatiles.  You can recover a very little bit from the
> regolith, if you're willing to process a lot of regolith.
>
> A note of caution:  you're assuming that nitrogen is an inert gas.  This
> isn't necessarily true when hot metals are involved.  I'm not sure about
> aluminum, but I know titanium will burn fiercely in nitrogen (in fact,
> the ash from titanium burning in air is about 80% titanium nitride).
> Without an ignition source, the combination might be stable enough.



        Molten aluminum is stable enough in air which is 80% nitrogen.
However, there may be some formation of protective oxide layers, and the
pressures involved are nowhere near the pressures needed for rockets.
Anyway, the point is probably moot if the pressurizing gas has to be imported
from the earth - in this case helium would have a fraction of the mass and be
a truly inert gas for use in pressurization.

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

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

Date: Fri, 1 Jan 1993 00:57:34 GMT
From: Nick Janow <[e-mail]>
Subject: Aluminum as rocket fuel?
Newsgroups: sci.space

[e-mail] (Bruce Dunn) writes:

> I think the fundamental problem with this [MHD pumps] is where to get the
> large amounts of power needed.  Even moderate sized rocket engines use
> turbopumps generating several thousand kilowatts of power.

Yah, I thought of that this morning.  You could generate it with an MHD
generator in the nozzle, but the mass of the whole system would probably be
too high.

> Paul Deitz has pointed out in E-mail to me that molten aluminum would
> be an ideal candidate for pressure feeding.

Yah, that sounds like a better idea; much simpler.

> A useful technique might be to have the molten aluminum stored in a
> spherical steel tank pressurized by injecting liquid nitrogen into the tank
> (which because of the heat will immediately vaporize).  Is nitrogen
> available from the moon?

Not according to the books I have.  Lots of oxygen in the minerals, but only
a trace of any other normally gasseous elements.  I suppose nitrogen--or
other inert gas--would have to be imported.  It could be mixed with oxygen,
since molten aluminum forms an oxide slag cover.  Does anyone know what level
of oxygen partial pressure is dangerous during aluminum casting?

To Henry: I've never heard of aluminum being very reactive with nitrogen.
Titanium is unusual.

As for the other problem (nozzle degradation), could oxygen be vented at the
perimeter of the reaction chamber and nozzle throat to protect the (ceramic)
surfaces from abrasion and clogging?  The engine is supposed to run with
excess oxygen; why not make use of that?  Has there been any research into
nozzles protected by a gas layer?

--

[e-mail]

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

Date: Fri, 1 Jan 1993 03:25:15 GMT
From: Henry Spencer <[e-mail]>
Subject: Aluminum as rocket fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>... I suppose nitrogen--or
>other inert gas--would have to be imported.  It could be mixed with oxygen,
>since molten aluminum forms an oxide slag cover...

Probably workable, although pressurant injection will have to be smooth
enough not to disturb the surface too much.  (This is something that can
be a problem with some other kinds of pressurization, e.g. pressurizing
LOX with GOX -- there can be substantial mixing that cools the pressurant
gas considerably.)

>To Henry: I've never heard of aluminum being very reactive with nitrogen.
>Titanium is unusual.

That's my impression too... but aluminum's pussycat reputation is mostly
due to its oxide film -- it *is* a fiercely reactive metal.  Probably
okay, but if I were head of the design bureau :-), I'd like to see this
checked before committing to it.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 31 Dec 92 17:49:14 GMT
From: Paul Campbell <taniwha!paul>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Thompson Reynolds) writes:
>
>In article <[e-mail]>, [e-mail] (Karl Dishaw) writes:

>My thoughts were along the line of constructing a hollow cylinder of
>powdered aluminum, into which you would pump LOX at a controlled rate.

>I seem to remember a somewhat similar design which pumps LOX into a tube of
>rubber?  To stop the "engine", stop the flow of LOX.

>Obviously such a design would only be useful in a vacuum, and is probably
>no more reusable than an SRB.

Well, existing AP/rubber motors (like the SRBs) have the oxidizer embedded in
the rubber (the AP) - they also tend to include some aluminium because it
gives better thrust (the mix is critical because you want to control burn time,
keep chamber temps and pressures in a safe range etc etc - having seen the
results of NOT keeping the chamber pressure in safe range ....BANG).

A LOX/Rubber system would probably have Al embedded in the rubber anyway for
the same reasons. I'm a bit leary about it being restartable, certainly you
can shut it off, but after burning for a while the mechanical stabiliy of
the rubber is going to be a bit off - garbage may have blocked the nozzle
etc etc.

I doubt an Al engine will be reusable without lots of cleaning --- alumina's
going to be real hard to get off!! (Probably harder to clean than an SRB)
Why wouldn't it work in an atmosphere?

    Paul



--
Paul Campbell    UUCP: ..!mtxinu!taniwha!paul     AppleLink: CAMPBELL.P
"Finally after much thought he tied a dollar bill to the top of the tree, it
seemed to fit - after all it was the premier capitalist holiday, besides after
the 'fall' of communism a star didn't seem appropriate anymore ..."

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

Date: Thu, 31 Dec 1992 23:47:22 GMT
From: Jay Scott <[e-mail]>
Subject: averting doom
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment

John McCarthy writes:
>By the way, it seems to me that if the above idea is sound, it settles
>the question of the stability of the solar system - in the negative.
>Very likely an asteroid could be tamed over a sufficiently long time
>with as small an expenditure of delta-v as might be desired.  Once
>tamed it could be used with infinitesimal external force to expel a
>planet from the system.  This tells us that the current trajectory of
>the solar system is arbitarily close to one in which a planet is
>expelled.  Of course, the probability that a planet actually would be
>expelled by this mechanism in some particular finite time is extremely
>low, because maintaining the required sequence of encounters requires
>an improbable precision in the initial conditions.  I suppose a lower
>bound on the probability could be computed and from it an expected
>upper bound on the gravitational lifetime of the solar system could be
>obtained.

Without being so rash as to do any actual calculations, I
would guess that this does not say much about the stability
question. I would guess that an asteriod is so much more likely
to be ejected from the solar system, or smashed to dust by
collisions, or fall into a planet, than to be captured into
a destructive resonant orbit that the asteriods will all be gone
before they destabilize the solar system.

I guess that light pressure effects or gravitational radiation
are more likely limiting factors. But don't listen to me, I don't
even know which one is bigger for planets (light pressure effects
are bigger for small objects).

    Jay Scott
    [e-mail]

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

Date: 31 Dec 92 22:35:17 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DC cost estimates
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:

>Allen generally takes projected "worst-case" cost estimates for DC
>and multiplies them by two or more in making his calculations, which
>I think shows he is aware of the problem.

Actually, I doubled the estimates I have seen. They are more likely to
be the reasonable estimates and not 'worst-case' estimates.


>I should make one additional point regarding Allen's calculations - they
>don't include the large opportunity cost if the Shuttle program should
>be cancelled before DC is fully operational

I con't follow this. It seems to me that if Shuttle is cancled it could
more than double the market for DC flights. This could roughly cut DC
costs in half.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------114 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 31 Dec 1992 16:40:22 GMT
From: Mike Kirby <[e-mail]>
Subject: Government-run programs  Was: Re: Just
Newsgroups: sci.space

In article [e-mail], Dr. Norman J. LaFave <[e-mail]> writes:
>In article <[e-mail]> Paul Dietz,
>[e-mail] writes:
>>Well, Doc, I can't, because I do not recall where or just when this
>>poll was conducted (it was some years ago).
>
>Here's a clue Paul, the results of polls change with time and not all
>polls are accurate.
>
>>However, if you wish to
>>call me a liar about it, I shall try to cope.
>
>I'm not calling you a liar Paul. However I am a scientist, and as a
>scientist,
>I like to make my own judgements.
>
>Norman
>
>Dr. Norman J. LaFave
>Senior Engineer
>Lockheed Engineering and Sciences Company
>
>
>
>
>When the going gets weird, the weird turn pro
>                               Hunter Thompson


Give it a rest guys.  Pauls assertion, while not backed up with
scientific evidence seems quite reasonable.  I for one would prefer to
have universal health care than a space program if forced to make a choice.  I
believe, however, that we as a society can support both without ridiculous
taxes.

Both of you quibble like PHd's.  Let's move the discussion on.

Mike Kirby
Xerox Corp
E-Mail: [e-mail]

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

Date: 31 Dec 1992 22:44:42 GMT
From: David Gutierrez <[e-mail]>
Subject: January 3, 1993
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (Michael Corbin) writes:
>On  Sunday  evening,  January  3rd,  you  will  be  taken  on  an
>incredible  journey back to July 1947.  To Roswell,  New  Mexico,
>sight of one of the most important events in the history of  man:
>the  crash  of  a disk, alleged to be an  alien  spacecraft,  the
>recovery  of  alien  bodies, the subsequent  coverup  by  the  US

<more UFO stuff deleted>

>Join us on Galaxy Six, Channel 17, Audio 7.5 MHz.

Yeah, these guys must be from Galaxy Six.


David Gutierrez
[e-mail]

"Only fools are positive." - Moe Howard

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

Date: 1 Jan 93 03:06:02 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Let's be more specific (was: Stupid Shut Cost arguements)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>>Shuttle's costs were all accounted for too. The customer, the US
>>taxpayer, wanted R&D done to develop a reusable spacecraft.
>
>OK Gary you win. I'll accept that there is nothing wrong with Governement
>engaging in activities which would get you or I put in jail. It's OK for
>NASA to spend $34 billion and then pretend they didn't.

They don't pretend that they didn't. The expenditures are all public
record. Government does use different accounting rules because government
is not a business. I hammer on this because of your constant claims that
NASA is doing something illegal or unethical. They are not. They are operating
exactly as they are chartered to operate. If you have a problem with that
charter, take it up with Congress, don't bash NASA for following the rules.

>Under these rules, let's look at the costs. The follwoing cost are
>from a spreadsheet I put together to evaluate these costs. We get:
>
>
>                                Shuttle       SSTO
>1. Launches per year [1]:         10           10
>2. Amortization years [2]:        30           10
>3. Development costs [3]:          0         $3,000M
>4. Production costs [4]:        $1,500M      $  333M
>5. Amortization costs:          $   66M      $   58M
>6. Launch costs [6]:            $  550M      $   20M
>7. Total launch cost (5 + 6):   $  616M      $   78M
>8. Cost per pound to LEO:       $10,272      $  1304
>
>So even ignoring $34 billion in Shuttle costs AND doubling SSTO
>costs, SSTO comes out ahead. Even if you doubled Shuttle flight
>rates (which not even NASA pretends any more) and quadrupled
>all SSTO costs, SSTO still wins.
>
>[1] I used the number of Shuttle launches scheduled for this year and next.
>    Doubling this number will not change the end result. For SSTO, I assume
>    it takes 80% the domestic MLV market and that the market doesn't grow.
>    I think both of these assumptions are unrealistic but it makes SSTO
>    look worse.

If cost and performance estimates for DC hold up, it may indeed capture
80% of the MLV market, but not right away. I think most potential customers
will want to see a track record of successful launches first. That may take
several years to develop. The competition, especially Arienne and Long
March, may be expected to cut prices sharply in response. That could lead
to long legal battles over dumping. DC's backers may need deep pockets to
keep going until they win that 80% market share.

>[2] Amortization happens over 30 years for Shuttle vs 10 years for SSTO.
>    SSTO must recoup costs faster since competitors can be expected. Allowing
>    SSTO more time will greatly reduce its costs.

Agree.

>[3] Shuttle gets a free ride here. To keep Gary happy we won't worry about
>    the $34 billion Shuttle development costs. To also keep Gary happy, we
>    WILL amortize SSTO development costs and double those costs just in
>    case.

Development costs still look optimistic, but I'll grant this one. The
development *timeline* which you don't include, I think will be longer
than expected. That impacts everything in the short run. I point to
Pegasus as a current example of the effect of optimistic development
scheduling. That causes financial problems for a commercial venture
that government agencies can shrug off.

>[4] Again, we use Gary's number for the cost of an orbiter. I have doubled
>    the cost of an SSTO to add margin for error.

I accept these numbers outright.

>[6] SSTO launch costs are again, double the estimated costs to add a margin.

Here's where I have the most problem with your numbers. I accept that
NASA spends $550 million per launch in total Shuttle program costs.
I further accept that that's very high. But I would point out that
it's a government launcher, run under government rules, with government
overhead. Estimates of actual variable costs for a Shuttle launch range
from $37 to $150 million per launch. That makes it look much better in
comparison to DC numbers. Is this relevant? Yes if we want to compare
*vehicles*, no if we want to compare *programs*. It's important to realize
that DC is projected to operate under a completely different set of rules
than Shuttle is forced to use. Thus we have an apples and oranges
comparison. Shuttle will always cost more, even under commercial
operators and commercial rules. But not as much more as your numbers
indicate. And those extra costs buy some capabilities that DC doesn't
offer. Am I saying NASA should sell Shuttle? You bet. Will it happen?
Not a chance.

If DC flies with anything like the performance and costs that are
projected, it will be a big commercial success. I think those
numbers are still optimistic and that the program risks are still
large, however. Shuttle was a cheap $300 a pound launcher when it
was a paper airplane too. Even with a 3X stretchout of development time,
and a 3X increase in projected costs, it'll beat government run Shuttle
costs, but would have trouble against actual Shuttle costs if Shuttle
were run under comparable commercial rules. What I'm saying in a nutshell
is that the proposed DC is expected to be cheaper than the operating Shuttle
because they are required to operate in different manners by law and by
government and corporate culture.  Thus your Shuttle bashing rightfully
should be government operating methods bashing. I'll happily join you in
*that*. Government can't do anything as efficiently as the private sector.

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     |                     | emory!ke4zv![e-mail]

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

Date: Thu, 31 Dec 1992 20:24:40 GMT
From: "Charles J. Divine" <[e-mail]>
Subject: Public support for the space program
Newsgroups: sci.space,talk.politics.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>This poll asked 1,234 Americans what categories of public spending
>they would like to see increased.  The results:
>
>    Education            76%
>    Drugs                75
>    Homeless            71
>    Health Care            67
>    Pollution            59
>    AIDS                59
>    Job Training & Placement    56
>    Help low-income families    56
>    Aid farmers            48
>    Health insurance        48
>    Aid college students        44
>    Child care services        41
>    First-time home buyers        37
>    Space exploration        21
>    Defense spending        17
>
>When a subgroup was asked if they were willing to pay additional taxes
>to increase federal spending for an item, suport for space exploration
>was also next to last, at 13% (the top 4 categories in the list
>remained above 50%).
>
>Another poll conducted July 1990 (The Gallup Poll Monthly, Sept. 1990,
>pages 44-45) showed a decline in support for the space program.
>In response to the question
>
>   "On the whole, do you feel our investment
>   in space research is worthwhile or do you think it would be better
>   spent on domestic programs such as health care and education?",
>
>the response was:
>
>    Year        Worthwhile    Domestic    No opinion
>    1989           43%          52          5
>    1990           39          57          4
>
>In response to the question
>
>  "I am going to ask you a question about government spending.
>   In answering, please bear in mind that sooner or later all
>   government spending has to be taken out of the taxes that you
>   and other Americans pay.  Thinking about the US space program,
>   tell me whether the amount of money now being spent for that purpose
>   should be increased, kept at the present level, reduced, or ended
>   altogether?"
>
>    Year        Increase       Same   Reduce   End    No Opinion
>    1984           21%        48    23    5    3
>    1986           26        50    14    5    5
>    1989           27        42    22    4    5
>    1990           17        37    32     10    4
>
>I imagine the jump in 1986 was a result of the Challenger disaster.
>
>The polling data does show that the public favors manned (48%) over
>unmanned (34%) programs.
>
>    Paul F. Dietz
>    [e-mail]

One problem with these polls is the fact that they reflect the public
lack of knowledge about the areas being ranked, the amounts of money
being spent and the effectiveness of the efforts expended.

Back in the early 80s (1983 I think) I attended a Princeton Conference
on Space Manufacturing.  A sociologist reported an interesting discovery
on these polls.  He first verified the conclusions you present:  little
real support for space spending.  Even more wanted to reduce the
spending than you report.

He then went on to ask why the critics wanted to cut space spending.

One reason frequently offerred was that the critics objected to
spending well in excess of $100 billion a year on military projects.

The sociologist then constructed a second experiment.  He informed a
subject population of critics of how much money was spent on NASA and
what it was spent on (civilian projects, rather than military).

The results?  The overwhelming number of critics then said "Is that
all we're spending?  We should be spending MORE.

For more details, check the early 80s proceedings of the conference.
They're available from the AIAA, possibly in good libraries as well.


In general, while I trust and support democratic means of decision
making, I don't always think the public always knows the truth.

Some of us who have investigated various programs you cite with more
support suspect that support would vanish if the public were even a
little bit better informed.

--
Chuck Divine

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

Date: Thu, 31 Dec 1992 20:48:38 GMT
From: Ed McCreary <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>NASA  has adopted the COSPAR guidelines on planetary protection and i believe
>even has an office for this.  They are concerned about contamination in
>both ways.  They reccomend, heat sterilization, radiation,  gas and chemicals.
>
>The big concern now is not so much establishing earth organisms on foreign
>bodies, but destroyin/contaminating archaeology studies of exo-biology.
>
>I know the Mars Observer orbit was constrained under planetary protection
>guidelines to stay off the surface for X thousand years.

True.  After it's mission is finished, MO will be raised to a high
enough orbit to prevent it's re-entry for X thousand years.

On a related note, the designers of Viking were worried that
the Soviets would land a probe on Mars before their landing without
following strict sterilization procedures.  This, they felt, might
contaminate Viking's biological results.  Luckily, the soviets decided
to follow similar guidlines.

--
Ed McCreary                                               ,__o
[e-mail]                       _-\_<,
"If it were not for laughter, there would be no Tao."  (*)/'(*)

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

Date: 31 Dec 92 23:18:42 GMT
From: Henry Spencer <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ed McCreary) writes:
>... After it's mission is finished, MO will be raised to a high
>enough orbit to prevent it's re-entry for X thousand years.

This may be a little academic, since as I recall, as of its shutdown in
1972, Mariner 9's estimated orbital lifetime was only half a century.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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Date: Thu, 31 Dec 1992 22:52:28 GMT
From: Henry Spencer <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
>> No, some of the S-IVB-based SSTO proposals were reusable...
>
>        I stand corrected, although somewhat puzzled. If you have the details
>handy Henry, could you inform us how it was planned to recover a cylindrical
>stage without having it break up the way the Shuttle ET breaks up when it
>hits the atmosphere?  Presumably this must involve some mechanism for keeping
>the stage oriented and tumble free during re-entry.  What heat shield
>materials were planned in this era prior to the Shuttle tiles and blankets?

I don't have a lot of detail.  The proposal I recall was in three phases.
Phase one recovered an S-IVB with minimal modifications (ocean recovery
using parachutes and retrorockets) as a demonstration, using the stage's
existing RCS system plus three steel-mesh ballutes for nose-first
stabilization, and ablative thermal protection.  Phase two switched to
land recovery, using landing legs plus crushable honeycomb behind the
heatshield.  Phase three did a substantial rebuild of the engine area
to use an aerospike engine, which doubled as a liquid-hydrogen-cooled
heatshield for tail-first reentry.  After phase three successfully
demonstrated an engine suitable for SSTO operations and a fully-reusable
recovery mechanism, an operational SSTO vehicle would be developed
using lighter structures etc.  (The version I saw sounded like they
weren't sure a direct S-IVB derivative could achieve SSTO itself.)
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 1 Jan 93 02:16:48 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>
>The Space Shuttle is simply the highest cost (per pound) launch vehicle ever
>operated.

At $37,500 a pound Pegasus is over three times the cost of Shuttle. Care to
venture a guess what Vanguard's cost per pound was? Shuttle *is* expensive
to operate, but it offers capabilities not found on any other current system.
It is not the highest cost way to do some tasks, it's the only way. That
makes it the cheapest way until something better is flying.

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     |                     | emory!ke4zv![e-mail]

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End of Space Digest Volume 15 : Issue 621
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