Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO185.ZIP/V15NO185

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Date: Fri, 11 Sep 92 05:04:24
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #185
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri, 11 Sep 92       Volume 15 : Issue 185

Today's Topics:
                 20 Questions About the Delta Clipper
                     3 booster questions (2 msgs)
             Climate cycles from Earth's orbital geometry
      Launch order (was: is this the 50th space shuttle launch?)
                             Mars Direct
      One Small Step for a Space Activist... Vol 3 No 9 (3 msgs)
                  Pluto Fast Flyby mission goals...
               QUERY Re: Pluto Direct/ options (3 msgs)
                              Relativity
                              spacesuits
                                 SPS
                        SSTO has been achieved

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Date: Fri, 11 Sep 1992 02:06:22 GMT
From: Greg Moore <[e-mail]>
Subject: 20 Questions About the Delta Clipper
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>> actual wear and tear on the engines.  You may find the atmospheric
>transit
>> has strange affects (look at the British Comet) that negatively
>affect
>> wear and tear, requiring more maintainance than required.  And this
>
>>
>
>
>The problem with the Comet had nothing at all to do with engines. It
>had to do with metal fatigue on the fuselage and an insufficient
>number of rip stops. This is not likely to be a problem on DCX as
>materials are much better understood now. Not to mention that
>simulation, while not perfect, allows problems like this to be
>uncovered before prototyping. It even eliminates the need for
>fullscale models (as has been noted by Dani I believe) and thus cuts
>cost at the same time it cuts design risk.
>
Sorry, I was not clear above.  I did not mean that the Comet faield due
to engine problems.  The problems were partly a result of extrapolating
the known into the unknown.  THEIR engineering tests didn't indicate
the stress fatigue would be a problem.

    Bringing the anology to the DC-X and later, I'm curious as to
what problems they expect with the cycling of pressure differentials
(i.e. sea-level to vacumn) and tempature ranges will have on the
engines.  Yes, our knowledge is better, but is it enough?

>The DCX is a simple craft using off the shelf parts and well
>understood technology. There may be some flight regimes in which
>there is something to be learned, but I suspect there is not much
>from a science viewpoint. Unlike other vehicles built in the past,
>its design is not a research project. This is a skunkworks aviation
>project whose only goal is operational hardware.
>
    The key there is "some flight regimes in which there is
something to be learned"  I think we might learn a lot.  I just
hope known of it endangers the craft.

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

Date: Fri, 11 Sep 1992 00:08:31 GMT
From: Nick Szabo <[e-mail]>
Subject: 3 booster questions
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>[1].What makes Titan so expensive?

As is normal, cost is a function of economics and politics as well
as technology.

First, Titan like Delta and Atlas is a reworked ICBM design, not
something designed from scratch as a launcher.  That may add
significantly to the cost, though there has been a notable failure
of anybody to build a launcher from scratch that gives big savings
(Ariane gives some small savings, but at the cost of reliability,
and Atlas has caught up to Ariane on cost with the 2AS).

Second, Martin Marietta has a lock on many large government contracts,
espically the USAF Titan IV contract, for reasons having little to do with
efficiency.  The more Martin charges, the more money they make.  In
their defense, this situation is by no means unique to MM or Titan,
and Titan does have an explary reliability record, justifying a bit
higher cost per pound in the eyes of rational customers.


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

Date: 11 Sep 92 00:28:00 GMT
From: [e-mail]
Subject: 3 Booster Questions
Newsgroups: sci.space

In response to Josh's statment about single engines for the booster phase of an
HLV.

Josh the NLS one booster which as an Atlas II class launcher only uses one
STME booster (600,000 lbs thrust) for 20,000 lbs to orbit. Why? Lower labor
costs.  Titan IV costs much because of all of the labor involved in the build
up as well as the reliability issues that others have mentioned.  Funny that
I did not know this three weeks ago (about NLS having single engine) when
I spoke of the single engine "Baby Saturn" approach. I have to up the payload
to orbit value to 60,000-65,000 for the F1A/STME combo to orbit. It still costs
less than an Altas to fly.  A Rockwell engineer I spoke with at the WSC thought
the baby Saturn might be as low as 55 million per launch.  This gets the cost
per lb down to less than $1000 bucks a pound.  This is mostly due to labor
savings in the booster construction.  Reliablity is a large question BUT 65 F1
engines fired without failure during the Apollo program.  This does give a
baseline for an optimistic flight reliablilty percentage.

Dennis, University of Alabama Huntsville

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

Date: Fri, 11 Sep 1992 03:31:36 GMT
From: Chris Gellasch <[e-mail]>
Subject: Climate cycles from Earth's orbital geometry
Newsgroups: sci.geo.geology,sci.astro,sci.space,sci.geo.meteorology

In article <[e-mail]> [e-mail] (Joe Cain) writes:
>
>    We were just going over some sedimentary cycles in a class
>today which related to an article in EOS.* I would
>like to find some material which discusses the Milankovitch-type
>forcing functions which lead to climate cycles. i.e.
>
>precesssion of the equinoxes  19, 23 K years
>obliquity of Earth's axis     41, 54 K years
>eccentricity of orbit         95, 123, 413, and 2035 K years
>
>I am looking for something about the level of Scientific American with
>some pretty pictures that discusses the geologic findings in this
>area.  This is for a beginning planetary geology class for
>non-scientists. Has anyone seen anything recently?
>
>
I am taking a cylcostratigraphy seminar course this semester and we
have been looking at papers by A.G. Fischer.  He has published quite
a number of papers on cylcicity relating to orbital variations.  I
have some of the papers with me and I will list them.

    Fischer, A.G. 1981. Climate Oscillations in the Biosphere.
        In: Biotic Crises in Ecological and Evolutionary Time,
        M.H. Nitecki. Academic Press. p. 103-131.
      Fischer, A.G. 1986. Climatic Rythms Recorded in Strata. Annual
        Review of Earth and Planetary Science. v. 14 p. 351-376.
    Gilbert, G.K. 1895. Sedimentary Measurement of Geology Time.
        Jour. Geol. 3:121-127.


The first paper deals more with 300 MY "super cycles" but does talk about
the shorter Milankovich cylces.  Gilbert was one of the first to see these
cycles but could not prove it (no radiometric dating).  These papers
are not as straight forward as you may be looking for but they deal
with the subject in a Sed/Strat context.  I can look up other, more
straight forward, articles if these don't work.

Speaking of cycles, does anyone else have input about these Milankovich
cycles found in the stratigraphic record?

Chris Gellasch
[e-mail]  (use this address, not the one in the header)
Indiana Univ.

--
-------------------------------------------------------------------------------
Chris Gellasch                                        [e-mail]
-------------------------------------------------------------------------------

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

Date: 10 Sep 92 22:41:03 GMT
From: "Shadan M. Ardalan" <[e-mail]>
Subject: Launch order (was: is this the 50th space shuttle launch?)
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Doug Brann) writes:
>
>In article <[e-mail]>, [e-mail] (Richard Ottolini) writes:
>>
>>The LA Times said so.
>>But I see the number sts-47 used here.
>>How many have actually been launched so far?
>
>This is the 50th shuttle mission.  The STS numbers do not match the number
>of missions.  The numbers are assigned when the mission is planned and due
>to delays and schedule changes the STS numbers became out of order.  For
>example STS-50 was the Columbia Microgravity Lab a couple of months back and
>was the 48th shuttle mission. The Voyager's were not launched in order either.

The numbering of the Voyager's was not based on launch order....
Instead, NASA based their numbering on their trajectories.......
Here`s what I`m talking about....................................


Voyager 1 was launched on September 1977......(i.e., launched second)
Voyager 2 was launched on August 1977.........(i.e., launched first)

BUT......

Voyager 1 arrived at Jupiter on March 1979....(i.e., arrived first)
Voyager 2 arriver at Jupiter on July 1979.....(i.e., arrived second)

Pretty neat, huh :-)....

Shadan M. Ardalan
[e-mail]

P.S. BTW, they also arrive at Saturn in that order....
     Source: NASA Facts regarding the Voyager Mission

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

Date: 10 Sep 92 23:37:25 GMT
From: Nick Szabo <[e-mail]>
Subject: Mars Direct
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Andreas Michael Weder) writes:
>>I'd say, forget about that. Even a manned mission to Mars would cost
>>*at least* 500 billion dollars (according to a NASA researcher).
>
>According to a NASA politician, you mean.
>
>There is no technical reason why it has to cost that much.  See Bob Zubrin's
>"Mars direct" proposal for an example of a method that ought to cost about
>a tenth that much, total, for the first ten missions.  If enough people prod
>me, I'll type in my notes from his talk, although there was a good summary
>paper about it a year or two ago in JBIS.

There is no "technical" reason why anything should cost anything; that
is a judgement of economics, and in this case of politics, as well as
of technology.  I have previously shown that Mars Direct, while being
a considerable improvement, would still cost $150 billion for a single
4-astronaut mission to Mars.  The two orders of magnitude improvement
postulated here is sheer fantasy.  We can just as easily improve
automated missions to the planets by two orders of magnitude; in fact
the improvement in spacecraft technology is proceeding much faster than
improvement in space station technology, so that cost breakthroughs are
much more likely for automated projects.  We will have hundreds of automated
stations, sampling robots, propellant plants and much else on Mars before
astronauts ever set foot there.

In fact the biggest savings in Mars Direct comes from putting an
automated propellant manufacturing plant on the surface of Mars.
There is also an automated sample-return version of Mars Direct that
uses two currently operational launchers, Titan IVs, to return hundreds
of kilograms of samples to Earth for a $2 billion, a considerable
savings over current Mars sample return designs and a whopping savings
over the astronaut version for a similar function.


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

Date: Thu, 10 Sep 1992 22:33:22 GMT
From: Nick Szabo <[e-mail]>
Subject: One Small Step for a Space Activist... Vol 3 No 9
Newsgroups: talk.politics.space,sci.space

First off, I'd like to congratulate Allen on this effort and
express my support for this direction.  I do have some questions
and comments on the specifics, though.

> There is an old saying in Mexico: What cannot be remedied
> must be endured. With the July House appropriations vote and
> with the retirement of Rep. Traxler (D-MI) it looks like Space
> Station Freedom is out of remedy mode and into endure mode.
> With all its flaws and costs it looks like Freedom WILL be
> built (in some form anyway).

Fred is still being funded one year at a time.  This year it
took some significant hits. The probability of Fred being
completed, while rising, is still only around 50%, so the
market needs to be adjusted by that factor (to start with).
The probability of SSF being a significant milestone in space
development remains very low; it adds practically no functionality
of importance to future endeavors, while consuming a large sum
in opportunity costs (cf. my post, "The Opportunity Costs of
SSF").  The Shuttle also consumes large amounts of funding,
so I applaud this effort to find a superior alternative to the Shuttle.

> On the plus side, station supply will mean placing a lot of
> mass into LEO, and this could make the market for launch
> services a LOT bigger,
> ...but non-Shuttle
> based resupply could mean that the entire Shuttle program
> can be phased out, freeing up roughly three BILLION every year.

Shuttle should be phased out with launchers shared by the military
and commerce, and eventually by SSTO.  Developing a unique capability
for one program doesn't make sense, especially a program as inconsquential
as SSF.

> So what do we need to do? We need to: 1)Fly about 160,000
> pounds of supplies and experiments up and about 50,000
> pounds back down (returned cargo will need low-G return);
> 2)Fly four crew to and from Freedom four times a year; and
> 3)An Orbital Transfer Vehicle needed to transport payloads
> to Freedom (this is needed since we are eliminating
> Shuttle).

I don't understand the 160,000 pounds.  Shuttle only carries
50,000 pounds. What in blazes does #3 mean?  We only need to circularize
at 300 nm, normal launchers can do that.

> A heavy lift vehicle would be one way to meet requirement one.
> such an HLV would lift 100,000 pounds to Freedom orbit and would
> carry a reusable logistics module. The logistics module would
> have an aerodynamic shape (perhaps like DC-Y or an Apollo
> capsule) and be capable of returning 20,000 pounds to Earth.

I thought you said we need 160,000 pounds?  In any case, why
can't we use Titan IV?  At 40,000 pounds, it can carry nearly
as much as the Shuttle.

> Such an HLV should be a commercial procurement where the
> government buys launch services only (as required by current
> federal law).

I agree with the commercial aquisition approach, but a launcher
custom-made for a single NASA program is a very poor candidate for
commercial aquisition. This service has a politically risky future,
both in terms of funding SSF and non-use of the Shuttle.  A 50% chance
of funding with a 25% chance of NASA actually using the service instead
of Shuttle gives a 87% chance that the company will lose its shirt trying
to develop the beast.

> Two candidates are Heavy Lift Delta (see One
> Small Step... Vol. 2 No 2) and Titan V (see One Small
> Step... Vol. 2 No 3). Both manufacturers have already offered
> to sell launch services for either vehicle for less than $200
> million per launch (including development costs).

MM already charges $280 million for Titan IV; how are they
going to launch more than twice the payload with the same
tech for less than $200 million?

It makes more sense to use the Shuttle phase-out to fund
new technology, like AMROC and SSTO, along with sharing
the existing fleet with military and commerce, instead of
stretching out the ancient missiles to even more bizzarre
lengths.  Titan IV, Atlas 2AS, Ariane 44L, and similarly
sized launchers with newer technology should be sufficient for
serving a rationally designed space station operation.

Again, while we quibble on the specifics, I applaud the
direction being taken here for sharing resources between
NASA and other space programs, instead of keeping NASA fixed
on, and then stuck with, its own limited in-house capabilities.


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

Date: 11 Sep 92 00:14:05 GMT
From: "Frederick A. Ringwald" <[e-mail]>
Subject: One Small Step for a Space Activist... Vol 3 No 9
Newsgroups: talk.politics.space,sci.space

In article <[e-mail]>
[e-mail] (Nick Szabo) writes:

> Fred is still being funded one year at a time.  This year it
> took some significant hits. The probability of Fred being
> completed, while rising, is still only around 50%, so the
> market needs to be adjusted by that factor (to start with).

Yes, as a space scientist, I know this feeling all too well.

Fred   ;-)/2

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

Date: 11 Sep 1992 02:09:49 GMT
From: [e-mail]
Subject: One Small Step for a Space Activist... Vol 3 No 9
Newsgroups: talk.politics.space,sci.space

First, [e-mail] (Michael V. Kent) wrote:

>>NASA intends to use only the Shuttle for resupply ONLY until something
>>better comes along.

Then, [e-mail] (Allen W. Sherzer) replied:

>As it currently stands Shuttle and Freedom together spend all the money
>which could go toward a Shuttle replacement. NASA therefore intends
>to use the Shuttle forever.

Goldin says we should consider the Shuttle program to last "at least"
until 2005, but not much beyond that.  12 years != forever.

No word on where a Shuttle replacement might come from, or how it
would be funded.

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

                  "HERE MEN FROM THE PLANET EARTH
                    FIRST SET FOOT UPON THE MOON
                           JULY 1969, A.D.
                  WE CAME IN PEACE FOR ALL MANKIND."

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

Date: Fri, 11 Sep 1992 04:22:00 GMT
From: "Horowitz, Irwin Kenneth" <[e-mail]>
Subject: Pluto Fast Flyby mission goals...
Newsgroups: sci.space

Folks,
    Hearing all these wild ideas passed around on this Pluto flyby has
led me to try to remind everyone of a few things concerning this mission.
First, Staehle is trying to bring back the concept of "faster, better,
cheaper" that Goldin is pushing, which was so successful in the '60s.
As a result, the primary concern for this mission is COST.  After that,
is a rapid schedule.  Finally, they'll address the performance aspects.
    As a result, this mission WILL NOT use any exotic or unproven
technology, just because they strike someone's fancy.  There are a lot more
"down-to-Earth" missions that can be used as technology testbeds.  No ion
thrusters.  No aerobrakes.  They are also limiting the scientific payload to
only those instruments that have been deemed most critical to a Pluto flyby.
These include a CCD camera, a UV spectrometer, an IR mapping spectrometer, as
well as the radio science that can be done using the main antenna.  This means
no magnetometer.  No dust collectors.  Nothing else.
    The second criterion is schedule.  They want to get to Pluto before
its atmosphere freezes out, so that it can be studied.  As to when that will
happen, we can't really predict too well.  But the sooner we get there, the
better chance we'll have of studying that atmosphere.  That means we want a
quick development schedule, as well as a short flight time.  The current plans
are to launch in 1998 on an 8 year direct flight (hopefully).  No gravity
assists.  No secondary encounters.  AND NO ORBIT INSERTION!  It just can't
be done within the contraints of the mission.
    And finally, on the cost for the mission...Staehle has been given
a direct order from Goldin to keep the cost of the entire mission under
$400M, and we believe that it can be done.  There is to be no cost overruns
on this project, or it will be killed by NASA.
    Remember, the last thing we need is to overdesign this mission like
CRAF/Cassini.
-------------------------------------------------------------------------------
Irwin Horowitz                        |
Astronomy Department                  |"Whoever heard of a female astronomer?"
California Institute of Technology    |--Charlene Sinclair, "Dinosaurs"
[e-mail]                |
[e-mail]                 |
-------------------------------------------------------------------------------

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

Date: Thu, 10 Sep 92 23:38:37 GMT
From: Joshua Bell <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>[e-mail] (Henry Spencer) writes:
>
>> In article <[e-mail]> [e-mail]
>> writes:
>> In what? :-)  Pluto does have an atmosphere of sorts at the moment, but I'd
>> guess it's too thin to do much aerobraking in, even if we knew
>> its properties well enough to plan an aerobraking mission, which we don't.
>
>Would it be possible to aerobrake at Uranus or Neptune, perhaps also using the
>atmosphere to change trajectory significantly?  This would provide a fast
>flight for much of the journey and have the remaining part at a speed slow
>enough for aerobraking in Pluto's atmosphere, or at least a much slower pass by
>Pluto.  It would also allow a mission at Uranus or Neptune.
>
>I can see lots of problems with this, but sometimes wild ideas are workable.

Looking at my National Geographic map from Aug 1990, Uranus is
getting rather far from an eyeballed route to Pluto. It'd mean
sending the probe out away (maybe 120 degrees or so on the
ecliptic) from Pluto, and having it whip around. If the intent is
slowing the probe down, you will probably end up with an even
slower mission. Neptune is only 50 degrees 'off course'. I can
imagine a slingshot (ignoring the fact that you're going against
the orbit - can you slingshot that way?), but I'll leave it to
the experts to judge on the breaking maneuver.

Question for the real experts:

A few years back I remember seeing tentative 'maps' of Pluto,
based on observing the spectrum of the Pluto-Charon system during
the eclipse cycle. The maps were rather simple - large white ice
caps, a redish-brown surface, a large black/brown spot on one
side, and a smaller white spot on the other. Is there any
planning of the probe's to take advantage of what little we know
about Pluto and 'aiming' for these spots, as the probe will
likely shoot past, not wait around 6 days (?) for Pluto to
revolve?

Joshua
| Tremble only if you build false accounts and stand pridefully upon them    |
|                                       - Lord Leto II, God Emperor of Dune  |
|                                                                            |
| [e-mail]  Academic Computing Services, University of Calgary |

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

Date: Fri, 11 Sep 1992 02:05:07 GMT
From: "robert.f.casey" <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

Something to consider if you want to areobrake your probe: you'd have to build
it to take a lot of wind and blowing.  And the weight of an Apollo capsule type
heat shield.  Probably end up being similar to the weight of a retrorocket.
And less predictable and controllable than the rocket engine.

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

Date: Wed, 09 Sep 1992 16:58:00 -0500
From: Shawn McCarthy <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

 > Although an orbiter has been discussed, the current mission
 > design calls for only a flyby.  To go into orbit, you need to travel more
 > slowly, thus flight times are longer.  And you need to carry more fuel,
 > which impacts the size of the instrument payload.  All kinds of
 > tradeoffs.

Has the possibility of a light-sail been looked into? use it for accelleration
from the 'bright' area near the earth, then brake off Jupiter's light... (more
complex than that, but thats the general idea)...

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

Date: Wed, 09 Sep 1992 16:53:00 -0500
From: Shawn McCarthy <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

Ok.. you look like you know what ur talking about (considerably more than i do
anyway.. :>  ) got a question: what if that train is moving just 5mph slower
than c (as measured from the station) and i run forwards at 6mph? According to
the train, i am moving at 6mph.. what does the station see? (or move a flag
foreward at that speed on the outside, so they can see it) ... when the object
(me or the flag) moves past c according to the station, what happens? or is that
a case of the train being shorter (from the station) so the speed really ISN'T
faster than c..?

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

Date: Fri, 11 Sep 92 02:14:58 GMT
From: "Amy L. Cooprider" <[e-mail]>
Subject: spacesuits
Newsgroups: sci.space

Does anyone know the latest figures for how much a spacesuit weighs??
I`ve heard of figures between 150 and 300 pounds.  This is somewhat trivial...
I only need the values to compute the payload of a vehicle for my senior
design course.

Thanks!!

-ALC

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

Date: 10 Sep 92 22:38:54 GMT
From: Nick Szabo <[e-mail]>
Subject: SPS
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>Actually, you don't have to fool around with aluminum-oxygen (which is
>a hassle as a rocket fuel, because both the aluminum and the aluminum
>oxide are solids, where you'd really like liquid and gas respectively).
>Jordin Kare's latest laser-launcher design, the heat-exchanger rocket,
>needs liquid hydrogen for launch from Earth but would work well enough
>on liquid oxygen for a lunar launch.  You'd still have to do some of
>the same work on chamber/nozzle materials, I expect.

After you spent the $trillions needed to get the power plant, power
storage, laser, etc. for this launcher system to the moon.


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

Date: Thu, 10 Sep 1992 21:11:55 GMT
From: "Kevin W. Plaxco" <[e-mail]>
Subject: SSTO has been achieved
Newsgroups: sci.space

As the subject line says, a Single Stage ascent To Orbit has been
achieved a half dozen times already, the last taking place almost
20 years ago.  The Lunar module ascent stage achieved lunar orbit
without dropping any stages (the lower section of the descent stage
was abandoned upon liftoff, serving as a launch platform).

The fact that lunar escape velocity is 1/6 that of earth, and that
without an atmosphere a 15 km high orbit is stable (for a few
orbits at least) and that the reduced forces (due to the lack of
aerodynamic stress and the reduced force of gravity) involved
lighten the craft substantially, a lunar SSTO was an achievable
task in 1969.

But what about a martian SSTO?  I have seen several discussions
about the logistics of a manned (or even unmanned return) mars
mission, but I have never seen a proposal for how to achieve
mars orbit after the mission has ended.  How difficult will this be?

Presumably, since numerous people here believe DC-Y will succeed,
similar technology will prevail on mars (where the conditions, while
more difficult than on the moon, are still easier than on the Earth).
But what about an unmanned sample return mission?  What would the
minimum weight be for a sample return craft capable of achieving
mars orbit (or solar orbit)?

-Kevin







--

            -Kevin

         Be particular

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

End of Space Digest Volume 15 : Issue 185
------------------------------