Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_6/V13_603.TXT

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Subject: SPACE Digest V13 #603

SPACE Digest                                     Volume 13 : Issue 603

Today's Topics:
              Re: SPACE Digest V13 #565
          Re: SPACE STATION FREEDOM WOUNDED
          Re: SPACE STATION FREEDOM WOUNDED
      Re: Fred vs. Exploration: head-to-head competition
           Re: Should Galileo be rerouted?
        Re: Gravity! What Gravity!?! Try This!
             Re: Laser launchers
      Re: 14 Astronauts have died for space exploration?

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Date: 19 May 91 18:31:11 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: SPACE Digest V13 #565

In article <[e-mail]> [e-mail] writes:
>
>>Mining the asteroids for materials to_be_used_in_space makes sense over
>>the long term. There is no hurry in the next twenty to fifty years,
>>however. Meanwhile we need to keep our pet scientists happy with
>>pretty pictures from the big gravity sinks.
>
>I think your 'ten-to-twenty years' comment shows that you grew up in an
>age when space was not that important because it was a place for
>scientific experiments and national prestige stunts, both of which cost
>losts of money.

Actually the time frame stated was "twenty to fifty" years, and I think
that is highly optimistic. I grew up in a time when only Jules Verne
thought travel to outer space was even possible. Nevertheless, with
Congress swinging the meataxe at space related items and pouring the
money into their S&L buddies' pockets through HUD, the prospect of
space industries, and their need for cheap materials, seems to be
receding rather than getting closer. I predict that space related
spending will continue to decline as a percentage of Federal revenues
until America wakes up *again* as it did in 1957, and by then it may
well be too late to catch up.

>Thoses time-scales will change when it appears that money can be made.
>Drastically.  I'm betting my life on it.  If it DOESN"T happen in my
>lifetime, my carrer will suck, and my wife will hate me, and I'll be a
>miserable fucker and die bitter and angry at the whole world.  :-)
>(I'm joking, but it's proabably true)

I don't see anyone doing the development needed who isn't counting on
the government to pay the bill in one way or another. Private investors
putting hundreds of billions of their own money at risk for a highly
speculative payoff twenty to fifty years down the road just doesn't
seem in the cards. Once the government spends that money, and the
infrastructure is in place, and the speculation turns to relative
certainty, then private industry will be willing to risk it's own
capital in a big way.

>The resources I'm thinking of may be salable (even at VERY low prices) in the
>very short-term.  I.E. before real operations get started.
>Take nickel.  It's current price is around $1/lb.  With a typical Nickel
>Asteroid, you could sell it for $.05/lb, and still make a klilling. (Do you
>know how much nickel would be in an asteroid 1km wide?).  Could any mining
>company compete?  More importantly, could we get them to invest?

More importantly, what does it cost to get that asteroid into LEO so
that mining and return missions could be done? What does it cost to
do the mining and return missions? Now what does the nickel cost per
pound?

Something the size of our little Jupiter probe isn't going to go fetch
that monster chunk of nickel. We don't have an HLV to launch anything
bigger. We have just lost funding for a possible in space assembly
point. We don't have anything to fetch the asteroid with, nor is
there public or private funding to develop such a thing. Even if we
were fortunate enough to discover an Earth orbit crossing pure nickel
asteroid that only required 1000 m/s delta vee tommorrow, it would be
five to ten years before we could even build up a probe to go take
a look at it. With our lack of heavy lift, even a simple probe would
probably take a roundabout trajectory that would take years to achieve
rendezvous. Then the huge recovery mechanism must be put in place.
Even 1000 m/s isn't easy to achieve with a mass of 4*10^12 pounds.
The time cost of money would make such an investment prohibitive for
the private sector.

Let's look at some numbers:

Annual worldwide consumption of nickel:    475,000 tons (950,000,000 pounds)
Total global expenditure for nickel at $1 per pound:   $950 million/year
Total global expenditure for nickel at $.05 per pound: $47.5 million/year
Total mass of 1 km nickel asteroid: 4*10^12 pounds
Years at current global consumption rates to deplete asteroid: 4210 years

Now a venture capitalist is going to want to see better than a 10% annual
return on his money for a risky startup venture. With a total *gross*
revenue of $47.5 million per year from the asteroid, the venture capitalist
is going to be willing to put up less than $470 million dollars. A lot
less considering that payback doesn't start the first year. I'm not a
good enough wiz with a financial calculator to give a precise answer,
maybe someone else is. Anyway, considering that there will be substantial
operating costs to mine the asteroid as well as horrendous initial costs
to move it to LEO, can you do it all for $470 million? If not, your
project won't find private funds. If you *do* manage to recover one
asteroid though, you won't have to go get another for over 4,000 years.
So after you prove the concept by returning *one*, getting investors
for the second should be easy in 4000 years when you need a second one.

>It's interesting to note that the most abundant source
>of nickel in the world has been determined to be the site of an ancient
>meteor impact (See Doomsday_Has_Been_Canceled for more of these neat things).
>Think of the savings if we caught the next on BEFORE it fell.

Think of the savings of simply using the one we got delivered for free.
Diverting an asteroid to LEO will cause one positive effect, the Christic
Institute will go into orbit. :-) With all the publicity received by the
Dinosaur Killer, advocating deliberately moving an asteroid near Earth
will generate mass protests that will make the anti-nukes look positively
pro-technology.

Gary

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Date: 20 May 91 19:26:26 GMT
From: agate!tornado.Berkeley.EDU![e-mail]  (George William Herbert)
Subject: Re: SPACE STATION FREEDOM WOUNDED

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>[...]
>ESA and NASDA sign long term agreements with a reliable partner, the
>Soviet Union, and proceed to develop space, garnering all the benefits
>while the US continues to slide into third world status.

Did I just hear the Soviet Union described as a 'reliable partner' ???

Are these the same Soviets whose next station was cancelled for _total_
lack of budget, not relative priority disagreements?  The ones whose Mars '94
probe is now lacking 80% of its funding, and who are starting to come to ESA
and the French with hat in hand so it will fly at all?  The ones who built
an honest-to-god HLV and may have the program zeroed because a large percentage
of their population wants to eat instead???

Talk to a space scientist who knows someone in the Soviet union in a similar
job.  They're not happy right now.

[flames to me, not the newsgroup... i think i'm far enough off topic as is]

-george
.

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Date: 20 May 91 22:48:07 GMT
From: agate!spool.mu.edu!mips!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!jpl-devvax![e-mail]  (Douglas Creel)
Subject: Re: SPACE STATION FREEDOM WOUNDED

>The something wrong is people who devote their attention to shallow
>heroes instead of the real heroes of space like James Van Allen,
>Ed Danielson, Eleanor Helin, Steve Ostro, and the many others who

Please clear something up for me Mr. Szabo. Just who exactly is it that
you consider "shallow" heroes. Is it perhaps the three astronauts who died
on the pad during the Apollo program, or is it the seven men and women who
died on board Challenger?  I'd really like to know how you can compare the
likes of James Van Allen to these people who made the ultimate sacrifice
in the service of their country. I'm waiting to hear what you have to say.

Douglas D. Creel
Navigation Systems Section (Mars Observer Project)
Jet Propulsion Laboratory

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

Date: 21 May 91 00:14:28 GMT
From: swrinde!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!juliet.caltech.edu![e-mail]  (Horowitz, Irwin Kenneth)
Subject: Re: Fred vs. Exploration: head-to-head competition

In article <[e-mail]>, [e-mail] (Douglas Creel) writes...
>I find it humorous how people cite the "wisdom" of Congres when it suits their
>own personal beliefs, and then attack Congress when its decisions don't support
>their views. How someone can trust the judgement of a Congressional
>subcommittee, which is nothing but a bunch of lawyers whose knowledge of science
>and engineering is woefully pitiful, over that of NASAs' leadership is beyond
>my comprehension. And by the way, NASA's leadership is compromised of more
>than just astronauts. I don't recall William Lenoir ever riding on a shuttle,
>and last time I checked he was in favor of the station.
>
Just want to point out a correction here...Bill Lenoir did ride on the shuttle
in its early days (STS-5 or STS-6 I believe).
-------------------------------------------------------------------------------
Irwin Horowitz                        |"Suppose they went nowhere?"-McCoy
Astronomy Department                  |"Then this will be your big chance
California Institute of Technology    | to get away from it all!"-Kirk
[e-mail]               |       from STII:TWOK
[e-mail]                 |
-------------------------------------------------------------------------------

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

Date: 18 May 91 08:58:36 GMT
From: ogicse!sequent!muncher.sequent.com![e-mail]
Subject: Re: Should Galileo be rerouted?

In article <[e-mail]> [e-mail] (Matthew DeLuca) writes:

>>>If the first two are useless rocks, what makes you think
>>>the next dozen are going to be any better?
>
>I think of it in this manner: say rock #1 is a dud, and rock #2 is a
>dud.  Knowing that these are two samples of the asteroids out there,
>do you (a) go on to rock #3, hoping that rocks #1 and #2 were flukes,
>or (b) go on to where you *know* you will learn something?  If this were
>a game show, it would definitely be option (b) for me.

These arguments suffer from their abstractness.  There are a wide
variety of asteroids and comets, and things classed as asteroids
that are probably dead comets, and things living in the outer
asteroid belt that are classified as asteroids but are chemically
closer to comets that have never been active.  There are metallic
asteroids which are core fragments of a once larger condensed object.
There are asteroids made primarily of basalt, asteroids made primarily
of olivine, asteroids with carbon and clay, asteroids that have
undergone substantial collision and asteroids that have not, and
a large number of asteroids that are mixtures of these types.
There are old comets with mostly water and dust and new comets with
large amounts of CO2 and CH4.  There are comet fragments ranging
in from dust to Tungaska-sized (100,000 tons) to the comets
themselves, and it is unknown how many intermediate sized fragments
exist or how much water they contain.

And that is the tip of the iceberg of the detail we know, and know
we don't know, from the feeble studies done to date.  With a reasonably
funded, greatly expanded program, the amount of detail and variety will
be even more substantial.

So we won't be saying "rocks #1, #2, ..., #n were dull, therefore all
rocks are dull."  We will be saying things like "this kind of rock
is more promising than that kind", and "feature A1 and B2 are more
important than features A2 and B1, and rocks 9, 13, and 41 are most
likely to exhibit these features, so let's go take a look at those
with these particular kinds of instruments."



--
Nick Szabo                [e-mail]
"If you understand something the first time you see it, you probably
knew it already.  The more bewildered you are, the more successful
the mission was." -- Ed Stone, Voyager space explorer

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

Date: 18 May 91 20:35:05 GMT
From: vax5.cit.cornell.edu![e-mail]
Subject: Re: Gravity! What Gravity!?! Try This!

THIS POSTING WAS A TEST TO SEE WHAT RESPONCE WOULD BE LIKE!

ALTHOUGH IT WAS BASED ON AN IDEA I ONCE HAD IN THIS REGARDS.

THANKS FOR THE RESPONCES!

THESE COMMENTS ARE MY OWN

             RICK

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

Date: 18 May 91 23:18:51 GMT
From: valid!caber![e-mail]  (Louis K. Scheffer)
Subject: Re: Laser launchers

[e-mail] (Gary Coffman) writes:

[.......]

>We know several things about the beam power levels.

>1. The power level will have to be at least as high as the power level
>   produced by a chemical rocket lifting the same mass. Gigawatts.
    Let's make a rough guess.  We can afford to orbit smaller payloads
    with a laser launcher.  We stick with known technology, and assume
    a metal nozzle, and water working fluid.  We can heat the water to
    4000 degrees C before we melt the nozzle.  This gives an exhaust
    velocity of 4 Km/sec.  To reach the 7 Km/sec vehicle velocity
    to orbit, we need a mass ratio at least e^(7/4) or about 7.  Let's
    assume 10 (what current single stage rockets have).  We then have
    a 10,000 Kg launch mass.  If we start at 2.5 gees, when we have
    used half the fluid we are at 5 gees acceleration.  Our speed at
    that point is about 2 Km/sec.  Thus the power required is:
    2000 m/sec * 50 M/sec^2 * 5000 kg = 500 Mw.  If the back end of the
    rocket has area 10 m^2, this is a power density of 50 Mw/m^2.
    (The Saturn 5 delivered 35 Gw through an diameter of about 10 m,
    or about 350 Mw/m^2, for comparison.)
>2. The power level must be high enough to turn enough ice to explosive
>   plasma to give the same thrust level as a chemical rocket. Gigawatts.
    No, you just need to heat it up to about 4000 degrees.  Plasma is
    not a requirement.
>3. A beam power level high enough to turn ice to plasma will also be
>   high enough to turn air to plasma.
    This seems wrong on several counts.  First, you do not need to turn
    the ice to plasma.  Second, surely you pick a wavelength that water
    absorbs better than nitrogen and oxygen.  You still get absorption
    by the water waper in the air, but water vapor is only a small
    percentage of air.  If you use visible light, for example, only
    a tiny percentage is absorbed by the air at these levels, but we
    can arrange the nozzle to absorb close to 100%.
>4. For a highly dispersed beam source (multiple lasers in a widely
>   spaced ground array) the geometry of the situation shows that
>   somewhere below the apex of the converging beams the power density
>   reaches the plasma point of air.
    This also seems unduly pessimistic.  First, we don't have plasma.
    Second, the power density is only high right behind the nozzle.
    At this point we can afford a fair amount of spread since the
    nozzle represents a target with a large subtended angle.  Third,
    since the rocket is moving at a good clip, we only need the air behind
    the nozzle to maintain good conditions for a few milliseconds at most.
    Each of these arguments alone imply that is is possible to deposit
    almost all the energy in the nozzle.
>5. As air pressure decreases, the power needed to ionize what air remains
>   decreases.
    True, but once again, we are not ionizing anything.  We also can use
    less thrust once we are above most of the atmosphere.

> [...]  During the early phases of launch, the beams will
>be converging at nearly right angles to the vehicle. This seems to preclude
>precise steering of your ice vehicles.

    This is not at all clear.  Assume the vehicle has a 1 second time
    constant for off center thrust producing pitching moment.  We can
    change the aim of lasers with about 1 KHz bandwidth.  Thus we should
    be able to maintain control of the vehicle until the geometry becomes
    unfavorable by about a factor of 1000.  This happens at 89.6 degrees
    to the line of flight.

[...]

>Ok, I concede this one. I hadn't considered a tapered cable. Still, growing
>a single crystaline strand, WITH A TAPER, that would reach to geosync, sounds
>rather unlikely for the simple reason that crystals like to determine their
>own shape. I still think this is a fundamental rather than developmental
>problem. Note that we are talking about beanstalks here and not dynamic
>tethers. They have another set of practical problems as launcher replacements.

This is clearly not a fundamental problem.  Conceptually, just grow a big
enough crystal, of whatever shape it wants, then machine the tapered strand
out of it.  The more practical approach is to get it to grow in that shape
in the first place.

-Lou Scheffer

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

Date: 17 May 91 13:43:28 GMT
From: dev8b.mdcbbs.com![e-mail]
Subject: Re: 14 Astronauts have died for space exploration?

In article <Added.sc=[e-mail]>, [e-mail] (Bob Rehak Ext. 3-9437, AIS Central Services  -  Swen Parson 146) writes:
>
> 14 astronauts?  Last time I counted there were only 10.
>
> Apollo I: Grissom, White, and Chaffee.
> STS-61L Challenger: Scobee, Smith, Resnik, Onizuka, McNair,
>                     Jarvis, and McAuliffe.
>
> A couple have died flight testing aircraft that was not related to
> space exploration and a couple have did in car accidents...I think.

If Grissom, White, and Chaffee (who died on the ground) are considered
as "Lost in the line of duty", the same should apply to the astronauts
who died in training flights. Just because they didn't make the evening news
doesn't mean that their contributions or sacrifices should go unheeded.



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End of SPACE Digest V13 #603
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