Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v13_6/v13_655.txt

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Subject: SPACE Digest V13 #655

SPACE Digest                                     Volume 13 : Issue 655

Today's Topics:
          Re: Extra Terrestrial Intelligence
          Re: vacuum energies for propolsion
              Re: Privatization
               Re: satellite refuelling
         Re: Info on spacecraft power storage wanted
         Re: Self-sustaining infrastructures
               Re: satellite refuelling
             Re: Babies in Space
Re: Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence)
         Re: Self-sustaining infrastructures

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
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----------------------------------------------------------------------

Date: 29 May 91 16:14:08 GMT
From: dev8g.mdcbbs.com![e-mail]
Subject: Re: Extra Terrestrial Intelligence

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

> (5) Maybe we're the only inhabited planet in the universe...
>
> Any other comments on this would be greatly appreciated


  There are two general classes of stars called Population I and
Population II stars. Population I stars have heavy elements in them
from their creation, while Population II stars are lacking in
heavy elements. The designations are reversed chronologically
as the Population II stars exist prior to the Population I stars.
When a Population II star ends its life and goes nova, that is
the source of the heavy elements which get swept up into a Population I
star and its planets, which is where the heavy elements that make us up
originate.

Now then, a quick survey of the stars immediatly surrounding us reveals
(surprise) lots and lots of Population II (no heavy elements) stars!
No heavy elements are available to the solar systems which accompany
these stars, hence, life as we know it is not likely to have evolved, nor
would any life forms on these planets have the heavy elements on which our
technologies are based.

  There might very well be many advanced cultures in our galaxy, but it
appears that WE are the oldest, most advanced species in this neck
of the galatic woods! Being way off in our own little corner may explain
a lack of interest on the part of other space-faring races.


==========================================================================
\\\\    Michael Rivero      | "I drank WHAT!" |"Why bother with marriage?|
  (.    [e-mail] | Socrates  -------------------Just find a   |
   )>   DISCLAIMER:::       |-----------| "Life is CHEAP! |woman you hate
  ==    "Hey man, I wasn't  |Looking4luv| But toilet paper|and buy her a |
---/    even here then!"    |Settle4sex!| is EXPENSIVE!"  |  house!"     |
++++++++++++++++++++++++++++++++++++++++-------------------+++++++++++++++

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

Date: 30 May 91 04:22:43 GMT
From: cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!unixhub!slacvm![e-mail]  (Jon J Thaler)
Subject: Re: vacuum energies for propolsion

In article <[e-mail]>, [e-mail] (John K. Gibbons) says:
>
>               On the other hand, we know damned little about what is
>happening at the Planck length, where vacuum fluctuations become significant.

This is incorrect.  Vacuum fluctuations are important and measureable at
presently accessible lengths.  For example they modify the effective
strength of the EM force by about 5% at the highest accessible energies.

The possible existence of a lower energy state than our favorite vacuum is
highly constrained by the known long lifetime of the universe.

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

Date: 30 May 91 15:00:12 GMT
From: mentor.cc.purdue.edu!pop.stat.purdue.edu![e-mail]  (Herman Rubin)
Subject: Re: Privatization

In article <[e-mail]>, [e-mail] (Charles Frank Radley) writes:

> How will you ensure that the billions simply do not get embezzled if
> a private concenr gets it ?

>   I like the idea of a public government agency habndling sums of
> money this big.   They are completely open to public scrutiny and
> we know exactly where every penny gets spent.
>    Large sums of money temp people to do some pretty weird things you know,
> jjto that is the main problem with the S & L industry....

A government will not openly embezzle the funds, but they will divert
them.  I suspect that misuse of funds is far more common in the government
than in the private sector, and is least in the for-profit sector.  Those
who invest in something do not want their investment wasted.

There is plenty of scrutiny in how every penny gets spent in all firms
except those with only a few owners, and even there it is not that free.
Look at the income tax laws.

This has been reported elsewhere, but the S&L problem was due to the
combination of GOVERNMENT insurance and economic pressures combined
with deregulation.  It was foreseen, the S&Ls were subject to public
accounting, and improper activities were only a small part of the problem.
--
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: [phone]
[e-mail] (Internet, bitnet)   {purdue,pur-ee}!l.cc!hrubin(UUCP)

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

Date: 30 May 91 19:06:59 GMT
From: hela![e-mail]  (Allen W. Sherzer)
Subject: Re: satellite refuelling

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

  [refuelling sattellites]

>You missed another option, which is to decrease the payload mass in
>order to allow more stationkeeping fuel for the same launcher.

That is a viable option right now. No new technology would be needed.
The fact that it isn't done indicates that it is not a good tradeoff.
In other words the capability lost by reduced mass translates to less
cash flow which would make the satellite unprofitable.

>For most satellites, the cost of a refueling mission will not be
>significantly smaller than the cost of launching a new generation, more
>capable satellite.

Depdend on the cost. If I can refuel the satellite for less than $100M
it is likely to be worth it.

  Allen

--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |   DETROIT: Where the weak are killed and eaten.         |
|   [e-mail]   |                                                         |
+---------------------------------------------------------------------------+

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

Date: 29 May 91 21:32:52 GMT
From: van-bc!rsoft!mindlink![e-mail]  (Bruce Dunn)
Subject: Re: Info on spacecraft power storage wanted


     There was a bit of a flurry several months ago about a development by
Sanyo.  Apparently they have a way of making an extremely high capacity
capacitor out of activated carbon (presumably coated with an insulating layer).
No details were given in the press reports, but for a while the idea of
powering electric vehicles from the device was mentioned.  This apparently
floundered on lack of long term storage capacity of the capacitor.  However, if
extremely high capacity capacitors can indeed be made, they may make it
possible to get short term discharge rates from a battery system much higher
than can be supported by the batteries directly.  Since battery capacity is
often inversly proportional to design discharge rate, peak shaving by a
capacitor system might give higher energy storage per unit power supply mass.
--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 31 May 91 03:49:55 GMT
From: agate!earthquake.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Self-sustaining infrastructures

In article <[e-mail]> [e-mail] writes:
>Not at all.  I am assuming that we can decrease payload mass if a
>larger launch vehicle is not available and longer lifetime is desired
>(it often isn't, BTW).  This is a common engineering tradeoff.
>
A hell of a lot of time, effort and money goes into making a satellite as
small as possible NOW. You want to try to get substantial mass reduction
beyond that?

>BTW, what are the cost proposals for developing refueling infrastructure?
>I think it would blow the cost of doing the payload mass/lifetime tradeoff
>out of the water.  I suspect we are talking $billions for a problem that
>costs, at most, a few $million per satellite.
>
In fact, I'm in the middle of doing such a cost estimate (though a very
rough one...) in my spare time. I had intended to wait untill I finished,
but...

For a 2-man station, of a soviet Mir-type, able to maintain/refuel/repair
50 satellites / year, the OMV to move the satellites around, and the logistical
support of this system...

approximately $ 5,000 Million to develop/launch
        1,500 Million per year to support

This comes to $30 million per satellite repaired. This is less than launch
costs for most satellites, and therefore cheaper than launching a replacement.

I can go into greater detail if there is any interest...

                    Frank Crary

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

Date: 31 May 91 12:59:09 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!ox.com!hela![e-mail]  (Allen W. Sherzer)
Subject: Re: satellite refuelling

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

>The real fact is that it is the central planners, not the satellite builders
>and operators, who are pushing refueling capability.

It's no different from any large scale infrastructure effort. Builders won't
add costs to allow refueling when no refueling companies exist and nobody
will enter the refueling market without satellites which can be refueled.

Again, it's like the early days of avation and the Kelly Act. Without it and
the incentives it provided (multi-engines, advanced navigation and large
cargo areas) we wouldn't have the aerospace industry we have today.

    Allen

--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |   DETROIT: Where the weak are killed and eaten.         |
|   [e-mail]   |                                                         |
+---------------------------------------------------------------------------+

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

Date: 31 May 91 17:29:45 GMT
From: dog.ee.lbl.gov!hellgate.utah.edu!caen!ox.com!fmsrl7![e-mail]  (Ron Carter)
Subject: Re: Babies in Space

In article <[e-mail]> [e-mail] (Curtis Yarvin) writes:
>In article <[e-mail]> [e-mail] (Ron Carter) writes:
>>A fetus floating in amniotic fluid is already experiencing nearly zero-G
>>conditions, and has to resist no gravitational loads.
>Balls.  Buoyancy is not antigravity.

I never said it was.

However, the stresses on a bone from its difference in density
with the flesh surrounding it are minuscule compared to the
stress involved in holding up a body against gravity.  The
gravitational stress is almost completely absent when floating,
compared to, say, walking.

>When you drop a wrench in a submarine, does it fall to the deck?  Or does it
>just hang there?

(I ought to flame you properly for getting the question completely wrong.)

If I raise my arm and drop it when I'm in air in 1 G, it falls
very quickly, and the bone takes significant linear and torsional
stresses while supporting the arm.  If I do it in 1 G in water,
the arm falls (due to the greater density of bone and muscle
compared to water), but very slowly.  The comparative stresses
are much smaller.  If I did it in 0 G, it would not fall at all.
The question is, how great are the biological effects of the
difference between 1 G in water and 0 G, for the maturation of
bone?  I'd bet they're smaller than the difference between 1 G
in water and 1 G in air.

>A baby in the amniotic sac experiences the same gravitational load as a baby
>lying in a parking lot.  The difference is that, in the former case, the force
>which opposes gravity is buoyancy, which is well-distributed over the body
>surface and thus causes minimal stress.  The same effect could be achieved
>by immobilizing the critter and placing it on an ideal contour couch.

Immobilizing someone is not under consideration, and would have
effects of its own.  Eliminating muscular stresses would not
only have effects on the bones, but also on the muscles.

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

Date: 1 Jun 91 18:29:17 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!jarthur!nntp-server.caltech.edu!iago.caltech.edu![e-mail]  (Horowitz, Irwin Kenneth)
Subject: Re: Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence)

In article <[e-mail]>, [e-mail] (Mark Luce) writes...
>/ hpfcso:sci.space / [e-mail] / 10:14 am  May 29, 1991 /
>In article <[e-mail]>, [e-mail] writes:
>
>> (5) Maybe we're the only inhabited planet in the universe...
>>
>> Any other comments on this would be greatly appreciated
>
>
>  There are two general classes of stars called Population I and
>Population II stars. Population I stars have heavy elements in them
>from their creation, while Population II stars are lacking in
>heavy elements. The designations are reversed chronologically
>as the Population II stars exist prior to the Population I stars.
>When a Population II star ends its life and goes nova, that is
>the source of the heavy elements which get swept up into a Population I
>star and its planets, which is where the heavy elements that make us up
>originate.
>
>Now then, a quick survey of the stars immediatly surrounding us reveals
>(surprise) lots and lots of Population II (no heavy elements) stars!

Sorry to burst your bubble here, but Pop I stars far outnumber Pop II stars
in "our little neck of the woods."  I believe that the numbers are on the
order of 1%-2% of the stars in the solar neighborhood are Pop II.  However,
in the galactic halo, the vast majority of stars are Pop II (since no active
star formation is occuring in these regions today).

>No heavy elements are available to the solar systems which accompany
>these stars, hence, life as we know it is not likely to have evolved, nor
>would any life forms on these planets have the heavy elements on which our
>technologies are based.
>
>  There might very well be many advanced cultures in our galaxy, but it
>appears that WE are the oldest, most advanced species in this neck
>of the galatic woods! Being way off in our own little corner may explain
>a lack of interest on the part of other space-faring races.
>
>     > I don't know about other nearby stars, but according to an article
>     > in the April 1991 issue of Astronomy magazine, the Alpha Centauri
>     > system has a *higher* metal content than the Solar System, and is
>     > believed to be somewhat older to boot (about 6 billion years).
>     > Don't write off our neck of the woods just yet...
>==========================================================================
>\\\\    Michael Rivero      | "I drank WHAT!" |"Why bother with marriage?|
>  (.    [e-mail] | Socrates  -------------------Just find a   |
>   )>   DISCLAIMER:::       |-----------| "Life is CHEAP! |woman you hate
>  ==    "Hey man, I wasn't  |Looking4luv| But toilet paper|and buy her a |
>---/    even here then!"    |Settle4sex!| is EXPENSIVE!"  |  house!"     |
>++++++++++++++++++++++++++++++++++++++++-------------------+++++++++++++++
>----------
-------------------------------------------------------------------------------
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: 1 Jun 91 19:23:56 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!samsung!umich!ox.com!hela![e-mail]  (Allen W. Sherzer)
Subject: Re: Self-sustaining infrastructures

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

>* The best cost estimate for a four-man station is $120,000 million (GAO).

This is a large part of your problem Nick. You look at one station which
costs $120B and from that conclude that ALL stations must cost $120B. The
GAO doesn't think that is true, why do you?

>* You didn't even bother to amortize the $5 billion.

During my daughters writing class this morning I did some rough numbers.
I (and my trusty HP 12C calculator) came up with the following:

Let's assume the station is similar to the design proposed by LLNL and we
use a Titan derived HLV for launch.

Development costs (in millions of $$):

Station: $1,000
OMV:     $  600
HLV:     $  500
         -------
         $2,100

This is over three years and assume that 1/3 the money is spent in each of
the three years. To give our investors a 10% return we must pay back the
future value of our investment which amounts to $2,437M. To amortize this
over ten years (continuing to pay our investors 10%) will cost $386M per
year.

For transport we will use the Soyuz (I use Syouz because I know what they
cost; if you want another, build it) at $50M each and a Titan derived HLV
which costs $250M per launch and lifts 150K pounds. We will buy four
launches per year where two are supply runs and two are combination crew/
supply runs.  Finally toss in $100M/year for whatever. This comes to:

$  386M - Amortize of station, OMV, and HLV development costs
$1,100M - Transport (4 HLVs and two Soyuz)
$  100M - Misc costs
-------
$1,586M - Total cost
$  159M - Profit margine of 10%
-------
$1,745M - Total price

Now we have a station, transport, and supplies for the crew. We also have
half a million pounds of stuff we can lift as well to sell. If we can sell
this stuff for at least $3500/pound we break even.

Now if satellite manufacturers build their satellites with satndard busses
and interfaces along with refueling we could lift up fuel and parts. This
would allow us to refuel, repair, and upgrade satellites in orbit. If we
use 20,000 pounds of material per satellite we could repair and upgrade
25 satellites per year at a cost of $70M per satellite. which looks on
the verge of being practical. A few years of learning curve would also
make significant reductions to transport costs making it look even
better.

The problem of course is that even if there where that many satellites
to repair we won't see standard busses and refueling facilities. That's
because without the station discussed above there's no point. On the other
hand, without that station there is no poing in making satellites repairable.

  Allen
--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |   DETROIT: Where the weak are killed and eaten.         |
|   [e-mail]   |                                                         |
+---------------------------------------------------------------------------+

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

End of SPACE Digest V13 #655
*******************