Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_0/V13_014.TXT

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Subject: SPACE Digest V13 #014

SPACE Digest                                      Volume 13 : Issue 14

Today's Topics:
        Re: Solar cell factor/Space computers
             Re: Interstellar Light Sails
      Re: orbiting Earth in the stratosphere by balloon.
               Interstellar Light Sails
               Re: Interstellar travel
              BRICKS file format
               Re: Interstellar travel
               Re: Interstellar travel
               Re: Interstellar travel
        Re: Recent Newsstand Magazine Articles
             Re: Interstellar Light Sails

Administrivia:

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Date: 30 Dec 90 00:26:31 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: Solar cell factor/Space computers
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In article <[e-mail]> [e-mail] ("86FTSCCQ") writes:
>1) If I have a solar cell that puts out 0.5a at 6 volts on Earth,
>   how much power will it produce of the various planets/sattels in
>   our solar system? Is there a straight forward set of factors ...

Look up the distances from the Sun, and remember that the sunlight intensity
diminishes as the square of distance.  That's all you need, barring possible
complications like nonlinear behavior in the cells.  (One thing to be careful
of is the cell temperature, by the way.)

>2) Is it possible to make "spaceable" a regular circuit board....
>   such as a embedded computer hardware controller?

Depends; what do you mean by "spaceable"?  Almost anything that doesn't need
convection for cooling can fly in the shuttle cabin -- for example, Radio
Shack Model 100s have flown unmodified.  If you're talking about use in an
unpressurized satellite, you need to worry a little about outgassing in
vacuum and a lot about temperature control.  For long missions or critical
applications, you also need to worry about radiation effects, both gradual
degradation due to accumulated dose and transient hiccups due to single
particle hits.
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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Date: 30 Dec 90 00:41:07 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: Interstellar Light Sails
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In article <[e-mail]> [e-mail] (Andrew Peter Anselmo) writes:
>Anybody given any thought in this newsgroup about Robert L. Fowards'
>interstellar light sail ships? ...   Has this idea
>been shot down, and am I basing this idea on fuzzy science-fiction science?

Forward generally does his homework; he's not above fudging the details when
necessary for story continuity (for example, the neutronic life in Dragon's
Egg is not workable), but his lightsails in particular showed up in serious
papers before he used them in his fiction.  If you can build the laser system
on the necessary colossal scale, laser sails are workable.
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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Date: 29 Dec 90 00:19:48 GMT
From: zaphod.mps.ohio-state.edu!swrinde!mips!news.cs.indiana.edu!msi.umn.edu!cs.umn.edu!kksys!wd0gol!newave![e-mail]  (John A. Weeks III)
Organization: NeWave Communications Ltd, Eden Prairie, MN
Subject: Re: orbiting Earth in the stratosphere by balloon.
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In article <[e-mail]> [e-mail] writes:
> There was an item in an aerospace magazine last October about a planned
> nonstop flight around the world in a high altitude balloon.

I have heard about this, too, but I do not recall the starting date.
One of the crew and main sponsor is the head of Virgin Records.  They
made a crossing of the Atlantic Ocean a few years back.

-john-

--
===============================================================================
John A. Weeks III               [phone]               [e-mail]
NeWave Communications                 ...uunet!rosevax!tcnet!wd0gol!newave!john
===============================================================================

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Date: 29 Dec 90 21:21:53 GMT
From: usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!cunixf.cc.columbia.edu![e-mail]  (Andrew Peter Anselmo)
Organization: Columbia University
Subject: Interstellar Light Sails
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Anybody given any thought in this newsgroup about Robert L. Fowards'
interstellar light sail ships?  They do away with a lot of the nastiness
of carrying your own fuel.  The basic premise is to use a ring of lasers in
orbit around Mercury (powered from the sun) to boost a light sail.  I know
Doc Foward is a big proponent of light sails; the interstellar light sail
concept was in a fiction book of his _Flight of the Dragonfly_.  Any comments?
Has anybody seen, heard or read about what I'm babbling about?  Has this idea
been shot down, and am I basing this idea on fuzzy science-fiction science?

Thanks.
   Andrew Peter Anselmo / Department of Mechanical Engineering / 220 SW Mudd
Columbia University in the City of New York, New York, NY 10027 (212)-854-2965
BITNET: [e-mail]                    DECNET: CUMEVA::ANSELMO
                   <<< Independently Owned and Operated >>>

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Date: 30 Dec 90 00:37:15 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: Interstellar travel
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In article <[e-mail]> [e-mail] (John McCarthy) writes:
>Here's a method of interstellar travel based entirely on present science
>and technology...
>The idea is to use an ordinary fission reactor to generate electricity,
>and use the electricity to expel a working fluid at an appropriate
>velocity...

I'm not sure I would call this entirely based on current technology, since
it puts very heavy demands on the reactor technology, given the weight
constraints.  (Any electrical-propulsion system suffers badly on this,
in fact, since electricity is a very cumbersome way of handling large
amounts of power.  A chemical rocket engine the size of a large man has
the same useful power output as the very biggest power plants.)

However, it's really not terribly difficult to establish John's basic
point, that interstellar travel is clearly feasible if travel times of
centuries are acceptable.  There are too many different methods that
should be feasible within the next hundred years or so; it requires a
really huge leap of faith to conclude that they are *all* unworkable.
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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Date: 30 Dec 90 00:45:55 GMT
From: ccncsu!typhoon.atmos.colostate.edu![e-mail]  (Bill Thorson)
Organization: CSU Dept. of Atmospheric Science
Subject: BRICKS file format
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   Is there anyone out there who has ever heard of the BRICKS image file
format.  I believe it is either created or just used by a company called
Intl. Imaging Systems I(2)S.  I know this company is using it for
satellite images so that may be the primary use for the format.

  If you know something, please let me know.  I would like to get the
specs. for this file format.

Bill Thorson

#!/bin/sh
#-----------------------------------------------------------------------#
echo Bill Thorson                   [e-mail]
echo Dept of Atmospheric Science    [phone]
echo Colorado State University
echo Ft. Collins,  CO  80523        Cray||Sun||Amiga -- I can't decide?
#-----------------------------------------------------------------------#

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Date: 29 Dec 90 11:27:42 GMT
From: prometheus![e-mail]  (Paul M. Koloc)
Subject: Re: Interstellar travel

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Mark Gellis) writes:
>>...the lack of discussion of fusion drives...I know there are a
>>LOT of technical problems involved, but doesn't a mass production
>>facility for anti-matter involve just as many problems?

>Believe it or not, they actually look to be easier problems.

I don't believe it.

>Deuterium is almost useless as a fusion fuel for high-performance rockets
>because of the fierce neutron emission, which is not just a radiation
>hazard but also a very serious heating problem.

AND, the destructive heating comes from the hot neutrons.

>>... By the way, what would be involved in an anti-matter
>>mass production facility, one large enough to provide a large
>>civilization with fuel for all its spacecraft?

>It depends on how many spacecraft, and how ambitious they are.  If you're
>willing to start with a large, ambitious program of solar-system exploration
>(manned) plus extensive operations in Earth orbit, something the size of
>the Hanford nuclear works would do.  (That is, it's within the scale of
>what has already been done in very-large-scale industrial activity.)

Large, ambitious program... ??  Sounds pitifully small to me, and we
don't need a miserly energy ration for the ships in such an undertaking.

On the other hand, what this planet does NOT need is a few hundreds more
Hanfords.    So let's get serious with advanced fusion concepts.

+---------------------------------------------------------+**********+
|                                                         +Commercial*
| Paul M. Koloc, President          [phone]        ***FUSION***
| Prometheus II, Ltd.; College Park, MD 20740-0222        ***in the***
| mimsy!prometheus!pmk; [e-mail]               **Nineties**
+---------------------------------------------------------************

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Date: 30 Dec 90 13:35:39 GMT
From: zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!dali.cs.montana.edu!milton!byron![e-mail]  (Joshua Geller)
Organization: University of Washington, Seattle
Subject: Re: Interstellar travel
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In article <[e-mail]>
[e-mail] (Henry Spencer) writes:

>The sheer size needed is a practical obstacle, as are the costs of the
>bombs and the legal problems of exploding nuclear bombs in space.  But
>it is pretty definitely workable, although rather marginal as an
>interstellar propulsion system.

But (please correct me if I am mistaken) a near ideal interplanetary drive?

>--
>"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
>points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry


@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@
{ As any intelligent user should realize,| If I had a steel Q-tip, I would    }
{ my opinions have nothing to do with the| stuff it in my ear, turn on 10,000 }
{ University of Washington or any group  | volts, and channel god.            }
{ of humans or individual human soever.  |                      Spamgod       }
{ ---------------------------------------|----------------------------------- }
{ Joshua Geller [e-mail] (USmail Seattle, 98102-1752)  }
@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@*@

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

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Date: 30 Dec 90 22:25:59 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: Interstellar travel
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In article <[e-mail]> [e-mail] (Joshua Geller) writes:
>>[thermonuclear Orion]
>>The sheer size needed is a practical obstacle, as are the costs of the
>>bombs and the legal problems of exploding nuclear bombs in space.  But
>>it is pretty definitely workable, although rather marginal as an
>>interstellar propulsion system.
>
>But (please correct me if I am mistaken) a near ideal interplanetary drive?

Only if you can build small thermonuclear bombs cheaply, in particular if
you can build them without the expensive fission component.  Dyson's
interstellar Orion ship was the size of Chicago, large enough to make
cost-effective use of existing fusion bombs.  Orion does not scale down
terribly well; apart from the cost angle, the limited information now
available on Orion design (it's mostly still classified) strongly suggests
that performance drops as the ship shrinks.

There is also reason for concern -- not well appreciated at the time --
about the effects of nuclear explosions in space on electronic equipment.
If you're using Orion ships within the solar system, and in particular
near Earth, you're going to be operating them in relatively close proximity
to a lot of sensitive equipment.  ("Close" here can mean tens or even
hundreds of thousands of kilometers.)  Near Earth there is the added
complication of charged particles being trapped by the Van Allen belts;
the handful of nuclear tests that were run at very high altitudes thirty
years ago were very hard on the satellites then in orbit.

The best way to build an Orion is to take it to its logical extreme and
use fusion microexplosions ignited by particle beams (lasers are probably
too heavy for spaceflight applications) and channeled by a magnetic nozzle.
This is a bit unsatisfactory because we can't quite build one of those
yet, while we could build a more orthodox Orion, but the microexplosion
approach is generally a better drive.
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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

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Date: 30 Dec 90 23:39:42 GMT
From: haven!uvaarpa!murdoch!faraday.clas.Virginia.EDU![e-mail]  (Laura Hayes Burchard)
Organization: University of Virginia
Subject: Re: Recent Newsstand Magazine Articles
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While we're on the subject, I noticed in Time that the New York Times
failed in its attempt to get the tapes of the Challenger's final moments
released, with NASA arguing that the privacy of the astronauts' families
demanded that they be kept secret.  I'm curious; have the families
actually said this?  I recall that in the immediate aftermath, at least
one family was attempting to get them released for use in a suit against
NASA.

I don't particularly want the tapes released, but I'd like to know that
there was an honest transcript.


--
Laura Burchard    [e-mail]    [e-mail]
October 3:  After 45 bitter years of separation, East and West Germany
unite to form a single nation, chastened by the past, hopeful for the future.
October 4:  Germany invades Poland.      --Dave Barry's Year in Review 1990

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

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Date: 30 Dec 90 10:09:33 GMT
From: prometheus![e-mail]  (Paul M. Koloc)
Organization: Prometheus II, Ltd.
Subject: Re: Interstellar Light Sails
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In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Andrew Peter Anselmo) writes:
>>Anybody given any thought in this newsgroup about Robert L. Fowards'
>>interstellar light sail ships? ...   Has this idea
>>been shot down, and am I basing this idea on fuzzy science-fiction science?

>                          .. .      If you can build the laser system
>on the necessary colossal scale, laser sails are workable.

Let's look into the future hazards of this approach:

A fleet of Sophians  were vaporized when they cut through the beam
(during a heated debate).

After a few decades of flawless performance, the mirror was sabotaged
by the Helicons (a tribe of radical solar orbital environmentalists).

A ship, The Henry (no relation), strayed just out of the beam,
(temporary guidance failure).

Beam traffic increased to the point where the system power convertor blew.

                       But what the heck
                   Our highways are cruised
                        by drunk drivers
                   (with/without licenses).

+---------------------------------------------------------+**********+
|                                                         +Commercial*
| Paul M. Koloc, President          [phone]        ***FUSION***
| Prometheus II, Ltd.; College Park, MD 20740-0222        ***in the***
| mimsy!prometheus!pmk; [e-mail]               **Nineties**
+---------------------------------------------------------************

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

End of SPACE Digest V13 #014
*******************