Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_0/V16NO026.TXT

Internet Message Format | 1993-07-13 | 34KB

Date: Sat,  9 Jan 93 05:06:30
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #026
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat,  9 Jan 93       Volume 16 : Issue 026

Today's Topics:
                  *** BUSSARD RAMSCOOP *** (3 msgs)
                *** METEOSAT weather images, SORRY ***
                            averting doom
                     Bussard Ramscoop: Some FAQ?
                 Justification for the Space Program
      Let's be more specific (was: Stupid Shut Cost arguements)
          Making Antimatter (was: *** BUSSARD RAMSCOOP ***)
                      RTG's on the Lunar Module
                         russian solar sail?+
Should NASA operate shuttles (was Re: Shuttle a research tool) (2 msgs)
              Subjective Safety Measure(Re: man-rating)
     Who can launch antisats? (was Re: DoD launcher use) (2 msgs)

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

Date: 8 Jan 93 17:26:42 GMT
From: Henry Spencer <[e-mail]>
Subject: *** BUSSARD RAMSCOOP ***
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>How can
>we talk about the performance of antimatter propulsion without knowing
>the mass fuel ratio? How much hardware does it take to contain a "tank" of
>antimatter (magnetic fields, etc.)? ...

Open question; the detailed engineering has not been done.  As usual, you
could make a wide variety of assumptions, from cautious-first-generation
to ambitious-long-term-possibilities.

>How do they contain the antimatter before injection into the collider?  If
>I remember correctly they have it going around in a racetrack in a holding
>facility, no???

That's right.  They work with antiprotons, not neutral antimatter atoms,
and they never do slow them all the way down to zero.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 8 Jan 93 17:31:32 GMT
From: Henry Spencer <[e-mail]>
Subject: *** BUSSARD RAMSCOOP ***
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Dave Jones) writes:
>You're just using the antimatter to heat hydrogen, so the rocket's
>efficiency is of the same order as the Nerva nuclear design: Isp = 850-1500
>or so, depending on how well it can be engineered.

Right premise, WRONG conclusion.  Nerva's exhaust velocity (aka Isp) was
limited by the maximum temperature of its core materials.  That is utterly
irrelevant to an antimatter rocket.  Gaseous-core fission rockets, which
are a more realistic comparison, appear to be capable of exhaust velocities
of hundreds or thousands of km/s (i.e., Isp in the 10000s or 100000s).
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 8 Jan 93 18:33:56 GMT
From: Jon J Thaler <[e-mail]>
Subject: *** BUSSARD RAMSCOOP ***
Newsgroups: sci.space

[e-mail] (Gregory N. Bond) says:

> Current antiproton production is geared towards physics, not
> rocketry.  It is probably possible to create antimatter more
> efficiently if that is the primary goal.

This is probably incorrect, for two reasons:
* Antiproton production and capture  efficiency limits the rate
  at which antiproton storage rings can be filled.  If easily
  obtainable improvements were available, I expect that they
  would have been used already.
* A rocket fuel needs to be cheaply contained.  Storage rings
  are expensive.  Unfortuantely, antiprotons are created moving,
  so they will need to be brought to rest to simplify the containment
  problem.  This is an additional manipulation that the physicists
  don't need to perform.

> However the energy cost is
> huge because conservation tells you that you only create antimatter
> with at least E=mc^2 input energy.
> It will release twice this amount when mixed with ordinary matter.
> Now if we could generate antiprotons with better than 50% efficiency,
> we have an inexhaustible energy supply......

There is no free lunch.  Baryon number is conserved.  This means it costs
the same 2mc^2 (at least) to make an antiproton that one gets back when
it annihilates.

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

Date: 8 Jan 93 17:14:47 GMT
From: Franck Roussel <[e-mail]>
Subject: *** METEOSAT weather images, SORRY ***
Newsgroups: sci.space

Hello everybody!

I am interested in METEOSAT weather images. I know there are many
  anonymous FTP sites, such:
    - cumulus.met.ed.ac.uk  in directory /images
    - nic.funet.fi               ''      /pub/sci/meteosat
  where satellite images of World,Atlantic,Europe are displayed.

Does anybody knows about other anonymous FTP sites like those ?

Especially, is there a server at the Meteorological Space Center
  of Lannion (Brittany) ?  I tried the FTP site "lannion.cnet.fr",
  but after typing the command 'ftp lannion.cnet.fr' it answered me:
    'Connected to lannion.cnet.fr'
    '421 Service not available, remote server has closed connection'


Thanks for all answers to my questions
Roussel

------------------------------------------------------------------------
Firstname: Frank                      E-mail: [e-mail]
Lastname : ROUSSEL                    Telephone: + 33 99 83 26 10

Address1 : 175, rue Belle Epine       CityStateZip: 35510
Address2 : CESSON SEVIGNE             Country: FRANCE
----------- Science without conscience is only soul's ruin  ------------

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

Date: 8 Jan 93 18:30:19 GMT
From: "Richard A. Schumacher" <[e-mail]>
Subject: averting doom
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment,talk.bizarre

>Do you seriously believe that a species capable of creating
>and enjoying The Love Boat is capable also of learning
>galactic engineering?

Of course. Our ancestors of only a few thousand years ago would have
been amazed at the technology of the Love Boat. If humans ever
build Dyson spheres or whatnot, at least one of them will be a theme
park. (Disneyplanet? Six Flags Over Alpha Centauri?)

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

Date: 8 Jan 93 18:56:17 GMT
From: Scott A Koester <[e-mail]>
Subject: Bussard Ramscoop: Some FAQ?
Newsgroups: sci.space

  I've read many articles on the Bussard Ramscoop and antiprotons (effectively
anti-matter) and I am intensly facinated and interested by this.  I would like
to see if anyone would like to write up an FAQ on this as I would like to have
some concrete condensed (meaning all in one place) information on this.  I
would do it..but I'm only a sophomore on college and am trying to bone up on
stuff....even though I might not understand some of it..I am ever daring to
try, plus I'm sure some others would like to see this also.  If there already
is one...someone just hit me and send it to me in email? Thanks....


Scott Koester

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

Date: Fri, 8 Jan 1993 17:47:55 GMT
From: "James L. Felder" <[e-mail]>
Subject: Justification for the Space Program
Newsgroups: sci.space

Thank you for the considered and considerate reply.  I would like to follow
up on a few of the points you made.

In article <[e-mail]>, [e-mail]
(Paul Dietz) wrote:
>

> There are a number of problems with this argument...
>
>   "We live on a planet with finite resources"
>
> Finite does not mean limited.  First, the amount present may be so
> large as to be effectively unlimited.  Fertile nuclear materials
> (U-238 and Th-232) fall into this class.  Second, aside from
> nuclear uses, elements are not consumed in use, they merely become
> less concentrated.  The free energy required to extract materials
> goes as the log of the dilution (higher in practice, but practice
> changes).

I see societal problems even bigger than those facing the space program in
siting breeder reactors and the attendent fuel reprocessing facilities and
waste disposal sites.  The Japanese government is already beginning to face
severe pressure to slow or halt their breeder program. A further problem I
see is that all the energy conversion to useable form (electricity) occurs
within the biosphere.  I do not have a feel for how much thermal energy can
be released into the biosphere before it contributes a significant amount
directly to global warming (as opposed to CO2's indirect contribution
through increased solar absorbtion).  Maybe you have some information on
this. I would love to see it (seriously, no flame). Conversion in orbit
with an efficient microwave downlink reduces the amount of thermal energy
released into the biosphere for an equal amount of useable energy.
Assuming that a nuke plant is 40% efficient and the microwave link is 95%,
the reduction is substantial.

I agree that elements are not consumed, only distributed.  However, it will
in the future require more time, money and effort to collect a given amount
of a material than it does now.  More raw material will have to be mined to
extract what we need, with attendent damage to the environment.  In general
it will become an increasing strain to gather the raw materials that are
need to keep us going.  Space originating materials will never come close
to supplying all that raw goods and energy that we need. I'm not that
naive.  But it might fill the gap not covered by recycling.

>
>   "Resources are being used up faster than they are being replaced"
>
> That a resource is limited and not renewable matters only if its
> is very hard to replace with some substitute.  Fossil fuels are
> an example -- there is no reason why we should not be able
> to survive indefinitely without them, if some other source of
> energy is available.

And no matter what we will have to learn to do without them.  And will
probably be cursed by future generations for burning such a useful
commodity simply to heat our homes.

But the source that replaces it must be socially as well as technically and
economically feasable.  Unless the world politic has a very great change of
heart, I don't see nuclear energy being a fundimental part of the
replacement strategy
>
>   [paraphrased] "Growth is necessary to avoid social calamity"
>
> Then we are in big trouble, since growth in resource use cannot
> continue forever.  For example, if energy use grows 1%/year,
> then in 10,000 years we are consuming the entire power output
> of the observable universe.

We are in big trouble.  And there is no technical cure.  The societies of
the world including the western industrial ones, must undergo radical
change.  But it won't happen overnight.  In the interum, some effort must
be made to supply world economies that are continuing to grow.  This is
independent, though, of how we do it. I make no claim that this is
justification for a space program, just that something must be done to
supply a growing demand.

>
> In the short term, however, there is no reason why resource use
> on earth cannot be increased.  There is no reason why we could
> not supply several times the current population with several times
> the current US per capita energy consumption indefinitely.

Yes, but at what cost to the environment?

>
>    "No inexhaustible energy source on earth"
>
> At least two are already in the engineering stages (solar and fission
> breeder).
>
> "Too Expensive!" you may say.  Well, now, yes, but manufacturing
> productivity increases about 3%/year.  It gets cheaper to make things.
> Moreover, if we had to make a lot of solar collectors or nuclear
> reactors, economies of scale would drive costs down still further.
> And it's a lot easier to start down a learning curve when you can
> build smallish things on the ground rather than enormous things in space.
> Realize that the current world output of PV modules would take
> more than a century to make enough to cover one 10 GW powersat.
> Space colonization schemes are implicitly assuming big productivity
> increases.

No, to unreliable.  Terrestrial solar energy has a problem because of
intermittent illumination.  Either a large storage capacity must be
included in the system, or another source must come on-line at night and
during periods of cloud cover.  The large required land area makes solar
problematic for large portion of the world.  Plus places like Cleveland
goes days or weeks with hardly a glimpse of the sun.

It might be a misconception on my part based on media coverage, but it
seems that nuclear plants have frequent shut downs for one reason or
another, often times for days or weeks.  A system that relied on a majority
of its energy from nuclear power would have to have a significant extra
capacity included, or a more reliable source ready to come on line at a
moments notice.

Without a track record, though, nothing can be said for powersats, so this
again probably isn't a compeling argument.  It at least doesn't share the
intermittent illumination problem of land based solar, plus the power
source never goes off-line :-).

I don't think that powersats of any size or number could be built using
terrestrial solar cells.  Launch costs and energy investment alone would
eat your lunch.  On orbit manufacture using in-situ non-terrestrial
materials would seem the only feesible method.  That brings its own set of
problems, but hey, TANSTAAFL.

>
>    "If we don't go now, resources will be too expensive"
>
> This "window of opportunity" argument falls apart under close
> examination.  Resource prices have typically fallen over time, even as
> richer deposits have been exhausted.  Moreover, a space program uses
> relatively little in the way of natural resources.  What it does use a
> lot of is labor, talent and knowledge.
>
> Look at the price of a shuttle orbiter.  It costs more than its own
> weight in gold.  The cost of the elements and energy that do go into
> its manufacture is a piddling small fraction of its total cost.  The
> same is true of an airliner.  The raw aluminum in a 747, for example,
> would cost perhaps a quarter of a million dollars.
>
> Increased raw material prices would only make a space program *more*
> feasible, by increasing the potential profit.

The price of raw materials in the space program is trivial, but that isn't
my point.  It is the price of raw materials and energy to the entire
economy that is the problem. I think that an increasing drag on the ecomomy
will be felt as these prices go up.  Either the prices of finished goods
must escalate, or the compensation for human effort must decrease.  Both
will result in a reduced standard of living, no facts just gut feel.  In
addition, we will have to expend more and more of our total effort in
simply producing the raw materials.  I don't think it will be very long
before the public has enough trouble keeping their heads above water that
they will not spend any money on something as speculative as the space
program.  That is the window of opportunity I was speaking about.

All this would of couse be obviated if we could just fundimentally alter
human behavior.  Persuade the world's population that the world has enough
people, so please don't have anymore, or at most only a few of you. And
that they must learn to recycle EVERTHING, not just soda bottles and
newspapers.  This must occur at some point in time, but it won't be easy
and it won't happen soon, IMHO.  But in the mean time, do we let a social
window of opportunity to expand beyond the surface of our world slip by.

I hope I am wrong about the window of opportunity to have a significant
space program, and that we can find ways to live within the means of this
planet to provide. But for what we spend on it, the space program seems
like cheap insurance to me. I say lets continue to learn how to live in
work in space. Lets explore our solar system to see if their are things out
there that we could feasibly use (both on the surface and in orbit). Lets
at least get ready to be able to live and work in space.  Then take another
look and see if we really do need to, or even can, build powersats,
colonies, moon bases and all the rest.

Hey, what is this soap box doing here!  Sorry, let me just climb down off
of here and I'll be on my way :-}.


James L. Felder            [phone]         -My opinions are MINE-
Sverdrup Technology, Inc.  [e-mail]  I think that should
NASA Lewis Research Center Cleveland 44135        cover all bases,
                                                  don't you.

"Some people drink from the fountain of knowledge -
    other people gargle"

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

Date: Fri, 8 Jan 1993 17:53:30 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Let's be more specific (was: Stupid Shut Cost arguements)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Jeff Greason ~) writes:

>While your arguments about availability are sound in principle, they
>ignore the element of risk.  Shuttle availability has a long time window
>to availability, in months, but it is reasonably likely to be available
>when predicted to be, with some error margin <error margin because the
>schedule is ill-controlled, only "reasonably likely" because of the
>possiblity of another crippling accident shutting the STS down>

It wouldn't take a crippling accident to ground the Shuttle fleet
for several months.  History has shown that.  It could be something
as simple as a crane running into the side of the orbiter stack
or a problem with the APUs.

If an orbiter hits one of the wild pigs, which live just yards from
the Shuttle runway,  it could put the vehicle out of action for more
than a year, resulting in delays or cancellations of many payloads.

And when (not if -- given enough Shuttle missions, it will happen)
there is another fatal accident, Congress and the White House will
shut the program down for at least another two years *if not permanently*.

If assured access to space was a concern, NASA would being buying
Soyuz spacecraft/launchers right now, just to hedge its bet.


>One point that gets lost is that while DC-X is "bent metal" and will
>solidly demonstrate the "quick turn" aspects of a launch vehicle (or
>not), it will NOT demonstrate the key SSTO capability of a vehicle with
>the extremely small "dry mass" necessary to make SSTO work

The "extreme mass ratio" is an aerospace legend.  We've been
building vehicles with similar mass ratios for the last 30
years.  The Shuttle external tank has the right mass.  So
did the Saturn S-IVB stage.


>This is a fairly long-winded lead in to say that no matter how great DC
>may be, you cannot stop shuttle flights before an operational DC capability
>exists,

But we will, the first time someone whose nameplate says "astronaut"
gets killed.

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

Date: Fri, 8 Jan 1993 16:45:55 GMT
From: Henry Spencer <[e-mail]>
Subject: Making Antimatter (was: *** BUSSARD RAMSCOOP ***)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("F.Baube x554") writes:
>> Kilogram quantities are probably going to have to be made in space,
>> not so much for handling reasons (although those aren't trivial)
>> as because of the sheer amounts of *energy* needed.
>
>I hope this means DEEP space, as opposed to Earth orbit.

Relax; we're talking giant powersats in Mercury's orbit, or something
of that scale.  Earth orbit is too cramped and doesn't get enough sun.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 8 Jan 93 18:08:45 GMT
From: Henry Spencer <[e-mail]>
Subject: RTG's on the Lunar Module
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>> The radiation hazard from plutonium 238 is insignificant; it's pretty much
>> a pure alpha emitter, and human skin stops alpha particles completely.  (A
>> sheet of paper will do likewise.)  You don't want to eat the stuff...
>
>Somewhere in the recesses of my mind lies a memory of a scientist
>who offered to eat some plutonium if the journalist covering the
>event would eat the same amount of caffeine.  No takers, obviously,
>but does this mean that it would be safe to eat plutonium?

Plutonium 239 would not be very toxic if eaten as the metal, I would think.
(Whereas caffeine in bite-and-chew quantities would be lethal.)  I don't
know as I'd call it "safe", but it might not be certain death.  Inhaling it
into the lungs as fine dust is the quick way to die from plutonium.  The
metal probably wouldn't be absorbed very efficiently when eaten.

Eating any heavy metal isn't exactly recommended, mind you.

>...it should be passed in due course with only the mucus coating
>the alimentary canal getting irradiated.

Most of the body isn't radiation-sensitive enough to be hurt much by
a relatively long-lived isotope like Pu239.  As I recall, what kills you
is getting it into your bone marrow.

Eating Pu238 wouldn't be any worse in terms of radiation, but it would
be extremely painful and possibly fatal because the stuff is *hot*.
Thermally, not radioactively.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Fri, 8 Jan 1993 16:43:47 GMT
From: Henry Spencer <[e-mail]>
Subject: russian solar sail?+
Newsgroups: sci.space

In article <ida.726473333@atomic> ida@atomic (David Goldschmidt) writes:
>>The stability produced by that spin is actively undesirable if you have
>>a maneuverability requirement...
>
>Heliogyros would actually be quite good at this.  You wouldn't have to
>turn the plane of rotation; you could just "feather" the blades
>when moving towards the sun.

Thrust modulation schemes are indeed an alternative to turning the sail.
(You should have seen the first Canadian Solar Sail Project design...
thrust modulation up the wazoo.  It would also have had the most moving
parts ever launched in a single spacecraft, and deployment would have been
a mechanical nightmare.  That's where pushing for maneuverability leads...)

Unfortunately, in the case of the heliogyro, there is a design constraint:
having to feather the blades adds awkward complications at the hub, since
now the hub ends of the blades must remain clear of each other through
a 90-degree pitch change.  If you limit required pitch changes, the
packaging problems at the hub are simplified, because you can stack the
blades in multiple layers.  Since you want a large number of wide blades
to compensate for the heliogyro's fundamental scaling disadvantage (area
scales linearly, rather than quadratically, with diameter), packaging
is a real problem at a modest-sized hub.  With 90-degree pitch changes,
layers have to be separated by a full blade width.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 8 Jan 93 18:17:01 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Should NASA operate shuttles (was Re: Shuttle a research tool)
Newsgroups: sci.space

Source-Info:  Sender is really [e-mail]

In article <[e-mail]> [e-mail] (Francois Yergeau) writes:

>This idea is based on the assumption that _large_ cost reductions could
>be achieved by the private sector, which I'm not ready to buy.  The
>shuttle is intrinsically expensive, with its maintenance-intensive...

So then maybe it isn't Shuttle. By opening up a market you encourage
competition. Let's say your correct and Shuttle can't be cost reduced.
But with a commercial market we would have a private contractor
collecting $6+ billion for eight flights. Presto chango we suddenly
have a commercial manned space market which is several times the size of
the existing launch market.

This would be more than enough to get several companies working on SSTO
and numerous other alternatives. Soon, Shuttle could no longer survive
the new cheap competition and it would be replaced.

But this can't happen now since NASA will use Shuttle no matter what.

>Note that I'm not denying that savings are possible, but I'm still not
>convinced that they would materialize, were NASA to try.

NASA's budget for luanch services is more than enough to justify
development of lots of cheap alternatives *IF* NASA used the market
instead of fighting it.

>Besides, who would need Delta Clipper if the shuttle could be made
>cheap?

Hey, if Shuttle becomes cheap I won't care about DC. I want to see low
cost reliable access to space. At this time, I think DC is our best
shot.

My goal is a spacefaring civilization, not a vehicle.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------106 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 8 Jan 93 16:53:53 GMT
From: Francois Yergeau <[e-mail]>
Subject: Should NASA operate shuttles (was Re: Shuttle a research tool)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Francois Yergeau) writes:
>>The market, for one thing.  Spin off shuttle to the private sector, and
>>you're likely to get at most one provider, and one buyer (NASA).
>
>Nonsense. Run KSC like an airport and Shuttle like an airliner. There is
>no reason that several companies couldn't buy Shuttles and lease the
>hanger facilities like any other airport.

This idea is based on the assumption that _large_ cost reductions could
be achieved by the private sector, which I'm not ready to buy.  The
shuttle is intrinsically expensive, with its maintenance-intensive
SSMEs, tiles, etc, and the standing army needed to operate it.  The
shuttle is no airliner, sorry.  This, IMHO, precludes important market
expansion, and you end up with a situation not unlike military
procurement, where $80 screwdrivers are not unheard of.  Talk about
cost reductions.

Note that I'm not denying that savings are possible, but I'm still not
convinced that they would materialize, were NASA to try.

Besides, who would need Delta Clipper if the shuttle could be made
cheap?

--
Francois Yergeau ([e-mail]) |  De gustibus et coloribus
Centre d'Optique, Photonique et Laser    |  non disputandum
Departement de Physique                  |          -proverbe scolastique
Universite Laval, Ste-Foy, QC, Canada    |

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

Date: Fri, 8 Jan 1993 17:39:33 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Subjective Safety Measure(Re: man-rating)
Newsgroups: sci.space,sci.aeronautics

In article <[e-mail]> [e-mail] (Thomas Clarke) writes:
>In article <[e-mail]> [e-mail]
>(Dillon Pyron) writes:
>> BTW, the STS [Space Transporation System/the Shuttle]
>> is the safest transportation system we have, based on fatalities
>> per passenger mile.  But who would pay $1 billion apiece for a 747?  (Please
>> attach a smiley to the safety record).
>
>The rating of transportation system safety by fatalities per
>passenger mile always struck me as bogus.  Subjectively, what
>matters is the probability of exit.  That is if I climb in and
>close the door, what are my chances of opening the door and
>climbing out.  By this measure the STS is only about 1 in 50,
>although it probably isn't as dangerous as, say, a fighter in combat.
>
>Does anyone have any idea how various means of transport rate
>according to probability of exit.  Is the private car better than
>a commerical airliner?  {Lots of safe little trips would up the
>exit probability.}

Hmmm. Interesting way to look at transport safety. There are about
140 million auto trips a day in the US. About 110 people a day die
in crashes. So you have about 1.3 million trips per fatality. I
don't know how many aircraft flights occur in the US per day, nor
how to account for multiple passengers, or how many fatalities occur
each year on average, but let's make some reasonable guesses.

Atlanta's Hartsfield handles one takeoff or landing per minute at peak
times and vacilates between being the busiest airport in the US with
O'Hare. Call that 720 flights a day. Multiply by the top 20 airports
and assume they're equally busy. That's 14,400 flights a day. Assuming
an average of 200 passengers per flight, that's 2.8 million exits per day.
Fatalities are certainly less than 1,000 per year average in the US from
air crashes, or about 2.8 per day. So we have about 1 million exits per
fatality on aircraft, probably quite a bit better. Using your measure,
aircraft and autos are about equally safe, a non-intuitive result.

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: Fri, 8 Jan 1993 17:40:32 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Who can launch antisats? (was Re: DoD launcher use)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Doug Mohney) writes:

>You're being silly. If you're going to treat the nuke as "just another
>weapon" you don't need the Clancyesque plot. Just nuke the friggin' carrier
>and be done with it. It's only full-scale war, after all, right Ed?

Well, Tom Clancy at least understands the technology and how it works.

Just finding a carrier at sea, let alone hitting it, is not easy.
Don't believe everything Dan Rather tells you.  It's a moving
target, which will probably move out of the target area between
the time you launch your ballistic missile and the time the warhead
lands.

Hitting a satellite is almost trivial by comparison.



>It is not for nothing DARPA has a love with microsats and ways to get them
>quickly into orbit. And what DARPA is doing is in the sunshine.

Microsats are incapable of replacing photorecon satellites.  The
laws of physics prevent it.  To get adequate resolution, you need
a large mirror (or large radar).  Black programs use the same laws
of physics as everybody else.



>Of course. So why did we get the UN to rubber stamp it first? C'mon Ed,
>stop helping me out here. We really didn't NEED to get the UN's blessing,
>did we?

Of course we didn't.  The United States has gone to war numerous
times in the past.  It has never needed permission of the United
Nations before.  It was George Bush who set that (dangerous) precendent.



>>Besides, your claim was that "international public opinion" would
>>*prevent* nations like Iraq from making hostile acts.

>Prevent a degree of hostile acts. Why didn't the Iraqis use chemical weapons
>against allied forces in Desert Storm?

Not because he was afraid someone would say something bad about
him at a UN cocktail party.

Hint: the people who planned the initial airstrikes were not
complete idiots.

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

Date: 8 Jan 93 18:20:05 GMT
From: Henry Spencer <[e-mail]>
Subject: Who can launch antisats? (was Re: DoD launcher use)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:
>>It is not for nothing DARPA has a love with microsats and ways to get them
>>quickly into orbit. And what DARPA is doing is in the sunshine.
>
>Microsats are incapable of replacing photorecon satellites.  The
>laws of physics prevent it.  To get adequate resolution, you need
>a large mirror (or large radar)...

Define "adequate".  Microsat levels of resolution should be adequate
for many military requirements.  Tactical commanders don't care about
the license-plate numbers on the tanks...

>>... We really didn't NEED to get the UN's blessing, did we?
>
>Of course we didn't.  The United States has gone to war numerous
>times in the past.  It has never needed permission of the United
>Nations before.  It was George Bush who set that (dangerous) precendent.

Careful here...  I don't know exactly what legal maneuvers took place
when the US formally joined the UN, but if the UN Charter has the status
of a Senate-ratified treaty, that means it has the force of law in the
US... and one of the clauses in there is a renunciation of war as an
instrument of national policy.

Of course, that just means everybody calls it a "police action" instead...
--
"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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End of Space Digest Volume 16 : Issue 026
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