Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_5/V16NO581.TXT

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Date: Mon, 17 May 93 05:20:29
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Subject: Space Digest V16 #581
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Space Digest                Mon, 17 May 93       Volume 16 : Issue 581

Today's Topics:
                   Life on Earth (or elsewhere : -)
             Neil Armstrong's first words (the real ones)
             No. Re: Space Marketing would be wonderfull.
                 Space Marketing would be wonderfull.

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Date: Mon, 17 May 1993 07:52:46 GMT
From: Dave Michelson <[e-mail]>
Subject: Life on Earth (or elsewhere : -)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("F.Baube[tm]") writes:
>
>There was also a discussion here of bilateral symmetry --
>the Burgess shale shows there this was NOT the only body plan
>to have been tried on Earth.  Some real science-fiction-type
>critters were found in the shale.  It's pretty amazing stuff.

Hasn't some of the early work on the Burgess shale been discredited in
recent years?

--
Dave Michelson  --  [e-mail]  --  University of British Columbia

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

Date: Mon, 17 May 1993 07:07:54 GMT
From: Leigh Palmer <[e-mail]>
Subject: Neil Armstrong's first words (the real ones)
Newsgroups: sci.space

I watched the landing live, including that part, and I didn't hear the
statement conventionally attributed to Armstrong.

There were other statements I did hear about seeing purple rocks. The
astronauts had been primed by their geology teachers to look for purple
rocks. The geologists said that the presence of purple rocks would be a
very important discovery. The reports, however, were a "practical joke"
played on the geologists by Armstrong and Aldrin; there were no purple
rocks. If Apollo 11 had not returned safely to Earth it is possible that
no further expeditions to the moon would have been made, and our only
direct geological evidence would have been the statement about purple
rocks.

I've always felt that sending jet jockeys on an expedition and passing
them off as scientists was a bad, even fraudulent, idea. That "joke" only
reinforced my feelings.

Leigh

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

Date: Mon, 17 May 1993 06:11:28 GMT
From: Frank Crary <[e-mail]>
Subject: No. Re: Space Marketing would be wonderfull.
Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher

In article <[e-mail]> [e-mail] (David Fox) writes:
>   Think for a moment about the technology required to do that.  By
>   the time they could make the Earth's sky look like Las Vegas,
>   the people could afford to go backpacking on the Moon. Round
>   trip costs for 500 kg to the Moon would be about the same as
>   5000 kg in a Low Earth "advertising" orbit: Very roughly the
>   same cost as a smallish billboard, therefore. If such ads were
>   to become common place, that would have to be a very low price...

>This is nonsense.  Its like saying that by the time commercials
>on television become commonplace every citizen will have their own
>hour long nationally broadcast TV program.

No, it's like saying that by the time commercials on television became
commonplace, every citizen could afford thier own ham radio. While
a trip to the Moon sounds absurdly far fetched, so is making the
sky look like Las Vegas. It would take thousands of the satellites
we are talking about, each of which would cost $50 million using
today's technology. To make the sky look like Las Vegas, the
cost of sending things into space would have to go down to only
a few percent of todays costs.

>   There's always been a problem of having to get
>   away from civilization before you can really find "natural"
>   scenery. 100 years ago, this usually didn't take a trip
>   of over 5 miles. Today, most people would have to go 100 miles
>   or more. If we ever get to the point where we have billboards
>   on orbit, that essentially means that no place on Earth is still
>   "wild." While that may or may not be a good thing, the orbital
>   billboards aren't the problem: They are just a symptom of
>   growing, densely-populated civilization. Banning such ads will
>   not save your view of the night sky, because by the time
>   such ads could become widespread you will probably have trouble
>   finding a place without street lights, where you can _see_
>   the stars...

>The rest of your post is strange mishmash of "its already really bad"
>and "it doesn't really matter if it gets worse."  You should try to
>figure out what you are really arguing for.  (Kneejerk anti-environ-
>mentalism?)

Sorry, it seems quite clear to me: If you object to such things, you
are wasting your time worring about one minor aspect of the problem.
Either openly oppose growth in general or accept its consequences.
(I'm not sure if that is "kneejerk" by your standards. It's
avoiding hypocracy by mine.)

>P.S.  A passing sattelite does not have the same effect on visible
>light astronomy as an object as bright as the full moon.

To be as bright as the full moon, in a 300-km orbit, it would
have to be about 1-km across. There are currently only two
ways to launch an object that size: Take over a major economic
power and spend half the GNP on the largest space station every
considered outside of science fiction, or launch a balloon.
A balloon cuts down on launch weight immensely, but it
also gives you a very low-density object. Atmospheric
drag would pull it out of orbit in a matter of days. So these
billboards are either not as bright as advertised, or they
only last for a few days. Since I can't immagine anyone spending
tens of millions on that little time, I assume the
"as bright as the full moon" reference is an exageration.

                                           Frank Crary
                                           CU Boulder

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

Date: Mon, 17 May 1993 06:24:35 GMT
From: Frank Crary <[e-mail]>
Subject: Space Marketing would be wonderfull.
Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher

In article <[e-mail]> [e-mail] (George F. Krumins) writes:
>>...ground-based, visible light astronomy (what these proposed
>>orbiting billboards would upset) is already a dying field: The
>>opacity and distortions caused by the atmosphere itself have
>>driven most of the field to use radio, far infrared or space-based
>>telescopes...

>And haven't you heard anything about adaptive optics?  A lot of research
>was done with "Star Wars" funding, and some is now being shared with
>astronomers.  This shows great promise.

And also great limits: Adaptive optics don't work in the visable, and
don't work well in anything I'd call the near infrared. They are
very impressive below, say, 25 THz but that's hardly "visable" light.

>...Soon, probably within a few
>years, even the largest telescopes will be able to resolve to their
>theoretical limit _despite_ the distortions of the atmosphere.

That's extremely doubtfull: Adaptive optics require moving the
optical elements around with cycle times (including time for
vibrations to die down) of order 10-50 miliseconds. Unless you
make "the largest telescopes" out of tens of thousands of seperate
pieces, active corrections will be of limited value to these
telescopes (judging from the expense and development problems
associated with the new, 36-element mirror, I don't think
thousands of elements is likely.)

>To say that "visible light astronomy is already a dying field" is
>pure hokum...

If you say so, but most of the papers I see are based on spacecraft,
orbital telescope, radio telescope or high-altitude infrared
observations.

                                               Frank Crary
                                               CU Boulder

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Subject: Re: Space Marketing would be wonderfull.
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In article <[e-mail]> [e-mail] (R. Lee Hawkins) writes:
>>because of his doubtfull credibility as an astronomer. Modern,
>>ground-based, visible light astronomy (what these proposed
>>orbiting billboards would upset) is already a dying field: The

>Ahh, perhaps that's why we've (astronomers) have just built *2* 10-meter
>ground-based scopes and are studying designs for larger ones.

Exactly what fraction of current research is done on the big,
visable light telescopes? From what I've seen, 10% or less
(down from amlost 100% 25 years ago.) That sounds like "dying"
to me...

>Seriously, though, you're never going to get a 10-meter scope into orbit
>as cheaply as you can build one on the ground, and with adaptive optics
>and a good site, the difference in quality is narrowed quite a bit
>anyway.

That would be true, if adaptive optics worked well in the visable.
But take a look at the papers on the subject: They refer to anything
up to 100 microns as "visable". I don't know about you, but most
people have trouble seeing beyond 7 microns or so... There are
reasons to think adaptive optics will not work at shorter
wavelengths without truely radical improvements in technology.

As for better locations, the Antarctic is one of the best and
I'd have trouble imagining an ad in a completely polar orbit...
The next best I can think of is on the KAO (an airplane),
considering the scedueling they put into each flight, avoiding
an object in a known orbit should be travial.

>...Also, scopes in low orbit (like Hubble) can only observe things
>continuously for ~45 minutes at a time, which can be a serious
>limitation.

Which is why everyone involved in orbital astronomy is proposing
telescopes in higher orbits (thermal loading is also a factor:
Without the reflected sunlight and blackbody emissions from the Earth
it is _much_ easier to cool a detector to helium temperatures...)

>>...In any case, a bright point of light passing through
>>the field doesn't ruin observations. If that were the case, the

>I sure as hell does if the 'point of light' is half a degree in extent
>and as bright as the moon.  Have you ever noticed how much brighter the
>night sky is on a moonlit night?

I find that claim hard to believe: A _peak_ brightness or size
along these lines is possible, but since we are talking about
something at a height of only 300-500 km, the brightness would
drop off sharply if it were away from the horizon. (as sec(z)^2)
You would have to be almost underneath it for it to get a
significant amount of scattered light.

>>                                             Frank Crary
>>                                             CU Boulder

>What deparment are you in anyway, Philosophy?  You obviously are not
>qualified to speak about astronomy...

The sign the office door says, "Astrophysical, Planetary and
Atmospheric Sciences." Although perhaps my degree in astrophysics
from Berkeley doesn't qualify me either... On the other hand,
I just might not be too attached to one particular way of collecting
astronomical data.

                                                  Frank Crary
                                                  CU Boulder

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End of Space Digest Volume 16 : Issue 581
------------------------------