Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_2/V11_293.TXT

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Subject: SPACE Digest V11 #293

SPACE Digest                                     Volume 11 : Issue 293

Today's Topics:
      Re: Discovery's Spin in 2010 (Was Re: Artificial gravity)
                 subscription
           Re: Questions about the Voyagers
      Re: Listening to the Star (was RE: Drake Equation)
       Re: Drake Equation (was Re: Interstellar travel)
              Re: Decompression and 2001
       Re: Drake Equation (was Re: Interstellar travel)
               Re: voyager images on cd
      Re: Discovery's Spin in 2010 (Was Re: Artificial gravity)
     Pegasus launch planes - Altitude First, speed later?
            Earth Observing System
                NASA PI wanted
----------------------------------------------------------------------

Date: 17 Apr 90 17:53:45 GMT
From: hpfcso!hpfcdj![e-mail]  (Bob Myers)
Subject: Re: Discovery's Spin in 2010 (Was Re: Artificial gravity)

>One thing that has always impressed me about 2001 was the lack of
>sound in the outer-space (ie outside of spacecraft) shots; no
>Star Wars-like deep, low freq rumble of powerful thrust engines.
>Any other such movies with silent space?  Even Alien, with "in space
>no one can hear you scream", you could hear the engines from "outside".

Exactly!  This was especially striking during _2010_'s "aerobraking" sequence,
when suddenly we DID hear noise from the outside, as all hell broke loose
during the dip into Jupiter's atmosphere.  A vastly underrated movie, IMHO.

(And has it ever bothered you that the damn engines in "Star Wars" or "Alien"
are ALWAYS RUNNING???  Now, look - if you've got an FTL drive, then why would
you always be accelerating whenever you travel in normal space - especially
since the direction of the accelaration doesn't seem to have the slightest
thing to do with where the designer of your ship chose to hang the decks!)

Three cheers - at least - for Arthur C., and his above-and-beyond-the-call-of
-Hollywood attention to the details!


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
[e-mail]               |  sentient life-form on this planet.

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

Date: Thu, 19 Apr 90 17:25:53 -0700
From: [e-mail]
Subject: subscription


Is this where I subscribe to SPACE Digest.  If so please add my subscription.

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

Date: 19 Apr 90 14:41:13 GMT
From: philmtl!philabs!briar.philips.com![e-mail]  (Robert Casey)
Subject: Re: Questions about the Voyagers

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>I don't know what the situation is right now, but in the long run, as
>projects like Magellan and Galileo demand increasing chunks of DSN's time,
>much of the (fairly boring and routine) data the Voyagers are sending will
>be lost.  It won't all be lost, as there is still some value to it
>
I would have thought that the Voyagers would store the data for transmission
at scheduled times, chosen to be received at Earth when the antennas are not
needed for the newer probes.  Use the on-board "video" tape that was used to
store images at planet encounters for storing the cruise data?
=============================================================================
communism sucks

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

Date: 18 Apr 90 16:39:53 GMT
From: att!cbnewsl!moss![e-mail]  (Forrest Gehrke,2C-119,7239,ATTBL)
Subject: Re: Listening to the Star (was RE: Drake Equation)

In article <[e-mail]>, [e-mail] (Robert McGwier) writes:
> From article <[e-mail]>, by [e-mail] (Philip Nettleton):
> > From vn Tue Apr 17 10:55:55 1990
> >
> > The point that people are forgetting is the impracticality of advanced
> > civilisations using radio signals, especially if they're technologically
> > advanced enough to have colonised other worlds and thereby need to keep in
> > contact.
> >
>
> I couldn't agree more.  While visiting JPL a couple of years ago, I met
> with the folks who were doing advanced research for the Casini (Saturn
> orbiter, titan probe) mission.  Even at that time they were working on
> single photon laser detectors so that LIGHT could be used as the data
> link back to earth achieving incredible data rates.
>

Everything is going to be point-to-point laser, or closed circuit optical
cable, eh?

What will you do when there is heavy fog, cloud cover or rain?
At space ports, how will you control traffic?   Or do we wait
for fair weather?

Suppose our distant colony on Barnard's planet #3 just happens to
have a dust cloud in between?

Flag signals have been used between ships for a couple centuries.
Why are they still used?  Anything that increases the level of
fail-safety by redundancy will always be used.

Forrest Gehrke [e-mail]

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

Date: 19 Apr 90 04:22:43 GMT
From: zephyr.ens.tek.com!wrgate!mrloog![e-mail]  (Dan Tilque)
Subject: Re: Drake Equation (was Re: Interstellar travel)

[e-mail] (Daniel Briggs) writes:
>I can't speak for any of the deliberate attempts at SETI that have
>been made, but I think I can add a bit to the SNR on how radio astronomy
>is "normally" practiced.
>
>For those who don't care to read the whole thing here, the short
>answer is that I agree with Forrest Gehrke.  We haven't heard anything
>yet because for the most part we haven't been listening.

Ok, you convinced me for the most part.  The rest of this article is few
technical nits which will probably not modify your argument in the
least.

>I don't happen to know the exact numbers, but we
>are probably talking tens of thousands of eligible suns within that
>[50 ly] radius.

There are about 50 star systems containing about 70 stars within 16 ly
of Earth.  If this is a representative sample (a reasonable assumption)
that gives about 1500 star systems in that 50 ly radius.

>Enough digression.  Assume that we can only evesdrop on the
>extraterrestrial Lawrence Welk Show if we can detect the isotropic
>transmission.  I have no good idea of what to assume for a transmitter
>power.  I think that 1 GW is pretty damned big by today's standards.

By today's standards 1 GW is huge for a single transmitter.  I was
thinking of the collective power of all sources.  Typical radars emit
about 5 MW and TV stations about the same, I think.  The largest single
emitters are probably certain phased array radars run by both the U.S.
and Soviet military which are designed to detect ICBMs, but I don't know
what they typically emit.  I'm not sure how many TV stations and radar
systems there are so I can't say what the collective output is.  A
horseback guess would say that it's on the order of 10 GW.

Of course, this is just our current output.  However, your figures
(which I've deleted) seem to indicate that our output would have to go up
by several orders of magnitude before being detectable by our current radio
telescopes at 50 ly.

---
Dan Tilque    --    [e-mail]

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

Date: 19 Apr 90 23:23:15 GMT
From: [e-mail]  (Andrew Bennett)
Subject: Re: Decompression and 2001

In article <[e-mail]>,
[e-mail] writes:
|> > I am wondering wheter or not a human body exposed to void would explode...
|>
|> I have often wondered about this as well, and recall reading a sci-fi story
|> or two where humans moved between two craft in open space without suits
|> (supposedly the decompression problems were solved by hyperventilating, then
|> expelling all air from the lungs and leaving your breathing passages open
|> 8-O ?).  Also, in light of recent comments concerning the degree of accuracy
|> of the portrayal of space flight, etc. in the film _2001_, I couldn't help
|> but wonder about the scene where Dave is forced to blow the pod door and
|> reenter Discovery through the emergency hatch.  It would appear that he is
|> in the vacuum of space for a fair number of seconds, and what's more he
|> takes a deep breath and holds it to the point where the veins are bulging
|> from his forehead just before the explosive bolts blow.  What gives?
|>
|> Gregg TeHennepe                        | Minicomputer Specialist
|> [e-mail]                  | Connecticut College, New London, CT


I have read (from multiple sources) that an individual should be able to
survive about 30 sec. in a vacuum (give or take, depending on the individual).
Your ear drums would probably rupture, you'd get a bloody nose and you'd have
a sinus headache not to be believed.  Your eyes and tear ducts will not fare
well, either (some bleeding from the ducts).

The most serious problem(s) are damage to your lungs (the avolii(sp?) don't
like low pressures) and the 'bends' (nitrogen nucleation in the body).  So
holding your breath is a good idea, for your lungs' sake.

Basically, Dave would have made it, but he would have been *very* unhappy.
Then again, he didn't look too pleased in the next scene, did he?  :)

-----------------------------------------------------------------------------
Andrew Bennett                               The comments above are not
MIT Supercomputer Consultant                 representative of MIT.  They
Rm. 11-124H, 77 Massachusetts Ave.           are the rantings of an over-
Cambridge, MA  02139  [phone]         caffinated mind.
[e-mail]
-----------------------------------------------------------------------------

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

Date: 19 Apr 90 04:36:40 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Drake Equation (was Re: Interstellar travel)

In article <[e-mail]> [e-mail] (Tim Bedding) writes:
>No, but if a supernova went off by chance, it would make sense to start
>sending signals in the _opposite_ direction.  Any ETs who studied the SN
>closely might notice the signal (or may be smart enough to look for it).

Right, now what might we send to make it through the SN signal?  Hmm, how
about a rapidly, regularly pulsating beacon... yeah I like it :-)

--
If the human mind were simple enough to understand,   =))  Tom Neff
we'd be too simple to understand it. -- Emerson Pugh  ((=  [e-mail]

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

Date: 19 Apr 90 23:01:38 GMT
From: agate!shelby!med!hanauma![e-mail]  (Richard Ottolini)
Subject: Re: voyager images on cd

In article <[e-mail]> [e-mail] (Gavin Eadie) writes:
>In fact the Neptune images are not yet released. Jupiter, Saturn and
>Uranus are available from NSSDC on CD-ROM.

Miya from Ames said last summer that he thought JPL/policy was one year
delay from acquisition in order to give the principal investigators who
did the work first crack at the data.

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

Date: 19 Apr 90 15:28:17 GMT
From: spock![e-mail]  (Peter Sheriff)
Subject: Re: Discovery's Spin in 2010 (Was Re: Artificial gravity)


     Isn't it lucky for us that we can't hear the sun :-)

     As an aside, I just read an article on museums in the U.S.A.
The author was commenting on the need for museums to teach the public
things that they would not learn at school. He said that one museum
set up a display to show the effects of gravity in a vacuum after
they found that many people attributed gravitational effects to air
pressure. He also stated that many people were sill unconvinced.

                            Pete

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

Date: 20 Apr 90 05:11:55 GMT
From: sam.cs.cmu.edu![e-mail]  (Vincent Cate)
Subject: Pegasus launch planes - Altitude First, speed later?


Mary Shafer:
>Concorde is limited to 2.06 Mach.  Any faster than than and the wing spars
>soften in the heat.
>
>In my opinion, Concorde is a bad launch aircraft, too.  There are only
>a few of them, they're obsolete, and they're expensive.  Each of the
>two airlines have one plane that they're cannibalizing for spares.

I just calculated that the energy needed to lift something (say
a Pegasus) 30,000 feet is about the same as that needed to make it
go 1,000 MPH.   This means the fact that the Concorde flies at 70,000
feet instead of the B-52's 40,000 feet may be enough to increase
the payload by more than 300 lbs by itself.  The extra 700 MPH or
so in speed probably gives an additional 200 lbs.  At $10,000/lb
this would be worth around $5,000,000.

And how expensive is the Concorde to operate?  Well, they sell one-
way tickets from New York to London for $3,607.  This is an expensive
plane.  I don't know many people who would pay $3,607 for a one-way
ticket to London.  There are about 100 seats so this comes to about
$400,000/flight.  Yes, this is alot of money; however, it is far below the
the ~ $5,000,000 value of the increased payload to orbit!!!!!  Even
expensive planes are very cheap compared to rockets!!!!  Maybe British
Airways should stop selling tickets to people and start launching
rockets.


Alan Duester:
>I recall seeing an article about a year or two ago about how
>OSC/Hercules was going to switch launch airplanes after the first dozen
>or so test flights. At that time, the plan was for a dedicated, modified
>MD-11 or DC-10, with longer landing gear, and a slot cut in the plane's
>belly to accept the tail fin.

and

Joseph C. Pistritto:
>A number of people have commented on the possibility of launching
>the Pegasus from a supersonic carrier aircraft.  A really major
>problem in doing this is the problem of stable separation.
>...
>And any of this defeats the purpose, to make a vehicle cheap enough
>for a private company to develop.  Remember, the $40 million they
>spent on the Pegasus bankrupted (literally) the company, they were
>overextended on their credit lines the day of the launch!

Looks like OSC may be planning on going just for altitude first off.
As I said above, an extra 6 miles up is about equal in energy to
an extra 1,000 MPH.  So extra altitude probably gives the best return
on investment at this time.  My guess is that they want to use a DC-10
or a 747 to get their little payload up really high.  A loaded 747
can go to 50,000 feet, so I would not be at all surprised if one with
about half the flying weight (tanks not nearly full and little payload)
could get to over 70,000 feet.  This should be worth millions per flight
and does not seem to be any where near as hard as using a supersonic plane.

   -- Vince

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

Date: 19 Apr 90 01:34:51 GMT
From: zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k![e-mail]  (Rick 'Transputer' Stein)
Subject: Earth Observing System

I recently read in sci.physics (Bob Piner's "What's New" column) about
NASA's proposed Earth Observing System (EOS).  He claimed that this
orbital platform would generate 1800 terabytes of data over a 5 year
period.  I don't know about you folks, but 1800 Tbytes is a helluva'
lot of data. I understand that the Library of Congress holds 4-6 Tbytes
in its entire archive.  My questions are as follows:

1) Given that EOS will generate 1 Tbyte/day, how will this data be
managed?

2) How do you analyze 1 Tbyte of data, let alone 1800 Tbytes?

3) If a scientist were to apply some visualization technique to
this volume of data, on what type of machine would he do it?  Can you
stuff 1 Tbyte into a graphics workstation and learn anything?

4) Is anyone at NASA asking these kinds of questions, given the
prior revelations about poor archive procedures and data loss?
--
Richard M. Stein (aka, Rick 'Transputer' Stein)
Sole proprietor of Rick's Software Toxic Waste Dump and Kitty Litter Co.
"You build 'em, we bury 'em." uucp: ...{spsd, zardoz, felix}!dhw68k!stein

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

Date: 18 Apr 90 01:40:50 GMT
From: mvac23![e-mail]  (Thomas Lapp)
Subject: NASA PI wanted

Many years ago (it seems), NASA placed two devices on Martian soil and then
proceeded to analyze the soil to determine (among other things) whether or
not there was life on Mars.

I'm wondering if anyone can point me to a person or persons in NASA who were
the PI (principle investigators) for the soil analyzation experiments.  I'd
like to get more info on what experiments were done and what was expected and
what was found.

Thanks,
                         - tom

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

End of SPACE Digest V11 #293
*******************