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Subject: SPACE Digest V11 #269

SPACE Digest                                     Volume 11 : Issue 269

Today's Topics:
         Drake Equation (was Re: Interstellar travel)
          Re: Pegasus launch from Valkyrie  (or ...
                  HST Images
         Gerry Bull Murder and "Doomsday Gun"
              Re^2: Interstellar travel
          Re: Pegasus launch from Valkyrie  (or ...
              Re: STS26 program
     Hubble Space Telescope Update (Forwarded) - 04/12/90
           Apollo 13, STS-1, Vostok 1 anniversaries
               Re: Interstellar travel
          Re: Pegasus launch from Valkyrie  (or ...
               Re: Interstellar travel
----------------------------------------------------------------------

Date: 14 Apr 90 01:05:41 GMT
From: zephyr.ens.tek.com!wrgate!mrloog![e-mail]  (Dan Tilque)
Subject: Drake Equation (was Re: Interstellar travel)

[e-mail] writes:
>
>Nope, that's the Drake equation.  The Fermi paradox basically says,
>"Where is everybody???"  The Drake equation suggests that the galaxy should
>be teeming with life, given the number of stars we have.

The Drake equation is an attempt to quantify how many technologically
advanced civilizations there are in the galaxy.  If they (i.e. Drake,
Sagan, et al.) could come up with a high enough estimate, they could
justify doing what they wanted to do anyway: a radio search for alien
radio signals.

What the Drake equation really does is to identify our areas of
uncertainty a little more precisely.  Instead of one big uncertainty,
we now have a couple of reasonably certain numbers, one or two numbers
we can guess at with some degree of certainty, and a lot of numbers
which are totally unknown.

What this means is that the Drake equation didn't suggest anything.
With equal certainty, you can substitute numbers into the equation to
get less than one such civilization per universe or a civilization for
every 100 stars.

>*Our* presence
>as a technological society can readily be detected within a 50ly radius;
>yet we have found no signs, similar or other, that life exists elsewhere in
>the universe.

Since we've been listening to the sky at radio frequencies for > 40
years now and haven't discovered any alien generated signals, it's
probably safe to say that there are no civilizations like ours within
that 50 ly radius.  This seems to be better limiting data than the
results of the Drake equation.


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

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

Date: 14 Apr 90 02:30:34 GMT
From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Pegasus launch from Valkyrie  (or ...

In article <[e-mail]> [e-mail] (john.a.welsh) writes:
>[B-58] They had external pods so
>they could carry more than their bomb bays could hold, though I
>am not sure if they could go supersonic with the pods...

The B-58 in fact had no bomb bay; *all* the payload was in the pod.  And
yes, they could go supersonic with the pod in place, although the one
major constraint on going supersonic was "pod fuel tanks empty", which
might imply a constraint on how much weight could be in the pod at
supersonic speed.
--
With features like this,      |     Henry Spencer at U of Toronto Zoology
who needs bugs?               | uunet!attcan!utzoo!henry [e-mail]

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

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From: [e-mail]
Subject:  HST Images

  What's to stop some enterprising amateur (or professional) astronomer
from intercepting the signals from the HST and decoding them himself?  Would
this be a particuarly difficult operation?  If it is possible, what be the
legal situation?

Andy Greenshields [[e-mail]]

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

Date: 12 Apr 90 16:45:54 GMT
From: shlump.nac.dec.com!quik07.enet.dec.com![e-mail]  (Ben Burch)
Subject: Gerry Bull Murder and "Doomsday Gun"

In article <[e-mail]>, [e-mail]
(Kieran A. Carroll) writes:
> Bull appears to have kept working on his idea of gun-launching satellites
> into orbit right until his death; a London-based magazine, "The Middle
> East", reported in its March edition that Iraq had developed an interest
> in "firing satellittes or weapons into low earth orbit." I can't help but
> feel that Bull was not an arms dealer entirely by choice. I can easily
> imagine him as a space enthusiast with a vision for a revolutionary
> technology, one that could greatly benefit the development of space (by
> bringing about lowered launch costs), who turned to arms trading as a
> means of bringing in money to keep his research going. Perhaps if Canada
> and the United States had not given up on developing new space launch
> technologies in the late 1960's, Gerry Bull would be alive today (or
> perhaps not...)

Does anybody else see a connection between the Murder of Gerry Bull and the
siezure, reported yesterday on CNN et. al. of a "Doomsday Gun" allegedly
destined for Iraq?  If I recall, this "gun" was described as 150 feet long
(about 60 meters to the rest of you), and was supposed to have been able to
strike at targets in Isreal and Iran from a point inside Iraq.  The Iraqis
claim that the siezed goods were pipes for a petrochemical operation.  British
ballistics experts were supposed to be investigating today.

From the article partially quoted above, this seems to have been right up
Bull's alley, especially when one understands that Iraq is one of the
half-dozen or so nations with an orbital ballistic missile technology.  One
would assume that the Iraqis would have had to test this gun, and that a
"peaceful" mission would have had to be fabricated to justify it.  This would
have allowed the promise of HARP to have been realized.

Comments?

- Ben Burch   ([e-mail])

"Views expressed herein are not those of Digital Equipment Corporation."

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

Date: 15 Apr 90 11:33:27 GMT
From: mcsun!unido!tub!tubopal![e-mail]  (Thomas Cervera)
Subject: Re^2: Interstellar travel

[e-mail] (Al Bowers) writes:

>In article <[e-mail]> [e-mail] (Jeffrey Kirk Bennett) writes:

>2. I don't see mankind inventing practical anti-matter propulsion or
>whatever the current idea is in the next century or two. But, since

>   Nuclear drives are available now, and with a limited development of
>   technology it appears that .12c is possible.

  I'd just like to know how one feels when interplanetary matter (meteors) or
interstellar matter (gases and dust) collides with the spacecraft at .12 c ;-)
  I'm not really sure, but if my memory serves me right, Sirius (Canis Minor
alpha), for example, is somewhat 11 ly apart. A trip to that star (it's not
the closest, I know) would take decades (spacecraft's time) at .12 c.
  This implies a high probability of such collisions, IMHO.

-thomas

--
Thomas Cervera         | UUCP:   [e-mail]
SysMan RKOFBI (PDP/VAX)|         ...!unido!tub!opal!alderaan (Europe)
D-1000 Berlin 30       |         ...!pyramid!tub!opal!alderaan (World)
Motzstrasze 14         | BITNET: [e-mail] (saves $$$)

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

Date: 15 Apr 90 13:55:30 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watcgl!watnow![e-mail]  (Mark Earnshaw)
Subject: Re: Pegasus launch from Valkyrie  (or ...

In article <[e-mail]> [e-mail] (Mary Shafer (OFV)) writes:
>The only drawback I see at first glance is that the B-58 is too close
>to the ground.  The gear wouldn't touch if there was a Pegasus under
>the wing.
>
>But this is also true of the F-111 and someone proposed a mag-lev cart
>for takeoff.  I believe that a largish fighter has taken off using a
>ground-effect cart, rather than gear (although I can't confirm this
>'til Monday, when I get to work and references).
>
>Or you could put gear on Pegasus.
>
>Or use fall-away gear like the outriggers on the U-2.

Would this cause trouble if something went wrong during the pre-launch part of
the flight?  If the carrier plane were forced to land without actually having
launched Pegasus, then I assume that there would be problems if it had taken
off from a cart or had used fall-away gear.  I suppose Pegasus could be ditched
somewhere (nearest body of water?), but I don't think that this would do it
or its payload much good.

Of course, if Pegasus' reliability is a guaranteed 100%, then this would not be
a concern.  :-)

--------------------------------------------------------------------------------
Mark Earnshaw, Systems Design Engineering       {uunet,utai}!watmath!watnow!mark
University of Waterloo, Ontario, Canada         [e-mail].{edu,cdn}

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

Date: 11 Apr 90 01:15:45 GMT
From: mailrus!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Rick Ellis)
Subject: Re: STS26 program

In a message of <Apr 05 12:39>, Christopher Schaller ([e-mail] ) writes:

 CS> About a week ago, I recieved a copy of the STS26 program that has been
 CS> circulating. What version of ZIP do you use to uncompress this.

Pkunzip 1.00 and above should unzip anything that's zipped.



--
Rick Ellis
...!{dhw68k,zardoz,lawnet,conexch}!ofa123!rick                             [e-mail]
714 544-0934 2400/1200/300

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

Date: 13 Apr 90 00:19:50 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update (Forwarded) - 04/12/90



                     April 12, 1990

HST UPDATE:  NASA managers set April 25 as the new
target launch date for Shuttle Mission STS-31.  This date is based
on the decision to remove and replace Auxiliary Power Unit (APU)
No. 1 on Space Shuttle Discovery and to allow time for recharging
the Hubble Space Telescope (HST) batteries.  The decision to
replace APU #1 comes after examination of the APU controller by the
manufacturer, which verified that no problems existed within the
controller.  A new APU, scheduled for delivery to KSC this week,
will serve as the replacement APU on Discovery.  The recharging of
the HST batteries will be accomplished by removing the batteries
from the telescope and charging them in a laboratory.  This allows
the batteries to be serviced under the most favorable conditions
while HST remains in the clean environment of the cargo bay.  There
will be a press conference tomorrow at 9:30 a.m. concerning the HST
Scrub Turnaround Status.  The conference will be carried on NASA
Select TV.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |

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

Date: 12 Apr 90 14:46:33 GMT
From: zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!asuvax!mcdphx!udc![e-mail]  (Roger Noe)
Subject: Apollo 13, STS-1, Vostok 1 anniversaries

It's too bad we couldn't have added the Hubble telescope to the list of
anniversaries observed at this time of year.  April 13, 1990 will be the
twentieth anniversary of the explosion which crippled the Apollo 13
service module, which would have stranded astronauts Lovell, Swigert,
and Haise in space had it not been for their resourcefulness and that
of the ground support crew.  It was the last time BC (before Challenger)
that the U.S. came so close to having astronauts die during a mission.
April 12 will be the ninth anniversary of the day Young and Crippen
lifted off aboard Columbia on STS-1, the first shuttle mission.  Twenty
years before on that very same day, Yuri Gagarin became the first human
being in Earth orbit on Vostok 1.  Next year we'll be celebrating thirty
years of space exploration by humans (April 12 in what's left of the USSR,
May 5 in the USA).
--
Roger Noe               Motorola Microcomputer Division, Urbana Design Center
Phone:  [phone]        1101 East University Avenue, Urbana, IL 61801 USA
Internet:  [e-mail]                 UUCPnet:  uiucuxc!udc!rnoe
Latitude/Longitude:  40:06:55 N./88:11:40 W.

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

Date: 12 Apr 90 01:17:23 GMT
From: cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!rpi!crdgw1!ge-dab!puma!andrew.ATL.GE.COM![e-mail]  (John F Nixon)
Subject: Re: Interstellar travel

[e-mail] (Jeffrey Kirk Bennett) writes:

-I noticed a lot of talk about interstellar travel a while back, and
-I'm a little confused. Am I wrong, or is there a point to thinking
-about such things? It seems to me that there a a couple principles
-which make it completely impractical- but I'm not a physicist, so
-please expand or correct me if I'm wrong.

There is a point to thinking about such things.  It exercises the mind,
and it is rare that something can be completely dismissed out of hand.

-1. The goal is to find intelligent life and/or a habitable planet.

Exploration for the sake of observing the Universe is also a very
valuable thing to do.

-2. I don't see mankind inventing practical anti-matter propulsion or
-whatever the current idea is in the next century or two.

Leonardo didn't let a couple of centuries bother his technological
speculation.

-The point is, due to relativistic mechanics, wouldn't it be a 1-way
-trip?

If you simply go real fast (c - epsilon) then yes, from the point of
view of the people on earth, the trip is one way.  The spacetravelers
could make a two way trip, returning to earth decades to centuries to
millenia later, depending on the distance.  This is a nifty way to do
time travel while you see the Universe.  I'll sign up...

-3. Assuming all the fuel is burned during the acceleration and
-deceleration phases, how would the craft return?

Refuel at the other end.

-4. Even if it had the fuel to return, how would it find the Earth again,
-since it is not exactly standing still, and may have moved unpredictably
-due to passing stars, black holes, etc...

Good question, although in trips of less than tens of millenia, nothing
much is likely to disturb our galatic orbit.  Space is BIG, and things change
S  L  O  W  L  Y.

-What I'm saying is basically this: We don't have the technology to
-do it.

Today, or for the next few years.  But I hope not forever.

[stuff about the same applying to Space Aliens travelling to Earth]

This assumes they haven't made the Big Discovery, which enables you to
traverse vast interstellar distances in a wink.  You can say it is highly
improbable, and we cannot do it, nor do we understand how it could be done
without violating causality, but you cannot flatly state no chance.  Also,
the Space Aliens could bring their home with them; they just happen to be
passing by at the moment.

The probability is near zero, though...

----
[e-mail]                    ...steinmetz!atl.decnet!jnxion

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

Date: 12 Apr 90 16:23:23 GMT
From: snorkelwacker!usc!cs.utexas.edu!mailrus!news-server.csri.toronto.edu!torsqnt!lethe!tvcent!comspec!censor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Pegasus launch from Valkyrie  (or ...

In article <[e-mail]> [e-mail] (David Smith) writes:
>space plane with a large drop tank, to be air launched from the back of a 747.
>Not just an ordinary 747.  This one had an SSME mounted in the tail to get a
>healthy climb rate at a steep angle.

Actually, later they discarded the SSME idea in favor of burning hydrogen
in the bypass ducts of the turbofans!  As I recall, it more than doubles
the thrust and will not hurt the engine if you don't do it for more than
about 30 seconds.

The biggest problem with using a 747 as a first stage is simply the limited
cargo load.  NASA's shuttle carrier has major structural reinforcements and
is still at the limit of what a 747 can do.
--
With features like this,      |     Henry Spencer at U of Toronto Zoology
who needs bugs?               | uunet!attcan!utzoo!henry [e-mail]

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

Date: 13 Apr 90 09:36:41 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Interstellar travel

In article <[e-mail]> [e-mail] (Gregory Milligan) writes:
>    I'm sure that people tried to discourage Columbus with much
    ^^^^^^^^
>the same arguments (with obvious adjustments for available technology,
>of course).

On what basis.

Certainly not anything historical!

I just reviewed Jeff's arguments (which I wish he'd posted in under 80
columns; read Eugene's Reminders posting folks!  Not everyone has an
ultrawide window in a fancy workstation) and none of them have anything
to do with the situation prevailing in Columbus' time.

I hate the kind of facile nonsense quoted above.  It damages the debate.

Study Columbus or leave him out of the discussion, sez I.

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

End of SPACE Digest V11 #269
*******************