Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_1/V16NO193.TXT

Internet Message Format | 1993-07-13 | 35KB

Date: Wed, 17 Feb 93 05:18:41
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #193
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed, 17 Feb 93       Volume 16 : Issue 193

Today's Topics:
                          "Late 'L5' Society
                    *advocate* anonymous postings
             Are Landsat Satellites receivable? (2 msgs)
                          Cassini Fact Sheet
                  Getting people into Space Program!
  Have anybody data about Soviet rocket test launches in 1945-1992?
                  Looking for NSSDC CDROM Catalog *
                  parachutes on Challenger? (2 msgs)
                     space news from Jan 4 AW&ST
                SSF Petition (freedom fighters, etc.)
                      Ulysses Update - 02/16/93
                          wind on the moon?

    Welcome to the Space Digest!!  Please send your messages to
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Date: Mon, 15 Feb 1993 01:29:19 GMT
From: Tanya Sienko <[e-mail]>
Subject: "Late 'L5' Society
Newsgroups: sci.space

[e-mail] writes:
>Space Studies Instutute...does fantastic work in mass drivers and other
>nuts-and-bolts designs we'll need up there.

At least it used to do so.  Does anyone know just what they are doing along
those lines *NOW*?  SSI has unfortunately had some difficulties and doesn't
seem to quite be the group it was some years ago.  Some of their top
advisors are concerned that SSI isn't really accomplishing much now.  Can
anyone shed some light on this please?

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

Date: Tue, 16 Feb 1993 17:34:30 GMT
From: 8 February 1993 <[e-mail]>
Subject: *advocate* anonymous postings
Newsgroups: news.admin.policy,comp.org.eff.talk,alt.privacy,sci.space,sci.astro,sci.crypt

Now that we've seen that pseudonymous postings are not an
unmitigated evil by demonstrating their accountability and
responsibility, we need to go further and to *promote*
pseudonymous postings as a positive good.

The reason that they are to be encouraged is that the
pseudonymous article distance the ego of the poster
from the content of the message. That is, defense of
the posting is divorced from defense of the self and
conversely, advocacy of a position is separated from
simple self-promotion.

Look in a text of fallacies.  A good number are fallacies of
ad hominem (personal attacks).  These kinds of attacks
would be blunted in  blind and double-blind arguments
because (1) by not directly identifying the originator
of a post, less of his or her personal feelings are
"on the line" and (2) by revealing less personal and
irrelevant information the opponent has less of a toehold
by which she or he might launch personal attacks.

This does not mean arguments would become less passionate,
but the passion is redirected from a defense of a self-image
to the defense of a *position.*

Thus the exhortation by *emotional pressure* or by
"pinpointing an enemy", which is by far and away the
the key ingredients of propaganda, is short-circuited.
The fog of personal special pleading and posturing
is blown away, leaving the stark contours of argument.

Moreover, appeals based mainly on submission to badges
of authority, such as the posting site or the reputation
or power of the poster is muted.  This removes another
constraint to Usenet readers using evidence of their own
sense coupled with conclusions derived from independent
thought with facts that can be gleaned from good postings.

True, a lot of sludge will be channeled by Anonymous.  But
of far more importance will the occasional Copernican theory
(still censored in some areas until the early 19th C.) be able
to surface without intimidation or retribution.

Anonymous postings demand a lot from the readership in
requiring skill to prune and select from a broader array of
responses; responses that may be incorrect, in poor taste or
just plain dumb.  This burden of selection and analysis will
certainly increase as anonymous postings become the norm.

For those who are unable or afraid to boldly take this step into
the future of a free society, you can still use the N key or the
kill file to prepackage your Usenet information stream.

But for the rest of us, this difficult and frustrating process of
learning effective strategies of analysis and resolution is identical
with education in our free society, a society that is slowly
transcending national boundaries at the speed of light.
-------------------------------------------------------------------------
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------------------------------

Date: Tue, 16 Feb 1993 18:53:53 GMT
From: Martin Connors <[e-mail]>
Subject: Are Landsat Satellites receivable?
Newsgroups: sci.space

In article <[e-mail]> [e-mail]
(Willie Smith) writes:
> These are the folks who have the government-collected (taxpayer
> funded) Landsat data for sale 'at cost'.
There was also mention made in this thread about Russian space data with
2m resolution. Can anyone confidently tell me what is the best resolution
spy satellites can attain in practice in imaging the surface of the Earth
(near sea level) and in what wavelength bands?
--
Martin Connors         |
Space Research         | [e-mail]  [phone]
University of Alberta  |

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

Date: 16 Feb 93 21:11:42 GMT
From: Richard Ottolini <[e-mail]>
Subject: Are Landsat Satellites receivable?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Martin Connors) writes:
>In article <[e-mail]> [e-mail]
>(Willie Smith) writes:
>> These are the folks who have the government-collected (taxpayer
>> funded) Landsat data for sale 'at cost'.
>There was also mention made in this thread about Russian space data with
>2m resolution. Can anyone confidently tell me what is the best resolution
>spy satellites can attain in practice in imaging the surface of the Earth
>(near sea level) and in what wavelength bands?

The Russians were selling their photographic data at a remote
sensing conference in Pasadena last week.  I one image of
Washington DC you could count the cars in the Pentagon
parking lot.  Cars are 2-3 meters wide and 5-8 long.
It wasn't clear with suitable image processing if you could
tell the types of cars.

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

Date: 16 Feb 93 20:36:20 GMT
From: Joe Cain <[e-mail]>
Subject: Cassini Fact Sheet
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>                     FACT SHEET: THE CASSINI MISSION
>                           February 15, 1993
>
>Titan
>
>- although the most daring speculate
>about the possibility of lifeforms in covered lakes of liquid
>hydrocarbons warmed by the planet's internal heat.

What is the latest theory? I thought the temperature modelling
indicated temperatures too low for the ethane/methane (ca 1 km deep)
liquid ocean suggested in Owen's chapter in "New Solar System."

Darn, wish the launch was earlier!  Not only that, but to have to use
such a weak rocket to take so long to get there! Some of us might not
make it to 2005!


Joseph Cain        [e-mail]
[e-mail]        scri::cain
[phone]        FAX [phone] or -0098

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

Date: Tue, 16 Feb 1993 16:45:42 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Getting people into Space Program!
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>In article <[e-mail]| [e-mail] (Gary Coffman) writes:
>|I don't have any hard cost numbers, but Mary may. I do know that
>|when the SR71 was in military service it didn't take off until
>|it's tankers were in the air. I suspect it would need 3 or 4
>|refuelings to make it to Australia. The X-15 certainly wasn't
>|a long range aircraft, and was not designed for in flight refueling.
>|
>
>MARY is the net expert on both of these birds, probably having more
>time around the programs then all the rest of us combined.
>The SR-71 tanked after takeoff, but that was because the tanks
>leaked until warm.   I am not sure if the SR-71 range is still
>classified, speed I think still is.  But I'd be surprised if
>a 71 couldn't make australia on one tank from LA  the thing used
>to fly from turkey to finland  and pakistan deep into china
>and back.

I know that when they were doing runs across the US that tankers
were in the air off the Carolina coast before the 71 lifted off
the runway on the left coast. I watched several refuelings from the
Hampton Center radar site.

>|>All comments aside,  I would expect the DC-1 to not cost more then a
>|>small multiple of either the SR-71 or X-15.  and to start have
>|>a operational record very similiar to either.
>|
>|I wouldn't be at all surprised either. I expect DC-1 would have about
>|the same cost per pound-mile as X-15, updated for inflation.
>|
>
>But the X-15 program was put together on a very modest budget.
>It was quick off the boards and built and explored space and hardware.
>Unlike NASP which has been a drawing board angel since 1983.
>I really think project management is almost more important
>then technical goals.

Sure the X-15 was quick off the board, but it had development problems
in flight test. It also was a lousy cargo plane. (Not intended to
be one I know, still note I said same cost per pound-mile above.)
Designing to different technical goals gives different aircraft with
different development costs and schedules. Good management is always
important, but that doesn't make comparing apples to oranges any more
valid.

>|>The X-15 had 3? aircraft built to acquire data and flight characterestics,
>|>and aside from some program difficulties. Wrecking one bird, killing
>|>an astronaut??? and bending some metal, plus burning some incredible
>|>holes in places you'd never expect.
>|>
>|>I would imagine the X-15 test program should provide a
>|>guide to the difficulties of the DC test program.
>|
>|Yep.
>|
>
>BUt the X-15 was a massive success, for a very difficult problem
>and it delivered a functionally operational spacecraft.
>If the 15 could fly,  why do you seem so sceptical of the
>Delta Clipper.  The STS and Fred and NASP seem to be managed
>as a welfare project not a product project.

I'm skeptical of DC because comparing a small manned air-launched cruise
missile to a passenger/cargo hauler is stretching the point. The X-15
was a success, trouble plagued as any experimental craft is, but still
a success at achieving it's experimental goals. But a DC with the exact
same track record would *not* be a success. For DC to be a success it has
to approach airliner standards of reliability and cost, and I think that's
a much harder problem for a very high performance aerospace craft. Pegasus,
a much closer cousin to X-15, is still not a commercial success even though
it's performance to date is as good as the performance of the X-15 at a
similar point in it's research program. DC has to do much better.

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     |                     |

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

Date: Tue, 16 Feb 1993 19:30:23 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Have anybody data about Soviet rocket test launches in 1945-1992?
Newsgroups: sci.space

[e-mail] (Voevodin S.A.) writes:

>      Sir,


>      Please send me any data about Soviet rocket test launches in 1945-1992.
>--
>-----------------------------------------------------------------------
>Sergey A. Voevodin
>8 Okruzhnoy proezd 11-2, 156014 Kostroma, Russia

I'm not sure why you posted this to "world" domain. Wouldn't
someone in Russia be in a better position to find out about
all this than someone here in the US?

Also, 1945-1992 is a _VERY_ large time period. Could you be
a little more specific?

>e-mail: [e-mail]          tel: [phone]

Have a nice day!


--
Phil Fraering         |"...drag them, kicking and screaming,
[e-mail]|into the Century of the Fruitbat." - Terry Pratchett,
                       _Reaper Man_

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

Date: Tue, 16 Feb 1993 18:49:00 GMT
From: "NSSDC, NASA Goddard Space Flight Center, Hughes STX" <[e-mail]>
Subject: Looking for NSSDC CDROM Catalog *
Newsgroups: sci.space,sci.astro

In article <[e-mail]>, [e-mail] (Ryan Korniloff) writes...
>It would be appreciated if somone could Email me the latest NSSDS CDROM
>Catalog. I have the print out but not the file on disk.
>Thanks in advance
>
>
>         --- Ryan Korniloff
>         --- [e-mail]
>
> Dear Ryan:
>
>    The CD-ROM catalog in now online on the NSSDC Data and
>    Information Service - NODIS.
>
>    You may connect to this by using telnet (the service is free
>    to all.)
>
>    TELNET nssdca.gsfc.nasa.gov
>    USERNAME: NODIS
>
>    At this point leave name, address and other good stuff, and
>    you will see a 15 choice menu.  Option 15 lists our CD-ROM
>    holdings.  You may also request one to be mailed (hardcopy, its
>    the Feb. 1993 issue, not a xerox !) to you or you may ask for
>    the electronic version (use with caution lots of changes !).
>
>    To request electronic version/hardcopy send email to;
>
>    [e-mail]
>
>    or call [phone].
>
>    Thanks,
>
>    Syed.
>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The views expressed above are mine, and mine alone.  I do this with the
understanding that the Constitution on the United States of America guarantees
this right to all within its shores.  This message was typed in my own time and
on my own free will.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Syed S. Towheed >>>>>>>>

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

Date: 16 Feb 93 18:40:29 GMT
From: Dillon Pyron <[e-mail]>
Subject: parachutes on Challenger?
Newsgroups: sci.space

In article <bern.729358787@kleopatra>, [e-mail] (Jochen Bern) writes:

>Not from that Pilot, but quite reasonable: I've read that most Ejection
>Seats contain Devices which will pull Arms, Legs and whatever you name
>close to the Seat immediately before you get blown up. The only Diffi-
>culty I see is how to hold the Blanket in Front of your Face when your
>Arms get pulled. Of course, you shouldn't have put Hands or Feet into
>a Place where they can't be just pulled away.

When I sneaked a ride in the backseat of an F4 (the pilot in question retired
as a two star and has since died, so I can't get him in too much trouble), I
was told to keep my feet in close and my hands on my thighs.  Not because I
might screw with something, but just to keep them safe "in case ..."  Mach 2
over the North Sea at 500 ft.  One hell of a thirteenth birthday present!!!!
>
>In another Mag, I saw a Photo of a Ejection Seat Test with some actual
>Aircraft Type (Tornado?). The Pilot was shot out *first*. Exhausts weren't
>a Problem since the two Cabins were (seemed to be) separated.
>
>BTW, are there any Attempts to incorporate this russian Eject-Head-down
>Capability into western Airplanes? (The Para gets opened by a small
>"Gas Generator" Explosion.)

I'm screaming along at 600 knots when somebody puts a Stinger in the plane's
tail pipe.  I grab the handle, bang and ... a pine tree does a proctological
exam  :-).  Nah, I think most US and other NATO pilots would pass on that one.
I suspect the Soviet pilots weren't too fond of it, either.
>
>Just my .02 (Flamers, .45 available on Request),
                   smoothbore 9mm, subsonic.  It works for the Mossad  :-(
>                                J. Bern
--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |No people gave up their rights all at once.
[e-mail]          |Preserve the Bill of Rights.
PADI DM-54909                     |Protect the Second Amendment.

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

Date: Tue, 16 Feb 1993 19:43:33 GMT
From: Dillon Pyron <[e-mail]>
Subject: parachutes on Challenger?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (R. Lee Hawkins) writes:
>>>The right solution for future vehicles is the one used today for airliners:
>>>build them redundant and fail-safe so you don't *need* escape systems.  Any
>>>escape system is far inferior to being able to save the whole vehicle.
>>
>>I'm not sure the above is a very valid engineering or statistical comparison.
>>Airliners fly thousands of flights each day while the Shuttle flys less
>>than 12 per *year*.  To build things that don't fail, you have to
>>understand all the failure modes, both expected and unexpected (remember
>>the Comet?  The DC-10 engines?), and this unfortunately seems to require
>>a few crashes now and then and some of deaths...
>
>Precisely.  Practical spaceships will have to have turnaround times short
>enough that they can fly at least a few hundred test flights before they
>enter operational service -- there is no other way to test them adequately,
>regardless of what NASA says -- and their programs will have to be set up
>to tolerate occasional crashes, because crashes *will* happen no matter
>what you do.  We've already had one, plus a few near-misses, in the early
>test phase of the Shuttle.  (Don't kid yourself; fifty flights is still
>the early test phase, regardless of what it's called.)

Amen!  Test vehicles are meant for "burn & learn".  We can't build safety in
until we know what isn't safe.  When we are putting up 2-3 flights a day, then
we are on the road to real safety.
>
>>... Also, the shuttle is just a *wee* bit more complicated
>>than a DC-10 or 747...
>
>No it's not.  A few parts of it undergo higher stresses, but the overall
>complexity is quite similar.

I had been told at JSC that a competent, high-time 747/DC-10/L1011 captain
could fly the shuttle with a procedures review and a little simulator time
(procedures review could be several days long).  Compare this with the move
from a Beech Baron to a B737.
--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |No people gave up their rights all at once.
[e-mail]          |Preserve the Bill of Rights.
PADI DM-54909                     |Protect the Second Amendment.

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

Date: Tue, 16 Feb 1993 19:35:25 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: space news from Jan 4 AW&ST
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>... However, Lockheed does its own satellite testing
>horizontally, and has experience with what it calls "ship and shoot",
>which would be used for Proton:  the satellite would be installed into
>its payload fairing, sealed in, and then shipped to the launch site
>as a single unit that would simply be bolted to the Proton by the
>Khrunichev crews.  This might reduce concerns about technology transfer.
>Lockheed says that Proton's electrical and mechanical interfaces to
>its payloads are very simple and there are no plans to change this.
>There is a possibility of some minor modernization of Proton.

How did Lockheed get this experience?

--
Phil Fraering         |"...drag them, kicking and screaming,
[e-mail]|into the Century of the Fruitbat." - Terry Pratchett,
                       _Reaper Man_

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

Date: 16 Feb 93 17:02:37 GMT
From: Bob McGwier <growler!n4hy>
Subject: SSF Petition (freedom fighters, etc.)
Newsgroups: sci.space,talk.politics.space

And people I know are actually belivers in Clinton's ability to sell his
package.  SSF is but one of the things that Clinton may or may not want
to cut back on and already the grassroots organizations, and aerospace
industry lobbyist are lining up.  I have no hopes that in a years time the
deficit will be one dollar smaller if things like SSF, which to my mind
should NOT be in the budget when you have a $350 billion deficit looming,
cannot be cut.

Bob
--
------------------------------------------------------------------------------
Robert W. McGwier                  | Bob's interests include amateur radio,
Institute for Defense Analyses     | astronomy, and golf (10 handicap fanatic)
Center for Communications Research | Asst. Scoutmaster BSA Troop 5700
Princeton, N.J. 08520              | [e-mail] (internet)
------------------------------------------------------------------------------

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

Date: 16 Feb 1993 18:56 UT
From: Ron Baalke <[e-mail]>
Subject: Ulysses Update - 02/16/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from:
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE TECHNOLOGY
PASADENA, CALIF. 91109. TELEPHONE [phone]

                     ULYSSES MISSION STATUS
                        February 16, 1993

     The Ulysses spacecraft went into an automatic safe mode at
about 4:50 p.m. Pacific Standard Time on Sunday, Feb. 14, while
it was being tracked by the Deep Space Network facility near
Madrid, Spain.  All instruments were automatically switched off
by on-board computers, followed by switch-off of spacecraft
telemetry.  The loss of communication lasted about five hours and
10 minutes.

     Once the telemetry was regained, spacecraft health checks
confirmed that Ulysses had reconfigured itself correctly.  An
investigation into the cause of the anomaly was under way.

     Progress has been made to restore the spacecraft to its
normal operational condition.  Three of the spacecraft's nine
science instruments are now fully operational.  All but one of
the remaining instruments were expected to be restored during the
next tracking pass over the Goldstone Deep Space Network
facility, which was completed at about 10 a.m. today.  The Solar
Wind Ion Composition experiment operates at high voltage and
requires additional time to be switched on.

     Today Ulysses is approximately 610 million kilometers (379
million miles) from Earth, traveling at a heliocentric velocity
of about 35,000 kilometers per hour (22,000 miles per hour).  The
spacecraft is about 18 degrees south of the ecliptic plane,
slowly looping its way back toward the sun, where it will begin
its primary mission in June 1994 of studying the sun's poles.
One-way light time to Earth is about 38 minutes.

                             #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | If you don't stand for
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | something, you'll fall
|_____|/  |_|/       |_____|/                     | for anything.

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

Date: 16 Feb 93 19:13:30 GMT
From: Dillon Pyron <[e-mail]>
Subject: wind on the moon?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Ray Swartz (Oh, that guy again)) writes:
>In article <ldsoderb.729538124@reading>, [e-mail] (David S. Oderberg) writes:
>>Is there anyone out there - perhaps from JPL? - who might solve the
>>following problem. I am aware that there is supposed to be no wind
>>on the moon, since there is no atmosphere. There is certainly
>>no wind capable of blowing a flag. On the well-known "one small
>>step for man" film, the flag stands bolt upright, held up, it
>>is said, by wire supports.
>>
>>So far so good. But I _also_ recently saw film, said by the presenter
>>(a non-NASA physicist) to be NASA film of an Apollo mission, 11 if I
>>recall (not sure), in which the US flag FLUTTERS as if in a strong
>>breeze. It well and truly WAVES and FLAPS as surely as it would have
>>had it been in a strong breeze on Earth. I cannot recall for certain
>>whether it was a colour film, but I _think_ so. It was of higher
>>quality than the "one small step" grainy b&w film.
>
>
>    If you notice, that film was shot from above, and throughout the 5 or
>so seconds, from an increasing height.  What this film shows is the flag
>reacting to the rockets on the lunar module as the module was taking off from
>the lunar surface.  In a sense, the rocket exhaust could be considered a
>"wind", of a very short duration.  Other than at that event, the flag was quite
>stationary in all of the films I saw (and I NEVER pass up an opportunity to see
>them).
>

I remember Walter Cronkite (the most trusted man in America) saying, at the
time, that a spring wire would allow the flag to vibrate, producing a motion
that looked like waving.  Or so my fuzzy memory tells me.
--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |No people gave up their rights all at once.
[e-mail]          |Preserve the Bill of Rights.
PADI DM-54909                     |Protect the Second Amendment.

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


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From: Stuart A Kingsley <[e-mail]>
Newsgroups: sci.astro,sci.space
Subject: First Night's Observations at the AMOSETI Observatory
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                     THE AMATEUR OPTICAl SETI OBSERVATORY

                         OBSERVATIONS - THE FIRST DAY

The is the first in a regular series of reports on progress at the world's
first Amateur Optical SETI Observatory.

Last night, Wednesday, February 10, 1993 was a historic day for my Amateur
Optical SETI Observatory.  During the past week, I have constructed a
wideband photomultiplier tube (PMT) optical receiver, with the aim of
getting a "feel" for AMOSETI by first detecting stellar photons.

The "signal" in these tests will be later characterized as "background
noise", but for the moment I am interested in "just detecting" stellar
photons from some of the brightest stars.  This is done without any optical
predetection filtering, and the side-on PMT "sees" a large part of the focal
plane field-of-view.  No eyepiece projection is used - the PMT is simply
placed in the approximate position of the focal plane.  These test
essentially amount to using the optical receiver as a wideband photometer.

I had tried to do these measurements the previous night, but cloud cover
prevented observations except for a quick "look" at Venus.  Needless-to-say,
no ETI signals were detected from "hot Venusians"!

Yesterday afternoon was like an early summer's day, so I set up again with
the hope of a clear night.  Alas, the sky was rather hazy and became
increasingly hazy during the late evening.  However, I was able to detected
interstellar photons from some of the brightest stars.


Equipment:

1.   10" Meade F/10 LX200 Schmidt-Cassegrain (SCT).

2.   Photomultiplier direct detection optical receiver, consisting of:
     Shibaden HS401 PMT, 10 kohm transimpedance amplifier, 80 MHz bandwidth,
     and a 33 dB wideband video amplifier (> 100 MHz).

3.   Low voltage 24 V dc power supply for optical receiver front-end.

4.   High voltage -1000 V dc PMT power supply.

5.   10 MHz oscilloscope.

6.   Radio Shack Ch. 3/4 TV modulator.

7.   TV monitor (inside house).


The PMT and high-voltage power supply were from my "junk box" of stuff
brought with me from the United Kingdom in 1981.  The TV monitor acts as a
4 MHz video display device, the sound channel also being fed by the same
signal, so that low-frequency fluctuations in signal could be "heard" in the
speaker.  This was achieved by using a Y-splitter to feed the amplified PMT
signal into both the video and audio inputs of the Radio Shack TV modulator.

The gain of the electronics in the front end is just sufficient to produce
detectable (thermal noise) "snow" on the monitor.  Powering-up the PMT
produced a substantial increase in "snow", so that the screen looked like
and the audio sounded like, what one would expect for a TV tuned to a blank
channel.  However, this time the "snow" was not due to thermal noise but to
shot-noise, and predominantly photon-noise when the SCT was pointed at a
bright star.

Using the SCT hand-control for fine positioning, the oscilloscope display of
video output signal from the PMT front-end could be seen to increase
substantially when the SCT was pointed at a bright star.  Because the drive
system of the LX200 is excellent and the PMT was "seeing" not just the star
but a considerable portion of sky around it, the signal remained constant
over the observation times.  Note, the SCT was set up in the Altazimuth Mode
not in the Equatorial Mode.  Because field rotation is not a problem for
Optical SETI, there is no need to use an equatorial mount, unlike the case
for astrophotography.  Perhaps the main advantage of the "equatorial wedge"
for this application, is to allow the telescope to be aimed near the zenith
without equipment mounted at the rear of the telescope hitting the fork
mount.

The following stars were observed, along with several others:

1.   Betegeuse
2.   Rigel
3.   Sirius


Substantial low-frequency amplitude fluctuations were noted for bright
stars.  For a fanciful moment, I imagined that I was detecting an ETI signal
- no such luck!  Of course, most of the stars observed were inappropriate
for supporting life anyway.  On the TV monitor, the low-frequency amplitude
fluctuations showed as a just discernable full-screen flicker in the "snow",
with a quiet rumble from the speaker.  These "signals" are assumed to have
been caused by atmospheric turbulence, i.e., starlight twinkle.  These
fluctuations were somewhat larger than I had anticipated in view of the fact
that the PMT photocathode was supposed to be intercepting light not just
from the star but also its surrounding area, so that the effects of the
dancing image of the star would be integrated out.  The intensity of the
fluctuations appeared essentially independent of the focusing of the primary
mirror.

I tried some slow sweeping of the sky with the hand control (ala All Sky
Survey) but nothing detected.  The hazy sky prevented detection of the more
numerous fainter stars.

Presently, I have plans to record my observing sessions on standard VHS
cassettes at slow speed.  Thus, it will be possible to log over 8 hours of
observations on one tape.  This is a fairly inexpensive wave of logging a
lot of data.  I am presently looking for a means to produce one or more
picture-in-picture (PIP) signals, so that I can combine the photon signal
with a video-camera or CCD image of the sky.  This is a separate issue as to
the use of Windows on a dedicated PC (to be purchased shortly), for logging
various aspects of the signals flowing from (and to) my telescope.
Panasonic makes a special effects video generator that provides a PIP
facility, but it is rather expensive.  I would also like to insert the date,
time, R.A. and Dec. information within the overall recorded video signal.  I
would be pleased to hear if anyone has some other suggestions or could point
me in the direction of suitable, low-cost video equipment.  It may be that
in the end the best way to implement this will be via a PC, and use a VGA to
NTSC conversion board.


Conclusion

This is just the start.  With this "feel" for how a PMT performs in the
low-sensitivity direct detection mode, I am now better able to select the
appropriate high-sensitivity and fast PMT system that Hamamatsu has agreed
to donate to my observatory.  This device will hopefully have its own
integral photon-counter discriminator, a device that I do not have in my
present setup.  As for the basic bandwidth of the overall system, I may
compromise for now and start with a more modest 10 to 100 MHz bandwidth,
instead of the desired (ultimate) 1 GHz bandwidth.  For sure, keeping my
bandwidth requirements modest at this time makes life a lot easier for
detection, date logging and display.  This of course, begs the question as
to whether there are ETI pulses out there with pulse durations longer than
10 to 100 ns.


File: AMOSETI.001
February 11, 1993
V 1.01


Dr. Stuart A. Kingsley
Director: The Optical SETI Observatory
Internet: [e-mail]
CompuServe: 72376,3545
Tel: [phone]
Fax: [phone]
BBS: [phone]

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End of Space Digest Volume 16 : Issue 193
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