Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO157.ZIP/V15NO157

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Date: Wed,  2 Sep 92 05:03:19
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #157
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed,  2 Sep 92       Volume 15 : Issue 157

Today's Topics:
              Another Shuttle Tank Reuse Idea, From NASA
                        soviet rovers on mars
                                 SPS
                        Tether and Space Junk
                 Upload Astronomy Lab for MS Win 3.x
                     Voyager 1 Update - 09/01/92
                         Whales and Dolphins
              What is the speed of light measured from?
         With telepresence, who needs people in Earth orbit?
                 World Space Congress on NASA Select

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Date: 1 Sep 92 14:57:57 EDT
From: "John F. Woods" <[e-mail]>
Subject: Another Shuttle Tank Reuse Idea, From NASA
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (John F. Woods) writes:
>>...hydrogen tank inside would be removed, leaving the oxygen tank and
>>intertank structures, to which would be added living quarters,
>>instrumentation, an airlock, and small thrusters and fuel tanks...
>Small correction... I doubt it really said that... because there is
>no hydrogen tank "inside".  There is one, 1, 00001, layer of metal
>between the liquid hydrogen and the outside world.  (There is some
>spray-on insulation on the outside of the metal.)  The tank wall
>and the outer shell are one and the same.  If you cut away the
>hydrogen tank, you're cutting away roughly the lower two-thirds
>of the ET.  Still might be a sensible idea, although it seems a
>shame to throw away most of the internal volume (the oxygen tank
>is much smaller).

I wish my copy weren't at home so I could check for sure, but I'm pretty
sure this is exactly what they do.  I suspect that the concern is where one
attaches the engines; if you attach them to the nice, sturdy intertank
structures (as the diagram indicated) you either have to fire them through
a tank or get the tank out of the way :-).  The LOX tank is probably sturdier
and hence more suitable for keeping.

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

Date: 2 Sep 92 12:31:42 GMT
From: [e-mail]
Subject: soviet rovers on mars
Newsgroups: sci.space

JD>They also had a Soyuz return capsule.  I would hate to spend a year
JD>in micro-gravity and then ride back in that rascal.  It didn't look

I read in the UK magazine Flight International that NASA were
considering using the Soyuz decent capsule as an escape system
on the Freedom space station.

JD>very comfortable.  It is a big improvement over the Vostok return
JD>capsule however.  I never knew that the hatch was blown at 22,000 ft
JD>and the cosmonaut jumped out. Sheeeesh.

He/She was shot out on an ejector seat.  The Soviets maintained for
many years that Gagarin did not eject - something to do do with claiming
the record - but later, it is reported, admitted he did.

Bill ~ Tue ~ 01-09-92 ~
---
 ~ DeLuxe}/386 1.25 #9224 ~
--
ALMAC BBS Ltd. 0324-665371
Dos based USENET access,  call for details!

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

Date: 2 Sep 92 02:13:07 GMT
From: John Roberts <[e-mail]>
Subject: SPS
Newsgroups: sci.space

-From: [e-mail] (Frederick A. Ringwald)
-Subject: Re: SPS fouling astronomy (long)
-Date: 18 Aug 92 01:18:53 GMT
-Organization: Dartmouth College, Hanover, NH

-Of course, breakthroughs being breakthroughs, they're unpredictable,
-and so by definition you can't count on them for anything in advance.
-But, SPS itself will require it own breakthroughs in space launch and
-operations technologies.

An excellent point. And as you point out, this shows that the worries about
light pollution are a little premature. SPS will probably be just something to
think about for a long time.

-For example, anything the Space Shuttle now
-carries has to be worth about its weight in gold, to be profitable
-(that's $4e8/65000 lbs, or about $400/oz).

Very minor point: gold is sold by the Troy ounce, with 12 Troy ounces to a
Troy pound. I left my conversion tables at work, but the numbers are fairly
widely available. It's still in the same ballpark.

-So, there's an incentive
-to automate as much as possible, and to develop less expensive
-technologies for getting lunar material into space, such as
-electromagnetic mass drivers and powdered aluminum/oxygen rockets.

Ah, one of my favorites! Apparently a private company actually built a
working aluminum-oxygen rocket last year. I believe the combustion chamber
and nozzle were made of ceramic material to prevent oxidation. This is
important, because I think you get the best specific impulse with an excess
of oxygen, and hot oxygen is bad for most metals.

-SPS is also not without its own unique problems. Microwave power
-transmission presents safety problems, and terawatts of transmitted
-power may well generate enough static to interfere with
-telecommunications, not to mention cause the demise of ground-based
-(i.e., inexpensive) radio astronomy.

You would handle it like microwave ovens - allocate a narrow frequency
band for the transmission of power. Well away from that band, there shouldn't
be much of a problem.

-Then there's the cosmic ray project, to
-analyze waves in the interplanetary medium. (They wanted to hire me to
-take care of it, but I turned them down. Living at the South Pole would
-be fun, for three weeks, but they wanted me to stay for 53 weeks!

I don't blame you - I wouldn't want to stay at the South Pole for 53
weeks either! :-)

John Roberts
[e-mail]

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

Date: 2 Sep 92 02:31:46 GMT
From: John Roberts <[e-mail]>
Subject: Tether and Space Junk
Newsgroups: sci.space

-From: [e-mail] (clifford bettis)
-Subject: Tether and Space Junk
-Date: 16 Aug 92 15:25:18 GMT
-Organization: University of Nebraska - Lincoln

-I have been waiting to see this issue discussed: in the event of
-serious difficult with the tethered satellite experiment, I understand
-that one option was to cut the tether. Wouldn't a 20 km cable in orbit
-be the environmental equivalent of a drift net for space craft and
-pose an unacceptable hazard?
-Cliff Bettis

As long as it can be tracked, it shouldn't be much worse than what's up
there already. The current safety rules for the Shuttle require that it
be kept quite a few miles from any known debris. I vaguely recall a figure
of 30 miles, but that may not be correct.

If you use a really long tether to attach a satellite to a large spacecraft
in LEO, you could probably arrange it so cutting the tether will make the
orbit of the satellite so eccentric that it will quickly be caught in the
atmosphere and burn up, pulling the tether with it. This should work whether
the satellite is above or below the spacecraft. (Anyone care to work out
the numbers? A few hundred feet per second ought to do it.)

Probably a more significant concern for long-term use of tethers is that
a really long tether represents a pretty large orbital cross-section, so
there's a significant risk that a tether in use for a long time could be
damaged or cut by a small piece of orbital debris. Atmospheric drag is
probably also a valid concern.

John Roberts
[e-mail]

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

Date: 2 Sep 92 02:09:28 GMT
From: Eric Bergman-Terrell <[e-mail]>
Subject: Upload Astronomy Lab for MS Win 3.x
Newsgroups: comp.windows.ms.programmer,comp.windows.ms.misc,comp.ibm.pc.misc,comp.os.ms-windows.apps,sci.space,sci.astro,sci.edu

In article <[e-mail]> [e-mail] (David "Fuzzy" Wells) writes:
>This file is available at ftp.cica.indiana.edu in the windows area.
>            Fuzzy
>

Anyone know if it the most current version (1.13)?

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

Date: Wed, 2 Sep 1992 05:03:42 GMT
From: Ron Baalke <[e-mail]>
Subject: Voyager 1 Update - 09/01/92
Newsgroups: sci.space,sci.astro

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

                      Voyager Status Report
                        September 1, 1992

               The Voyager 1 spacecraft used its onboard fault
protection program to maintain communications with the ground
this morning, after it experienced a failure in the piece of
equipment that allows the spacecraft to send telemetry signals to
Earth.

               Ground controllers lost the downlink signal from
Voyager 1 at 2:08 PDT this morning at the Tidbinbilla Deep Space
Network tracking station in Australia.  Telemetry data indicated
a failure of the Ultra Stable Oscillator as the cause of the loss
of downlink signal.

               Voyager 1 responded autonomously to the problem
and switched to the auxiliary oscillator.  The spacecraft
reconfigured itself in less than 10 minutes and continued sending
telemetry to the ground.   Spacecraft controllers at JPL have no
plans to change this current configuration.

               Both the Voyager 1 and Voyager 2 spacecraft
continue in good health and are conducting fields and particles
experiments and ultraviolet observations.  Voyager 1 was launched
15 years ago this week, on Sept. 5, 1977.  Voyager 2 was launched
on Aug. 20, 1977.

               Voyager 1 is currently 4.6 billion miles (7.4
billion kilometers) from Earth.

               Voyager 2 is currently 3.5 billion miles (5.6
billion kilometers) from Earth.

                              #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: 2 Sep 92 01:53:10 GMT
From: John Roberts <[e-mail]>
Subject: Whales and Dolphins
Newsgroups: sci.space

-From: [e-mail] (Edward V. Wright)
-Subject: Re: Whales and Dolphins
-Date: 17 Aug 92 20:58:11 GMT
-Organization: Engineering, CONVEX Computer Corp., Richardson, Tx., USA

-In <[e-mail]> [e-mail] (John Roberts) writes:

->Reread what I posted. Humans take calculated risks, and sometimes there
->are mistakes in the calculations.

-Reread what I posted.  There are many people whose job is to save other
-people's lives *regardless* of the risk to their own.

-Suppose, for example, the President of United States, or one of his
-family, was kidnapped by a foreign power.  Do you believe that the
-United States government would not try to rescue him if it believed
-more than one soldier would die in the attempt?

Wow, you must really love this "discussion", since when the arguments start
to get scarce you chop up my own arguments and send them back to me! :-)

Seriously, if you wish to continue a debate over a long period of time,
you should keep records of what's been said, and refer to them occasionally.
I covered this *exact* point in a previous post:

.....................
|From: [e-mail] (John Roberts)
|Newsgroups: sci.space
|Subject: Re: Whales and Dolphins
|Message-ID: <[e-mail]>
|Date: 4 Aug 92 01:38:32 GMT

|-From: [e-mail] (Edward V. Wright)
|-Subject: Re: Whales and Dolphins
|-Date: 31 Jul 92 16:01:27 GMT

|-Oh?  So you've never heard of search parties going out looking
|-for a lost person, in bad weather, although several people may
|-die in the attempt?  Especially if the lost person is a child?
|-Sounds very human to me.

|Human search parties won't go out to rescue one person if the expected
|outcome is that several people *will* die in the attempt. (Unless it's
|the President or something.) There are many occasions when a search is
|called off because conditions are "too dangerous". A greater level of
|risk might be accepted if there are more people to be rescued, and less
|risk might be taken if rescue is considered unlikely. For an organized
|search, there has to be a calculation of the tradeoffs involved. (Note
|that this discussion is of cases where the threat is nonhuman in nature.)
[End of quoted text.]
.....................

Note that I already *said* the President would be an exception. In another
post I commented that one might consider highly trained or otherwise unique
and valuable individuals, or individuals in "unique" and valuable positions
to merit greater effort/risk to insure their well-being than a random member
of the general population. That's a rational choice, based on a desire to
protect the overall interests of the organization. That would hardly be
the case for the beginning of the envisioned "typical" mass beaching scenario.

You also missed a very important point from the end of the quoted portion
of my previous post. In your kidnapping example, there's an intelligent
adversary involved. While the country might not be too upset if some
particular president were hauled away by a foreign power and kept in a
small cage for several years (after all, there's a Vice President waiting
to take over), they still have to consider the possible effect of the
precedent on future actions. It would be difficult for a country the size
and complexity of the US to function well if its presidents were lugged
off on a regular basis. So it becomes very much worthwhile for the country
to "teach them a lesson" by vigorous retaliation. In this case the relative
tradeoff of lives (even lives of hostages of no particular merit) becomes
less important than demonstrating to the foreign power that kidnapping
is not a profitable technique to use in the future. Unless you wish to
claim that the whales are somehow "teaching the beach a lesson" by throwing
themselves on it, you should avoid examples that include an intelligent
adversary.

->Whales that beach themselves entirely seldom if ever survive (though on
->the "R-rated Gory Animal Videos" series commercials on television, they
->show a killer whale getting its head out on the beach to chomp a sea lion).

-Nope.  Not true.  Not even close.  Killer whales have been known to
-deliberately wash schools of fish up onto the beach, then beach themselves
-to snatch up the helpless, flopping fish, and roll back into the water.
-They have been observed and photographed doing this.  You aren't proving
-that whales aren't intelligent.  You're simply showing how little you
-know about whales.

You agree with me that killer whales have been seen to put themselves on the
beach to catch prey then return themselves to the water, and then claim that
this point of agreement shows that I don't know much about whales? I don't
quite understand your point. (Dolphins can also be trained to throw themselves
completely out of the water onto dry land - I've seen it done. I guess the
fact that I know this shows that I'm even less knowledgable about whales. :-)

I had only heard of the term "beaching" to refer to whales grimly or
frantically casting themselves on the beach to die. You seem to use the same
term for whales having a jolly romp on the beach, gulping down fish and
sea lions. Since by implication you must be more knowledgable about whales,
could you please explain the similarities or differences between these two
activities, and what the motivations for lethal beaching are?

->If whales have anything akin to human intelligence, and if they have a
->community that communicates and passes down lore, then they must realize
->that if they beach themselves, they're going to die,

-If humans have anything akin to intelligence, and if they have a
-community that communicates and passes down lore, then they must
-realize that if they beach themselves, they're going to be exposed
-to dangerous levels of UV radiation, contract skin cancer and die.
-Ergo, humans cannot be intelligent.

Lying on the beach for a few hours isn't nearly as dangerous for a human as
it is for a whale, and if there are harmful effects, they may not show up for
decades, as opposed to killing them the same day. If whales have no more
awareness of dangers that can kill them in a day than humans have of dangers
that can affect them over the course of 30-50 years, then that doesn't strike
me as a strong indicator of human-type intelligence in whales.

Note that I'm not saying that I don't consider whales to be intelligent.
As I stated earlier, I consider some species to be pretty stupid, while others
are much brighter. The most intelligent whales *may* have intelligence not
too different from that of humans, though I don't consider that to be proven.
There have been some encouraging signs, but I don't consider mass beaching
to be one of those signs - and I *think* there have been mass beachings of
killer whales.

->If what the whales do is deliberate suicide, it's even less akin to normal
->human behavior.

-Of course. One human being may voluntarily expose himself to
-dangerous levels of UV radiation at the beach, but certainly
-his entire family wouldn't follow, would they?

You could have argued your point a lot better by mentioning a group of
teenagers deciding to start smoking or taking drugs.

-If one human
-is out drinking with his buddies, gets drunk and jumps into
-his car, his friends aren't going to pile in with him, are they?
-Nah, that could never happen, could it?

Let me introduce an analogy: one of the classic challenges of plane geometry
is to trisect an arbitrary angle using the ancient Greek methods of
straightedge and compass. This was proved to be mathematically impossible
a century or more ago, but that hasn't stopped some people from trying.
One particularly ingenious attempt I saw in a math book showed an angle that
was indeed trisected. It looked very convincing, until the author pointed
out that given the construction technique, the inventor had in fact taken
an arbitrary angle and *tripled* (not trisected) it. Since the generated
angle was made three times the original angle, *of course* the original angle
was one third of the generated angle - but it wasn't a valid arbitrary
trisection.

This is close to what you've been doing with most of your arguments. You
attempt to show that many humans exhibit behavior that's as stupid or
irrational as some of the things whales have been seen to do. From this it
supposedly follows that humans and whales have comparable intelligence or
intelligence/emotion ratio, and since "by definition" humans are intelligent,
that implies that whales are intelligent too.

I don't see what ultimate usefulness this line of reasoning is supposed to
have. I'm not interested in proving that humans can be as stupid as whales
or whatever space alien life forms we might encounter. It's much more
interesting to try to determine whether whales or other life forms can
exhibit any of the positive aspects of what we call human intelligence.

John Roberts              | "APE HAS KILLED APE."
[e-mail] | "APE HAS KILLED APE." - from "Battle for the Planet
                          | "APE HAS KILLED APE."   of the Apes"
                          | "I guess they just joined the human race."

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

Date: 1 Sep 92 21:52:52 GMT
From: Steven Moon <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (pete) writes:
|> In article <[e-mail]>,
|> [e-mail] (robert.f.casey) writes...
|> >Makes you wonder how the "particle" of light "knows" how fast or slow to
|> >speed up by to be travelling at the -speed o' light- at or near the
|> >local frame of reference.  Does it "feel" the local gravity, or something?
|> >
|>
|> What you have to understand is that c is not just a velocity.
|> The way this universe is constructed, it's like a point that
|> time and space both pivot on. You could say that c is infinitely

I don't see your point.  If you consider c = infinity you are then
just dealing with Galelian transformations.  If you are considering the
point of view of a photon, this is a philosophical question.

|> fast, for anything travelling at it, it's just that the geometry
|> - in fact the _logic_  - of the universe requires that it not
|> be seen as infinitely fast by other observers. For instance,

The logic (as you call it) of the Universe says (as far as SR) that
physical laws are the same in all reference frames as well as the speed of light.

|> if you board some wonderful rocket, which can sustain constant
|> acceleration ( in your frame of reference ) and commence
|> accelerating, it will seem to you that you just keep getting
|> faster and faster, and you pass c without incident. The only

This is not true.  In order to measure the velocity of your 'wonderful' rocket
you must make some measurements.  You take you watch and meter stick and measure
some object at rest w.r.t. the inertial frame you started in (say the Universe)
So measure the position of some Star at two different times.  You will not
come up with some velocity > c.

|> catch is that in the rest of the universe you travel through,
|> time seems to be going by faster and faster relative to yourself,
|> such that to observers in other frames, your velocity never
|> quite reaches c. They also see your time slowing down, so they
|> can understand why you might think yourself going faster than
|> c ( for simplicity I've left out all the interesting details
|> of how times can be compared between reference frames).

I would suggest brushing up on your SR.  A.P.French's book is, in my
opinion, one  of the best.  Some wonderful light reading would include 'Mr.
Tompkins in Paperback.'  The first story is about a place where the speed of light
is quite small and SR effects can be observed with a bike.

|>     Now for light, and anything else travelling at c, duration
|> of time has slowed to 0 as seen from any other reference frame,
|> so this can be seen as equivalent to travelling infinitely
|> fast. This sort of solves the problem that led Einstein to
|> relativity in the first place - how, if one were in the frame of
|> reference travelling with light, and observed the (now stationary)
|> electromagnetic fields which comprise it, one would see
|> the EM fields vary in amplitude periodically
|> in space, which according to Maxwell's equations shouldn't
|> be possible without electric charges at the local maxima.
|> The solution is that in relativity, this frame of reference
|> is not well defined, and it occupies no time, so it's
|> never really there to contradict Maxwell. Thus light always
|> knows how fast to go: as fast as possible.
|>     The moral of the story is that the world is not at all
|> as it seems, and nothing like our naive Aristotelian/Newtonian
|> intuitions.

I, honestly don't know how to respond to this.  Study special relativity.
Getting all your information second hand from popularized books and TV shows
is quite dangerous.

|> ========================================================================
|> Wait until time is fully dilated                          Pete Vincent
|> before releasing tangent bundle...

.Steve

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

Date: 1 Sep 92 19:39:08 GMT
From: Roger Arnold <[e-mail]>
Subject: With telepresence, who needs people in Earth orbit?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Allen W. Sherzer) writes:
> In article <[e-mail]> [e-mail] (Phew) writes:
>
> >Depending solely on telepresence in space would limit human intervention to
> >any reasonable "real time" sense to about the Moon or so...
>
> Using only telepresence is limited not only to distance but also to scale.
> The available bandwidth is limited and telepresence in any realistic sense
> will use up a lot of it.
>
>     Allen

Not to pick on Allen, in particular; his just happened to be the message
I was reading when my irritation level over this whole thread crossed
the posting threshold.  Actually, his statement is technically correct.
It's the implication that I object to.

Many space activists appear to view telepresence as a threat to a
cherished and beleagured manned space program.  Most of the discussion
here has been cast in a "manned vs." context.  So a lot of diversionary
non-issues get tossed about: "it can't do everything", "it's limited by
time lag", "it's limited by bandwidth".  Plus the biggest confusion
factor of all: failure to distinguish between teleoperation and robotics.
It's easy to make telepresence look bad or difficult if you can get away
with discussing it in terms of the capabilities of autonomous robots.

Just so people know where I'm coming from, I'll note that I grew up
on on the writings of Heinlein, Clark, Willey Ley, Dandridge Cole,
and other visionaries of that generation.  I believe in the critical
importance of getting human beings off the planet and into space.  But
I'm totally disillusioned with NASA and the manned space program as a
route to that end.  I wish Goldin the best of luck in reforming NASA,
but pardon me if I don't hold my breath.

If it ever did, western culture no longer has the will or vitality to
move into space in pursuit of a vision.  Sure, if we applied the same
fraction of GNP that went into building cathedrals in the Middle Ages,
or the pyramids in ancient Egypt, we could easily support lunar and
Martian colonies.  But it's unrealistic to expect that to happen.
And probably just as well, when you consider the politics behind the
building of those wonderful cathedrals.  In any case, barring a really
drastic change in the social climate, any human move into space will
have to be economically motivated.  Otherwise, it just won't happen.
We will see large numbers of people living and working in space when--
and only when--it makes economic sense for them to be there.  And it
*will* eventually make sense, if we can get the level of commercial
activity high enough and the cost of transportation low enough.

I see telepresence not as competition to manned space activity, but
as a bridge to the level of space activity that will be necessary to
bring costs down and make it worth building real space stations.  A
teleoperated research facility in low earth orbit would find no short-
age of commercial customers.  If they only had to pay for delivery of
small quantities of material and a share in amortization of the equip-
ment in orbit, it would be a bargain.

Most of the objections to teleoperation that people raise, or the
problems that they posit as standing in the way, are easily avoided.
It's absurd to tie teloperation in low earth orbit to a communication
path involving two round trips to Clark orbit.  Build a necklace of
co-orbiting microsats to relay signals from the facility to whichever
satellite is currently in position to downlink.  It's easiest if the
orbit is equatorial, and so what if that means using Pegasus or Ariane
for launches?  But it's not much harder with an inclined orbit.  You
need a number of downlink receiver sites, linked by high-bandwidth
fibre optics to the operation center.  And probably three operations
centers on different continents that hand off control on 8-hour shifts.
The longest round trip time delay for teleoperation is only 150
milliseconds.  That happens when the station is on the opposite side
of the earth from the active operations center.  For most of each
orbit, the delay would be under 100 milliseconds.  At that level of
delay, force feedback is quite manageable.

Obviously, there are limits to what you can do with telepresence from
earth.  That doesn't mean that what you *can* do isn't worth doing.

--
Roger Arnold
[e-mail]

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

Date: 2 Sep 92 04:32:37 GMT
From: John Roberts <[e-mail]>
Subject: World Space Congress on NASA Select
Newsgroups: sci.space

They appear to be showing considerable coverage of the World Space Congress
on NASA Select. I'm trying to tape as much of it as I can, but I won't
have a chance to look at it until later. Bill Higgins is scheduled to present
a paper on Friday morning.

On Monday night, they replayed the Planetary Society conference discussing
justifications for the exploration of Mars. Carl Sagan spoke, and also
at least one person from Russia. I haven't watched it in detail yet.

John Roberts
[e-mail]

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

End of Space Digest Volume 15 : Issue 157
------------------------------