Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO164.ZIP/V15NO164

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Date: Fri,  4 Sep 92 05:00:04
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #164
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri,  4 Sep 92       Volume 15 : Issue 164

Today's Topics:
                        Antarctica (was: SPS)
                     Clinton/Gore Space Position
                Inflatable Space Stations - Why Not ?
                   Laser distance record? (5 msgs)
                       Shuttle traking programs
             Sizing of launch vehicles (was Saturn Class)
                          Special Relativity
             SPS feasibility and other space development
                            Teleoperation
             TOPEX, demise of SEASAT & nuclear sub wakes
              What is the speed of light measured from?
         With telepresence, who needs people in Earth orbit?

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

Date: Thu, 03 Sep 92 16:51:56 GMT
From: Doug Mohney <[e-mail]>
Subject: Antarctica (was: SPS)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Matthew DeLuca) writes:

>Besides, there's gravity in Antarctica; I think some of the mystique
>of space exploration and colonization is the fact that when you are
>floating in the middle of your spacecraft of habitat, you know you aren't
>in Kansas anymore.  With just freezing weather and snow and ice, you
>could be in Toronto for all you can tell the difference. :-)

Not true. There's only one Henry and he's in Toronto.

                 Support U.N. military force against Serbia

  -- >                  [e-mail]                        < --

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

Date: 3 Sep 1992 10:57 EST
From: Tom Quesinberry <[e-mail]>
Subject: Clinton/Gore Space Position
Newsgroups: sci.space

I found this on Case Western Reserve University's excellent
cleveland.freenet, and I thought It might interest sci.space
readers.

The Republican Position was not posted on freenet, so I have not
included it. If it's posted later I will provide it to sci.space.

                       Quiz

 -------------------------------------------------------------------------
  Tom Quesinberry                 | E-MAIL: [e-mail]
  Research Analysis Center/CSD    | PBX:    [phone]
  Lewis Research Center/NASA      | LIFE:   I would rather see starlight
  Cleveland, Ohio 44135           |             than streetlights.
 -------------------------------------------------------------------------
                  * Some Ignorance Is Indestructible



---------------------------------------------------
Article 100 of nptn.campaign92.dems:
Newsgroups: nptn.campaign92.dems
Path: usenet.ins.cwru.edu!nptn.org!tmg
From: [e-mail] (Tom Grundner)
Subject: SPACE PROGRAM: Position Paper
Message-ID: <[e-mail]>
Organization: National Public Telecomputing Network
Date: Mon, 31 Aug 1992 15:25:04 GMT
Approved: [e-mail]

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


CLINTON/GORE ON AMERICA'S SPACE PROGRAM



The end of the Cold War offers new opportunities
and new challenges for our civilian space program.
In recent years the program has lacked vision and
leadership.  Because the Reagan and Bush
administrations have failed to establish priorities
and to match program needs with available
resources, the National Aeronautics and Space
Administration (NASA) has been saddled with more
missions than it can successfully accomplish.

Bill Clinton and Al Gore support a strong U.S.
civilian space program -- for its scientific value,
its economic and environmental benefits, its role
in building new partnerships with other countries,
and its inspiration of our nations youth.  A
Clinton/Gore Administration space program will seek
to meet the needs of the United States and other
nations while moving toward our long-term space
objectives, including human exploration of the
solar system.  A Clinton/Gore space program will
also promote the development of new technologies,
create new jobs for our highly-skilled former
defense workers, and increase our understanding of
the planet and its delicate environmental balance.

Move beyond the Cold War

*   Restore the historical funding equilibrium
    between NASA and the Defense Departments space
    program. The Reagan and Bush Administrations
    spent more on defense space initiatives than
    on civilian space projects.

*    Achieve greater cooperation in space with our
     traditional allies in Europe and Japan, as
     well as with Russia.  Greater U.S.-Russian
     cooperation in space will benefit both
     countries, combining the vast knowledge and
     resources both countries have gathered since
     the launch of Sputnik in 1957.

     Improve the American economy through space

*    Direct NASA to give high priority to continued
     improvement of the American civil aircraft
     industry, which faces increasing international
     competition.  NASA research can play an
     important role in developing less polluting,
     more fuel efficient, and quieter aircraft.

*    Work to improve our space industries
     competitiveness.  Well direct NASA to develop
     cutting-edge rocket and satellite
     technologies.  We will also develop a new,
     cost effective, and reliable launch system to
     maximize scientific and commercial payloads.

Link NASA and the environment

*    Support NASA efforts -- like Mission to Planet
     Earth -- to improve our understanding of the
     global environment.

*    Call on NASA to develop smaller, more focused
     missions which address pressing environmental
     concerns.

Strengthen NASA and education

*    Direct NASA to expand educational programs
     that improve American performance in math and
     science. Space education can help maintain our
     technological edge and improve our
     competitiveness.

*    Direct NASA to expand the outreach of its
     educational efforts beyond its five field
     centers, so that millions more people can
     learn about space.

*    Maintain the Space Shuttles integral role in
     our civilian space program.  The Shuttle is
     extremely complex and will always be expensive
     and difficult to operate.  But we must take
     full advantage of its unique capabilities.

*    Support completion of  Space Station Freedom,
     basing its development on the twin principles
     of greater cooperation and burden sharing with
     our allies. By organizing effectively on this
     project, we can pave the way for future joint
     international ventures, both in space and on
     Earth.

     Encourage planetary exploration through the best
     space science

*    Stress efforts to learn about other planets.
     These improve our understanding of our own
     world and stimulate advances in computers,
     sensors, image processing and communications.

*    Fully utilize robotic missions to learn more
     about the universe.

*    Although we cannot yet commit major resources
     to human planetary exploration, this dream
     should be among the considerations that guide
     our science and engineering.  Because the
     entire world will share the benefits of human
     planetary explorations, the costs for any such
     projects should be borne by other nations as
     well as the United States.

The Record

*    Senator Al Gore chairs the Senate Subcommittee
     on Science, Technology, and Space, which has
     primary responsibility for NASA and plays a
     key role in efforts to strengthen and
     revitalize America's space program.

*    Strongly favors a balanced manned and unmanned
     space program. Supports completion of Space
     Station Freedom and enhancements to the fleet
     of Space Shuttles to ensure safety and
     reliability.

*    Has championed Mission to Planet Earth, an
     initiative designed to gather comprehensive
     information on the Earth's changing
     environment. He strongly supports  efforts to
     channel information on the Earth's environment
     to teachers and school children.

*    Strongly supports efforts to strengthen our
     leadership in aviation.

*    Has tried to use space exploration as a bridge
     to international cooperation, not competition.
     Pushed the administration to investigate the
     possibilities for integrating surviving
     elements of the Soviet space program into the
     U.S. program in ways beneficial to America and
     its aerospace workers.

*    Following the Challenger disaster, Senator
     Gore uncovered quality assurance deficiencies
     at NASA, gaining a greater commitment to
     quality assurance and accountability at NASA.



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

Date: Thu, 3 Sep 1992 14:50:36 GMT
From: Jim Sims <[e-mail]>
Subject: Inflatable Space Stations - Why Not ?
Newsgroups: sci.space

>I have read in several sf stories about using the shuttle main tanks as
>modules for space habitats...just having the shuttle carry the tank with it
>into orbit.  Some authors stated that it would not take any extra fuel(??)
>to do so.

>Any of you experts out there have an answer as to why NASA doesn't use the
>tanks as at least a temporary habitation?

 Maybe this should go into the FAQ so new readers will quit asking it
 repeatedly?

 There are many reasons why we dont use the ETs. *I* believe most of them
 are smokescreens to preserve fred, your mileage may vary...

 (1) It would "cost" several hundred (up to coupla thousand depending on
 the orbit) pounds of payload to boost the ETs to the same orbit as the
 shuttle. No free lunch, kids....

 (2) Not all shuttle flights are to the same orbit, not all these orbits
 are places you'd wanna put an ET "hotel". For example, the HST orbit was
 as high as the shuttle could reasonably go with that weight of payload and
 have fuel for two re-dockings with the payload in case of snafus during
 post-deployment (and still come home ;-)

 (3) Since the foam isn't that well attached (least it wasn't when I was
 working at Michoud - there were big-time delamination problems on a few),
 you'd like increase the debris up htere *a lot*. Making sure it stays
 sub-orbital avoids this problem (and acknowleding and fixing it as well :-(

 (4) Once you get the ET up there, you need to do a coupla things:
  (a) remove remaining Hydrogen and Oxygen - sounds like a win, since the
  shuttle *never* empties the ET on the way up- typically 5% ?? of the fuel
  goes into the ocean or atmosphere on the way back down... But, how ya
  gonna get it out?

  (b) you need a docking port and/or at least a entry hatch - cutting a
  hole in 1" aluminum has likely never been tried in space. welding (burn a
  hole) in space is non-trivial as well....

  other problems left to the imaginative reader....

---------------------------------------------------------------------------
 [e-mail]                               The MITRE Corporation
 DECUS AI SIG Symposium Representative            7525 Colshire Drive   MS Z421
 the opinions are mine, who'd wanna claim 'em?          McLean, Va.   22102

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

Date: 3 Sep 1992 20:11:59 GMT
From: Jeff Bytof <[e-mail]>
Subject: Laser distance record?
Newsgroups: sci.space

>In article <[e-mail]> [e-mail] (SCOTT I CHASE) writes:
>>In article <[e-mail]>, [e-mail] (Jeff Bytof)
>writes...
>>>To date, what is the farthest that a laser has been seen from?
>>>
>>>I recall a successful experiment sending a laser beam from the
>>>Earth to a Surveyor lander on the Moon in the sixties.  That would
>>>make the current record approx. 384,400 km?
>>
>>If you allow masers, then the answer is best measured in parsecs.  Oh... you
>>want man-made lasers.  Never mind.
>>

>I seem to recall reading something about natural lasers in the atmoshere
> of Venus??????

Gee, I thought my question was clearly stated :-(.

Manmade transmitter, manmade receiver, confirmation of receipt,
of a Laser (optical maser) signal.  What is the maximum confirmed
link distance of said system?

Jeff Bytof
[e-mail]

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

Date: 3 Sep 92 18:45:45 GMT
From: Jeff Bytof <[e-mail]>
Subject: Laser distance record?
Newsgroups: sci.space

To date, what is the farthest that a laser has been seen from?

I recall a successful experiment sending a laser beam from the
Earth to a Surveyor lander on the Moon in the sixties.  That would
make the current record approx. 384,400 km?

Jeff Bytof
[e-mail]

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

Date: 3 Sep 92 20:23:59 GMT
From: SCOTT I CHASE <[e-mail]>
Subject: Laser distance record?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Jeff Bytof) writes...
>To date, what is the farthest that a laser has been seen from?
>
>I recall a successful experiment sending a laser beam from the
>Earth to a Surveyor lander on the Moon in the sixties.  That would
>make the current record approx. 384,400 km?

If you allow masers, then the answer is best measured in parsecs.  Oh... you
want man-made lasers.  Never mind.

-Scott
--------------------
Scott I. Chase            "The question seems to be of such a character
[e-mail]        that if I should come to life after my death
                and some mathematician were to tell me that it
                had been definitely settled, I think I would
                immediately drop dead again."      - Vandiver

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

Date: Thu, 3 Sep 1992 19:38:38 GMT
From: Ed Faught <[e-mail]>
Subject: Laser distance record?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (SCOTT I CHASE) writes:
>In article <[e-mail]>, [e-mail] (Jeff Bytof)
writes...
>>To date, what is the farthest that a laser has been seen from?
>>
>>I recall a successful experiment sending a laser beam from the
>>Earth to a Surveyor lander on the Moon in the sixties.  That would
>>make the current record approx. 384,400 km?
>
>If you allow masers, then the answer is best measured in parsecs.  Oh... you
>want man-made lasers.  Never mind.
>
>-Scott
>--------------------
>Scott I. Chase            "The question seems to be of such a character
>[e-mail]        that if I should come to life after my death
>                and some mathematician were to tell me that it
>                had been definitely settled, I think I would
>                immediately drop dead again."      - Vandiver

I seem to recall reading something about natural lasers in the atmoshere of
Venus??????
--
Ed Faught  WA9WDM  [e-mail]
 Superconducting Super Collider Laboratory

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

Date: 3 Sep 1992 19:47:59 GMT
From: Jeff Bytof <[e-mail]>
Subject: Laser distance record?
Newsgroups: sci.space



>In article <[e-mail]>, [e-mail] (Jeff Bytof) writes...
>>To date, what is the farthest that a laser has been seen from?
>>
>>I recall a successful experiment sending a laser beam from the
>>Earth to a Surveyor lander on the Moon in the sixties.  That would
>>make the current record approx. 384,400 km?

>If you allow masers, then the answer is best measured in parsecs.  Oh... you
>want man-made lasers.  Never mind.

I mean the "link distance" between a transmitter and an actual reciever.

Jeff Bytof
[e-mail]

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

Date: Thu, 3 Sep 1992 19:18:54 GMT
From: Matthew Sheppard <[e-mail]>
Subject: Shuttle traking programs
Newsgroups: sci.space

I had in my possesion a shareware version of a program that showed the
shuttles current location on a world map.  You had to supply it with
certian numbers about the launch such as time and things and it kept
track of where it was.

Could someone point me to where I could find this program or even it's
name so I could find it on ARCHIE?  Please mail responses if possible,
and post them too.

--
| Matthew Sheppard  CLARKSON UNIVERSITY  [e-mail] |
| I'd rather have a bottle in front of me than a frontal lobotomy.ANoN |
| I don't want a pickle. DoD#477 TEP#477 RIDE FREE (8^]..etcetera..    |

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

Date: Thu, 3 Sep 92 12:23:58 BST
From: [e-mail]
Subject: Sizing of launch vehicles (was Saturn Class)

> programs are under different associate administrators).  The Space
> Station has mandated from the beginning that they will use the
Space
> Shuttle for delivery, so the question never was asked.
>


Dani:

As you are no doubt aware, it is being asked now. Goldin has a team
looking at all the options, including heavy lift and high inclination
orbits (which could utilize Energiya & allow joint ops with the
russians). Maybe it's just another study and then again, maybe it
ain't...

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

Date: Thu, 03 Sep 92 18:20:28 EDT
From: Tom <[e-mail]>
Subject: Special Relativity

>>>Neglecting the engineering problems of high speed travel through an
>>>imperfect vacuum, you can travel light centuries in subjective
>>>hours if you accelerate long enough. If you arrive at the Andromeda
>>>galaxy 2 weeks after leaving earth, you could be justified in
>>>thinking you travelled faster than c. It's just that the rest of
>>>the universe will have aged 2x10^8 years.

>> No. You would not feel you are going faaster, but the universe got smaller
>> and slower.  These are stardard result of Special Relativity.

I bet you can't describe the difference between these interpretations
of the same event, save that they are made by different observers.
One of the standard results of SR is the non-objectiveness of any frame.
(The frame of our near-c trip to M31 becomes inertial when the engines
are turned off, BTW)

Wasn't one of the confirmations of SR that unstable particles moving at
near c would decay past their expected places?  From our point of view,
their time slowed down.  From their point of view, our frame got shorter.
Aren't both interpretations correct?  We can easily extrapolate to the
case of an observer at lightspeed, as the original poster (whose name
I've stupidly deleted, and forgotten) has done.

Isn't all math, from calculus on up, based on an understanding
of limits?  I think c = infinity, (in the photon's frame) is a pretty
good way to get an intuitive idea of what's going on.  After all, c
is a limit, not a speed (for anything with mass).

Has anyone done any actual math in this vein?

-Tommy Mac                     .  "                  +
.------------------------  +                      *       +
|   Tom McWilliams; scrub       ,     .                        "        +
|  astronomy undergrad, at     *       +;.     .  '             There is
| Michigan State University   '                      .    "   no Gosh!
|   [e-mail]                        '      ,   *
|       [phone]       ;  +  '                                 *
'-----------------------

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

Date: 3 Sep 92 13:22:38 GMT
From: Nick Szabo <[e-mail]>
Subject: SPS feasibility and other space development
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>There are times when you follow hunches and gut feel on engineering
>issues because you simply don't have solid fact to go on.

This is quite different than persisting with a narrow set of hunches,
turned into religiously held beliefs, even if they have failed over
and over, at great cost, while ignoring the many superior alternatives.

>I think both Dennis and I and Allan would all agree that the fastest
>way to drive a technology (rather than science) into the the future
>capabilities we want is to build lots of quick and dirty prototypes
>that we can crash, blow up and otherwise mangle as a means of
>collecting EMPIRICAL data.

This is not at all what Dennis and Allen have been promoting.  They
have been advocating huge, expensive projects like HLVs, space stations,
astronauts to Mars, and SPS that, when they fail, bring big chunks of
the space program down with them.  They say we lack "vision"
or "guts" unless unless we are willing to bet the house on such singular
spectaculars.

I say we have lost too many houses on such bets, and look where we
are.  Let's indeed learn from our failures, and invest in projects
that, when they fail, indeed let us learn quickly and move on.
Let's invest in small, automated spacecraft that can hold a
wide variety of payloads, from biological adaptation to planetary
prospecting.  Let's explore the entire solar system, which we can do
with just a fraction of NASA's budget with many small spacecraft,
instead of prejudicially planning our space future as if we know all we
need to know, and any barriers or failures are of just due to "lack of
will" (what a god-awful cliche, used by everybody from HUD-boosters to
astronaut fans to promote their favorite piece of pork).

Let's make NASA support the commercial space industry, by buying their
launchers and leasing their communcations networks, instead of NASA
dictating their narrow, obsolete plans for the shape, size, and orbit of
space infrastructure to all the other space users.

Let's stop pushing $10's of billions of scarce funds down the ratholes of
bureacracy that surround the HLVs, the shuttles and space stations, long
after they have failed.  These techno-sacraments have little to do with
discovery, of either the scientific or engineering sort, and everything to
do with a disturbingly narrow, obsolete vision of how to move civilization
into space.

In short, you have expressed a great strategy for the space program,
a visions of diverse and quick experiments, nearly 180 degrees opposed
to the way things have been promoted in the space advocacy community
and done at NASA.  Let's turn the keel and get on course.


--
[e-mail]  Public Access User --- Not affiliated with TECHbooks
Public Access UNIX and Internet at [phone] (1200/2400, N81)

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

Date: 3 Sep 92 12:54:40 GMT
From: John Roberts <[e-mail]>
Subject: Teleoperation
Newsgroups: sci.space

-From: [e-mail] (Roger Arnold)
-Subject: Re: With telepresence, who needs people in Earth orbit?
-Date: 1 Sep 92 19:39:08 GMT
-Organization: Intergraph Advanced Processor Division - Palo Alto, CA

-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.

Fortunately, NASA is still working on telepresence and teleoperation. I
don't know the exact level of spending, and no doubt it would be nice if
it were higher than it is, but it's considerably better than ignoring the
subject entirely. I believe one of the cost-cutting measures for SSF was
to have the external robots operated largely from the ground rather than
exclusively by the astronauts on the station.

I would say that the subject line chosen isn't very useful if you want
to discuss constructive cooperation between humans and robots in space.

-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.

That's a pretty harsh accusation, and I think you're exaggerating. I don't
know about ESA, but the US is still working at it. Remember that many of the
cathedrals took on the order of a century to complete - the US has only been
really working on the space program for 30 years or so. Many space
enthusiasts are more impatient than that - they think that space colonies
could be built with something like the level of effort required to build
a local K-Mart, or else that we should speed things up by throwing hundreds
of billions of dollars a year at the problem. As has been shown by previous
missions, doing things in space is actually quite difficult compared to
doing them on the ground - anything that's actually been done has been
much harder than the wilder visionaries had thought. Current public support
for the civilian space effort seems to be around $15-20 bilion a year. As
Allen has pointed out, that's enough to eventually get quite a lot accomplished
if you spend it wisely, or even if you only spend part of it wisely. As you
point out, a large commercial interest could speed things considerably. Part
of what NASA's mission is to develop or encourage the development of space
technologies and markets that will attract private enterprise.

-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.

Sounds reasonable.

-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.

NASA wanted to build such a network several decades ago, and was overruled.
It would be pretty expensive now to set up such a network just as a
precursor to teleoperation. Much better to develop and demonstrate it with
the current communications system, then make a decision on whether to
change the communications. (Would Iridium work for this type of application?)

I've had a chance to play with the lunar delay simulator that Bill Higgins
has written about. It's surprisingly easy to learn - with about two minutes
of training, you can drive the robot around, use it to pick up and move
objects, etc. No doubt a trained operator could do better. Except for
applications that require the application of momentum (i.e. swinging a hammer
or driving a bulldozer through a pile of dirt), and applications that require
rapid response (i.e. cat juggling), the main effect is that operation is
greatly slowed down. But even with a slowdown of 10-20 times teleoperation
could be more economical than doing the same work with humans in space,
provided that it can be done at all with teleoperation.

Other challenges to near-term use of teleoperation:

 - A video display uses up a lot of bandwidth, and provides a lot less
   visual information than seeing the object in person. One thing that can
   help tremendously with this is true 3D or stereo imaging, using two
   cameras side by side. The currently popular way to display it is with
   alternating frames on a conventional video monitor, with liquid crystal
   shutter goggles to separate out the views to the two eyes. Doing this
   in the NTSC format (a pair of views every 1/30 of a second), flicker
   isn't really a problem if the light levels aren't too high. Faster
   refresh rates of course are possible if you have the bandwidth. The
   JPL people working on the small Mars rovers use this kind of 3D imaging.

 - Aside from feedback delay, most currently available remote-control
   general-purpose robots don't have particularly great dexterity and strength.
   Improving the strength shouldn't be too hard, but dexterity is very
   tricky - we're a long way from what humans can do, even in EVA suits.
   But there is progress - I saw some interesting robot hands at Bell Labs
   in Holmdel.

 - Sophisticated robots are among the most complicated mechanical devices
   around, and not particularly reliable even on Earth. In space, mechanical
   devices seem to break down even more easily. Building a teleoperated
   robot that can manipulate its environment isn't too difficult, but
   building one that can be used effectively to repair another robot of the
   same kind is a much more difficult task. When the robots start to break
   down, it can be very useful to have humans nearby to repair them. (This
   would apply to a space station, for instance, where humans are already
   present.)

John Roberts
[e-mail]

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

Date: 3 Sep 92 18:51:14 GMT
From: Lee Mellinger <[e-mail]>
Subject: TOPEX, demise of SEASAT & nuclear sub wakes
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gerald Cecil) writes:
:I think that the accepted explanation of its failure after only a few weeks wa
:a chip burnout, remarkable that there was no redundancy.) Have sub props been
:modified?  Does anyone have further details on the demise of SEASAT?
:--
:Gerald Cecil  [e-mail]  919-962-7169

The official cause of the failure was metal particles shorting across
the solar panel power slip rings causing a massive and nearly
instantaneous power failure.

Lee

"Mit Pulver und Blei, die Gedanken sind frei."

|Lee F. Mellinger                 Caltech/Jet Propulsion Laboratory - NASA
|4800 Oak Grove Drive, Pasadena, CA 91109 818/354-1163  FTS 792-1163
|[e-mail]

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

Date: 3 Sep 92 12:44:00 GMT
From: pete <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>,
[e-mail] (Richard Ottolini) writes...
>In article <[e-mail]>
>[e-mail] (pete) writes:
>>Neglecting the engineering problems of high speed travel through an
>>imperfect vacuum, you can travel light centuries in subjective
>>hours if you accelerate long enough. If you arrive at the Andromeda
>>galaxy 2 weeks after leaving earth, you could be justified in
>>thinking you travelled faster than c. It's just that the rest of
>>the universe will have aged 2x10^8 years.
>
>No. You would not feel you are going faaster, but the universe got smaller
>and slower.  These are stardard result of Special Relativity.

*sigh* ...I should just learn to keep my mouth shut.
OK consider: you've accelerated to .99999 c relative to your
original frame. Tangential to your world line at that instant
is an inertial frame, in which your speed is instantaneously 0.
Now consider this new frame to be the rest frame, and your
velocity relative to it is small, but steadily increasing as
you continue your constant acceleration. Clearly, a newtonian
approximation of your situation considered from this frame
will conclude that you continue to experience the full force
of your acceleration, just as you did when you first started
from your initial rest frame. That is, just because you are
travelling at nearly c relative to your initial frame doesn't
mean that in your frame you sense your acceleration decreasing.
And you have absolutely no reason to model the universe outside
as getting smaller. That's just silly. As far as you're
concerned, the simplest model is just that you're going
steadily faster. Now if you were able to detect the passing
of time in the universe at large, which is assumed to be at
rest relative to your initial frame, it would seem to you
that their time was going by faster and faster, til millenia
were going by with every breath.

===========================================================================
Jeez, I really _liked_ the image of                   Pete Vincent
time and space pivoting about the
speed of light. Had a nice Minkowski
sort of feel to it.

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

Date: Thu, 3 Sep 1992 15:21:29 GMT
From: Thomas Clarke <[e-mail]>
Subject: With telepresence, who needs people in Earth orbit?
Newsgroups: sci.space

In article <[e-mail]> [e-mail]
(Roger Arnold) writes:
> In article <[e-mail]>, [e-mail] (Allen W. Sherzer)
writes:

> 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?

Easier still, use the Motorola Iridium constellation of 77
satellites for teleoperation.  Iridium should work just as
well for LEO as for "cellular phones" on the ground.

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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End of Space Digest Volume 15 : Issue 164
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