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Subject: SPACE Digest V11 #64

SPACE Digest                                      Volume 11 : Issue 64

Today's Topics:
             Re: Shuttle launches
               Re: inter stellar travel
            Re: metric vs. imperial units
             Re: maintaining L5 position
   Soyuz TM-8 mission lands after 6 months on Russia's Mir station
            Re: metric vs. imperial units
              Re: NSS STATEMENT
         Did SEASAT See More Than It Was Supposed To?
----------------------------------------------------------------------

Date: 19 Feb 90 13:08:39 GMT
From: portal!portal!cup.portal.com![e-mail]  (Stephen R Fleming)
Subject: Re: Shuttle launches

[sorry for using bandwidth - E-mail bounced]

Tim,

>I will be making a pilgrimage to the northern hemisphere later this year
>and would love to see a shuttle launch.
>1) Is it worth it?

*I* think so.  I've seen four so far, including the very first (for which I
slept in a Toyota Celica on the side of the road) and I've been thrilled
each time.   Most of the griping I've heard is that "a Shuttle launch is
nothing compared to an Apollo V."  Well, that's probably true, but I never
saw an Apollo launch, and the Shuttle is pretty darn impressive on its own
merits.

>2) How far in advance are launch dates scheduled; is there a list of
>    launched scheduled for Sept (+/- 1 month) 1990?

I have no idea, but others on the net will know.

>3) Any suggestions or hints on observing strategy?

I followed the simplest possible strategy, which I recommend to anyone...
drive down the west bank of the Indian River until you reach the highest
density crowd, squeeze into a illegal parking space, turn the radio to an
all-news station, and sit on the hood.  I suppose there are more
sophisticated viewing methods, but this has worked well for me.

School of Physics, Sydney Uni... is Harry Messel still there wrestling
alligators?  If he has an E-mail address (and checks his account), I'd love
to know it... I was in his summer program many, many moons ago.

+-----------------------------------------------------------------------+
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------------------------------

Date: 19 Feb 90 10:52:01 GMT
From: eru!luth!sunic!chalmers!mathrt0.math.chalmers.se!hacke1![e-mail]  (Bertil Jonell)
Subject: Re: inter stellar travel

In article <[e-mail]> [e-mail] (Brian or James) writes:
> [Deleted]
>Imagine Lebanon's civil war in a L-5 style community. IMHO,
> [Deleted]
> Of course, that doesn't mean the 'Onealers' won't occur, just that from
>time to time, the poor people 'trapped' on planets might be needed to restart
>Oneal civilizations.

Why are "dirtsiders" needed to restart a wasted space habitat?
The other habitats could do it themselves.

Bertil K K Jonell @ Chalmers University of Technology, Gothenburg
NET: [e-mail]
VOICE: [phone] / [phone]     "Don't worry,I've got Pilot-7"
SNAILMAIL: Box 154,S-43900 Onsala,SWEDEN      (Famous last words)

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

Date: 19 Feb 90 15:07:52 GMT
From: elroy.jpl.nasa.gov!usc!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!attcan!telly!druid![e-mail]  (D'Arcy J.M. Cain)
Subject: Re: metric vs. imperial units

In article <[e-mail]> [e-mail] (Mike Peltier) writes:
> [...]
>When you start getting funky numbers going into a calculation, such
>as 5280, 12, 212, 32, etc, instead of 1000, 10, 100, 0, etc, you start
>introducting the potential for computational errors caused by the facts
>that computers can only represent numbers with limited significance,
>and use mantissa/exponent notation.
>
>Seeing as how you're at an institute of Computer Science, you should
>know about this stuff -- dividing 5 by 212 gives you:
>0.023584905...  Which a computer could only represent to a certain
>number of significant digits, and if you pile up those approximations,
>they will eventually throw your result off by a significant degree.
>However, if you divide 5 by 100, you get, very simply, 0.05, which
>is well within any computer's capability to represent exactly.
>
>Subtractive cancellation, round off errors, etc...  Anytime you
>get long strings of decimal numbers, these little mosters are
>bound to catch up with you.
>
>
Seems to me I heard this argument when Canada went metric and it doesn't
make any more sense today than it did then.  OK, 5/212 is less exact
than 5/100.  So 5 metres divided by 212 metres loses significance.  That
is a metric calculation.  The argument you are making is for decimal
over some other numbering system.  You can easily use decimal for Imperial
units just as easily as for metric.  Consider airline pilots who routinely
specify altitude as 5,000 feet, 10,000 feet etc.  That's decimal.  They
never convert to yards miles or inches.  It is perfectly allowable in
Imperial to state a distance as 0.5 feet instead of 6 inches.

Remember we are talking about real world measurements (it is a measuring
system, not some abtract mathematics) so a distance will often be inexact
to begin with.  A real world measurement might be ~254 cm.  That's 100
in.  Should we always convert to the most decimal number?


--
D'Arcy J.M. Cain (darcy@druid)     |   Thank goodness we don't get all
D'Arcy Cain Consulting             |   the government we pay for.
West Hill, Ontario, Canada         |
[phone]                     |

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

Date: 19 Feb 90 18:10:42 GMT
From: samsung!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: maintaining L5 position

In article <[e-mail]> [e-mail] (Martin J Brown-Jr) writes:
>I have read that L5 in the Earth-Luna system is a gravity "plain", not a
>"well"...

No, there is a real live gravity well there, albeit a rather broad and
shallow one, provided that the ratio of primary:secondary masses
exceeds a certain number (which the Earth-Moon system does).  The L1,
L2, and L3 points are gravity "saddles" -- stable against perturbations
in only some directions -- but L4 and L5 are true gravity wells.  In
particular, it is possible to have orbits "around" them, although the
orbits have slightly funny shapes.  Such an orbit may be more stable
against perturbations than trying to park at the point itself.

>... any perturbation from
>the sun will cause a space habitat to wander across the surface of
>the L5 "plain".
>So my question is:  can anyone give me any general concept of how much
>energy would be required to overcome the sun's perturbations and to
>keep an L5 habitat at or near the mathematical L5 point (Earth-Luna)?

At?  Probably quite expensive, there *are* perturbations and the restoring
forces from the gravity well are weak.  Near?  Zero, as witness the
Trojan asteroids in Jupiter's L4 and L5 points, which have been there
for a long time.  There has been considerable speculation on, and some
reporting sightings of, thin dust/debris clouds in the Earth-Moon L4/L5
points.

>You may assume that "stationkeeping" means anything within 100 kms of
>the mathematical L5 point...

I assume this is your definition of "at the L5 point", as opposed to
"near the L5 point".  If you're willing to settle for some tens of
thousands of kilometers instead, nature will do it for you.  Is there
a reason why you need such tight stationkeeping?
--
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry [e-mail]

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

Date: Tue, 20 Feb 90 00:04:43 EST
From: Glenn Chapman <[e-mail]>
To: <@cunyvm.cuny.edu:[e-mail]>,
        [e-mail], [e-mail],
        [e-mail], [e-mail],
        [e-mail], [e-mail]
Subject: Soyuz TM-8 mission lands after 6 months on Russia's Mir station

     On Feb. 19th cosmonauts Alexander Viktorenko and Alexander Serebrov
returned to earth in their Soyuz TM-8 craft.  Landing at about 7:35 am
Moscow Time (11:35 pm Feb. 18th EST) they were in orbit for 167 days, since
Sept. 5, 1989. Currently they are back in Star City, near Moscow.  TV
pictures of them showed them walking from the plane taking them there after
landing, obviously in good shape after a nearly 6 month mission.  They
performed 43 major scientific experiments during that time, oversaw the
docking of the Kvant 2 module, and five space walks, including testing
their "Space Bicycle" twice.  In addition the crew brought down the Protein
crystal growth samples for the Cambridge MA based Payload Systems, the
first commercial western crystal growth experiments from the Mir space
station.  These samples were brought up using the Progress TM-2 on Dec.
20th, activated on Dec. 23, so that they were running for about 58 days.
Payload systems statements note that most Protein samples cannot be
crystallized in the 11 day missions that are the longest currently run on
the NASA shuttle.  They have left behind for a 6 month mission on Mir
Anatoly Solovyov (Soyuz TM-5/Mir Jun. '88 for 9 days) and Alexander
Balandin, a new cosmonaut, which arrived on the Soyuz TM-9 Feb. 13th.
(Radio Moscow & Moscow TV Feb 17-19)
     French CNES has signed a deal $12 million for the 14 day mission to
the Mir space station in 1992.  All previous French/Soviet flights have
only been for exchange of data.  This mission, called Antares after a star
in the constellation Scorpio, will concentrate on biomedical and physics
experiments, for which they can bring up 300 Kg (660 lbs) and take down 12
Kg (26 lbs) of samples.  (Spaceflight Feb)  The European Space Agency and
the Soviet Ministry of Foreign Affairs have negociated a wide ranging
agreement on cooperative experiments in microgravity, earth observation,
and the space plane development area. (Space News Jan. 15)  The US based
Planetary Society has formed a design center in conjunction with the
Babakin Center, located near Moscow, to help work on the 1994 Soviet Mars
unmanned probe. This Proton booster launched probe will carry hot air
balloon rovers which will collect soil samples (Spaceflight Feb., Space
News Jan. 15)  The Russians are planning a mission like the ESA's Hipparcos
star mapping mission for the mid 1990's called Lomonosov after a famous
Soviet scientist. (Spaceflight Feb.)
     Sorry this report is a bit later than I wanted but our link to the net
has been down due to ice on the microwave dishes.
     The Russians are doing crew switch offs now and it bearly even rates a
notice on the news here.  Meanwhile we have people like Marsha Smith of the
Library of Congress making comments in the press about how delays in the
launch of Kvant 2 forced them to run their space walks more quickly then
they wished.  At least they get then done and continue to run a permanently
manned space station.  Meanwhile the NASA station bearly even exists on
paper.  Hopefully that will change.

                                                  Glenn Chapman
                                                  MIT Lincoln Lab

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

Date: 19 Feb 90 18:17:03 GMT
From: snorkelwacker!usc!samsung!umich!sharkey!amara![e-mail]  (S. Khai Mong)
Subject: Re: metric vs. imperial units

In article <[e-mail]> [e-mail] (Mike Peltier) writes:
>
>   When you start getting funky numbers going into a calculation, such
>   as 5280, 12, 212, 32, etc, instead of 1000, 10, 100, 0, etc, you start

32 is just fine for computers.

>   introducting the potential for computational errors caused by the facts
>   that computers can only represent numbers with limited significance,
>   and use mantissa/exponent notation.

Unless you have a weird decimal computer that emulates decimal
arithmetic in its computations, you are wrong.  Decimal is as bad as
any nonmetric (i.e. FPS) or whatever.  Now if we could only invent a
binary measurement system, it would be ideal for computers.  By the
way, we already have some of that in volume measurements --- pint,
quarts and gallons.  In fact Knuth, in the Art of Computer
Programming, states that the common units of liquid measurement in
England dating from the 13th centry were completely on a binary scale,
it goes through 13 orders of binary magnitude.

>   Seeing as how you're at an institute of Computer Science, you should
>   know about this stuff -- dividing 5 by 212 gives you:
>   0.023584905...  Which a computer could only represent to a certain
>   number of significant digits, and if you pile up those approximations,
>   they will eventually throw your result off by a significant degree.
>   However, if you divide 5 by 100, you get, very simply, 0.05, which
>   is well within any computer's capability to represent exactly.

Wrong in general. Most computers can't store 0.05 exactly in its
native floating point format.  Even computers that do, its very
inefficient.

Computers are really indifferent to the measurement units used.  What
you really have to worry more about is programming errors about units.
In that, metric is much more simpler, so therefore much less prone to
programming errors.
--
Sao Khai Mong:   Applied Dynamics, 3800 Stone School Road, Ann Arbor, Mi48108
[phone] (uunet|sharkey)!amara!khai  [e-mail]

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

Date: 19 Feb 90 09:30:38 GMT
From: agate![e-mail]  (William Baxter)
Subject: Re: NSS STATEMENT

In article <[e-mail]>, aws@vax3 (Allen W. Sherzer) writes:

>Official Notice from the National Space Society, February 14.

>The so-called "space activist alert" in regards to Mr. Scott Pace
>which has appeared on this bulletin board (as well as others) is
>not a National Space Society action.  Individuals who have
>initiated this alert are acting in their own right and not on the
>behalf of the National Space Society.

True.

>Furthermore, NSS considers this action to be completely
>unjustified and detrimental to the creation of a spacefaring
>civilization.  Scott Pace served as the Executive Vice President
>of NSS and Chairman of the NSS Legislative Committee for the past
>two years.  In this capacity Scott was responsible for
>championing support for space in Congress including commercial
>space programs.  HR 2674, the Commercial Space Transportation Act
>was reviewed by the committee during this time and was supported
>by NSS through written testimony to the House subcommittee on
>Space Science and Applications.

True.  Careful wording avoids the statement that Scott Pace actually
supported HR2674 in his capacity as NSS Legislative Committee chairman,
which would be false.

>Mr. Pace has recently resigned from his posts within the National
>Space Society because he has taken a position within the federal
>government.  In his new position, Scott is working to promote
>space commerce.  It is counter-productive to the National Space
>Society's efforts to support commercial space to pursue Mr.
>Pace's transfer or detachment from this position or to otherwise
>harass him.

In other words, although he has resigned his positions at the NSS, he
maintains close ties with the organization.  The NSS views are Scott
Pace's views, even now.

The point is this:  Those of us working to remove Mr. Pace from his
new position are doing so precisely because it will interfere with "the
National Space Society's efforts to support commercial space," a
euphemism for preventing the development of commercial space industries
for the forseeble future.  If we succeed, the remaining NSS leaders will
find it difficult to use the NSS as a stepping stone to positions of
administrative power as Mr. Pace has tried to do.  And since many of the
people who have supported HR2674 over NSS resistance are also working to
remove Scott Pace from his new position, their fears are well justified.

Help remove Scott Pace from a position of influence.  Write your letters
to the Secretary of Commerce today:
Robert A. Mosbacher
Secretary of Commerce
14th Street at Constitution Ave.
Washington, DC 20230


----
William Baxter

ARPA: web@{garnet,brahms,math}.Berkeley.EDU
UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web

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

Date: 16 Feb 90 05:36:17 GMT
From: cs.umn.edu!nis!wd0gol!newave![e-mail]  (John A. Weeks III)
Subject: Did SEASAT See More Than It Was Supposed To?


The Feb/March issue of Air & Space has a rather interesting
article on the Magellan Venus probe (pages 82-87).

I describing synthetic aperture radar, the article has the
following blurb (3rd to last paragraph on page 83):

    "JPL's study of options for its radar orbiter
    took as its base NASA's ocean-scanning SEASAT
    spacecraft, which in 1978 used synthetic aperture
    radar from a circular orbit so successfully
    that it showed things in the world's oceans
    that the Navy neither expected nor wanted to
    have shown."

Does anyone know exactly what is being alluded to here?

I would assume that the author is referring to one leg of
our strategic triad, rather than the locations of all of
the good fishing spots across the world.

-john-

--
===============================================================================
John A. Weeks III               [phone]               [e-mail]
NeWave Communications                ...uunet!rosevax!bungia!wd0gol!newave!john
===============================================================================

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

End of SPACE Digest V11 #64
*******************