Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V08/V8_308.TXT

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Date: Mon, 1 Aug 88 01:05:04 PDT
From: Ted Anderson <[e-mail]>
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Subject: SPACE Digest V8 #308

SPACE Digest                                      Volume 8 : Issue 308

Today's Topics:
Special communications system prepared for Neptune encounter (Forwarded)
      RE: Re: International agreements on space station
            astronomy newsletters
              Re: Orbital Launch Methods
              Lithium Batteries
               Re: Solar Sails
Proposals sought for space-based laser to study global winds (Forwarded)
        Trust Fund Proposed for Space Ventures
----------------------------------------------------------------------

Date: 20 Jul 88 20:03:57 GMT
From: [e-mail]  (Peter E. Yee)
Subject: Special communications system prepared for Neptune encounter (Forwarded)

Jeff Vincent
Headquarters, Washington, D.C.                      July 20, 1988

Paula Cleggett
Headquarters, Washington, D.C.

James H. Wilson
Jet Propulsion Laboratory, Pasadena, Calif.

Release:  88-102

SPECIAL COMMUNICATIONS SYSTEM PREPARED FOR NEPTUNE ENCOUNTER

     Scientists and engineers from NASA's Jet Propulsion
Laboratory (JPL), Pasadena, Calif., and the National Radio
Astronomy Observatory (NRAO), Socorro, N.M., are working together
in the high plains of central New Mexico to improve the ability
to receive spacecraft signals from the vicinity of planet
Neptune.  The researchers are currently testing a new deep-space
communications system with NASA's Voyager 2 spacecraft, which
will fly past the eighth planet next year.

     When Voyager 2 reaches Neptune in August 1989 to take close-
up pictures and thousands of other measurements, the spacecraft
will be nearly three billion miles from home.  Its signal
received on Earth will be extremely faint.

     Adding the 27 radio telescopes of the NRAO's Very Large
Array (VLA) to JPL's Deep Space Network (DSN), which communicates
with interplanetary spacecraft, will more than double the ability
to capture Voyager's signal.  The signal will be received eight
hours per day for 40 days of the encounter -- the period that
Voyager and Neptune will be above the horizon at the New Mexico
desert site.

     Under an agreement between NASA and the National Science
Foundation, which sponsors NRAO, engineers are installing new
receivers and microwave horns, tuned to Voyager's X-Band radio
frequency, on all the 82-foot dish antennas at the VLA.  Special
signal-processing and communication equipment has been added so
that the VLA will be linked by satellite to the DSN's Deep Space
Communications Complex at Goldstone, Calif.

     The new X-Band receiver systems were designed and built
cooperatively by JPL, VLA, and NRAO's Central Development
Laboratory at Charlottesville, Va.  Like those of the DSN, the
advanced receiver circuits are kept chilled with liquid helium to
suppress internal electronic noise.  NASA also has provided an
independent power generator for the array, which has suffered
power failures from summer lightning storms.

     This month's system test is the first chance to preview
Neptune operations with the whole worldwide communication system,
including elements at the VLA.  The Voyager spacecraft, now 2.4
billion miles from Earth, will transmit in its planetary
encounter mode, at data rates up to 21,600 bits per second (the
rate used for Voyager's encounter of Uranus in 1986).  Linked
electronically, the two systems -- 23 VLA antennas that now have
their X-Band receivers, and the 112-foot and 230-foot dishes at
Goldstone -- will function as a single receiving system.

     The VLA, located about 100 miles southwest of Albuquerque,
has, since 1980, enabled radio astronomers to study distant
stars, nebulae and galaxies by collecting and analyzing radio
emissions from these objects.

     The 27 mobile dishes are arrayed along a Y-shaped railroad
track and can be rearranged for different observations.  William
D. Brundage, VLA project engineer, is responsible for Voyager
preparations at Socorro.

     Voyager 2 was launched in August 1977, and has subsequently
explored the planetary system of Jupiter, Saturn, and Uranus.

     The DSN has been developing and operating as a NASA system
for nearly 30 years.  It has communicated with spacecraft and
astronauts on the Moon; tracked and commanded Earth-orbiting,
unmanned spacecraft, and those sent to explore comets and six of
the nine planets; and to probe the outer reaches of the solar
system.

     Besides the Goldstone complex, the DSN includes stations in
Spain and Australia, where Australia's Parkes Radio Telescope was
linked with the DSN's antennas in 1986 to support Voyager 2's
encounter of Uranus.  This link will be made again for next
year's encounter.  JPL's Donald W. Brown is interagency arraying
manager for the DSN, with overall responsibility for the Socorro
link.

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

Date:     Thu, 21 Jul 88 05:14 EDT
From: RON PICARD <[e-mail]>
Subject:  RE: Re: International agreements on space station

> Why do so many people forget the first "A" in "NASA"?

Good question...I have to plead guilty.  Probably because the "S"
is the only thing that makes the popular press.  I'd be interested
to hear what some of the "A" work includes although it might not
be suitable for the space network.

Ron Picard  ([e-mail])

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

Date: 21 Jul 88 19:14:20 GMT
From: [e-mail]  (Frank Simmons)
Subject: astronomy newsletters


 I represent the Arrowhead Astronomical Society. I am interested in knowing
 if there are other club members reading this ; if you would be interested
 in exchanging newsletters; and if you have an electronic newsletter you
 would not mind sharing.




Frank Simmons                      BITNET: [e-mail]
UMD Information Services           INTERNET : [e-mail]
Univ of Minn,Duluth                ATT   : [phone]/7587
10 University Drive                SYSTEM : VAX/VMS 4.7  JNET 3.0
Duluth MN 55812-2496

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

Date: 20 Jul 88 16:17:45 GMT
From: ns![e-mail]  (John Logajan x3118)
Subject: Re: Orbital Launch Methods

In article <[e-mail]>, [e-mail] (John Logajan x3118) writes:
> >>get into orbit more cheaply by first going straight up and then going
> >>horizontal at an altitude where the orbital speed would be much lower.

Okay, I put this scenario into a simulator and found that if I shoot a
projectile straight up at orbital velocity (from the surface of the earth)
it will reach an altitude of 4000 miles (just double its starting height
from the center of the earth -- hmmm coincidence?)

Orbital velocity at 4000 miles is quite significant, so I would say that
it is not cheaper to go straight up first and then fire horizontally.

Unless of course you have some form of launcher that is earth based, such
as an electro-magnetic launcher.  Then the economies of the launch system
might overcome the additional energy requirements needed for the "tennis
ball serve" launch.

- John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428 -
- {...rutgers!umn-cs, ...amdahl!bungia, ...uunet!rosevax!bungia} !ns!logajan -

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

Date:     Thu, 21 Jul 88 09:22:27 EDT
From: Peter Allsop <[e-mail]>
Subject:  Lithium Batteries

The BITNET summaries of Space Digest can be a bit behind, so
if this has already been said, sorry ...


In Digest 8 # 871 Paul Hass wrote:

> {stuff on explosive potential}  I have also heard of lithium batteries
>"outgassing" ie. spewing out the nasty electrolyte.  Lithium batteries
>are usually made of lithium and something from the other side of the
>periodic chart, iodine, bromine, chlorine, etc...

You heard correctly, Lithium batteries can excrete a real nasty
(read corrosive) liquid.  A few years ago the Canadian government made
it manditory for all civil aviation aircraft to carry an Emergency Locator
Transmitter (ELT) powered by a Lithium battery.  (Actually they required
it run for a minimum number of hours at low temperature, and it worked out
that a Lithium battery was the most feasible one to use).  Everybody complied
and things seemed great for about 6 months ... then the failure reports
starting coming in.  First came the reports of explosions, ELT's blowing
holes in the hulls of (fortunately) parked aircraft.  As I recall these
were attributed to overheating (solar), not shorts.  Then came the reports
of corrosion problems.  Several people had the batteries leak so badly that
they ate right through the housing of the ELT *and* the hull of the
aircraft (I saw one such case).  Not long after that came the NOTAM - pull
all ELT's with Lithium batteries from aircraft & inspect for damage.  When
we pulled ours I opened it up & literally poured the electronics out of
the case ... the components had been liquified!  The 1/8" aluminium case
of the ELT had been eaten almost all the way through in a few spots ...
far too close for comfort! NASA may be taking a rather conservative
approach in banning Lithium batteries, but their history is not encouraging.

             Peter Allsop <[e-mail]>       (old form)
                          <[e-mail]> (new form)

Science is truth, don't be mislead by facts.

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

Date: 21 Jul 88 15:48:08 GMT
From: [e-mail]  (David Palmer)
Subject: Re: Solar Sails

In article <[e-mail]> [e-mail] (Steve) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>Easy.  Special relativity tells us that there is no such thing as mass or
>>energy in isolation:  you always have both.  That means that energy, e.g.
>>light, has mass.  And so it does, and hence it has momentum, and bouncing
>>it off a reflective surface imparts momentum to said surface.  Light does
>
>If the light bounces off the sail, how does it impart momentum.  What
>energy of the photon is now reduced?  I think the photons must be
>ABSORBED by the sail for this to work.
>
>=Steve=

Momentum is a vector.   When a photon bounces vertically off a light-sail,
its momentum reverses itself, so the momentum it gives the light-sail
is twice its original momentum (in its original direction).

The energy given to the sail is taken away from the photon and appears
as a redshift.  N.B. the energy is equal to momentum transfer times
the velocity of the sail, so when the sail is stationary, there is
no energy transfer as well as no redshift.  (I know what I'm talking
about, so if you disagree, mail me first and I'll explain it.)

        David Palmer
        [e-mail]
        ...rutgers!cit-vax!tybalt.caltech.edu!palmer
            "Flowers -- Just say NO!!"
                    - Mighty Mouse

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

Date: 21 Jul 88 02:41:22 GMT
From: [e-mail]  (Peter E. Yee)
Subject: Proposals sought for space-based laser to study global winds (Forwarded)

Charles Redmond
Headquarters, Washington, D.C.                      July 21, 1988

Bob Lessels
Marshall Space Flight Center, Huntsville, Ala.


RELEASE:  88-103

PROPOSALS SOUGHT FOR SPACE-BASED LASER TO STUDY GLOBAL WINDS


     NASA's Marshall Space FLight Center, Huntsville, Ala., today
issued a request for design proposals for a new, space-based
remote sensing instrument to measurement wind characteristics,
thereby permitting scientists to better understand and contribute
to weather predictions on Earth.

     The Laser Atmospheric Wind Sounder will be an advanced light
detection and ranging (LIDAR) instrument.  Just as radar operates
by bouncing radio waves off distant objects and sonar bounces
sound waves off underwater objects, LIDAR bounces light waves,
generated by a laser, off atmospheric particles.  Analysis of the
reflected light will reveal the direction and speed of the winds
and provide information on the amount of particulate matter,
known as "aerosols", suspended in the atmosphere.

     The sounder will provide real-time global wind profiles for
the lowest weather-producing layer of the Earth's atmosphere.
Whether obtained globally using the polar-orbiting Earth
Observing System platform or from the tropics and subtropics
using the manned Space Station, the wind profiles will provide
essential data to improve understanding of the global
biogeochemical and hydrologic cycles and understanding of large
scale atmospheric circulation and climate dynamics.  This new
information also can be used by weather forecasters worldwide as
an aid in improving their numerical predictions.

     According to Carmine E. De Sanctis, chief of the Space
Science and Applications Group at the Marshall center, the
sounder could be operational by 1996 as one phase of NASA's
larger Earth Observing System initiative.

     The sounder would enable meteorologists at the National
Oceanic and Atmospheric Administration to develop more accurate
5-day weather forecasts.  At present, severe weather warnings can
be issued only for broad areas of the United States.

       A major problem is an inability to obtain global wind
velocity measurements.  "Most atmospheric wind velocity data is
obtained using sounding balloons," Dr. Vernon Keller, the
sounder's assistant project manager, said.  "Unfortunately, most
of these balloons are, of necessity, launched from land.  More
than two-thirds of the Earth's surface, however, is water, thus
there exist large areas of the globe -- particularly in the
southern hemisphere -- which receive only minimal measurement
coverage."

     The sounder will allow worldwide coverage with special
emphasis given to tropical and subtropical areas where,
previously, measurements have been sparse to non-existent.

     According to Richard Beranek, the sounder's project manager,
"It will enable forecasters to obtain wind velocity data from
ground level up to an altitude exceeding 40,000 feet.
Preliminary concepts involve using a proven carbon dioxide
coherent laser, operated at an eye-safe infrared wavelength, to
survey winds over Earth's entire surface at least once a day.
Data would be provided to meteorologists worldwide to assist in
developing weather projections to benefit all mankind."

     In addition to weather projections, researchers anticipate
the data will assist in analyzing the impact natural occurences,
such as volcanic eruptions, and human activity, such as the slash
and burn land clearing now under way in many developing
countries, are having on the global environment, Beranek said.

     Dr. Keller said the earliest work on the sounder began at
the Marshall center in 1967 with various designs being tested on
the ground.  In 1981, tests began using a laser atmospheric wind
sounder-like system aboard an aircraft.  Results obtained during
the last 21 years have left Marshall engineers feeling confident
in proposing the space-based system.

     "We hope to see a design emerge which will be flexible
enough to permit us to incorporate state-of-the-art advances in
lasers, optics and other related systems as they emerge over the
sounder's projected lifespan," De Sanctis said.  "The beneficial
impact it will have on enhancing our understanding of the
environment is certain to be very significant."

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

Date: 21 Jul 88 16:47:04 GMT
From: att!lzaz!lznv![e-mail]  (Paul S. R. Chisholm)
Subject: Trust Fund Proposed for Space Ventures

< "Would you buy a used operating system from these guys?" >

from Design News, 7/4/88, p. 26:

"With tight federal budgets, how can the nation pay to meet growing
opportunities in space?  New Jersey's Rep. Robert A. Roe, chairman of
the House Science, Space, and Technology Committee, proposes a trust
fund like the one that financed the interstate highway system.  He
thinks Americans would gladly buy bonds to support thrusts across space
frontiers.  Roe doubts that Uncle Sam alone could finance such costly
proposals as an inhabited base on the moon or a joint U.S.-Soviet
manned mission to Mars.  The National Aeronautics and Space
Administration has a tough enough fight getting funds for a manned
orbiting space facility. . . .  --Walter S. Wingo, Washington Editor"

[Typical of N.J. reps; "I'm in favor of the space program, if you can
build an interstate to orbit."]

-Paul S. R. Chisholm, {ihnp4,cbosgd,allegra,rutgers}!mtune!lznv!psc
AT&T Mail !psrchisholm, Internet [e-mail]
I'm not speaking for my employer, I'm just speaking my mind.

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

End of SPACE Digest V8 #308
*******************