PLEASE NOTE:


*

CCNet DIGEST, 9 September 1998
------------------------------

(1) ABRUPT CLIMATE DISASTER, PUNCTUATED EVOLUTION & HUMAN POPULATION
    CRASH
    Duncan Steel <dis@a011.aone.net.au>

(2) HOW COSMIC IMPACTS HAVE SHAPED THE MOON'S MAGNETIC FIELD
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(3) OUR FRIENDS THE METEORS
    Rolf Sinclair/NSF Physics Division <rsinclai@nsf.gov>

(4) PROPOSAL FOR A NEO SEARCH MISSION UNDER NASA'S DISCOVERY PROGRAM
    Michael Paine <mpaine@tpgi.com.au>

(5) LAUNCH FAILURE STATISTICS
    Duncan Steel <dis@a011.aone.net.au>

(6) HELP NEEDED FOR SCHOOL PROJECT
    Laura Bone <laurabone@sol.co.uk>

(7) WAS IMPACT OF ASTEROID 1998 QS52 POSSIBLE THIRTEEN YEARS AGO?
    Ted Bowell <elgb@lowell.Lowell.Edu>

(8) IRON-EATING BACTERIA & THE ORIGINS OF LIFE
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(9) COMETARY IMPACTS PROVIDE ESSENTIAL SOURCE FOR LUNAR
    COLONISATION: LATEST FINDINGS INDICATE LARGER AMOUNTS OF WATER
    ON MOON
    NASANews@hq.nasa.gov



================
(1) ABRUPT CLIMATE DISASTER, PUNCTUATED EVOLUTION & HUMAN POPULATION
    CRASH

From Duncan Steel <dis@a011.aone.net.au>

University Of Illinois At Urbana-Champaign
http://www.admin.uiuc.edu/NB/98.09/Volcanic.html 

Ancient 'Volcanic Winter' Tied To Rapid Genetic Divergence In Humans

CHAMPAIGN, Ill. -- A new hypothesis about recent human evolution
suggests  that a horrific "volcanic winter" 71,000 years ago, followed
by the coldest 1,000 years of the last Ice Age, brought widespread
famine and death to modern human populations around the world. The
abrupt "bottleneck," or decrease, in our ancestors' populations,   in
turn, brought about the rapid "differentiation" - or genetic
divergence - of the surviving populations.

The hypothesis, offered by anthropologist Stanley Ambrose of the
University of Illinois, proposes that a volcanic winter reduced
populations to "levels low enough for evolutionary changes, which
occur much faster in small populations, to produce rapid population
differentiation," Ambrose said. If, as he believes, the eruption of
Mount Toba in Sumatra caused the bottleneck, "then modern human races
may have diverged abruptly, only 70,000 years ago," Ambrose wrote in
the June issue of the Journal of Human Evolution.

Geneticists long have argued that the human species passed through a
recent bottleneck, but they never offered explanations for the
population crash or recovery, nor considered its consequences for
modern human diversification. Ambrose's model, which he calls the Weak
Garden of Eden/Volcanic Winter model, is an offshoot - with  
significant additions - of the Weak GOE model proposed by Henry
Harpending and others. The Weak GOE model proposes an African origin
for modern humans about 130,000 years ago, and credits the invention
and spread of advanced stone tool technology, 40,000 to 50,000 years
ago, for population growth after the bottleneck. Ambrose argues that
volcanic winter resulting from the super-eruption of Toba "caused the
bottleneck, and that populations may have expanded in response to
climatic warming 10,000 years before the advent of modern technology."

Ambrose has linked geneticists' research to that of volcanologists Michael
Rampino, Stephen Self, Greg Zielinski and colleagues, which shows the
super-eruption of Toba caused a volcanic winter that lasted six years
and significantly altered global climate for the next 1,000 years.
Those six years of "relentless volcanic winter" led to substantial  
lowering of global temperatures, drought and famine, and to a global
human population crash during which, if geneticists are correct, no
more than 15,000 to 40,000 people survived.

"The standard view of human evolution has been that modern populations
evolved from an ancient African ancestor. We assumed that they
differentiated gradually because we assumed ancestral populations were
large and stable," Ambrose said. But, he noted, genetic research now
demonstrates that changes in population size were sometimes  
dramatic. The new model resolves the paradox of the recent African
origin model: If we are all so recently "out of Africa," why don't we
all look like Africans?

"When our African recent ancestors passed through the prism of Toba's 
volcanic winter, a rainbow of differences appeared," Ambrose said.

Editor's Note: The original news release can be found at  
http://www.admin.uiuc.edu/NB/98.09/Volcanic.html 

=====================
(2) HOW COSMIC IMPACTS HAVE SHAPED THE MOON'S MAGNETIC FIELD

From Andrew Yee <ayee@nova.astro.utoronto.ca>

University of California-Berkeley

Contacts:
Robert Sanders, UC Berkeley
(510) 643-6998, rls@pa.urel.berkeley.edu

Bill Steigerwald, NASA GSFC
(301) 286-5017, wsteiger@pop100.gsfc.nasa.gov

EMBARGOED FOR 4 P.M. E.D.T. THURSDAY (9/3/98) -- TO COINCIDE WITH
PUBLICATION IN THE JOURNAL SCIENCE

LUNAR PROSPECTOR MEASUREMENTS SHOW HOW METEOR IMPACTS HAVE SHAPED THE
MOON'S MAGNETIC FIELD

Berkeley -- The first four months of data from the Lunar Prospector,
a satellite that has orbited the moon since January, has yielded a
wealth of new information about magnetic fields on the moon and the
possible geologic history of the lunar surface.

In particular, magnetic field measurements by an instrument built at
the University of California, Berkeley Space Sciences Laboratory
give strong support to the theory that giant meteor impacts billions
of years ago created areas of strong magnetic field diametrically
opposite the impact site on the lunar surface.

"We have analyzed data from most of two impact basins on the lunar
surface, Mare Imbrium and the Sea of Serenity, and remarkably the
correlation that we first glimpsed on the Apollo missions 25 years
ago still holds," said Robert Lin, a professor of physics at UC
Berkeley and one of the principal investigators for the magnetic
mapping project.

"The fact that regions of strong magnetic field cover whole basins
antipodal to the point of impact makes the hypothesis that the
magnetism has something to do with these large impacts seem much
firmer." These regions of strong magnetic field also create their
own miniature magnetospheres several hundred kilometers across, akin
to the much larger magnetospheres that surround planets like Earth
and block the solar wind.

"These mini-magnetospheres are close to the minimum size you can get
in the solar system, and are the smallest ever observed," said Lin,
who serves as director of the Space Sciences Laboratory. The
findings are reported in a special section of this week's issue of
the journal Science devoted to the first scientific findings from
Lunar Prospector, launched Jan. 6 of this year and the first NASA
moon mission in 25 years. Prospector has been orbiting the moon at
about 100 kilometers (63 miles) above the surface since its
insertion into a lunar polar orbit in mid-January, telemetering data
from five scientific instruments. Research papers discussing data
from these other instruments also appear in the Sept. 4 issue of
Science. The moon has no global magnetic field like the Earth
because it no longer has an internal dynamo, so it was a surprise
when magnetometers placed by astronauts on the surface in the 1970s
detected a faint magnetic field, as large as hundreds of nanoteslas
(the Earth's field is on the order of 30,000 nanoteslas). When Lin
and now professor emeritus of physics Kinsey Anderson built an
electron detector that flew aboard Apollo 15 in 1971 and Apollo 16
in 1972, they quickly realized they could use the instrument to
remotely map the magnetic fields on the surface.

Though crude and covering only about 10 percent of the lunar
surface, the measurements nevertheless indicated a correlation
between meteor impact basins -- dark, roughly circular features on
the face of the moon and strong magnetic fields on the diametrically
opposite side of the moon.

"What was a fairly good hint in the Apollo measurements has turned
into a strong correlation in the Lunar Prospector data," said David
Mitchell, a research physicist at UC Berkeley's Space Sciences
Laboratory. Lin and Anderson collaborated in building the current
electron reflectometer aboard the Lunar Prospector in the first
return mission since Apollo 16. Its polar orbit will allow the team
to map the entire surface of the moon with ten times the resolution,
down to 20-30 kilometers (12-20 miles). A complete map of the
surface will be completed within several months, Lin said, at which
point the instrument will remap in even greater detail the areas of
high magnetic field, down to about four kilometers resolution -- a
scale of about two miles. The first set of data, with resolution
down to 50 kilometers (31 miles), included measurements of nearly
the entire area opposite the impact basins called Mare Imbrium and
Mare Serenitatis, or Sea of Serenity. Magnetic fields were as high
as 40 nanoteslas, or about one one-thousandth that of the Earth.

Surprisingly, the magnetic field in these antipodal regions was
coherent over an area of a couple hundred kilometers -- about 100
miles -- rather than being a jumble of randomly oriented regions,
which is typical of most of the lunar surface. When this happens,
the area can screen out the solar wind that normally impinges on the
lunar surface, just as the Earth's magnetic field screens out the
high-energy particles in the solar wind. The electron reflectometer
observed a bow shock and magnetosheath, both created when the solar
wind hits a magnetosphere, and Mitchell predicts that with more
detailed measurements they are certain to detect the magnetosphere
directly.

Since the solar wind is thought to darken the lunar soil, this may
explain lighter areas of the moon, and in particular spiral swirls
called Reiner Gamma swirls. These albedo swirls are regions of
contrasting light and dark, reminiscent of cream stirred into
coffee. Lin and his colleagues think the lighter areas may be areas
screened from the solar wind by magnetic fields strong enough to
generate a mini-magnetosphere.

"Our previous look at the magnetic moon was during the Apollo
missions and it was very coarse," said Mario Acuna, a member of the
team located at NASA's Goddard Space Flight Center in Greenbelt, Md.
"The moon was previously interpreted as just a dead body with
nothing interesting going on. With the new magnetic field data from
Lunar Prospector, we are discovering that there is nothing dead
about the moon -- the interaction with the solar wind is much more
complex than it appeared. Using Lunar Prospector is like using a
magnifying glass because it has much higher resolution and can make
measurements with greater frequency. This is typical of science --
when you look closer, you see a lot more complexity."

Theorists came up with an explanation for magnetic fields antipodal
to impact basins not long after the Apollo measurements hinted at a
correlation. When a large meteor hits the moon, it and much of the
lunar surface is vaporized and thrown into space, forming a cloud of
debris and gas larger than the moon itself. Because of the heat
released in the collision, much of the gas is ionized plasma in
which the atoms are stripped of one or more electrons.

Such plasmas exclude magnetic fields, so as the cloud spread around
the moon it pushed the moon's magnetic field in front of it. When
the plasma cloud finally converged on the diametrically opposite
side of the moon -- a mere five minutes after impact -- the squeezed
magnetic field would be quite large, Lin said.

At the same time debris was falling back on the lunar surface,
concentrated at the antipodal site also. If this debris crashed into
the surface during the time when the magnetic field was high, it
could have undergone shock magnetization. When rock is shocked, as
when hit with a hammer, it can suddenly lose its own magnetic field
and acquire that of the surrounding region.

If the moon today has no magnetic field, then where did the original
magnetic field come from? Dating of Apollo moon rocks hints that
during the period 3.6-3.85 billion years ago the moon did have a
magnetic field, probably because its core was still liquid and
spinning enough to generate a magnetic field comparable to that of
the Earth. Mare Imbrium, Mare Serenitatis and two other impact
basins that show evidence of strong antipodal magnetic fields, Mare
Orientalis and Mare Crisium, all seem to have been created during
this time period when the moon had a magnetic field.

"The data are still sparse and the interpretation is still a guess,
but very soon I think we'll have proof that this is the story," Lin
said. The electron reflectometer determines the surface magnetic
field by measuring the energy and incoming direction of electrons
reflected from magnetic fields on the lunar surface. Charged
electrons from the solar wind corkscrew around the magnetic fields
as they approach the surface, and as the magnetic field increases
they spiral tighter and tighter until, if the field is strong enough
or the angle of approach shallow enough, they reverse direction and
corkscrew back into space. The energy and angle of approach of the
reflected electrons thus indicate the strength of the magnetic field
at the surface.

Collaborators on the electron reflectometer experiment include
project engineer David Curtis, physicist Charles W. Carlson and J.
McFadden at UC Berkeley's Space Sciences Laboratory; L.L. Hood of
the Lunar and Planetary Laboratory at the University of Arizona,
Tucson; and A. Binder at the Lunar Research Institute, Gilroy,
Calif. The UC Berkeley research was supported by NASA.

[NOTE: Full text of the technical papers in SCIENCE are available
for free access at http://www.sciencemag.org/content/current/]

=====================
(3) OUR FRIENDS THE METEORS

From Rolf Sinclair/NSF Physics Division <rsinclai@nsf.gov>

Hi Benny --

Here is a  contribution for your  CCNet DIGEST-- lighter than most
of the gloom-and-doom articles.

Rolf

*********

Meteors have their benign side. Not only can the trails of ionized
gas they leave be used to reflect radio signals for communication,
they can also be used to measure high-altitude wind velocities.

This is a standard technique, well used in the past. Of note is one
recent experiment carried out at the US Amundsen-Scott South Pole
Station. Using radar equipment developed at the Institute for
Experimental Meteorology (Obninsk, Russia), wind velocities in the
mesopause (ca. 95 km altitude) were determined by measuring the
Doppler shift of radar echoes from ionized trails (which are several
km in length and initially about 1 m radius). This was the first
experiment to measure high-altitude winds over the course of a full
year (January 1995-January 1996). From 20 to 80 useful reflections
were returned each hour on the average, giving one measure of the
flux of meteors above a certain not-accurately-defined size.
Watching the collection of data in the austral summer made one aware
of the steady but invisible bombardment of the top of the
atmosphere. These and similar data could be of use as an additional
monitor of the flux of meteors.

The results showed a long-term oscillation in the wind with a
12-hour period, with superimposed transient events. The results
agree well with wind velocities inferred from Doppler shifts of
emission from the OH radical at the same altitude.

The results appear in:

* J. M. Forbes, N. A. Makarov, and Yu. I. Portnyagin, Geophys. Res.
Lett. 22, 3247-3250 (1995);
* Yu. I. Portnyagin, J. M. Forbes, and N. A. Makarov, Geophys. Res.
Lett. 24, 81-84 (1997);
* G. Hernandez et al., Geophys. Res. Lett. 23, 1079-1082 (1996).

====================
(4) PROPOSAL FOR A NEO SEARCH MISSION UNDER NASA'S DISCOVERY PROGRAM

From Michael Paine <mpaine@tpgi.com.au>

Introduction

NASA's Discovery Program funds space missions planned by independent
groups, with expenditure capped at $150 million.

This is a proposal by a consortium of scientists around the world to
learn more about the population of Near Earth Objects (NEOS -
asteroids, comets and meteoroids). The total project expenditure over
the proposed ten year program is US$100million.

Mission Outline

It is planned to mount six NEO detection systems on a large stable
object which is in solar orbit in the region of interest. The NEO
detection systems would be independently operated but would relay
information about discoveries to a central repository. The repository
would also co-ordinate the search program to minimize duplication of
effort and to ensure that adequate sky coverage is achieved.

Costs can be minimized by deriving most of the hardware for the NEO
detection systems from existing space and defence programs. By using
the large sun-orbiting object as a platform, the fabrication and
commissioning costs can be kept to a minimum. Surprisingly,
transportation costs can also be minimized because the net change in
gravitational potential for delivery of the systems will be close to
zero.

Command at each NEO detection station would be provided by some of the
most advanced autonomous intelligence systems available. These are
highly adaptive systems which can adjust to new circumstances and
develop new technical solutions to problems.

Benefits

Over the proposed ten year mission period it is expected that the
project will be able to detect about 90% of large asteroids (diameter
1 km of more) in orbits which are potentially hazardous to the Earth
and would produce global effects if they collided with the Earth. Many
more smaller NEOs and some potentially hazardous comets will also be  
detected.

Recommendation

Given the exceptionally low costs to achieve these results, the
versatility of the mission and the current availability of technology,
it is recommended that the mission be undertaken as a high priority. 

For a more detailed (and serious) examination of the Spaceguard program
see  http://www1.tpgi.com.au/users/tps-seti/sg_prop.html  ;<)

+ - - - - - - - email signature file for Michael Paine  - - - - - - - +
|       On the web at http://www1.tpgi.com.au/users/mpaine/           |
|                    Fax Sydney (+61 2) 99753966                      | 
| Note: Attached files, if present, are MIME compliant. Please notify |
| sender if another format is required. See Netscape Mail Preferences.|
|     If you are sending attachments, I prefer 'short' file names!    |
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +

==================
(5) LAUNCH FAILURE STATISTICS

From Duncan Steel <dis@a011.aone.net.au>

Dear Benny,

Regarding that news story about launch failure statistics:

>Of the 40 or so unmanned missions NASA has contracted out since the
>Challenger disaster, only one has failed.
>
>Launches contracted by other agencies and commercial carriers have
>been less reliable. Among the rocket classes currently in service,
>there have been 29 failures in 497 launches carrying payloads for
>commercial services and the Air Force, a 5.6 percent failure rate.

This shows a shocking disregard for the facts, giving the impression
that NASA has done real well (NASA chose the right contractors?),
over the other launches. (And the 5.6 percent is wrong).

Just doing simple 'square root of the count' statistics one gets:

      Launches  Failures  Uncertainty    As Percentages

NASA:    40         1        +/- 1.0      2.5 +/- 2.5%
Other:  497        29        +/- 5.4      5.8 +/- 1.1%

Thus there is no significant difference.  One may claim that just by
chance the NASA-associated launches suffered only one loss, but it
could have been 2 or 3 or ?   Should NASA be lambasted if it had
chosen contractors which experienced (say) four losses in the 40
launches?  If it had suffered zero losses in 40 launches, would it
mean that there was zero chance of losing any future mission? With
such low numbers, no inference may be drawn.

On top of such trivialities as above, the situation is much more
complex than the story suggests.  Out of all these launches, which
were the most complicated missions?  Which were using new
technology, to test it out?  We'd never have invented
caterpillar-tracked bulldozers if we'd been happy with the invention
of the wheel.

>If all communication is lost ... the officer will destroy the rocket
>to protect people on the ground.

So he launches a missile at it?

Duncan Steel

==================
(6) HELP NEEDED FOR SCHOOL PROJECT

From Laura Bone <laurabone@sol.co.uk>

Hi!

I'm doind a really important school project on meteorites, asteriods
and comets and impact cratering. It accounts for thirty percent of
my marks and my University entrace could depend on it. I need to
learn as much as possible about meteorites, meteors, asteriods,
comets, NEO's and the actual mechanics of crater formation in  as
short a time as possible. Can anyone help?

Thanks
Laura

============================
(7) WAS IMPACT OF ASTEROID 1998 QS52 POSSIBLE THIRTEEN YEARS AGO?

From Ted Bowell <elgb@lowell.Lowell.Edu>

Dear colleagues:

You may recall the discovery of 1998 QS52 on 25 Aug 98 (see MPEC
1998-Q36). It is a large Earth crosser: D = 8 +/- 1 km (C class) or
D = 4 +/- 1 km (S class) that can currently approach all the inner
planets. From the appended list of MOIDs, you will note that the
asteroid's orbit exactly intersected that of the Earth in or near
February 1985. Thus a collision with the Earth on St. Valentine's
Day 1985 cannot be entirely ruled out.

Cheers...Ted

=======================
(8) IRON-EATING BACTERIA & THE ORIGINS OF LIFE

From Andrew Yee <ayee@nova.astro.utoronto.ca>

University of Massachusetts-Amherst

Contact: Elizabeth Luciano

Release: September 2, 1998

UMass Microbiologist Focuses on Iron-Eating Bacteria

Findings have implications on beginning of life on Earth

AMHERST, Mass. -- University of Massachusetts microbiologist Derek
Lovley has made a discovery which opens a window to understanding
how life began on Earth. Lovley has determined that certain kinds of
microorganisms, which live several miles below ground, can use iron
to metabolize their food. The findings are reported in the Sept. 3
issue of the journal Nature, and will be featured in an upcoming
segment of the television show "Discover Magazine," on the Discovery
Channel.

Lovley, head of the microbiology department, studies unusual forms
of anaerobic microorganisms: in other words, bacteria that transform
their food into energy without using oxygen. "The research helps us
to understand life on Earth a little bit better," Lovley said, "but
it also has a practical side." His previous research has
demonstrated that microorganisms that can grow on iron can be used
in treating contaminated groundwater. The microorganisms use
petroleum contaminants, such as benzene, as food, and literally eat
away at contamination. These organisms can also remove toxic metals
such as uranium and chromium from contaminated waters. His most
recent findings focus on "hyperthermophiles": literally, those who
love hot temperatures. Hyperthermophiles are the organisms most
closely related to early forms of life, from which modern bacteria,
plants, and animals have descended, Lovley said.

It was previously believed that some of the first microorganisms
used sulfur to grow. But geologists noted that sulfur did not exist
in the proper form on early Earth. There was, however, abundant
iron, so Lovley set about determining whether iron could serve as an
energy source for these early bacteria. "You can't go back three
billion years, but you can study these hyperthermophiles, which are
the modern organisms most closely related to early life," said
Lovley.

Studying seven species of hyperthermophiles, he determined that
every single one could use iron to metabolize its food. This lends
weight to the theory that iron was essential for the growth of early
life on Earth, according to Lovley. One type of hyperthermophile in
particular, thermotoga, used iron in a very central way, and sulfur
in a very trivial way, suggesting that iron was more central to the
metabolism of early organisms than sulfur. All of the
hyperthermophiles converted iron oxide to the magnetic mineral,
magnetite, during their growth on iron. This is significant because
geologists have found large accumulations of magnetite on early
Earth. Furthermore, magnetite found deep below the Earth's surface
and in a Martian meteorite has been thought to provide evidence for
the possibility of life existing in these extreme environments.

Derek Lovley may be reached at 413/545-9651 or
dlovley@microbio.umass.edu

=================
(9) COMETARY IMPACTS PROVIDE ESSENTIAL SOURCE FOR LUNAR
    COLONISATION: LATEST FINDINGS INDICATE LARGER AMOUNTS OF WATER
    ON MOON

From <NASANews@hq.nasa.gov>

Douglas Isbell
Headquarters, Washington, DC             September 3, 1998
(Phone:  202/358-1753)

David Morse
Ames Research Center, Moffett Field, CA
(Phone:  650/604-4724)

RELEASE:  98-158

LATEST LUNAR PROSPECTOR FINDINGS INDICATE LARGER AMOUNTS OF POLAR
WATER ICE

The north and south poles of the Moon may contain up to six billion
metric tons of water ice, a more than ten-fold increase over previous
estimates, according to scientists working with data from NASA's Lunar
Prospector mission.  

Growing evidence now suggests that water ice deposits of relatively
high concentration are trapped beneath the soil in the permanently
shadowed craters of both lunar polar regions. The researchers believe
that alternative explanations, such as concentrations of hydrogen from
the solar wind, are unlikely.

Mission scientists also report the detection of strong, localized
magnetic fields; delineation of new mass concentrations on the
surface; and the mapping of the global distribution of major rock
types, key resources and trace elements.  In addition, there are
strong suggestions that the Moon has a small, iron-rich core. The new
findings are published in the Sept. 4 issue of Science magazine.

"The Apollo program gave us an excellent picture of the Moon's basic
structure and its regional composition, along with some hints about
its origin and evolution," said Dr. Carl Pilcher, science director for
Solar System exploration in NASA's Office of Space Science,
Washington, DC.  "Lunar Prospector is now expanding that knowledge
into a global perspective. The indications of water ice at the poles
are tantalizing and likely to spark spirited debate among lunar
scientists."

In March, mission scientists reported a water signal with a minimum
abundance of one percent by weight of water ice in rocky lunar soil
(regolith) corresponding to an estimated total of 300 million metric
tons of ice at the Moon's poles. "We based those earlier,
conscientiously conservative estimates on graphs of neutron
spectrometer data, which showed distinctive dips over the lunar polar
regions," said Dr. Alan Binder of the Lunar Research Institute,
Gilroy, CA, the Lunar Prospector principal investigator.  "This
indicated significant hydrogen enrichment, a telltale signature of the
presence of water ice.

"Subsequent analysis, combined with improved lunar models, shows
conclusively that there is hydrogen at the Moon's poles," Binder said.
"Though other explanations are possible, we interpret the data to mean
that significant quantities of water ice are located in permanently
shadowed craters in both lunar polar regions.

"The data do not tell us definitively the form of the water ice,"
Binder added.  "However, if the main source is cometary impacts, as
most scientists believe, our expectation is that we have areas at both
poles with layers of near-pure water ice."  In fact, the new analysis
"indicates the presence of discrete, confined, near-pure water ice
deposits buried beneath as much as 18 inches (40 centimeters) of dry
regolith, with the water signature being 15 percent stronger at the
Moon's north pole than at the south."

How much water do scientists believe they have found? "It is difficult
to develop a numerical estimate," said Dr. William Feldman,
co-investigator and spectrometer specialist at the Department of
Energy's Los Alamos National Laboratory, NM.  "However, we calculate
that each polar region may contain as much as three billion metric
tons of water ice."

Feldman noted he had cautioned that earlier estimates "could be off by
a factor of ten," due to the inadequacy of existing lunar models.  The
new estimate is well within reason, he added, since it is still "one
to two orders of magnitude less than the amount of water predicted as
possibly delivered to, and retained on, the Moon by comets," according
to earlier projections by Dr. Jim Arnold of the University of
California at San Diego.

In other results, data from Lunar Prospector's gamma ray spectrometer
have been used to develop the first global maps of the Moon's
elemental composition.  The maps delineate large compositional
variations of thorium, potassium and iron over the lunar surface,
providing insights into the Moon's crust as it was formed.  The
distribution of thorium and potassium on the Moon's near side supports
the idea that some portion of materials rich in these trace elements
was scattered over a large area as a result of ejection by asteroid
and comet impacts.

While its magnetic field is relatively weak and not global in nature
like those of most planets, the Moon does contain magnetized rocks on
its upper surface, according to data from Lunar Prospector's
magnetometer and electron reflectometer.  The resultant strong, local
magnetic fields create the two smallest known magnetospheres in the
Solar System.

"The Moon was previously interpreted as just an unmagnetized body
without a major effect on what is going on in the solar wind,"
explained Dr. Mario Acuna, a member of the team located at NASA's
Goddard Space Flight Center, Greenbelt, MD.  "We are discovering that
there is nothing simple about the Moon as an obstacle to this
continuous flow of electrically charged gas from the Sun."

These mini-magnetospheres are located diametrically opposite to large
impact basins on the lunar surface, leading scientists to conclude
that the magnetic regions formed as the result of these titanic
impacts.  One theory is that these impacts produced a cloud of
electrically charged gas that expanded around the Moon in about five
minutes, compressing and amplifying the pre-existing, primitive
ambient magnetic field on the opposite side.  This field was then
"frozen" into the surface crust and retained as the Moon's then-molten
core solidified and the global field vanished.

Using data from Prospector's doppler gravity experiment, scientists
have developed the first precise gravity map of the entire lunar
surface.  In the process, they have discovered seven previously
unknown mass concentrations, lava-filled craters on the lunar surface
known to cause gravitational anomalies.  Three are located on the
Moon's near side and four on its far side.  This new, high-quality
information will help engineers determine the long-term,
altitude-related behavior of lunar-orbiting spacecraft, and more
accurately assess fuel needs for possible future Moon missions.

Finally, Lunar Prospector data suggests that the Moon has a small,
iron-rich core approximately 186 miles (300 kilometers) in radius,
which is toward the smaller end of the range predicted by most current
theories.  "This theory seems to best fit the available data and
models, but it is not a unique fit," cautioned Binder.  "We will be
able to say much more about this when we get magnetic data related to
core size later in the mission."  Ultimately, a precise figure for the
core size will help constrain models of how the Moon originally
formed.

Lunar Prospector was launched on Jan. 6, 1998, aboard a Lockheed
Martin Athena 2 solid-fuel rocket and entered lunar orbit on Jan. 11. 
After a one-year primary mission orbiting the Moon at a height of
approximately 63 miles (100 kilometers), mission controllers plan to
the lower the spacecraft's orbit substantially to obtain detailed
measurements. The $63 million mission is managed by NASA's Ames
Research Center, Moffett Field, CA.

Further information about Lunar Prospector, its science data return,
and relevant charts and graphics can be found on the project website
at: http://lunar.arc.nasa.gov

----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To subscribe, please
contact the moderator Benny J Peiser at < b.j.peiser@livjm.ac.uk >.
Information circulated on this network is for scholarly and educational
use only. The attached information may not be copied or reproduced for
any other purposes without prior permission of the copyright holders.
The electronic archive of the CCNet can be found at
http://abob.libs.uga.edu/bobk/cccmenu.html



CCCMENU CCC for 1998

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.