CCNet DIGEST, 2 December 1998

    Andrew Yee <>

    B. Abate et al., UNIVERSITY OF VIENNA

(3) LEONIDS IN 1965
    Rob McNaught <>

    Luigi Foschini <> wrote:

    Jiri Borovicka <>

    Association of the United States Army

    MSNBC online

    The New York Times, 1 December 1998


From Andrew Yee <>

Stanford University


CONTACT: David Salisbury, News Service
(650) 725-1944; e-mail

The Martian underground was safe place for early life

In the early years of the solar system, when giant chunks of rock and
ice pummeled the planets, the best place for life to survive -- if life
existed at all -- was in underground niches on Mars.

If Martian microbes existed, and survived the large impacts by hiding
in the Martian subsurface, they could have later traveled to Earth, via
meteorites, and seeded terrestrial life.

Those are two contentions put forth in a new paper by Norman H. Sleep,
professor of geophysics at Stanford, and Kevin Zahnle at NASA-Ames
Research Center in Mountain View. The paper, "Refugia from asteroid
impacts on early Mars and the early Earth," appeared in the Nov. 25
issue of the Journal of Geophysical Research (Planetary Sciences

"Early Mars may have been safer than the early Earth and probably was
habitable," Sleep says. That's because of the Red Planet's smaller size
and lack of large oceans. Earth's oceans, critical for supporting life
under normal conditions, may have been the planet's greatest liability
in the event of a really large impact -- a so-called "ocean-boiling
impact," according to Sleep and Zahnle.

Between about 3.8 billion and 4.5 billion years ago, no place in the
solar system was safe from the huge arsenal of asteroids and comets
left over from the formation of the planets. Sleep and Zahnle calculate
that Earth was probably hit repeatedly by objects up to 500 kilometers
across -- the distance from Los Angeles to San Francisco. Objects that
big probably missed Mars altogether, because it was a smaller target.
But if they did hit, the damage would have been less severe, because
Mars lacked large oceans to convert to a thick, long-lasting and
sterilizing steam atmosphere.

If primitive life was wiped out, possibly repeatedly, on Earth, but
managed to survive on Mars, it would not have been hard for Martian
life to re-seed Earth. Recent computer simulations have shown that,
during this early period, large amounts of material must have been
exchanged between the two planets. Some of the material blasted from
Earth in meteoritic impacts would have landed on Mars, and vice versa.
Even today, a Martian meteorite hits Earth about once every three days,
Sleep says. Several billion years ago, the impact rate was a thousand
times greater. That means millions of Martian meteorites made the trip
from Mars to Earth in just a few years, a short enough period for
spores or possibly even intact microorganisms buried deep in the
meteorites to survive, he calculates.

Sleep notes that even modest-sized impacts have been known to decimate
life on Earth. The asteroid that caused the mass extinction at the end
of the Cretaceous Period was only 10 to 20 kilometers across -- small
by early solar system standards. Yet, when it hit the Yucatan peninsula
65 million years ago, it ignited a fireball that spread out across most
of North America and launched tremendous amounts of pulverized rock
almost into orbit. As that rock dust fell back to Earth, enough heat
was released to set forest fires worldwide and to evaporate about a
meter of water from the world's oceans, Sleep says. The dinosaurs were
cooked -- literally.

That is mild compared to the damage from an object hundreds of
kilometers across, like those that were hurtling through space about 4
billion years ago. Hit the Earth with a 500-kilometer wide asteroid,
and it vaporizes the rocks at the site of impact and creates a
rock-vapor atmosphere that would radiate at temperatures of 2,000
degrees Celsius, like a star, Sleep says.

Such tremendous heat would boil off all the world's oceans and create a
steam atmosphere that would persist for about 3,000 years. That is long
enough to sterilize the Earth's outer crust down to nearly one
kilometer, according to Sleep and Zahnle. The planet is, in effect,

On Mars, an object 500 kilometers across would vaporize the rock at the
site of impact, as on Earth, but no long-lasting steam atmosphere would
result, so the thermal radiation would dissipate much more quickly.
Only the upper few hundred meters of the planet would be sterilized,
compared to the upper one kilometer on Earth, Sleep and Zahnle say.

What, if any, forms of life could have survived such devastation? Sleep
and Zahnle think the logical answer is the thermophilic -- that's Greek
for heat-loving -- organisms. Modern thermophilic organisms thrive at
temperatures up to about 100 degrees Celsius on Earth, Sleep says.

Such critters might have survived at a depth of about one kilometer
underground during the largest impacts on Earth, but the habitable zone
would have been quite narrow -- any shallower and they would have been
cooked by the energy of impact, and any deeper and they would have been
cooked by Earth's hot interior, the authors say.

By comparison, thermophilic organisms could have survived in a much
broader depth range on Mars -- from several hundred to several thousand
meters below ground, partly because of Mars' relatively cool interior,
but also because of Mars' lower gravity, which allows cracks to extend
deeper into the planet's interior and so provides living space for
microbes at greater depths than on Earth.

Sleep first began thinking about thermophilic organisms in the
mid-1980s, when colonies of these creatures were discovered in hot
water vents at the bottom of Earth's deepest oceans. Sleep imagined
that such undersea vents might provide a good refuge during asteroid
impacts, because they would be the last place to get boiled away by the
intense heat of a large impact. He reasoned that the thermophilic
organisms in such niches might survive large impacts.

Sleep thinks it is no coincidence that these creatures occupy the main
trunk on the tree of life, where the branches of more recent life are
joined. "Clearly bacteria and archaea root into thermophile organisms
-- and thermophile organisms are exactly the ones you'd expect to
survive if the ocean gets darn hot or boils," Sleep says.

The study was funded by the NASA Exobiology Program.


B. Abate, C. Koeberl, W.U. Reimold: Petrographic and geochemical study
of rocks at Shakiso, Ethiopia: no evidence for shock metamorphism.
JOURNAL OF AFRICAN EARTH SCIENCES, 1998, Vol.27, No.2, pp.295-298


We have performed field work and petrographic and geochemical studies
on rocks from the area around Shakiso, Ethiopia, where the existence of
an impact crater, based on the asserted presence of shatter cones and
breccias, was previously suggested. We did not find any evidence that
would support this claim. Copyright 1998, Institute for Scientific
Information Inc.

(3) LEONIDS IN 1965

From Rob McNaught <>

Here is some more on the 1965 maximum.

Plavcova (1968) "Radar Observations of the Leonids in 1965-66" in
"Physics and Dynamics of Meteors",pp 432-439 gives the time of maximum
        1965 Nov 17 05:45 UT  (Nov 17.240 UT)

as observed from the Ondrejov, Czechoslovakia, meteor radar.
This is the time given by Kresak (1993).  Plavcova states that the
bright meteors (echoes >10 secs) were evenly distributed over Nov 16
and 17, but that the faint meteors showed a pronounced peak on Nov 17
at the time given above.  This is the same longitude as observed in
1966 (about 0.003 deg difference). 

However a reanalysis of this data by Brown, Simek and Jones (1997)
shows a pretty messy plot with the above peak only one of two or more.
This reanalysis used only echos greater than 1 sec duration for
greater certainty in the analysis, whereas the Plavcova results
included echoes down to 0.3 sec.  As the Nov 17.240 UT peak was mostly
of faint meteors, the reanalysis may have masked the intensity of this

Anyway, it would appear that Kresak has converted this result to an
equivalent visual rate, unless someone knows otherwise.

In the same publication Bronsten "Observations of the Leonid Meteor
Shower in November 1966 in the USSR" pp 440-445 quotes OBSERVED rates
of 5-10 per second in 1966 from the Soviet arctic with very low radiant
elevations.  However the point I wish to mention is that McCrosky
comments in a discussion of this paper:

   "The Prairie Network observed over 1000 Leonid trails of M<-5 in
   1965.  Poor weather in 1966 limited the yield to about 500.  These
   data remain unreduced because of the difficulty in associating
   common trails when films contain 10 or 15 individual events.  With
   sufficient justification, we would entertain the idea of reducing
   this material.  Most of these show the typical Leonid terminal

The data from 1965 are thus quite heterogenous but agree on an early
broad peak of bright meteors.  The possibility of a peak of faint
meteors close to the "expected" time is indicated in the short echoes
need have no bearing on what will happen in 1999.

Cheers, Rob

Robert H. McNaught


From Luigi Foschini <> wrote:

Dear Benny,

we have put our radar data on Leonids 1998 at the address:
You can also find a very fine photo of a spectacular Leonid bolide at:
Dr. Luigi Foschini
CNR - Institute FISBAT
Via Gobetti 101, I-40129 Bologna (Italy)


From: Jiri Borovicka <>
Dear colleagues,
At the address
you can look at a Leonid meteor spectrum obtained during the Leonid
Airborne Mission.
Jiri Borovicka

From the Association of the United States Army
El Paso Convention Center
December 2- 4 1998
The Association of the United States Army (AUSA) will sponsor, an
unclassified symposium for AUSA sustaining members, military/DoD
guests, and industry leaders on "Space and Missile Defense - Critical
Enablers for Full Spectrum Dominance in the 21st Century" December 2-4,
1998 at the El Paso Civic and Convention Center in El Paso, Texas.
The initiatives outlined in Army Vision 2010, Joint Vision 2010 and
U.S. Space Command Vision for 2020 point to space and missile defense
as enablers of our joint future warfighting concepts. Frequent and
varied demands can be anticipated for our land forces, and as a result,
space and missile defense must be integrated into the full spectrum of
operations, from peacetime, domestic operations to large-scale force
projection operations. This integration is critical to achieve full
spectrum dominance. This symposium will focus on critical issues
surrounding missile defense and space operations and the Army’s
commitment to put the best technology into the hands of the best
trained soldiers in the world today. The symposium will consist of
individual and panel presentations, with corresponding dialog on the
following topics: The user’s perspective on the growing demands of 
space and missile defense in support of the joint warfighter,
technology for the future, and space and missile  defense acquisition
programs and initiatives.

From MSNBC online

Los Angeles Times says Chinese device could disable U.S. military’s
orbiting reconnaissance network
LOS ANGELES, Nov. 28 — A Pentagon study warns that China may be
developing an anti-satellite laser that could disable the U.S.
military’s orbiting reconnaissance network, the Los Angeles Times
reported Saturday.

THE EQUIPMENT — possibly developed with the help of former Soviet
scientists — would enable China to fire a laser beam hundreds of miles
into space to cripple America’s fleet of “spies in the sky,” the
Pentagon said in the report released earlier this month.
Hundreds of military satellites orbiting Earth give the United States
and allied forces logistical information about enemy troops and arms.
The satellites also assist military communications, navigation, and
other tactical information gathering.
Maj. Mike Birmingham, spokesman for the U.S. Space Command in Colorado
Springs, Colo., told the Times that the military is “fully aware that
others recognize our reliance on space” and that it must take
precautions “to guard against turning our dependence into a
Six years ago, China determined that the way to offset the United
States’ upper hand in technology was to develop satellite superiority,
said John Tkacik, a consultant to firms on Chinese affairs and former
U..S. foreign service officer. “I can’t think of any other reason they’d
be doing this,” he said.
According to Pentagon analysts, the Chinese government was impressed
with the United States’ use of satellite mapping and imaging during the
1991 Persian Gulf War.
Any anti-satellite laser the Chinese may build would probably be
similar to the so-called Miracl, a $1 billion-plus laser the U.S. Army
has been testing in New Mexico.
The Miracl, an acronym for the 1980s-vintage Mid-Infrared Advanced
Chemical Laser, burns chemicals and uses mirrors to focus a one
million-watt energy stream into a 6-foot-wide beam.
The U.S. Space Command says military satellites have backup
capabilities and an adversary would have to disable multiple aircraft
to shut down the armed forces’ communications and surveillance
Copyright, 1998 Associated Press


From the New York Times, 1 December 1998


Two weeks before he died, Dr. Carl Sagan dropped by to see Daniel S.
Goldin, the NASA Administrator. Sagan was deathly ill. His blue jeans
hung limp. He had no hair. His losing battle against the bone-marrow
disease myelodysplasia had taken a heavy toll.

But his mind was ablaze.

For an hour or two in Goldin's office at the Washington headquarters of
the National Aeronautics and Space Administration, Dr. Sagan, the
astronomer, laid out a series of visions about the future of space
exploration. So lively was the discussion that the two men continued it
over dinner in nearby Georgetown.

"He was talking with intensity," Mr. Goldin marveled. "A man on his
deathbed. This is the Carl Sagan I love, a man so full of hope and
optimism that he never gave up. He never gave up."

That meeting was the last of dozens between Sagan and Goldin, who
credits the astronomer with major NASA initiatives for this century and
the next.

When Sagan died two years ago this month at age 62, most eulogies
focused on his career in popularizing science and conveying the wonders
of the universe to millions of people. But in addition to his
celebrity, or perhaps even despite it, Sagan was a serious and gifted
researcher who pushed back the frontiers of planetary science, molded a
number of gifted students and wielded great influence behind the scenes
in Washington. Time and again he came to the rescue of the politically
beleaguered search for intelligent life in the universe.

So today his legacy lives on, most especially in the actual doing of
science and space exploration, areas where his élan was mostly unknown
to people who read his books and watched his television shows. Most
centrally, his legacy is addressing one of Dr. Sagan's most durable
curiosities -- the riddle of whether life exists beyond Earth.

As NASA prepares to mount thorough explorations of the two most likely
sites in the solar system, Mars and Europa, it is Sagan's protégés who
are in charge. Indeed, his greatest student may be one who never took a
class, Goldin, the commander of this star fleet.

Of those who did take courses, one of the top students was Steven W.
Squyres, 42. Now a Cornell University professor, Squyres chairs
a 15-person NASA advisory committee on exploration of the solar system.

He also heads a 20-member NASA team designing a Martian rover meant to
land on the planet in 2003, probe its terrain, drill into hard
volcanic rock and fire samples back to Earth. From the rocky samples,
scientists hope to extract Martian microbes, either fossil or extant,
proving the reality of aliens.

Squyers said his scientific skills owe much to Sagan, including a knack
for knowing what to ignore and what to watch. "In light of his
marvelous communication skills, lots of people lose sight of how he was
also a hell of a physicist," Dr. Squyres said. "His work could be
brilliant," and brilliantly presented. "Carl was able to show you how
to cut to the heart of the matter. That was the most important thing he
ever taught me," Squyres said.

Another top student is Christopher F. Chyba, 39. For NASA, he is
probing even farther into the hinterlands.

He chairs a 12-person panel drafting plans for a spacecraft that the
agency in 2003 wants to fire toward Europa, a large moon of Jupiter
whose icy, cracked surface hints strongly of an interior ocean. NASA
and many scientists want to know if the sea exists and if alien life
thrives in its inky depths.

Chyba said one of most important lessons Sagan taught him was the value
of raw curiosity. "He had a willingness to address a broad sweep of
issues, even if you couldn't always get answers," he said.

Brash and brilliant, a poor kid aiming high, Dr. Sagan entered the
University of Chicago in 1951 at age 16, got a bachelor's degree in
liberal arts in 1954 and one in physics in 1955, a master's in physics
in 1956 and a Ph.D. in astronomy and astrophysics in 1960, ready to
shake up his field.

Astronomy at the time was in love with stars and suspicious of planets,
whose study had produced an embarrassment of false claims early in the
century about dying civilizations on Mars. But Dr. Sagan was deeply
curious about extraterrestrial life and pursued the topic with vigor,
prodding others to do the same. He was rigorous, despite his enthusiasm.
One of his credos, often repeated by experts, was "extraordinary claims
require extraordinary evidence."

As a 27-year-old astronomer, he found his avocation in 1961 when he
attended a small meeting with diverse experts to figure out whether a
radio search for alien civilizations was worthwhile. The group decided
it was, and that Earth's own galaxy, the Milky Way, in theory held up
to 100,000 advanced civilizations, many with powerful transmitters and
other technologies that might be detected from afar. Thus was planted an
important seed.

A polymath, Sagan wrote his first scientific paper on the origin of the
gene, the basic unit of heredity, in 1957. In 1962, he wrote a paper
with Joshua Lederberg, a Nobel laureate in biology, on possible Martian
life. In 1962 and 1963, he won an appointment at Stanford University's
medical school to explore that topic.

"He knew more about biology than any astronomer I'd ever met," recalled
Dr. Frank Drake, an astronomer and a pioneer of the extraterrestrial

Despite Sagan's devotion to aliens, his early achievements helped show
that they were less likely in some places than scientists had
previously thought. While in his 20's, he deduced that mysterious radio
emissions from Venus were caused by surface temperatures around 900
degrees, far too hot for life.

By 1967, Sagan took aim at Mars from a post at Harvard. Some scientists
said the planet's seasonal color variations were caused by plant life.
But he and a graduate student, James Pollack, proposed that the
variations were instead caused by wind storms and blowing Martian dust,
which turned out to be right.

Sagan went to Cornell in 1968 and stayed there until he died. His
influence grew as he edited a leading journal and helped found the
American Astronomical Society's Division for Planetary Sciences, raising
his field's status. Division membership soared from 100 or so in 1970 to
about 1,400 today.

As an explorer, Sagan played important roles in helping NASA loft the 
world's first wave of interplanetary probes, including ones to Venus,
Mars, Jupiter, Saturn, Uranus and Neptune. He was on the team that set
two landers on Mars in 1976. The craft, to his dismay, found no hint of

Far from giving up the extraterrestrial hunt, he increasingly looked
toward the stars. In 1975 and 1976, Sagan and Drake searched for alien 
civilizations with the huge dish antenna at Arecibo, Puerto Rico. The
radio telescope, the world's largest, had never before been so used.

In 1982, Sagan rushed to the defense of such work after Senator William
Proxmire tried to get it cut from the Federal budget as a waste of
money. First, after a tête-à-tête, he got the Senator to end his
criticism. Then, he won public backing for such hunts from 70 of the
world's top scientists, including seven Nobel laureates.

"We urge the organization of a coordinated, worldwide, and systematic
search for extraterrestrial intelligence," Dr. Sagan's group wrote in
Science, the nation's foremost scientific journal.

Part of his growing influence came from the great popularity of his
books, most of which were best sellers. "The Dragons of Eden" (Random
House, 1977) won a Pulitzer Prize. Others included "Broca's Brain"
(Random House, 1979) and "Cosmos" (Random House, 1980). "Contact"
(Simon & Schuster, 1985), his only fictional work, told of a
radio-telescope hunt that stumbled on an alien civilization.

Dr. Sagan became increasingly political in the 1980's. In books, talks
and protests, he faulted nuclear-arms testing, the Reagan
Administration's Star Wars anti-missile plan and, inspired by a dust
storm on Mars, warned that nuclear war could result in a
smoke-shrouded, deeply frozen Earth that he and colleagues called
"nuclear winter."

His leap from the ivory tower to television studios and executive
suites annoyed some peers. Science magazine in 1982 looked askance at
The Cosmos Store, a venture Dr. Sagan set up to make cosmic books and
calendars. The National Academy of Sciences, the nation's premier
scientific club, landed a heavy blow in 1992 by rejecting him for

"Carl was so superb at public relations that this engendered some
jealousy among colleagues who weren't," said Elliott Levinthal, a
Stanford professor who worked with Dr. Sagan for many years.

Despite the academy rebuff, he grew even more powerful. Starting in
1992, Goldin, the newly installed NASA Administrator, a former
aerospace engineer and executive, consulted Sagan for advice and
developed a respect for his energy and views during dozens of meetings.

The bond was strengthened by personal history.. Both had grown up in New
York and gone to its public schools, Goldin in the Bronx and Sagan in

"Carl didn't come up with solutions," Goldin recalled in an interview.
"He posed questions."

The most influential questions, Goldin said, had to do with the puzzle
of extraterrestrial life and how best to address it. Sagan, he said,
especially bore in on how to probe Mars, whose greater warmth and
wetness in its early days were seen as possibly having given rise to
microbes or other forms of life.

Historically, NASA had taken a Cadillac approach to space exploration,
launching costly probes rarely. The more costly the probes got, the
rarer and more complex they became. In 1992, only one spacecraft was
scheduled to fly to Mars, a $1 billion orbiter known as Observer, the
nation's first mission to the red planet in 17 years.

"His argument was that this is not a program, it's a single event, it's
the last ship out of port," Goldin recalled.. "Although I had a lot of
my own thoughts, and had talked to a lot of people, Carl convinced me I
had to develop a vision and a strategy for Mars." By early 1993, Mr.
Goldin said, a new plan was set. It featured low-cost orbiters and
landers to be flown every two years as Mars and Earth came into
alignment. The merit of the new approach was driven home in August 1993
when the costly Observer craft, as it neared the red planet, failed

The new series began last year when Mars Pathfinder landed and created
a sensation with its miniature rover. Others are to follow in 1999,
2001, 2003, 2005, 2007 and so on.

More generally, Goldin said, Sagan played a vital role in getting the
agency to deepen its biological roots. In 1994 and 1995, he said, he
met often with Dr. Sagan and other advisers to discuss how to sharpen
NASA's overall skills in examining Mars and more distant worlds for
signs of alien life.

In response to the ferment, NASA planned an Astrobiology Institute, a
consortium of academic and agency experts in various sciences, to
address the riddle of life in the universe.

Established this year, the institute is run by NASA's Ames Research
Center in California and has 11 institutional members, including teams
at Harvard, the University of Colorado and the Marine Biological
Laboratory in Woods Hole, Mass. Its budget, now $9 million, is
expected to grow to $100 million annually.

Sagan saw little of what he helped create late in life. He died Dec.
20, 1996, at the Fred Hutchinson Cancer Research Center in Seattle,
before the Mars Pathfinder landed with its Sojourner rover and the
Astrobiology Institute took off.

But his students are leading the new hunt for extraterrestrial life,
with Squyres focusing on Mars, and Chyba on Europa.

On May 18, Chyba wrote NASA as chairman of the panel drawing up plans
for a Europa orbiter. That project, he said, was in the agency's
"greatest traditions" of exploration, presenting large challenges as
well as enormous potential payoffs.

"Should the 2003 orbiter demonstrate the existence of an ocean," he
wrote, Europa will rapidly become "a primary focus" in the next
century's hunt for extraterrestrial life.

"The whole program," Chyba said, "is carrying Carl's torch."

Copyright 1998, The New York Times

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