PLEASE NOTE:


*

CCNet 82/2001 - 26 June 2001
----------------------------


"With increasingly ambitious missions planned to Mars and beyond,
and with solar energy having demonstrated its limitations, engineers and
managers inside and outside NASA say nuclear energy may be powering its
way to a new dawn in space."
--Rob Britt, Space.com, 25 June 2001


Q. If you strapped rockets onto Rush Limbaugh and launched him into
space, would he have enough mass and density to pull the Earth away from
the sun?
A. "I think he's a little too light. But that's an interesting
theory."
Q. Will this story hurt your credibility? Will people think you guys
are ... well, a little weird?
A. "Well, it's a little bit maddening because I worked very hard to
become a serious scientist. Now I'm kind of put in the role of a
crank. Only a crank would try to put a rocket on an asteroid and ... it
sounds pretty stupid, doesn't it?"
--Interview with Fred Adams (U. of Michigan), St Petersburg
Times, 25 June 2001



(1) A METEOR SHOWER THIS WEEK?
    Space Weather News, 25 June 2001

(2) NEW SOLAR-POWERED HYPERION ROBOT STAYS IN SYNC WITH THE SUN
    NASANews@hq.nasa.gov

(3) NUCLEAR POWER POISED FOR RE-ENTRY INTO SPACE
    Space.com, 25 June 2001

(4) DID TOO MUCH RAIN BRING DOWN ANCIENT CIVILISATION?
    Nature Science Update, 25 June 2001

(5) INTERESTING PAPERS IN "GEOLOGY"
    Hermann Burchard <burchar@mail.math.okstate.edu>

(6) ENVIRONMENTAL CHANGE & HUMAN EVOLUTION
    Nature Science Update, 25 June 2001

(7) PLANETARY PROTECTION: HALF-YEAR STATUS REPORT
    Andy Smith <astrosafe@yahoo.com>

(8) INACCURATE QUOTE?
    Lew Gramer <dedalus@latrade.com>

(9) SUPERCONTINENTS AND SNOWBALL EARTH EVENTS
    Karunakar Marasakatla <karunakarm@hotmail.com>

(10) AND FINALLY: IN A NEWS FLASH, SCIENTISTS GET BURNED
     St. Petersburg Times, 25 June 2001


========
(1) A METEOR SHOWER THIS WEEK?

From Space Weather News, 25 June 2001
http://www.spaceweather.com

METEOR SHOWER: On June 26th and 27th Earth will pass through the dusty
debris trail of comet 7P/Pons-Winnecke, triggering the annual "June Bootid"
meteor shower. Most years the June Bootids are meek: a typical shower
consists of only a few visible meteors each hour -- but not always.
In 1998 sky watchers enjoyed an intense Bootid outburst. What will happen
this year? No one knows, but meteor enthusiasts will be watching the heavens
for a possible flurry of shooting stars. Tune in to SpaceWeather.com for
observing tips and more information about the shower. And don't forget to
try listening to the June Bootids using our online meteor radar.

==========
(2) NEW SOLAR-POWERED HYPERION ROBOT STAYS IN SYNC WITH THE SUN

From NASANews@hq.nasa.gov

Don Savage/Dolores Beasley
Headquarters, Washington, DC          June 25, 2001
(Phone: 202/358-1547)

Anne Watzman
Carnegie Mellon, Pittsburgh, PA
(Phone: 412/268-3830)

RELEASE: 01-127

NEW SOLAR-POWERED HYPERION ROBOT STAYS IN SYNC WITH THE SUN

A new robotic explorer, smart enough to know when it's lost or in trouble
and designed to follow the Sun in a whole new way, is ready to face its
first test in the harsh elements of the Canadian Arctic.

The prototype robot, named Hyperion, has the potential to be self-sufficient
and will help researchers test a technique called Sun-synchronous
navigation.

Sun-synchronous navigation involves tracking the Sun while exploring
terrain. If Hyperion is successful, future autonomous robots could obtain
continuous solar power for long-term exploration of distant planets and
moons.

The robot must know its position and orientation with respect to the Sun
while it explores its surroundings. It navigates to capture enough sunlight
to power itself while traveling through rough terrain and trying to reach
important scientific objectives.
 
Researchers at Carnegie Mellon's Robotics Institute, Pittsburgh, PA, with
support from NASA developed Hyperion, named for a Titan of Greek mythology
who fathered the Sun, moon and the dawn. The word Hyperion roughly
translates to "he who follows the Sun."

"Near the poles of the moon, the idea is for a robot to move with the dawn,
and always remain in sunlight as it explores its environment," said Robotics
Institute Research Scientist David Wettergreen, a co-investigator on the
project. The robot represents the latest in a series of terrestrial testbeds
for planetary explorers the Institute has developed for the agency in a
relationship that spans more than a decade.

The field experiments with Hyperion will take place in Nunavut, Canada, on
the hilly, rock-strewn terrain of Devon Island, the largest uninhabited
island in the world. There is a narrow window, between July 10 and July 20,
to conduct the experiments.
 
Researchers believe that at the right latitude and speed, robotic explorers
should get enough sunlight to maintain continuous operation. For some
missions, by following the dawn, these rovers may also be able to regulate
their temperatures by staying in the transition region between frigid night
and scorching daytime temperatures. They would travel with the sunrise and
never have to hibernate overnight.

"The reasons for developing Sun-synchronous rovers are twofold: capability
and reliability," said Melvin Montemerlo, NASA program executive, Office of
Space Science, Washington, DC. "Since they're always in sunlight, they never
have to go into a sleep mode and there's a greater science return for the
dollar. Secondly, you don't have to power down at night so you don't have to
worry about making it through a cold night and about powering up again when
the sunlight returns in the morning."

"Sun-synchronous navigation would enable robots to undertake missions of
months or years. To travel vast distances on the moon or Mars is what is
called for to make the revolutionary
discoveries," said principal investigator William L. "Red" Whittaker,
Carnegie Mellon's Fredkin research professor and a pioneer in the
development of mobile robots.

Hyperion is 2 meters long, 2 meters wide and almost 3 meters tall, with a
near vertically mounted solar panel measuring 3.5 square meters. It carries
this panel mounted upright to catch the low-angle sunlight of the Polar
Regions.

Hyperion operates on about 200 watts of power. It is fabricated of aluminum
tubing and has four wheels on two axles. On the front axle, a frame supports
stereo cameras and a laser scanner. All of Hyperion's computers, electronics
and batteries are mounted in a body enclosure between the axles. The robot
weighs 156 kilograms, or nearly 345 pounds. Wettergreen said Hyperion has
enough intelligence to know when there's a problem and can send a message to
human operators to ask for help.

Hyperion is a concept vehicle designed to operate only on Earth. Robots
designed for flight missions would require specialized components, such as
space-qualified motors and computers.

Wettergreen will lead the field experiment with six colleagues. The team
intends to produce status reports, images and online movies throughout the
field experiment. More information about Hyperion and the Sun-Synchronous
Navigation Project can be found at:
           http://www.frc.ri.cmu.edu/sunsync/

==========
(3) NUCLEAR POWER POISED FOR RE-ENTRY INTO SPACE

From Space.com, 25 June 2001
http://www.space.com/businesstechnology/nuclear_space_010625-3.html

By Robert Roy Britt
Senior Science Writer

With increasingly ambitious missions planned to Mars and beyond, and with
solar energy having demonstrated its limitations, engineers and managers
inside and outside NASA say nuclear energy may be powering its way to a new
dawn in space.

It's a possibility made more likely by recent shifts in U.S. energy and
military policies. It's also a move anticipated by antinuclear activists,
who are already planning their opposition to any effort to use nuclear power
in space.

Fueled by the desire to go farther and faster with fewer dollars, managers
at NASA's Jet Propulsion Laboratory -- where many of the agency's robotic
missions are conceived and carried out -- are analyzing how to justify the
use of nuclear power in space, both technically and in terms of the benefit
to science.

"We've been thinking about this, and trying to raise it as a question that
warrants some consideration, for a couple of years," says Firouz Naderi, a
longtime JPL manager and newly appointed leader of the Solar System's
Exploration Programs Directorate. "I think we are going to raise it again
and see if the [political] system is amenable to it."

In an interview at his JPL office, Naderi said any such political balloon
would have to be floated in Washington by NASA headquarters.

"I believe that if a good case can be made, not only for the science return
but for safety, then I could see that [nuclear power] could be in our
future," he said.

Others think Naderi may be right. And support could come from the top.

President Bush's recently released energy plan features increased reliance
on nuclear power back here on Earth. In several interviews, scientists and
mission planners said they were hopeful this might put space-based nuclear
power generation back on the table after suffering from years of what they
call misinformation.

"The fact that the country is willing again to consider use of nuclear
energy for commercial power may improve the prospects of applying this
technology to space exploration," said George Schmidt, deputy manager of the
Propulsion Research Center at NASA's Marshall Space Flight Center.

Two sides, very far apart

The last nuclear-powered spacecraft launched by NASA was Cassini in 1997.
Antinuclear activists protested heavily against it, saying a launch accident
or potential mishap in a 1999 Earth flyby en route to Saturn could kill
billions of people who might develop cancer after contact with radioactive
material.

Cassini scientists have called such claims "hogwash," saying that the
radiation risk is less than normal background radiation in the air or in
rocks.

Before the launch, NASA did admit that "there is a small potential for
public health effects." But in 1997, Cassini project manager Richard J.
Spehalski said the public was "badly misinformed by alarmists."

Spehalski said that even in the highly unlikely event that the 73 pounds of
plutonium on board were somehow released into the atmosphere in a breathable
form, and ingested, "the radiation dose an individual would receive over a
50-year period from that exposure would be ... 15,000 times less than a
natural lifetime exposure."

In the end, there were no Cassini accidents. Yet the dangers still are
debated.

Few debate the potential benefits of nuclear power in space. The life of a
Mars rover could be extended from days to years. Maneuverability would be
measured in miles instead of feet. And many engineers agree that a human
trip to Mars would go from highly impossible to practical.

Further, if humanity is ever to leave this planet permanently and set up
colonies on the Moon or Mars, a nuclear power station would be nearly
indispensable, most space industry experts agree.

No nukes in space

As talk of space-based nuclear power increases, so do the efforts of
opposition groups.

Bruce K. Gagnon is a coordinator for the Global Network Against Weapons and
Nuclear Power in Space. The organization represents 150 groups around the
world with, Gagnon says, millions of members.

Gagnon said the groups have been expecting space-based nuclear power
initiatives to resurface, and they've been making plans to mount a concerted
effort against all uses, from planetary exploration to military. The U.S.
military would benefit from having nuclear generators in space to power huge
orbiting radar stations for reconnaissance. And Bush is also pushing for a
fresh look at the so-called Star Wars missile defense system.

"We see a deadly connection between each of them," Gagnon said, arguing that
the nuclear industry views space as a new market and would love to get a
foot in the door any way it can.

Gagnon said the missile defense system would use nuclear energy aboard
satellites to refuel lasers that would shoot down foreign missiles. Bush has
not committed to any specific system, however, and some expect the weapons
would ultimately be ground-based or mounted on ships or aircraft.

Gagnon also argues that relying on nuclear power tends to kill research into
alternatives, such as solar power. "When you go with nuclear power you're
basically saying nothing else works," he says.

Exploration, not war

Meanwhile, those who plan missions to Mars and beyond have a more modest
goal: getting there. And they say that a new generation of nuclear
propulsion systems is safe.

Radioisotope thermoelectric generators, or RTGs as they are called, use the
natural decay process of plutonium to generate heat needed to protect a
spacecraft in the cold environment of space. Some of the heat is converted
to electricity, which can be used for flight propulsion or to power a
surface rover.

In future plans, conventional chemical rockets would be used to launch
spacecraft powered by RTGs, and the reactors would not be turned on until
after they are launched. Still, critics fear a release of plutonium during
launch or in the atmosphere, when a rocket is accidentally or intentionally
blown up.

In the case of such an accident "the radioactivity in the reactor is nil,
less than that received by laying on the beach in sunny California or in
Long Island," says Mohamed S. El-Genk, director of the Institute for Space
and Nuclear Power Studies at the University of New Mexico.

Gagnon, however, says the greatest danger might come well before a
spacecraft is even launched. In order to use nuclear power in space, he
points out, the Department of Energy would have to ramp up plutonium
production.

"As you contemplate expansion of the use of nuclear power in space, you'll
have a dramatic escalation in worker contamination," Gagnon said.

And finally, Gagnon said a launch accident is inevitable, due to faulty
parts, human error, or sheer odds.

Plenty of company

If nuclear power returns to space, it will find a lot of company. In the
most recent tally provided by the Bulletin of Atomic Scientists, there are
roughly 75 nuclear devices in space, 38 from the United States and 37 from
Russia. Of these, 46 are in Earth orbit, 12 were left on the Moon or Mars,
and 17 power deep-space probes.

And accidents have occurred.

In 1964, for example, an American satellite failed and re-entered Earth's
atmosphere. As planned, it jettisoned its nuclear payload, releasing
radiation over the Indian Ocean at an altitude of 75 miles, according to the
Bulletin.

In 1973, the Apollo 13 spacecraft carried an RTG to be used to power a
seismic station on the Moon. The mission was aborted and the spacecraft
returned to Earth. The RTG was attached to the lunar module, which broke up
on re-entry. NASA officials say the RTG re-entered intact, with no release
of plutonium, and now sits on the floor of the Pacific Ocean.

In 1978, a Soviet radar reconnaissance satellite malfunctioned and crashed
in Canada's Northwest Territory, releasing thousands of highly radioactive
fragments into a lake and the surrounding area.

No evidence has tied these mishaps to any cancer cases or deaths.

Destination Mars

Still, over the years, political and social pressure from these accidents,
and others in terrestrial nuclear reactors, have combined to compel NASA to
design Mars probes and rovers that rely on solar power.

But for robotic exploration, especially on the surface of a planet far from
the Sun, with nighttime darkness and changing seasons thwarting solar
collectors, nuclear power would be an indisputably more powerful exploration
tool.

A stark example of solar power's shortcomings was provided by the successful
Mars Pathfinder mission in 1997, which worked in tandem with the Sojourner
rover to beam back pictures of the surface of Mars. While outlasting its
30-day life expectancy, the craft's batteries died just shy of three months
after landing.

Researchers expected the batteries to die, because they required constant
recharging from the solar panels. Solar energy cannot be used directly,
because it fluctuates so much.

And solar panels are heavy, not to mention complicated to unfurl in space or
on a planet.

How to kill a mission

Bob Anderson, a geologist and mission planner, said in a recent interview at
JPL that the weight of solar panels and their poor performance compared to
nuclear power severely constrain the amount of science that can be done for
a given mission's price tag.

"Two things will kill a mission," Anderson says. "Power and mass."

And future Mars missions will require more of both. A pair of missions in
2003 will send the most advanced and capable rovers ever designed to study
Martian geology and search for signs of water. If there, this water could
provide the trail to any past life that might have existed on the Red
Planet.

The craft may be sent inside giant craters, where orbiting spacecraft have
spotted signs of water. But to ensure safety, the spacecraft will land in
flat areas, likely near the crater center.

"But the best information is probably in the rim," Anderson says.

Anderson is helping engineers design rovers that will allow the geologist to
remotely drill into rocks and figure out what they're made of. It is a
critical science tool, but also a tremendously power-draining activity, he
said.

Nuclear power could turn short, daytime-only missions into long, 24/7
operations, Anderson said. He notes, however, that rovers would have to be
redesigned to make all their parts capable of sustaining such a long
mission.

Naderi, the JPL manager, worries that Americans have been jaded into
assuming that going to Mars is a relatively simple operation nowadays. But
given that favorable planet alignments limit Mars missions to launching
every 26 months, he laments solar-powered rovers die before the next one can
be launched.

"People think [landing on Mars] is like driving to Grandma's on Sunday,"
Naderi said. "But it is expensive and it is horribly difficult to land on
Mars. Once you do, you want to last more than 90 days."

Living on the Moon

While nuclear power can improve the efficiency of a rover, some say it is
imperative for more ambitious missions.

An increasingly vocal group of space enthusiasts argues that the post-Apollo
space program is stagnant due to the lack of a major goal. Many think that
what's needed is a firm plan to set up permanent human colonies on the Moon
or Mars.

Peter Eckart, of the Institute for Astronautics at the Munich University of
Technology in Germany, says that if a lunar base is to be built anywhere
except at the poles, where sunlight is constant, then "the only reasonable
engineering solution is to go with nuclear power."

Likewise, others say, any future colonization of Mars will likely depend not
just on nuclear electric propulsion, but nuclear power generation on the
surface. Most engineers question whether even the most perfectly situated
site can be sustained by solar power. And at best, these sites would not
necessarily be located where researchers would want to explore.

Despite the benefits of nuclear power, Eckart is not one to discount the
dangers.

"I'm personally not too much in favor of using nuclear power on Earth, if we
can avoid it," he said after a recent conference on space colonization at
Princeton University. "But in space, it's not a problem."

Eckart calls the fear of contaminating the lunar surface with radiation
"total nonsense, because up in space there's so much radiation already --
all the galactic and cosmic radiation, all the stuff that's coming in from
the Sun. A nuclear reactor does not make a difference at all. The only risk
is launching it, and there you have to be careful from an engineering point
of view."

Such a system would be launched in safer pieces, then assembled once at its
destination, providing a further measure of safety, proponents say.
 
Three Mile Island in the rearview mirror

Several experts say that whether nuclear power flies again depends upon
public opinion. And while a significant chunk of the American public has
traditionally held a dim view of nuclear energy, there is evidence that
opinions can change, at least in the face of a compelling need.

Five years after the Three Mile Island accident in Pennsylvania, a
nonpartisan Field Institute poll found that roughly 61 percent of
Californians opposed nuclear power. But a new poll, released this May, found
that about 59 percent of Californians were in favor of building new nuclear
plants.

Pollsters suggested the obvious: Rolling blackouts and soaring electricity
bills had altered views.

Most space industry experts say there is no direct relationship between the
fate of Bush's energy proposal -- which offers tax breaks to the nuclear
energy industry and promises to re-evaluate a controversial limitation on
reprocessing nuclear waste into reusable fuel -- and the potential for a
nuclear powered space program.

But several of those interviewed by SPACE.com expressed optimism for a
political and social trickle-down effect.

"In order to line up national support, we need a NASA mission or missions
that would inspire Americans of all ages," says the University of New
Mexico's El-Genk.

Dusty plan, dying experts

A potentially more difficult challenge also looms, especially regarding the
construction of large-scale nuclear power plants to support Mars or lunar
colonies.

Even if the social barriers were suddenly lifted, it is unclear how quickly
NASA could ramp up the necessary technology, given that three decades worth
of plans for nuclear propulsion and space-based power generation are stuffed
away in dusty drawers around the country.

Professors are loath to bring the topic up, says El-Genk, and a generation
of engineers who understood the technology is largely retired or dead.

"University education in this area is nil, due to the very low enrollment in
nuclear engineering departments during the last two decades and the closure
or combining of more than half the nuclear engineering departments that
existed in the 80s," El-Genk told SPACE.com.

With this dying generation may die the dream of sending humans to Mars. Or,
at the least, the dream might be deferred until a new generation of
engineers can be re-educated.

So despite glimmers of hope within the space community, there is a
realization that a tremendous public and political education effort would be
needed to get nuclear energy off the ground and back into space.

Some worry the obstacle might be insurmountable.

Gary E. Mueller, an associate professor of nuclear engineering at the
University of Missouri-Rolla, said he's hopeful that Bush's efforts will
translate into increased use of nuclear power in space. But, tossing another
obstacle into the equation, he says NASA will have to find new money to
support research.

"Some leadership in Washington, which I hope the Bush administration will
provide, and leadership at NASA, which will not happen with [Dan] Goldin's
administration, is needed to clear up and shift political will and public
opinion," Mueller said.

If President Bush were to push for a nuclear-powered space program, the
effort would have a familial echo.

Bush's father spoke in 1989, on the 20th anniversary of the first Moon
landing, of America's need to return to the Moon and lay plans for putting
humans on Mars. His speech set no dates but spawned a flurry of studies and
committees, resulting in recommendations that included nuclear power as a
cornerstone for any possible Mars missions.

Twelve years later, there are still no plans for a humans-to-Mars mission.
And though space-based nuclear power may be on the brink of a return to the
political spotlight, it is also an idea with an uncertain future.

Copyright 2001, Space.com

=========
(4) DID TOO MUCH RAIN BRING DOWN ANCIENT CIVILISATION?

From Nature Science Update, 25 June 2001
http://www.nature.com/nsu/010628/010628-5.html

CULTURE RAINED OFF

Ancient Peruvian civilization may have fallen foul of El Niño.

PHILIP BALL

El Niño events may have altered the course of prehistoric civilization.
Around 3,000 years ago rainfall seems to have put paid to the Peruvian
progress it kicked off 3,000 years earlier, US
researchers now report.(1)

The coast of Peru is dotted with the remains of temples built between 5,800
and 2,800 years ago, during the Preceramic and Initial Periods. Predating
Egypt's pyramids, and often decorated with elaborate art, these monuments
attest to a highly organized civilization with its own religious and
political systems. At the end of this period, the temples seem to have been
abandoned.

A shift in climate patterns around 3,000 years ago may have triggered this
change, Daniel Sandweiss, of the University of Maine, and his coworkers
argue.

Now Peru's coast is strongly affected by El Niño events, which bring
torrential rainfall. Such floods would not have occurred before 5,800 years
ago. That's when El Niño events started, Sandweiss' team point out.

The coincidence of the onset of El Niño with the building of the first
temples implies that wetter episodes might have made agriculture possible,
and so helped to nurture a civilization.

Yet the shells of temperature-sensitive molluscs in coastal marine sediments
imply that El Niño may also have had a destructive side. These shells record
that the frequency of El Niño events increased roughly 3,200 years ago.

A bit of rain is a good thing. But too much of it, it seems, placed a fatal
stress on the temple-building civilization, which, as archaeological
evidence bears out, was literally washed away.

Indeed, the youngest temple, at Manchay Bajo, which was occupied until 2,800
years ago, was protected by a wall built to redirect water and mudslides
from two ravines that otherwise would have disgorged their contents onto it.

Climate-related rise and fall of civilizations has been seen elsewhere. In
1993, Harvey Weiss, of Yale University, and his colleagues claimed that
abrupt climate change about 4,200 years ago
caused a prolonged drought in the Middle East, affecting civilizations from
the Aegean Sea to the Indus River and leading to the collapse of the
Akkadian Empire in the Euphrates valley.

References

1. Sandweiss, D. H et al. Variation in Holocene El Niño frequencies: climate
records and cultural consequences in ancient Peru. Geology, 29, 603 - 606,
(2001).

© Nature News Service / Macmillan Magazines Ltd 2001

============
(5) INTERESTING PAPERS IN "GEOLOGY"

From Hermann Burchard <burchar@mail.math.okstate.edu>

Dear Benny,

there are some interesting articles in the current issue of GEOLOGY, a
journal of the GSA. 
http://www.gsajournals.org/

1. An article page 603 by Sandweiss et al. on Peruvian climate from 5800 to
2800 BP.
http://www.gsajournals.org/gsaonline/?request=get-abstract&issn=0091-7613&volume=029&issue=07&page=0603

2. Immediately following page 607 is an article about early man in Eastern
Indonesia. The date of 840 Ka is given for H. erectus. This would be EARLIER
than the Australasian Tektite strewn field.  Many of these people must have
got wiped out, as Mike Paine pointed out, who may be very
interested in this paper. A later influx replaced them by Paleomongolians
from further North (SE Asian natives are considered descendants from
Paleomongolians, while Northern Asian races are thought to be often strongly
intermixed from < 50 Ka with Western Eurasians). Western Indonesian dates
(Java) are earlier, 1.8 Ma (Berkeley, CA, Institute, run by Paul Renne).

The great thing is that E Indonesia is separated from Asia by deep water
channels never dry during the ice age. This was discovered by Wallace and
Darwin, who noted the dramatically different fauna on the East of the
Wallace Sea (Wallace published earlier than Darwin I think).  Hence 840 Ka
people did some non-trivial navigation, and most likely reached Australia.
From this paper, and based on all the available evidence, we may state
confidently that today's Aborigines in Australia are descended from those
early humans of 840 Ka. The usually given date of 50 Ka is much too low.
Some later influx is likely from New Guinea relatives in the North where
there was more selection pressure. The navigation and other skills of the
early immigrants likely were lost, not unlike the case of the
Easter-Islanders.

There may be more there on those GSA web pages of interest to you and CCNet
readers, have not had time to look.

Best regards,
Hermann

==========
(6) ENVIRONMENTAL CHANGE & HUMAN EVOLUTION

From Nature Science Update, 25 June 2001
http://www.nature.com/nsu/010510/010510-12.html

Asia dried Africa

The climatic changes that influenced human evolution may have started in
Indonesia.
10 May 2001
HEIKE LANGENBERG

Almost 3 million years ago a previously moist and warm east Africa, which
was covered with tropical woodlands and green landscapes, was transformed
into a dry, grass-covered savannah. It had been assumed1 that this climatic
change originated in the north Atlantic. Now Mark Cane from the
Lamont-Doherty Earth Observatory in Palisades, New York, and Peter Molnar of
the Massachusetts Institute of Technology argue that it could have been
caused by the closure of the Indonesian seaway.

Given that the human family tree diversified at around the same time, this
new hypothesis throws a new light on the factors that may have determined
our ancestors' evolution.

Permanent El Niño

The most popular explanation for the drying out of east Africa has been the
coincident onset of the first ice age. Huge ice sheets in the Northern
Hemisphere led to low surface temperatures in the north Atlantic. According
to this argument, less water evaporating from a cold north Atlantic led to
less rain over Africa.

Cane and Molnar propose an alternative explanation. Australia and New Guinea
are on a tectonic plate that moves north at about 70 km every million years.
Three to four million years ago, the researchers calculate, the displacement
and uplift of the Indonesian islands caused a fundamental redirection of
ocean currents that shifted the connection between the Pacific and Indian
oceans north. Instead of warm water from the south Pacific, cooler water
from the northern Pacific flowed through the seaway. Cooling the surface of
the Indian Ocean would have initiated a different wind system over east
Africa, bringing less rain.

So far, the theory is an addition to our present understanding of climate
change, rather than a contradiction. But Cane and Molnar go further. They
assert that before the northward displacement of the Indonesian Seaway, the
distribution of water masses in the Pacific Ocean was quite different from
that of today.

The researchers suggest that before the changes in Indonesia, the Pacific
Ocean would have been in a state of 'permanent El Niño'. Nowadays, large
amounts of heat are transported from the tropics to high latitudes in El
Niño years. New Guinea's northward displacement would have ended this heat
transport, triggering an ice age.

So according to Cane and Molnar, glacial cycles are a result of tectonic
changes between the Indian and Pacific oceans.

The Atlantic hypothesis

Previously, the closing of the Middle American Seaway has been the
explanation for the start of the ice age. A huge gap between North and South
America once allowed water to flow freely between the Atlantic and Pacific
oceans. But tectonic changes closed this ocean gateway about 3 million years
ago, lifting up the Isthmus of Panama, the thin sliver of land that connects
North and South America.

The closing of the Straight of Panama initiated the Gulf Stream in its
present form. Before the isthmus existed, part of the tropical water mass
had been diverted into the Pacific Ocean through the Americas. After that
route closed, the warm current flowed along the North American coast. A
change of such a magnitude would have had important consequences for climate
in the north Atlantic.

The first doubts about this hypothesis appeared in 1982, when Lloyd Keigwin
of Woods Hole Oceanographic Institution in Massachusetts found evidence that
the closing of the Isthmus of Panama influenced ocean circulation more than
a million years before the onset of the new climate regime.

Sixteen years later, Gerald Haug of ETH Zuerich and Ralf Tiedemann of the
GEOMAR research center in Kiel, Germany, investigated the paradox further,
with more accurate and more abundant data. "Our analysis supports Lloyd
Keigwin's data -- 4.2 million years ago at the latest, the division of water
masses between the Atlantic and Pacific oceans in the Straight of Panama was
complete," says Haug. So why did glaciation not start until 3 million years
ago?

"To build up an ice sheet, you need cold temperatures and moisture. The
evolution of the Isthmus of Panama provided the necessary moisture 4.2
million years ago at the latest, but to trigger glaciation you would also
need the temperatures to fall," Haug explains.

One important factor for global temperature change is solar radiation, which
oscillates regularly in cycles of about 20,000, 41,000 and 100,000 years
through variations in the Earth's orbit around the sun. The combination of
these cycles did not allow cool Northern Hemisphere summers -- essential for
an ice-sheet buildup -- for a long time. Between 4.5 and 3.1 million years
ago, the proto-ice sheet that formed in winter would have melted during the
warm summers.

But Cane does not believe this explanation. "A stronger Gulf Stream since
the closing of the Panama seaway does not only transport moisture to the
north Atlantic, but also heat. You will not get an ice sheet in this way. I
am convinced that past climate oscillations originate in the tropics, and
not in the north Atlantic."

Humans weather the storm

Cane and Molnar's proposed relationship between glacial cycles, changes in
African climate, displacement of the Indonesian Seaway and the closure of
the Straight of Panama also invites a re-evaluation of the idea that several
new species may have emerged in response to the aridification of East
Africa.

Thanks to a series of spectacular new fossil finds -- culminating earlier
this year in Kenyanthropus platyops, the first clear evidence of a second
species of human ancestor that existed between 4 and 3 million years ago --
the theory of climatic influence on early human evolution is not quite as
simple now as it was a few years ago. "We see a strong widening of the human
family tree between about 4 and 2 million years ago. But I do not believe
that there was a magic point in time when all this happened," says Daniel
Liebermann, an anthropologist at the George Washington University in
Washington DC.

The onset of cycles of glacial and interglacial climates not only dried
Africa out but also led to more variation in global climate. Richard Potts,
director of the Human Origins Program at the Smithsonian Institute in
Washington DC, believes that the extent of variability is most important for
human evolution. "A changing climate drives different populations apart and
brings them together again. This could have facilitated speciation," he
says.

Why, asks Potts, after the human family tree diverged into several species,
has only Homo sapiens survived to the present? He suggests that the
excellent adaptability of our species -- for example in contrast to the
cold-adapted Neanderthals -- secured our survival throughout the climatic
rollercoaster of the past.

Clearly, there is a lot left to discover about prehistoric climate change.
Too many significant changes at roughly the same time make it hard for
researchers to distinguish causes and effects. And perhaps it is not pure
chance that the north Atlantic region -- long thought to be the key to
climate variability -- is the home to a large proportion of climate
researchers.
 
References

Cane, M. A, Molnar, P. Closing of the Indonesian seaway as a precursor to
east African aridification around 3-4 million years ago. Nature 411, 157-162
(2001).
 
© Nature News Service / Macmillan Magazines Ltd 2001

============================
* LETTERS TO THE MODERATOR *
============================

(7) PLANETARY PROTECTION: HALF-YEAR STATUS REPORT

From Andy Smith <astrosafe@yahoo.com>

Hello Benny and CCNet,

We made it through another equinox without meeting KALI. Congratulations to
us all! Here are a few status inputs.

The Hunt

Almost 150 new NEO discovered this year, to-date. 28 (19%) are potentially
hazardous (PHA). 41 are larger than 1 kilometer (27%). However, this group
is only about 2% (or less) of the dangerous population and this shows how
many of the smaller (but still very dangerous) ones we are missing. We
clearly need to get some larger telescopes involved in this vital hunt, as
soon as possible. Anyone with ideas, please contact us. Also, we want to
thank Brian Marsden and the Minor Planet Center for their dedicated, top
quality effort.

LINEAR has found about 62% of the total. This excellent facility and team
are doing so much of the discovery work and we are very grateful to them for
their contribution. It is our understanding that they are using two 1 meter
search systems. Thanks to NASA, the U.S.Air Force and MIT(Lincoln Lab).

NEAT is now operating facilities at Maui and Palomar and their discovery
rate is increasing...about 17% of the total. LONEOS (Lowell Observatory) has
found about 14%. Both of these excellent programs are increasing their
discovery rates. Thanks to them and to NASA, the Air Force and many
contributors for helping them.

The Japanese Bisei Asteroid Observatory program is due to come on-line this
fall (October) and we are all waiting for that great event. It is very
important for the major search programs be tightly coordinated and the key
program leaders are meeting, at the Bisei dedication, to discuss this and
other important issues. We welcome that meeting and we hope they will
include the important role of the larger telescopes in their dialogue. Our
thanks to Syuzo Isobe for the work he is doing on the facility and the
meeting.

Another very impressive Web site is the NEO Dynamic Site (NEODys). They are
doing a terrific job of providing data on the NEO, to include
close-encounter predictions. They have identified 6 of the PHA as very
hazardous (our description and we call them VHA). There are about 60 PHA for
every VHA and 230 NEO. That means KALI is in a population of about 600 VHA
and we have good data on only about 6 of them....so much to do and, perhaps,
so little time. Thanks to Andrea Milani and the NEODys team for the
important work they are doing.

Again, we want to thank all of the CCNet devotees and specialists, around
the world, who are working, often as volunteers, to help in meeting this
challenge. It is clearly the greatest technical challenge in history and
millions of lives are at stake.

Also, special thanks to Arthur C. Clarke for calling this great menace to
our attention and continuing to remind us of it.

Happy Birthday Max

It is a great pleasure to call attention to the birthday of Max F.J.C.Wolf
(21 June 1863), who assembled the first asteroid photo-telescope and
discovered 228 asteroids, between 1891 and 1923. He was the first director
of the Konigstuhl Observatory, at the University of Heidelberg (the
University was established in 1385). He made the first application of the
stereo-comparator to this work and discovered the first Trojan asteroid, in
1906.  Happy equinox and happy birthday to Max and his family and all of our
colleagues in Germany.

Next SPE Conference

We are all looking forward to the next Space Protection of the Earth (SPE)
conference and to hearing more about the work being done by our Russian
colleagues, on dangerous asteroid/comet interception and deflection. It
looks like there is a good possiblity of a meeting in 2003.

Coastal City Asteroid/Comet Emergency (ACE) Preparedness

We are now prepared to advise coastal cities, with regard to the selection
of high-rise buildings for emergency Tsunami shelters and with some aspects
of quick evacuation planning and we invite all who have expertise in these
areas and want to help with this voluntary effort or who would like this
technical assistance, to contact us.

U. S. Congressional Natural Hazards Caucus (NHC)

This new program is well outlined on the Web. We are working to have
asteroid/comet hazards included on their list and we encourage all
preparedness advocates to promote the establishment of such groups in their
national congresses or legislatures. Please let us know if you have any
luck.

SPACE 2001

All plans for this excellent conference, here in Albuquerque (Aug 28-30),are
moving smoothly. We are planning another Asteroid/Comet Workshop (ACW),
which will include both emergency prevention/preparedness and asteroid/comet
resource mining and use. Both the American Institute of Aeronautics and
Astronautics (AIAA) and the Air Force are playing major roles in organizing
this conference and we are grateful to them for letting us host the
Workshop. More detail is available on the conference Web site. 

Cheers
Andy Smith
International Planetary Protection Alliance (IPPA)  
astrosafe@yahoo.com

========
(8) INACCURATE QUOTE?

From Lew Gramer <dedalus@latrade.com>

Benny, I was somewhat surprised by the following - sufficiently so to wonder
if it was really an accurate quote from Prof. Pasachoff!

>Professor Jay Pasachoff of Williams College in Massach-usetts said:
>"Watching the eclipse is a unique phenomenon. It is the only time Jupiter,
>Venus and Mercury make a daytime appearance. It is a spectacle like no other."

Surely the venerable coauthor of "Peterson Field Guid to Stars and Planets"
would be aware that all three planets CAN be sighted in full daylight, under
suitable conditions - Venus in fact being readily visible many days a year.

Clear skies,
Lew Gramer

==========
(9) SUPERCONTINENTS AND SNOWBALL EARTH EVENTS

From Karunakar Marasakatla <karunakarm@hotmail.com>

Dear Dr. Peiser,

I have worked on the snowball Earth scenario and come up with an explanation
to resolve the problem. I have summarized my work in a hypothesis and posted
it on the web at
http://www.geocities.com/karunakarm/unifiedtheory.html. I hope it will
generate some discussion in the CCNet discussion forum.

Regards
Karunakar Marasakatla
karunakarm@hotmail.com

====================
(10) AND FINALLY: IN A NEWS FLASH, SCIENTISTS GET BURNED

From St. Petersburg Times, 25 June 2001
http://www.sptimes.com/News/062501/Floridian/In_a_news_flash__scie.shtml

Three researchers and their obscure theory on how to save the Earth from a
hotter sun - a billion years from now - get a little too close to the media.


By TOM ZUCCO

You probably missed the story. The one last week about the scientists who
propose using an asteroid to slingshot the Earth farther from the sun as it
gets bigger and brighter.

There are two distinct conclusions you can draw from this.

First, we're all gonna burn to a crisp. Well, not us. It'll happen to the
schmos unlucky enough to be living on Earth about a billion years from now.
And you're thinking, "A billion years from now! I'm worried about being here
next year. Even Strom Thurmond won't be around in a billion years.
Probably."

The other thought is this: How can I get a job as a scientist? It's obvious
that all these people do every day is drop acid, log on to the Internet and
make up bizarre statements and theories. And they get all sorts of grant
money to do it. It's like being paid to be Timothy Leary.

Here, essentially, is what the story said:

Don Korycansky, a planetary scientist at the University of California at
Santa Cruz; Greg Laughlin, a scientist at NASA's Ames Research Center; and
Fred Adams, a University of Michigan physicist, came up with a proposal more
than a year ago that could address the problem of the sun becomming too hot.


Remember, that'll happen over hundreds of millions of years, as the sun
gradually grows stronger. It's like living in the same neighborhood with
Jennifer Lopez.

The scientists suggest finding an asteroid about 60 miles long and somehow
getting someone there to attach a rocket to it. (Do you know how hard it is
to get a plumber to come over, let alone a rocket guy?) Then the asteroid
would be sent into an orbit whose gravitational pull would very slowly start
to move the Earth away from the sun. It would also move Jupiter closer to
the sun. Like we care about Jupiter.

Important safety tip: The asteroid would have to pass within 10,000 miles of
Earth, which is actually cutting things pretty close. If the person who
attaches the rocket to the asteroid aims it even a little bit the wrong way,
we're all crispy critters a lot sooner than we thought.

But it was just a theory. Something to think about.

There was no mention of global warming.

And then the media got ahold of it.

Somehow, when this theory was published several months ago, a newspaper in
England announced that this was the "cure" for global warming. Forget carbon
dioxide emissions and holes in the ozone layer ... just move the pot away
from the stove.

Wrong.

Fred Adams, one of the scientists, explained during a recent phone interview
how a simple theory in an obscure journal (Astrophysics and Space Science)
was bent and tweaked into a story that made international headlines.


* * *
Question: What's up, Doc?

Answer: "This whole thing has gotten a bit out of hand. All we did was find
an orbit."

Q. Come on. No need to be modest.

A. "Well, okay. The research is interesting for a couple of reasons. It
tells you one can actually move planets around. That's important, because
over a billion years, the sun will get brighter and life on Earth won't
last. Whoever is living at that time might have something they can do about
it, and some people right now might find that comforting."

Q. So how did this turn into a "cure" for global warming?

A. "Some British newspaper started it."

Q. Figures. You know they run pictures of naked women in their papers?

A. "What happened was we used a phrase that they picked up on. We said you
might want to move the Earth because when the sun heats up, we'll be faced
with catastrophic global warming.

"They probably did a word search, and since we used it, they found the
research paper. If they read the abstract carefully, they'd know it had
nothing to do with global warming.

"And it wouldn't work because the time element is completely wrong. We're
talking hundreds of years with global warming, and hundreds of millions with
the intensity of the sun.

"All we've done is found an orbit. It's nothing profound, and it's in no way
a solution to global warming."

Q. Anybody else buy into the story?

A. "Rush Limbaugh did a radio program about it, and I'm still getting nasty
e-mail from people who think we're trying to move the Earth to cure global
warming. Limbaugh's people didn't call or contact us."

Q. If you strapped rockets onto Rush Limbaugh and launched him into space,
would he have enough mass and density to pull the Earth away from the sun?

A. "I think he's a little too light. But that's an interesting theory."

Q. Will this story hurt your credibility? Will people think you guys are ...
well, a little weird?

A. "Well, it's a little bit maddening because I worked very hard to become a
serious scientist. Now I'm kind of put in the role of a crank. Only a crank
would try to put a rocket on an asteroid and ... it sounds pretty stupid,
doesn't it?"

Q. Not at all. Then again, I'm one of those people who just likes to say the
word "asteroid." So what can I do, in the name of science, to help?

A. "I'm interested in sort of putting water on the fire here."

Q. Water on the fire? Very good!

A. "Really. All we did was find an orbit. It has nothing to do with global
warming. We just saw this problem and then this amusing spin got put on it."

Q. Amusing spin. And people think scientists aren't funny.

A. "Huh? Oh, sorry about that."

© Copyright 2001 St. Petersburg Times. All rights reserved. 

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