[meteorite-list] The Hunt For Alien Pond Scum
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:13 2004
The hunt for alien pond scum
AGENCY DEVISES ROAD MAP FOR SEARCH OF HARDY MICROBES IN
SPACE, ON EARTH
By Robert S. Boyd
The Mercury News
November 4, 2002
WASHINGTON - With growing support from the federal government, scientists
are accelerating their hunt for life beyond Earth.
They also are broadening the search to include organisms unlike any of those on our
home planet -- what some researchers call ``weird life.'' By this, they mean alien
forms of life that are not based on our familiar DNA but on a different genetic code.
In theory, creatures made of unusual biological or chemical structures might exist on
moons or planets that lack liquid water, a must for life as we know it.
``We are looking for organic life that might be different from Earth life,'' said John
Baross, a biologist at the University of Washington in Seattle, and co-chairman of
the Committee on the Origin and Evolution of Life at the National Academy of
Sciences, the nation's premier scientific organization.
According to David Deamer, a biochemist at the University of California-Santa
Cruz, there is ``a 50-50 chance'' that extraterrestrial life would have a different
chemistry from life on Earth.
The genetic code of every earthly creature, from bacteria to whales, is written in an
alphabet of four letters -- A, C, G and T. Each stands for a chemical compound
known as a base. ``Weird life,'' however, might have different or additional bases
and hence be written in a different alphabet -- say B, C, G and H.
In addition, all proteins -- the building blocks of terrestrial life -- are assembled
from a set of 20 chemical compounds known as amino acids. But laboratory
researchers already have created deviant proteins using more than 20 amino acids.
If extraterrestrial life turns out to be made of the same materials as on Earth,
scientists don't expect to find ``little green men.'' The creatures probably will
resemble pond scum, a film or mat of primitive microbes like the cyanobacteria that
colonized our planet nearly 4 billion years ago.
Even that would be a monumental discovery, proving that we are not alone in the
At the request of Congress, the National Academy committee is preparing a road
map to guide the quest for both Earth-like and unconventional extraterrestrial life.
The search is known as astrobiology, a combination of astronomy and biology.
``Astrobiology is no longer a joke. It is serious business,'' said Bruce Runegar,
director of NASA's Astrobiology Institute, a consortium of 11 universities and
research institutions that the National Aeronautics and Space Administration
established five years ago to coordinate the search.
To ensure that astrobiology is taken seriously, the academy committee decided at a
meeting in Washington earlier this month to quit using the term ``weird life'' in its
reports because it sounds too much like science fiction.
Instead, committee members came up with the awkward name, ``non-terrean life,''
as opposed to ``terrean life'' here on Earth.
`` `Weird life' was not sophisticated enough'' for the National Academy, Baross
Much of the committee's meeting was spent examining the work of the
Astrobiology Institute, which coordinates the research of 850 scientists and
Current astrobiology projects include:
* Collecting meteorites from Mars that might reveal signs of past or present life.
Scientists now doubt that the famous meteorite that was picked up in Antarctica in
1984 contains the fossils of ancient microbes, as once was claimed. But they are
adding a third search team to the two that already are hunting for more Martian
* Designing scientific instruments to fly on missions to Mars and the moons of
Jupiter and Saturn. NASA is testing robots that can drill through rock, soil and ice in
Antarctica and the Chilean desert. The first mission to collect Martian soil and
return it to Earth won't be until 2011 at the earliest.
In addition, a space probe will reach Titan, an Earth-sized moon orbiting Saturn, in
2005. Astrobiologists are interested in Titan because it may have lakes of liquid
hydrocarbons, such as methane, which might host an alternative form of life.
* Exploring the capacity of life to survive in extremely hostile environments on
Earth as a guide to what to look for on other planets. This month, astrobiologists
will dive to the bottom of a frozen lake in a volcano high in the Andes to test the
limits of life as it might be found on Europa, an ice-covered moon of Jupiter.
``By exploring extreme environments here on Earth, we'll be much more capable
when we get to another planet,'' said Michael Meyer, NASA's chief scientist for
* Doing laboratory experiments to create and study abnormal life forms so they
won't be overlooked. NASA missions designed to spot only Earth-like microbes
might miss bizarre organisms.
For example, Steven Benner, a biochemist at the University of Florida in
Gainesville, has created lifelike molecules with non-standard DNA codes, and
proteins with more than the standard 20 amino acids. His goal is to determine how
such alternative systems might be detected on other worlds.
``These are potential `bio-signatures' for both terrean-like life and `weird life'
forms,'' Benner wrote in a paper describing his lab's work. He is also helping to
design detectors to fly on NASA missions to Mars.
Search in Earth
The search for clues to extraterrestrial life is even going on under Earth's oceans.
The Ocean Drilling Program, an international research partnership, has been
studying the geology of the seafloor for 30 years, but it is starting to look for living
microbes and fossils underneath it. Such creatures might have counterparts on other
James Yoder, an ocean expert at the National Science Foundation, a federal agency
in Arlington, Va., said a drilling ship would start exploring the ``deeply buried
biosphere'' next year. ``The ODP has just started doing biology,'' he said.
Victoria Meadows, an astrobiologist at NASA's Jet Propulsion Laboratory in
Pasadena, builds computer models of extraterrestrial environments to see what
forms of life might be possible on other planets.
One project is to model what Earth would have looked like from space 2 billion
years ago, before its oxygen-rich atmosphere developed. The models could provide
clues to possible evidence of life, such as methane gas, on an apparently lifeless
Received on Tue 05 Nov 2002 01:27:34 PM PST