From: LARRY KLAES (ljk4@msn.com)
Date: Wed Nov 20 2002 - 07:28:39 PST
Star search: The quest for life, or something like it
Full story: http://seattletimes.nwsource.com/html/nationworld/134579049_alienlife13.html
By Robert S. Boyd
Knight Ridder Newspapers
WASHINGTON: Scientists are accelerating their hunt for life beyond Earth with growing support from the federal government.
They also are broadening the search to include organisms unlike any on our home planet, what some researchers call "weird life." By this they mean alien forms of life based not 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 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.
David Deamer, a biochemist at the University of California, Santa Cruz, said there is "a 50-50 chance" 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 researchers have created deviant proteins using more than 20 amino acids.
Think pond scum
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 nothing so much as pond scum, a film or mat of primitive microbes like the cyanobacteria that colonized our planet nearly 4 billion years ago.
More information
NASA Astrobiology Institute: nai.arc.nasa.gov
The Astrobiology Web: www.astrobiology.com Even that would be a monumental discovery, proving we are not alone in the universe.
At the request of Congress, the National Academy committee is preparing a "road map" to guide the quest for Earthlike 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 the National Aeronautics and Space Administration (NASA) Astrobiology Institute, a consortium of 11 universities and research institutions that the space agency established five years ago to coordinate the search.
To ensure astrobiology is taken seriously, the academy committee decided at an October meeting to quit using the term "weird life" in reports because it sounds too much like science fiction. Instead, committee members came up with the awkward name "nonterrean life," as opposed to "terrean life" on Earth. " 'Weird life' was not sophisticated enough" for the academy, Baross said.
Much of the committee's meeting was spent examining the work of the Astrobiology Institute, which coordinates the research of 850 scientists and engineers.
Current astrobiology projects include:
• Collecting meteorites from Mars that might reveal signs of past or present life. Scientists doubt 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 hunting for more Martian rocks.
• Designing instruments to fly 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, a moon orbiting Saturn, in 2005. Astrobiologists are interested in Titan because it may have lakes of liquid hydrocarbons, such as methane, which might shelter an alternative form of life.
• Exploring the capacity of life to survive in hostile environments on Earth as a guide to what to look for on other planets. Astrobiologists are diving 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.
• Doing laboratory experiments to create and study abnormal life forms so they won't be overlooked. NASA missions designed to spot only Earthlike microbes might miss such bizarre organisms.
For example, Steven Benner, a biochemist at the University of Florida in Gainesville, has created lifelike molecules with nonstandard 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.
Planned space missions related to astrobiology include:
• A giant infrared space telescope, SIRTF, to be launched in January, will be able to detect disks of dust and gas around other stars, where new planets are born. A gap in such a disk, like a hole in a doughnut, is a sign a planet is there.
• A series of Mars landers and orbiters will be launched every other year starting in 2003, scouting the Red Planet for sites where biological activity might be found.
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