Outer Space Not So Lifeless After All

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Outer Space Not So

Lifeless After All

By Robert C. Cowen

The Christian Science Monitor

6-18-4

 

Astronomers have a new take on what they once considered lifeless

outer space. They now think of our galaxy as a vast reactor for

biologically significant organic chemistry.

 

Materials that could jump-start organic evolution have shown up in

interstellar dust clouds and dusty planet-forming discs around many

stars. These findings fuel an increasingly strong suspicion that the

raw material of planet Earth was primed for life.

 

The infrared-sensing eyes of NASA's Spitzer Space Telescope made the

latest discovery. As NASA recently announced, Dan Watson and William

Forrest at the University of Rochester in New York

found "significant amounts of icy organic materials" around five

young stars in Spitzer data.

 

Water, methanol, and carbon dioxide coat dust particles around these

stars located 420 light-years away in the constellation Taurus. NASA

notes that, while such materials have been found elsewhere, "this is

the first time they were seen unambiguously in the dust making up

planet-forming gases."

 

Such discs appear to be common in our galaxy. Infrared light

penetrates dust, allowing astronomers to see into dusty areas.

Spitzer - launched last August - can image these areas with

unprecedented clarity and detail.

 

The telescope has been observing the nebula RCW 49, a stellar

nursery some 13,700 light-years away in the constellation Centaurus.

So far, it has provided early detailed data of discs around two of

more than 300 young stars.

 

The early data suggest all those stars have protoplanetary discs,

says Spitzer scientist Ed Churchwell from the University of

Wisconsin in Madison. "Spitzer has shown us that star and planet

formation is a very active process in our galaxy."

 

As data on interstellar chemicals have poured in over the past

decade, astronomers have abandoned their long-held prejudice against

such chemistry. They had thought that ultraviolet radiation from

stars, and other harsh conditions, would tear apart organic

molecules even if they did form.

 

However, dust can shield that chemistry. Many reactions occur within

protective icy coatings on dust particles. Some 130 organic

molecules have revealed themselves so far. They include such

interesting species as glycine, an amino acid; and ethylene glycol,

the antifreeze in your radiator.

 

Ethylene glycol is associated with formation of sugar molecules

necessary for life. It is what chemists call a reduced form of the

sugar glycolaldehyde. The research team that found the antifreeze

also detected this sugar in interstellar clouds.

 

"The discovery further demonstrates how important interstellar

chemistry may be in understanding the creation of biological

molecules on the Earth," said researcher Phillip R. Jewell when

these discoveries were reported in 2002. "Some scientists have even

speculated that the Earth could have been 'seeded' with complex

molecules from passing comets, which formed from the condensing gas

nebula that produced our solar system."

 

Discoveries since then have inspired some astrobiologists to move

from suspicion and speculation to at least mild conviction on this

point.

 

There is no consensus yet. But even skeptics find it interesting

that an interplanetary dust particle - snagged in the atmosphere by

a NASA aircraft - contains organic molecules that predate Earth.

 

Meanwhile, scientists are looking forward to the return in January

2006 of the Stardust spacecraft, which has captured dust from Comet

Wild 2. Its sample containers may hold more decisive data.

 

2004 The Christian Science Monitor. All rights reserved.

http://www.csmonitor.com/2004/0617/p17s01-stss.html