Star Search 1999
As Donald Brownlee watched from Kennedy Space Center in Florida last
month, Stardust blasted into the heavens. It's not likely many observers
considered the wistfully named mission's implications for the hunt for life
away from Earth, but Brownlee certainly did.
The astronomy professor is among scores of faculty taking part in the
ÃÛ¶¹ÊÓƵ's fledgling but groundbreaking doctoral program
in astrobiology, the search for life on other celestial bodies, which begins
this fall. He also is the principal investigator for ,
a seven-year mission designed to travel to comet Wild 2, capture samples
of comet dust and bring them back for analysis.
This is a mission Brownlee has dreamed of since 1980. Technological advances
and fortuitous events in space made it possible. In 1974, Wild 2 came close
enough to Jupiter that the giant planet's gravity altered the comet's orbit
around the Sun. Now instead of continuing to circle only among the outer
planets of the solar system, it actually passes relatively close to Earth.
Yet it hasn't been among the inner planets long enough for heat from the
sun to have destroyed or altered telltale properties, characteristics Brownlee
believes will provide new clues on the origins of the solar system and possibly
the universe itself.
An artist's rendition of the Stardust spacecraft approaching
comet Wild 2.
Last fall, as the Leonid meteor shower was concluding its annual display,
an excited television reporter was in Brownlee's office. NASA had flown
two planes high in the atmosphere to study Leonid particles and agency scientists
noted the probable existence of organic properties. Brownlee reached into
a file cabinet and withdrew a small rock, about the size of a charcoal briquette.
This chunk, he announced, was about 2 percent carbon, was rich in organic
material and was the first meteorite found to contain amino acids.
It has been known for some time, he explained, that comets carry organic
molecules.
They also carry water, a key component of life. It is thought that comets
might well have deposited the first water on Earth, and perhaps the amino
acids that evolved into life. If that is truly the case, then comets are
a bit like Johnny Appleseed, wandering the universe and sowing the seeds
of life as they go. Whether those seeds grow depends on the conditions they
encounter after they are planted.
"The building materials are there, and then the question is, 'Does
life occur?'" Brownlee said. "And who knows? I think most people
believe that it's probably very common that if you have the right environment
and you have the material, then life will evolve."-Vince Stricherz | 