- Life-sustaining conditions may exist on planet-like bodies
in deep, interstellar space, according to a California Institute of Technology
- In a paper published in the current journal Nature, David
J. Stevenson, professor of planetary science, draws on planetary theory
and his own calculations to explain how conditions supporting life could
exist beyond the known solar system.
- Stevenson,s theory is based upon a widely known planet
dispersal model. It states that Earth may have had one or more siblings
when the solar system was born, but they were jettisoned by gravity when
they got too close to Jupiter or other large planets.
- Stevenson believes these wandering planets are surrounded
by a blanket of hydrogen. He says hydrogen normally is transparent, but
when it reaches a high enough temperature it can absorb infrared light
and become opaque.
- "This opaque hydrogen layer could create a greenhouse
effect that may very well sustain oceans, " says Stevenson. "Scientists
call it the Goldilocks, scenario -- where conditions are neither too hot,
nor too cold."
- Although Stevenson says such rogue planets would derive
little or no energy from the sun, he believes that temperature and chemical
differences created by volcanic eruptions and lightning would create an
unstable environment that could produce a form of k inetic energy.
- "Life depends on the availability of free energy,"
he explains, "so it,s possible that organisms without sunlight could
develop and be sustained by energy resulting from these forces."
- He says it's unclear exactly how organisms could take
in the energy, but extraterrestrial life probably wouldn't resemble any
creature we know. Eyes, for example, would have to be adapted to darkness,
as only a red glow would be emitted from the volcanoes .
- Jack Lissauer, space scientist at NASA Ames Research
Center, says theories like those proposed by Stevenson are important to
current space exploration.
- "We have to be careful about setting limits to space
research," says Lissauer, "as it,s probable that life can survive
in very unearthly environments."
- Lissauer points out that NASA is currently planning a
year 2003 mission to Europa, one of Jupiter,s moons, which is very dark,
but that has an ocean thought to be composed of H20. "Like Stevenson,s
model, life-sustaining water could exist below Europa,s surface,"