SETI Institute Principal Investigator
In an astonishingly wide range of environments on Earth, life can survive and even prosper. “All organisms are adapted to their environments, and since all environments vary with time,” says biochemist Hiromi Kagawa, “all organisms have by necessity evolved biochemical strategies for coping with the changes they encounter within their environments.” To understand the environments of other planets where life might thrive, Kagawa draws on lessons from Earthly “extremophiles” — life forms that can endure some of the most inhospitable conditions imaginable. Some of these environments are extreme in temperature, others contain high concentrations of toxic chemicals, and still others are parched or exposed to high levels of radiation.
We know that meteorites travel from Mars to Earth. Is life hardy enough to survive such interplanetary journeys? “Our knowledge of extremophiles allows us to design strategies to protect the Earth and Mars from cross-contamination,” Kagawa says, “and to ponder the possibilities that early life may have been able to migrate across space.” Researching bacteria that thrive in acid hot springs of Japan, she explores how these organisms cope with their caustic, near-boiling surroundings.
Kagawa also studies the most radiation-resistant bacteria known, which can endure radiation levels 500 times greater than human cells can survive. While the DNA of less stalwart organisms would be irreparably damaged by such intense bombardment, these bacteria can mend their broken DNA within hours.
- SETI Institute Explorer, Special Edition 2005