Microbiologists Rocco Mancinelli and Lynn Rothschild have a thing for salt. Jagged hunks of it crowd the shelves of the couple's offices at the NASA Ames Research Center in Mountain View, California. Their favorite pieces are laced with translucent reds and greens that look like algae in a neglected pool. These crystals harbor colonies of hardy, salt-loving microbes called halophiles, a class of bacteria that can thrive in very nasty settings. So impressive are the survival skills of these single-celled organisms that Mancinelli and Rothschild suspect the microbes might be able to survive long journeys through the vacuum and radiation of space. And that possibility, in turn, could help explain how life began on Earth.
Mancinelli opens a drawer and points to scores of small, neatly arranged quartz disks. They were used to test whether the halophiles could survive a two-week flight on a satellite. "We dried about 10 million cells onto the surface of each quartz disk. When we analyzed them after the flight, we found that 10 percent to 75 percent had survived."
How? Rothschild says cells that thrive in a salty habitat evolve to endure long dry spells. That stress, along with the sun's relentless radiation, forces them to develop ways to mend nicks in their DNA. Their rich pigments may also provide protection.
"We don't have an answer yet for whether life could withstand space travel," muses Mancinelli. "But if it can, I wouldn't be surprised if a halophilic organism is the first extraterrestrial we find."
