Hitchhikers in Space
This might be surprising, but stowaways often hitch a ride on NASA spacecraft. No matter how hard scientists and technicians try to keep them off, some microscopic bacteria always find a way to climb aboard.
Researchers at Kennedy Space Center's Space Life Sciences (SLS) Lab are trying to find out how long these bacteria can stay alive.
Image left: Astrobiologist, Andrew Schuerger, preparing to load a bacterial experiment into the Space Life Sciences Lab Mars chamber. Image credit: NASA/KSC
"What are the limits of life," asks SLS microbiologist Wayne Nicholson. "How far can we push life toward the environment of another planet and can they survive?"
The jury is still out, Nicholson says. Scientists have not yet answered the question of whether or not bacteria can travel from planet to planet. Even if these "bugs" can survive through the dry vacuum of space, they still have to make a life for themselves in a foreign world.
Making the question more difficult, each planet has its own unique environment. Gravity, radiation, atmospheric gas and other variables all change from one planet to the next. Bacteria that might survive on Mars might not make it on Venus or Jupiter.
With NASA's Mars Exploration Rovers now traipsing across the Martian surface, study of these nomadic bacteria is concentrating on the Red Planet.
Andrew Schuerger, an astrobiologist at the SLS Lab, is doing a number of experiments using a "Mars chamber." By simulating the Mars environment, Schuerger can test to see if bacteria are able to survive, adapt and reproduce under such hostile conditions.
"I believe, based on my research, that we are not overtly contaminating Mars," Schuerger says.
Schuerger's research suggests that bacteria on the sun-exposed surfaces of landing spacecraft are killed off quickly by ultraviolet light. Bacteria hiding inside or underneath the craft may escape these lethal rays, but the Mars environment doesn't support their growth and reproduction.
As humans explore the universe, understanding these cosmic tagalongs has practical implications. Scientists around the globe want to know if life exists, or has ever existed outside of Earth.
By taking our "bugs" with us on our search, we risk mistaking life from Earth for extraterrestrial life. Discovering life on other planets requires being able to tell the difference between what we find and what we bring along.
"This could be the story of the century, but it could also be the embarrassment of the century," Nicholson says.
The question of space-traveling spores is not only a scientific issue, but also an ethical one. The human quest for discovery and dominion has already shown disastrous consequences on Earth.
Image right: Microscopic images of the bacteria, Bacillus subtilis, as it appears when dispersed on six different kinds of spacecraft materials. Image credit: University of Florida
When Europeans came to America, they brought germs with them that had devastating effects on the people already there. Today, scientists are learning much about how bacteria too small to see can have a big impact on new creatures and places.
Nicholson points out, however, that while humanity's past has some dark spots, we also have a history of conservation. Wildlife preserves and environmental protection laws are evidence that we are trying to learn from our previous mistakes.
As humans explore untouched worlds beyond our own, we have the opportunity to put our learning into practice before it's too late.
"Mars is a pristine environment," says Nicholson. "We are the only species that can actually think ahead and plan out our land use."
Jeff Neely, KSC Staff Writer
NASA's John F. Kennedy Space Center