A bacterium once accidentally taken to Mars has stunned scientists by growing better in space than on Earth.
Bacillus safensis was the only one of 48 bacteria tested on the International Space Station which preferred life at 400km above the ground, researchers from the University of California report.
Ironically, it was first discovered at the Kennedy Space Center in Florida, and takes its name from the Spacecraft Assembly Facility (SAF) where it was found.
In space, Bacillus safensis grows 60 percent better than on Earth, while 45 of the other bacteria tested showed no difference. Results on the remaining two were inconclusive.
They aren't sure why Bacillus safensis grows so well.
"A lot of people ask us why we sent microbes into space," says lead author Dr David Coil, a microbiologist at UC Davis.
"Understanding how microbes behave in microgravity is critically important for planning long-term manned spaceflight, but also has the possibility of providing new insights into how these microbes behave in human constructed environments on Earth."
Scientists have sequenced Bacillus safensis' genome and hope to find in it clues to why it grows so well in microgravity, compared to other bacteria.
Many of the bacteria were collected from sports teams, monuments, schools and museums.
"This initiative is not just about significant research," says Darlene Cavalier, one of the study's authors.
"It's about engaging the public in that research. Microbes that they collected are taking a ride on the International Space Station. They're the subject of research by microbiologists and astronauts. We hope this inspires youngsters as well as adults to become more aware of and involved in science."
It's virtually impossible to launch spacecraft without some degree of contamination. It's estimated Curiosity, currently on Mars, hosted nearly 30,000 microbes at launch.
Any that could survive the harsh conditions of outer space could potentially thrive on a rocky planet.
The latest discovery was published in open-access journal Peer J.