With NASA's Curiosity Rover safely on Mars and ready to search for signs of life, back on Earth attempts are underway to engineer bacteria that could thrive on the Red Planet.

A team of undergraduates from Stanford and Brown Universities are busy applying synthetic biology to space exploration, outfitting microbes to survive extreme Martian conditions and produce resources needed to sustain a human colony.

Though Mars is potentially a place where life may have survived at some point, it is not an especially friendly environment, and thriving there will not be easy – for humans or microbes. The average surface temperature of Mars is minus 80 degrees Fahrenheit, and the almost-nonexistent atmosphere is 95 percent carbon dioxide. Although water exists in Mars' ice caps and there's some evidence that giant oceans once covered the planet, today it's essentially a deep-frozen desert. Colonizing Mars would be challenging and pricey.

"Obviously, bringing up heavy machinery or building materials is going to be really expensive," said Brown student and team captain Ben Geilich. "The benefit of having bacteria that can do this for you is they're really small and very light. Once there, they could grow food, produce medicine, extract minerals, and build building material."

The project is part of the International Genetically Engineered Machines (iGEM) challenge, an annual synthetic biology competition that pits students around the world against each other in attempts to ingeniously hack living cells to perform new tasks. In a regional iGEM meet in October, Geilich's team will present what they call a Hell Cell, a suite of genetically engineered parts that could enable a bacterium to withstand severe cold, dryness and radiation. Geilich calls it "a genetic box of crayons for extremophile conditions."

In the Stanford-Brown iGEM lab, students work on designing bacteria that could survive on Mars. (Lynn Rothschild)

The Hell Cell includes genetic modules, or BioBricks, based on DNA from a variety of ultra-tough organisms, including a cold-resistant species of Siberian beetle that makes "antifreeze" proteins, a* *radiation-resistant bacterium that sequesters large amounts of the element manganese, and E. coli, which produces a nutrient that confers cold and drought resistance. The team is also investigating heat- and acid-tolerance mechanisms that could be useful in other planetary environments.

While they're currently experimenting with *E. coli, *BioBricks can be mixed and matched in other species, tailoring new strains to particular conditions. "You go into nature and find genes, and then you can recombine them into circuits that you cannot find in nature," explained Andre Burnier, one of the team's mentors and a lab technician at NASA's Ames Research Center.

To be really successful, the bacteria must do more than just survive on Mars. They need to perform functions useful for establishing a human colony one day. In addition to the Hell Cell suite, the team is developing bacteria that could extract minerals from Martian sediment or recycle rare metals from spacecraft electronics.

The team's main focus is on the latter, which requires engineering bacteria to separate metals from the silica that coats most electronics.

These projects expand on a Mars theme started last year, when the team designed BioBricks that allow bacteria to produce a cement-like material for building, and sugar for feeding other microbes.

Usefulness aside, sending bacteria to Mars poses certain ethical concerns. "If you were to release something into the environment that killed off the native fauna, that would be devastating to science," said Burnier. But if there isn't life there, and engineered bacteria could help humans explore, "the argument could be made that it would be a good thing."

The team is also testing whether life could conceivably exist in the acidic clouds around Venus by tweaking cloud-dwelling bacteria on Earth to survive in those conditions. Although the planet's surface is inhospitable, it's possible that life evolved long ago in its oceans and migrated upwards. Astronomer Carl Sagan proposed that possibility in the 1960s and NASA scientists have been interested ever since, but the synthetic biology approach is new.

"In the coming years, I think we're going to see a huge boom in stuff done with bacteria, only limited by our imagination and creativity," said Geilich.