Surviving Life on Mars

It remained a laboratory oddity for several years until the arrival of genetic engineering, the science of altering an organism's basic biological code, sometimes by splicing into it portions of another organism's code. Daly's group is inserting specialised genes to help in eliminating dangerous chemicals from waste sites. An established example of the value of such genetic engineering is found with E. coli, the bacteria found in the human gut, that has been engineered to produce large quantities of human insulin, which once had to be refined from human cadavers.

"Daly has been active in developing DR as a special model for bioremediation to clean radioactive supersites left over from the Cold War," Richmond explained. Some of those sites contain radioactive materials that are not easily removed by other microbes. While some other bacteria are being genetically engineered to thrive in toxic conditions while converting hazardous waste into reusable effluent, none can resist radiation the way D. radiodurans can.

Already, Daly and his colleagues have devised DR variants that can clean up mercury, a deadly heavy metal, and toluene, a dangerous solvent. This work was sponsored by the US Department of Energy.

The capability to insert genes also makes D. radiodurans a candidate for Mars pharmacists and to become "the plow that broke the plains" on Mars.

But first, it may help the search for life on Mars as a stand-in for Martian microbes in simulated Mars environments.

The changing face of Mars
Mars has gone through radical changes in our perception as a haven for life. After Sir Percival Lowell and a number of science fiction stories popularised Mars as a dying planet, US space probes in the 1960s and 1970s rewrote the book to show Mars as long dead, perhaps never alive.

Then came the discoveries hidden inside ALH84001(see our article 'Life on Mars?'). Soon thereafter, images and data from the Mars Global Surveyor, Mars Pathfinder, and Sojourner Rover spacecraft showed Mars indeed has significant quantities of water, and once had running water.

While Mars has become more tantalising, it is far from Eden. So the question is, if life was there, or is there, what are the best places to find it? Spacecraft surveying the planet to determine where water might survive beneath the surface, or where it once may have existed, are addressing this.