NASA’s robotic Phoenix Mars Lander that blasted off for the Red Planet last Saturday will hopefully resolve the question of whether or not our neighbouring world has ever played host to microbial life. The space probe is expected to land on the planet’s Arctic plains in May next year to begin an exhaustive search for organic compounds that could have been preserved in the Martian soil and ice. Phoenix will use a drill to reach beneath the soil and concrete-hard ice to gather frozen samples that could then be heated and their vapours analysed. Other soil samples will be mixed with water carried on the probe and examined by onboard microscopes. Once thought to be a dry, arid planet covered in red dirt, Mars is now believed to have huge reservoirs of ice (easily enough to deluge the planet if it melted).
This opens the door to an invaluable resource for manned Mars missions, with possibilities ranging from using it as a source of fuel, drinking water, and oxygen, to the very landscaping of the Martian surface for human settlement some day. The first hints of hidden water beneath Mars’ surface came in 2000 when Nasa’s Mars Global Surveyor spacecraft spotted hundreds of delicately filigreed gully systems that indicated swimming-pool volumes of water lying entombed underground, waiting for seasonal swings. The frozen material apparently accumulated in winter and sublimed — or evaporated — in summer in each hemisphere. Ice doesn’t melt into liquid water on Mars — instead, it sublimes, or changes directly from solid to gaseous state, much the same way ‘dry ice’ does here on Earth.
But doesn’t the lack of surface water and the harsh radiation at Mars make any surface life there very unlikely? Yes, and no. For given the fact that all evidence points to the existence of warm and wet places beneath the Martian surface even before life began on Earth, it’s not unlikely that some primitive micro-organisms could still be there. It is up to Phoenix to confirm this — either way — and complete an important part of the homework needed for eventual manned Mars missions, possibly a little more than a decade away.