The researchers propose that the system could operate on any Mars lander or rover and be made ready for launch in just five years. The key challenge they face is to make the instrument light enough to be flown, and resilient enough to survive the cold, -120°C Martian nights.
Michael Storrie-Lombardi and Jan-Peter Muller, of the Mullard Space Sciences Laboratory in the UK are carrying out experiments both in the laboratory and at Silver Lake in California, US - a well-known Mars analogue study site. "Being able to test the fluorescence signal both under laboratory conditions and in the field has been critical in ensuring the system will work on the surface of Mars," said Muller.
The approach uses ultraviolet fluorescence to illuminate soil and rock in search of tell-tale signs of life. In particular the group is searching for chemical compounds called polycyclic aromatic hydrocarbons (PAHs), which are believed to be one of the earliest forms of organic matter in the Universe. And, just like living organisms, PAHs fluoresce when excited by ultraviolet light.
"While using fluorescence to illuminate organic material has been carried out for decades, light sources were too large and unwieldy to use for a robotic mission to another planet," said Storrie-Lombardi. "However, new generations of LEDs, which are very small, reliable and energy efficient make this possible."
"Placed on a Mars rover, one of these LEDs positioned a few centimetres from a target can easily provide enough light to produce fluorescence in small PAHs," Storrie-Lombardi added. "But even more encouraging is the very recent development of a small 375 nm laser diode that can illuminate geological layers and crevices high up on otherwise inaccessible rock outcrops."
The tool is ideal for initial surveys as it requires no sample preparation, does not destroy sample material and requires only electrical power to operate, conserving precious water and other consumable resources for sister instruments.
Green laser module