With Viking, for example, soil had to be scooped up, placed into a chamber and heated to make the sample a gas before it could be analyzed. The Mars Science Laboratory will be able to do a more thorough sample analysis than Viking could, but it will still need to prepare its samples beforehand. The more a sample has to be handled, the greater chance there is for the equipment to malfunction or the analysis to fail.
On Earth, scientists do mass spectrometry within a vacuum chamber. But that requires either finding a small enough sample, or cutting down the sample to fit into the chamber. Any such efforts on Mars have to be done with a robotic rover that's controlled by human operators millions of miles away.
"Cutting rocks, picking them up and moving them around, all this adds complexity," Johnson said. "Complexity makes it more difficult to conduct experiments with a robotic rover. Plus, adding new tools so the instrument can do these extra tasks increase size, weight and power consumption. All this makes sending a mass spectrometer into space even more challenging."
Trying to simplify this work, Johnson and Hodyss at JPL, which manages NASA's Mars Exploration Project, turned to a technique called laser ablation. The method involves shooting a laser at the sample's surface, which creates a plume of molecules and ions that can then be analyzed by the mass spectrometer.
But how do you get the sample ions to enter the mass spectrometer? Even on our planet, that problem has plagued researchers for years. A large percentage of a sample was traditionally lost at this stage until recently, that is. PNNL researchers Dick Smith and Keqi Tang developed a new technology for mass spectrometers in the l
|Contact: Franny White|
DOE/Pacific Northwest National Laboratory