Main

The National Aeronautics and Space Administration (NASA) Viking Mars mission was both a historic landmark and a crushing disappointment. It generated striking images and offered invaluable geological and meteorological insights, but soil sample analyses revealed an apparent lack of organic molecules, suggesting an absence of life—little and green or otherwise. And so the quest for interplanetary life went on hiatus, or at least kept a low profile. “You kind of stayed in the closet,” explains Berkeley chemist Richard Mathies, “[and] didn't really tell anybody you were doing exobiology, because you were afraid you were going to get branded as a complete crank!”

New inspiration came after analysis of Antarctica's Allen Hills 84001 meteorite yielded tantalizing geological data that helped revive hopes of finding martian life. More recently, the Spirit and Opportunity missions provided compelling, if not indisputable, evidence that the martian surface contained liquid water—at some point. Finally, various studies suggest that the Viking lander's analytical equipment lacked the sensitivity to quantify truly scarce molecules, and that soil samples were taken too close to the planet's surface, where organic molecules would have been thoroughly degraded by the highly oxidizing conditions (Benner et al., 2000).

In 2009 or 2011, the European Space Agency (ESA) intends to embark on the ExoMars mobile rover mission, which will include a closer search for signs of life. To this end, Mathies and colleagues from several other institutions have developed the Mars Organic Analyzer (MOA), an innovative microfluidics-based capillary electophoresis system for the detection of amino acids—a prototype for the detector to be included in the ExoMars lander (Skelley et al., 2005).

Earth's nearest equivalent to the martian surface lies in an inhospitable patch of Chile's Atacama desert, where the soil is highly oxidized and even bacterial life is extremely scarce. Levels of organic molecules there fall below the limits of the Viking system's detection capabilities—but MOA passed with flying colors, detecting traces of several amino acids. “The system we're running,” says Mathies, “has low part-per-billion—to even tens-of-parts-per-trillion—sensitivity for these organic amines and amino acids. That's a sensitivity that's roughly 1,000 to 10,000 times better than Viking.” The team is now scaling up to develop MOA systems capable of processing hundreds of samples.

Mathies believes the ESA and NASA now recognize the potential of new biological and chemical techniques, and beyond finding life on Mars, suggests that as a proving ground for microfluidics, MOA may also find new life in chemistry research: “The real trend is that this stuff is no longer just gee-whiz lab-on-a-chip stuff; it's starting to go mainstream... I see this as the start of a revolution in the way lots of people do chemistry.”