Capillary Electrophoresis Could Be Our Best Bet For Detecting Life On Other Planets

It's the million-dollar question: is there life on other planets? We're doing a lot to answer that question—planning planetary missions, building spacecraft, landing rovers—but there's one effort that's arguably most important: detecting life once we get there. In 2017, researchers from NASA's Jet Propulsion Laboratory (JPL) announced a tool that could be the most promising life-hunting method yet.

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Something In The Water

Developed by JPL researchers Jessica S. Creamer, Maria F. Mora, and Peter Willis, the method relies on something called capillary electrophoresis, which allows investigators to separate molecules based on the ratio of their size to their electrical charge. This method has been around since the early 80s, but Creamer says this is the first time it's been tailored to detect extraterrestrial life. The method is surprisingly simple: it involves combining a sample of liquid—for instance, from an extraterrestrial ocean—with a special chemical, then shining a laser across the mixture in a technique known as laser-induced fluorescence detection. That separates the molecules by how quickly they respond to electric fields, helping researchers analyze amino acids—the building blocks of life—with 10,000 times the sensitivity of anything used on past missions. It can't be used on soil samples on its own yet, but because it can detect 17 different amino acids even in very briny water, it could be perfect for the ocean environments of Saturn's moon Enceladus and Jupiter's moon Europa.

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Why It's Better Than Anything We've Tried

Aside from its simplicity, the real benefit to the method is that it can tell the difference between amino acids produced by life and those produced by other processes. That's where past missions have gone wrong. The 1976 Viking 1 mission, for example, searched Mars for byproducts of life, which ended up producing a false positive result. Even the Curiosity rover fell short in its search for life when its attempts to identify organic chemicals in Martian soil samples were foiled by reactions with other materials in the samples.

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For better accuracy, this method hones in on the amino acids' "chirality." According to NASA, "Chiral molecules such as amino acids come in two forms that are mirror images of one another. Although amino acids from non-living sources contain approximately equal amounts of the 'left' and 'right'-handed forms, amino acids from living organisms on Earth are almost exclusively the 'left-handed' form." Scientists suspect that life on any planet will "choose" one form or the other for its amino acids, which is why this technique will use that as a telltale sign of life.

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Written by Curiosity Staff February 8, 2017

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