'Chemical Laptop' Could Search for Signs of Life Outside Earth

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What it's looking for

Amino acids come in two types: Left-handed and right-handed. Like the left and right hands of a person, these amino acids are mirror images of each other but contain the same components. Some scientists hypothesize that life on Earth evolved to use just left-handed amino acids because that standard was adopted early in life's history, sort of like the way VHS became the standard for video instead of Betamax in the 1980s. It's possible that life on other worlds might use the right-handed kind.   

"If a test found a 50-50 mixture of left-handed and right-handed amino acids, we could conclude that the sample was probably not of biological origin," Creamer said. "But if we were to find an excess of either left or right, that would be the golden ticket. That would be the best evidence so far that life exists on other planets."

The analysis of amino acids is particularly challenging because the left- and right-handed versions are equal in size and electric charge. Even more challenging is developing a method that can look for all the amino acids in a single analysis.

When the laptop is set to look for fatty acids, scientists are most interested in the length of the acids' carbon chain. This is an indication of what organisms are or were present.

How it works

The battery-powered Chemical Laptop needs a liquid sample to analyze, which is more difficult to obtain on a planetary body such as Mars. The group collaborated with JPL's Luther Beegle to incorporate an "espresso machine" technology, in which the sample is put into a tube with liquid water and heated to above 212 degrees Fahrenheit (100 degrees Celsius). The water then comes out carrying the organic molecules with it. The Sample Analysis at Mars (SAM) instrument suite on NASA's Mars Curiosity rover utilizes a similar principle, but it uses heat without water.

Once the water sample is fed into the Chemical Laptop, the device prepares the sample by mixing it with a fluorescent dye, which attaches the dye to the amino acids or fatty acids. The sample then flows into a microchip inside the device, where the amino acids or fatty acids can be separated from one another. At the end of the separation channel is a detection laser. The dye allows researchers see a signal corresponding to the amino acids or fatty acids when they pass the laser.

Inside a "separation channel" of the microchip, there are already chemical additives that mix with the sample. Some of these species will only interact with right-handed amino acids, and some will only interact with the left-handed variety. These additives will change the relative amount of time the left and right-handed amino acids are in the separation channel, allowing scientists to determine the "handedness" of amino acids in the sample. 

The Chemical Laptop, developed at JPL, analyzes liquid samples and detects amino acids and fatty acids. These are both chemicals that are essential to life.Credits: NASA/JPL-Caltech



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