You probably learned about amino acids in middle or high school—your teacher likely explained how they’re the “building blocks” of life. It’s true—amino acids help cells build the necessary proteins for muscles, tissues, and cells to function. Scientists have identified 20 amino acids as essential to life on Earth, but there are hundreds more, many of which don’t create proteins. Some of those may be essential to alien life, too.
At the 2017 Experimental Biology conference, Valparaiso University undergraduate research assistant, Claire Mammoser, presented work she conducted with colleagues, Laura Rowe and Shilpa Dhar, and with Bayland Brown from Ivy Tech Community College. Their project began with the assumption that extraterrestrial life also requires cellular building blocks, so they analyzed 15 amino acids, 10 “unnatural” (or non-protein forming) and five “natural” (or proteinogenic) ones, to see which might be viable in the extreme environments of space.
The researchers know which amino acids create proteins in terrestrial life forms, but didn’t want to limit their study to those. Extraterrestrials “might use amino acids that are known to us but not used to make proteins on Earth,” according to Mammoser. While there’s no way of knowing which amino acids might be key to alien life just yet, the group examined the amino acids to see which characteristics might lead to their viability on other worlds.
Microbial life may thrive beneath the icy surface of Jupiter’s moon, Europa. Credit: NASA/JPL/Ted Stryk
The team put the 15 amino acids through a series of tests, subjecting them to extreme heat and cold, gamma and ultraviolet radiation, and various pH levels. They developed these tests specifically because Mars, Europa, and Enceladus have environments with one or more of those conditions. They monitored the amino acids to see which were able to withstand these conditions and which broke down, and they looked for patterns among the ones that remained stable—does size matter? What about water binding or water holding capabilities? Mammoser explained their goal: “Finding trends in amino acid stability would give us an idea of what sort of amino acids may have survived in outer space long enough to create life.”
The results of the experiment are, of course, inconclusive for now. Further testing is required to isolate characteristics and amino acids that could survive off-Earth, and even when those are identified, there’s no proof they actually exist inside any extraterrestrials. Such an ambitious project will take a long time to yield concrete results, but this is a promising beginning. The group will soon test amino acids previously used in experiments conducted to obtain information about the origin of life; they will also test amino acids harvested from meteorites. Each round of tests will provide insight into which amino acids might—or don’t—have what it takes to survive in space and to become part of aliens’ genetic codes. It’s ironic to think that we might know something about extraterrestrials’ insides before we know about their outsides.