Lasers and liquids could help SDSU researchers detect amino acids on rocks from moons and other planets.
Have we been looking for aliens in the wrong places? San Diego State University chemists are developing ways to find signs of life on other planets by looking for the building blocks of proteins in a place they’ve never been able to test before: inside rocks.
After collaborating with researchers at NASA’s Jet Propulsion Laboratory (JPL) at La Cañada Flintridge in 2019, Jessica Torresa doctoral student in chemistry at SDSU, is experimenting with ways to extract amino acids from porous rocks that could be used on future rovers.
Previous research has looked for evidence of other life forms in water and soil, but not from solid materials.
Current methods of identifying amino acids cannot differentiate versions created by a living organism from those formed by random chemical reactions. And existing techniques usually require water – which would freeze or evaporate if placed on a space probe traveling to Mars or Europa, the ice-covered saltwater moon of Jupiter that some see as a prime candidate. for extraterrestrial life due to its underground ocean.
“The real novelty of our project is to approach the detection of life using alternative solvents better suited to space instead of water and organic solvents, which are very suitable on earth,” Torres said. “We hope to develop a microfluidic device capable of extracting, sampling and identifying amino acids in rocks. This is particularly new because JPL does not yet have a method to address this.
Torres is developing new chemical solvents specifically designed to work on an automated rover visiting another planet, where water and other common solvents like alcohols and acetone would not be viable.
In the laboratory, Chris Harrisonan adviser to Torres and an SDSU professor of chemistry, uses a process called capillary electrophoresis.
“It’s a cheaper way to detect life, and better in many ways,” Harrison said.
Capillary electrophoresis involves separating molecules by passing them through a liquid-filled tube narrower than an average human hair. A laser attached to the end of the tube is used to illuminate a phosphorescent molecule attached to an amino acid. When an amino acid passes in front of the laser, a sensor displays a peak of the laser-induced glow.
There are 20 different amino acids and each moves through the tube at varying speeds depending on size, electrical charge, and how they react with other chemicals. Torres’ current challenge is to try to configure a single peak for each of the contrasting amino acids; she hopes to eventually be able to identify an amino acid, even if it is only one among a billion other molecules.
“We are really lucky with the equipment we have here. I can do exactly the kinds of things I would do at JPL at SDSU,” Torres said. They were originally supposed to return to JPL during their PhD summers, but worked remotely during the pandemic.
Once they’ve optimized the chemicals they use to reliably separate and identify each of the 20 amino acids, the team plans to test their process on rock samples from the moon, Atacama Desert similar Mars and Mono Lake, which is two to three times saltier than Earth’s oceans.
“What we will bring with this new solvent will add flexibility to analysis on Earth and beyond,” Harrison said. “Sometimes it’s hard to see the impact of basic science until you put it in the hands of others and see the problems you’ve already solved for them.”