Efforts are on to trace signs of life on Mars and other planets, and researchers have come up with a chemistry-based technique to detect living organisms outside of Earth by analyzing the presence of amino acids.
Revealed by researchers at Jet Propulsion Laboratory of NASA in Pasadena, California, the new test has been claimed superior to the current methods used by spacecraft such as NASA's Curiosity rover.
The study has been published in Analytical Chemistry.
Detecting Amino Acids
There are a variety of amino acids, considered the basic building blocks of life on Earth. As such, detecting the presence of amino acids in alien worlds is a step toward finding signs of extraterrestrial life.
"Using our method, we are able to tell the difference between amino acids that come from non-living sources like meteorites versus amino acids that come from living organisms," said, Peter Willis of JPL, the principal investigator of the project.
The method uses capillary electrophoresis to separate components in a mixture of organic molecules. In this technique, a liquid sample is combined with a liquid reagent for chemical analysis under prescribed conditions.
A laser is then shone across the mixture in a process called laser-induced fluorescence detection, through which scientists are able to observe specific molecules moving at various speeds. When the charge is applied, the molecules are separated according to the speed at which they respond to the electric field.
The researchers modified the technique so they could detect more amino acid molecules in a single test. The improved method also enabled the researchers to detect the amino acids at any concentration level, even in samples with a high salt concentration.
To test the new method, the researchers analyzed the amino acids in California's Mono Lake, which is known to be highly alkaline and therefore a difficult place to find life in. The lake is also provided scientists with a possible sample of the environment existing in alien ocean worlds that are waiting to be explored.
With the improved method, they were able to analyze 17 amino acids at the same time. These amino acids, which the researchers call "the Signature 17 standard," were selected because of they are the most commonly occurring amino acids on the planet.
The benefits of the improved capillary electrophoresis test are its simplicity and ease of automation in testing liquid samples on ocean world missions.
A Clear Sign Of Life
The significant aspect in scouting for amino acids related to life is called chirality, a property of some molecules to come in two forms, left-handed or right-handed, which are mirror images of one another.
Non-living sources have amino acids that have both left-handed and right-handed molecules, while living organisms on Earth have amino acid molecules that are almost exclusively left-handed.
Since amino acid life on Earth are of the left-handed form, scientists are confident that alien amino acids too may come in either left- or right-handed forms, a clear indication of life.