Posted on Mar 31, 2018
In 2016, NASA sequenced DNA in space for the first time, but alien life, we may soon discover, may be vastly different on other planets and moons, particularly as we expand our efforts to explore ocean worlds with our solar system and beyond. “Most strategies for life detection rely upon finding features known to be associated with Earth's life, such as particular classes of molecules,” the researchers wrote.
DNA and RNA are the building blocks of life on Earth, but the molecules of life might differ substantially on another planet. A new paper by scientists at Georgetown University, published online this month in the journal Astrobiology, suggests a method for identifying alien life using modern genome sequencing technology and chemometrics, a field that uses a wealth of statistical pattern-recognition protocols to analyze chemical data in this case the components of DNA and RNA.
"Ultimately," the Georgetown team writes, "the chemometric fingerprints of living systems, which may differ significantly from nonliving systems, could provide an empirical, agnostic means of detecting life."
Nucleic acids like DNA form structures that will inherently bind to a host of materials and shapes, including organic molecules, minerals, and even metals. In the system that the researchers propose, reports Kristen V. Brown for Gizmodo, a technique sometimes used in cancer detection called the “systematic evolution of ligands by exponential enrichment,” researchers propose creating nucleic acids that can bind to organic molecules that are indicators of life.
The nucleic acids would theoretically act as a sort of sensor than can be amplified, and the binding patterns analyzed, to reveal a kind of biochemical signature—a “fingerprint,” as the researchers put it. The biochemistry of the alien life might be completely different from anything that we have seen on Earth, but if the molecular structures identified are complex, it’s a pretty good signal that it’s actually life.
Because nucleic acids are exponentially amplified by the polymerase chain reaction, even very small input signals could be translated into a robust readable output. The derived sequences could be identified by a small, portable sequencing device or by capture and optical imaging on a DNA microarray. Without presupposing any particular molecular framework, this agnostic approach to life detection could be used from Mars to the far reaches of the Solar System, all within the framework of an instrument drawing little heat and power.
The Georgetown researchers propose is just one idea for how to best ID alien life forms, but it is a much smaller and less complicated system than other methods for detecting molecular signs of life, such as the mass spectroscopy systems aboard the Mars rover Curiosity. The researchers point out that efforts to miniaturize genome sequencers, like Oxford Nanopore’s MinION, which fits in the palm of a hand, could one day make for extremely small, lightweight methods for astronauts to detect life forms in space.
“Without presupposing any particular molecular framework, this agnostic approach to life detection could be used from Mars to the far reaches of the Solar System, all within the framework of an instrument drawing little heat and power,” the researchers wrote.
The Daily Galaxy via Astrobiology and Gizmodo
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