[meteorite-list] A New Test for Life on Other Planets
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 16 Feb 2017 13:17:58 -0800 (PST)
A New Test for Life on Other Planets
Jet Propulsion Laboratory
January 26, 2017
A simple chemistry method could vastly enhance how scientists search for
signs of life on other planets.
The test uses a liquid-based technique known as capillary electrophoresis
to separate a mixture of organic molecules into its components. It was
designed specifically to analyze for amino acids, the structural building
blocks of all life on Earth. The method is 10,000 times more sensitive
than current methods employed by spacecraft like NASA's Mars Curiosity
rover, according to a new study published in Analytical Chemistry. The
study was carried out by researchers from NASA's Jet Propulsion Laboratory,
One of the key advantages of the authors' new way of using capillary electrophoresis
is that the process is relatively simple and easy to automate for liquid
samples expected on ocean world missions: it involves combining a liquid
sample with a liquid reagent, followed by chemical analysis under conditions
determined by the team. By shining a laser across the mixture -- a process
known as laser-induced fluorescence detection -- specific molecules can
be observed moving at different speeds. They get separated based on how
quickly they respond to electric fields.
While capillary electrophoresis has been around since the early 1980s,
this is the first time it has been tailored specifically to detect extraterrestrial
life on an ocean world, said lead author Jessica Creamer, a postdoctoral
scholar at JPL.
"Our method improves on previous attempts by increasing the number of
amino acids that can be detected in a single run," Creamer said. "Additionally,
it allows us to detect these amino acids at very low concentrations, even
in highly salty samples, with a very simple 'mix and analyze' process."
The researchers used the technique to analyze amino acids present in the
salt-rich waters of Mono Lake in California. The lake's exceptionally
high alkaline content makes it a challenging habitat for life, and an
excellent stand-in for salty waters believed to be on Mars, or the ocean
worlds of Saturn's moon Enceladus and Jupiter's moon Europa.
The researchers were able to simultaneously analyze 17 different amino
acids, which they are calling "the Signature 17 standard." These amino
acids were chosen for study because they are the most commonly found on
Earth or elsewhere.
"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 the project's principal investigator,
Peter Willis of JPL.
Key to detecting amino acids related to life is an aspect known as "chirality."
Chiral molecules such as amino acids come in two forms that are mirror
images of one another. Although amino acids from non-living sources contain
approximately equal amounts of the "left" and "right"-handed forms, amino
acids from living organisms on Earth are almost exclusively the "left-handed"
It is expected that amino acid life elsewhere would also need to "choose"
one of the two forms in order to create the structures of life. For this
reason, chirality of amino acids is considered one of the most powerful
signatures of life.
"One of NASA's highest-level objectives is the search for life in the
universe," Willis said. "Our best chance of finding life is by using powerful
liquid-based analyses like this one on ocean worlds."
Caltech in Pasadena, California, manages JPL for NASA.
News Media Contact
Jet Propulsion Laboratory, Pasadena, Calif.
andrew.c.good at jpl.nasa.gov
Received on Thu 16 Feb 2017 04:17:58 PM PST