U.S.A, Jan 30, 2017: NASA scientists have developed a new chemical assay that could aid the search for life on exoplanets by identifying the presence of amino acids, the compounds that make up proteins and are the building blocks of life.
The test uses a liquid-based technique known as capillary electrophoresis to separate a mixture of organic molecules into its components.
It was designed by researchers from NASA’s Jet Propulsion Laboratory (JPL) in the US specifically to analyse for amino acids, the structural building blocks of all life on Earth.
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The method is 10,000 times more sensitive than current methods employed by spacecraft like NASA’s Mars Curiosity rover, according to researchers.
One of the key advantages of the 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 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 analyse’ process,” she said.
The researchers used the technique to analyse amino acids present in the salt-rich waters of Mono Lake in California.
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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 analyse 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.
The study was published in the journal Analytical Chemistry. (IANS)
The discovery of cracks on the surface of Mars by NASA’s Curiosity rover in early 2017 are evidence of lakes that likely dried up 3.5 billion years ago, confirmed a study, revealing details about the red planet’s ancient climate.
In early 2017 scientists announced the discovery of possible desiccation cracks in Gale Crater, which was filled by lakes 3.5 billion years ago.
“We are now confident that these are mudcracks,” said lead author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena, US.
Since desiccation mudcracks form only where wet sediment is exposed to air, their position closer to the centre of the lake bed rather than the edge also suggests that lake levels rose and fell dramatically over time.
“The mudcracks show that the lakes in Gale Crater had gone through the same type of cycles that we see on Earth,” Stein added.
Although scientists have known almost since the moment Curiosity landed in 2012 that Gale Crater once contained lakes, “the mudcracks are exciting because they add context to our understanding of this ancient lacustrine system”, Stein explained, in the paper published in the journal Geology.
“We are capturing a moment in time. This research is just a chapter in a story that Curiosity has been building since the beginning of its mission,” he said.
For the study, the team focused on a coffee table-sized slab of rock nicknamed “Old Soaker”.
Old Soaker is crisscrossed with polygons identical in appearance to desiccation features on Earth.
They found that the polygons — confined to a single layer of rock and with sediment filling the cracks between them — formed from exposure to air, rather than other mechanisms such as thermal or hydraulic fracturing, the researchers said. IANS