Long before NASA’s Mars rover permanently touched the Red Planet on February 18, one of the goals of its top-level mission had already been established: to look for signs of ancient life on the Martian surface. In fact, the techniques used by one of the scientific instruments on board the rover may have applications on Saturn’s satellites Enceladus and Titan, as well as Jupiter’s lunar Europe.
“Persistence will look for a list to buy minerals, organic matter and other chemicals that can reveal microbial life after it thrived on Mars,” said Luther Beagle, chief researcher on the scanning habitat of Mars 2020 with Raman and luminescence. for Organic and Chemical Substances Tool (SHERLOC). “But the technology behind SHERLOC, which will search for past life in Martian rocks, is highly adaptable and can also be used to search for living microbes and chemical building blocks for life in the deep ice of Saturn’s and Jupiter’s moons.”
Enceladus, Europe, and even the nebulous moon Titan are thought to hide vast oceans of liquid water containing chemical compounds linked to biological processes beneath their thick icy exteriors – very different environments from modern Mars. If microbial life exists in these waters, scientists may be able to find evidence of this in ice as well. But how do we find this proof if it is locked deep in the ice?
Enter WATSON. Abbreviated from the Northern Ice Roof Underground Survey Wire Analysis Tool, the 1.2-meter (1.2-meter) prototype is under development at NASA’s Southern California Jet Propulsion Laboratory. It is related to the planetary deep training of Honeybee Robotics and this combination has been successfully tested in the extreme cold of the Greenland ice.
A smaller version of WATSON could one day board a future robotic mission to explore the habitability potential of one of these mysterious moons. The tool will scan the ice for biosigns – organic molecules created by biological processes. If it notices a future version of WATSON, with the additional ability to collect ice from the borehole wall, it may collect samples for further investigation.
By using Raman’s deep ultraviolet laser spectroscopy to analyze the materials where they are found, instead of immediately extracting ice samples and then studying the surface of the moon, the instrument will provide scientists with additional information about these samples by examining their whereabouts. in the context of their environment.
“It would be great to first look at what these samples actually look like in their natural environment before taking them and mixing them into a test slurry,” said Mike Malaska, an astrobiologist at JPL and a leading scientist at WATSON. “That’s why we’re developing this non-invasive tool for use in icy environments: to peek deep into the ice and identify clusters of organic compounds – perhaps even microbes – so they can be studied before analyzing them further and losing their natural context or modification of their structure. “
Although WATSON uses the same technique as Perseverance’s SHERLOC, there are differences. First, SHERLOC will analyze Martian rocks and sediments to look for signs of past microbial life that can be collected and returned to Earth from future missions for more in-depth study. And SHERLOC doesn’t drill holes. This makes it a separate tool.
But both rely on a deep ultraviolet laser and spectrometer, and when the WATSON ice instrument has a camera to monitor the texture and particles in the ice wall, Perseverance’s SHERLOC is paired with a high-resolution camera to take close-up photos of rock textures in support of his observations. This camera accidentally shares the same name as the ice exploration prototype: WATSON. In this case, however, the abbreviation means “Wide-angle topographic sensor for operations and electronic engineering”. (After all, any instrument with a name inspired by the famous fictional detective Sherlock Holmes is bound to inspire references to his partner.)
Enceladus on Earth
Just as SHERLOC underwent extensive tests on Earth before going to Mars, so must WATSON before being sent to the outer solar system. To see how the instrument could perform in Enceladus’ ice crust and extremely low moon temperatures, the WATSON team chose Greenland as an “Earth analogue” for field tests of the prototype during a 2019 campaign.
Earth analogues share similar characteristics with other places in our solar system. In the case of Greenland, the middle near the middle of the island’s ice sheet and far from the shore approaches the surface of Enceladus, where oceanic materials erupt from the fertile openings of the small moon and rain. Meanwhile, the distorted ice on the edge of Greenland’s glaciers near the coast could serve as an analogue for Europe’s curved deep ice crust.
During the campaign to survey an existing drilling station near Summit Station, a remote high-altitude observation station in Greenland, the tool was launched. As it descended more than 100 feet, WATSON used its UV laser to illuminate the walls of the ice, causing some molecules to glow. The spectrometer then measures their low brightness to give the team an idea of their structure and composition.
While finding biosigns in Greenland’s ice pack was no surprise – the tests were ultimately on Earth – mapping their distribution along the walls of the deep well raised new questions about how those characteristics got to where they are. The team found that microbes deep in the ice tended to collect in spots rather than in layers, as originally expected.
“We created maps while WATSON scanned the sides of the borehole and the grouping hotspots of blue-green and red – all of which are different types of organic materials,” Malaska said. “And what was interesting to me was that the distribution of these hotspots was almost the same everywhere we looked: Whether the map was created at 10 or 100 meters [33 or 330 feet] in depth, these compact little spots were there. “
By measuring the spectral signatures of these hotspots, the team identified colors corresponding to aromatic hydrocarbons (some that may originate from air pollution), lignins (compounds that help build cell walls in plants), and other biologically produced materials. (as complex organic acids also found in soils). In addition, the instrument records signatures similar to the glow produced by microbial clusters.
More tests need to be done – ideally in other analogues on Earth that are close to the conditions of other ice moons, but the team was encouraged by how sensitive WATSON was to such a wide variety of biosigns. This high sensitivity would be useful for missions in oceanic worlds where the distribution and density of potential biosigns are unknown, said Rohit Bhartia, chief researcher at WATSON and deputy chief researcher for SHERLOC, of Photon Systems in Covina, California. “If we had to collect a random sample, we would probably miss something very interesting, but through our first field tests, we are able to better understand the distribution of organic matter and microbes in the earth’s ice, which could help us drill into bark of Enceladus. “
The results of the field test were published in the journal Astrobiology in the fall of 2020 and presented at the fall meeting of the American Geophysical Union on December 11.
The detective aboard NASA’s Perseverance rover
Michael J. Malaska et al. Subsurface location of microbes and various hotspots with organic matter in the Greenland ice sheet, Astrobiology (2020). DOI: 10.1089 / ast.2020.2241
Quote: A trial for life in the ice sheets of the ocean worlds (2021, April 7), retrieved on April 8, 2021 from https://phys.org/news/2021-04-probing-life-icy-crusts-ocean .html
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