One of the most exciting aspects of space exploration today is how the field of astrobiology – the search for life in our Universe – has become so prominent. In the coming years, many robotic and even crewed missions will be bound for Mars that will aid in the ongoing search for life there. Beyond Mars, missions are planned for the outer Solar System that will explore satellites and bodies with icy exteriors and interior oceans – otherwise known as “Ocean Worlds.” These include the Jovian satellites Europa and Ganymede and Saturn’s moons Titan and Enceladus.
Similar to how missions to Mars have analyzed soil and rock samples for evidence of past life, the proposed missions will analyze liquid samples for the chemical signatures that we associate with life and biological processes (aka. “biosignatures”). To aid in this search, scientists at NASA’s Jet Propulsion Laboratory have designed the Ocean Worlds Life Surveyor (OWLS), a suite of eight scientific instruments designed to sniff out biosignatures. In the coming decades, this suite could be used by robotic probes bound for “Ocean Worlds” all across the Solar System to search for signs of life.
The search for evidence of life in “Ocean Worlds,” which takes several years to get to, poses some tremendous challenges. Not only is it a complex task to send probes to the outer Solar System and remain in contact with them (despite communication delays). In particular, the probe’s scientific equipment must be capable of withstanding intense radiation and cryogenic temperatures while also being able to take diverse, independent, and complementary measurements that could provide clear and viable indications of biosignatures.
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This is where the OWLS suite comes into play. The new device is designed to ingest liquid samples that are then analyzed by eight automated instruments that would require the work of several dozen people in a lab on Earth. The suite includes a front-end extractor that uses pressure and temperature to extract various solid and liquid samples. These are then processed by one of two subsystems, one that breaks up cells into their constituent parts and subjects them to multiple forms of chemical analysis and one that uses microscopes to look for visual clues.
The former is known as the Organic Capillary Electrophoresis Analysis System (OCEANS), which separates a wide range of molecules based on their charge, size, and mobility while in the presence of an electric field. These molecules are then subjected to chemical analysis using three different units, including the Laser-Induced Fluorescence (LIF) unit that searches for amino acids, the Mass Spectrometer (MS) unit that detects the distribution of organics (like fatty acids) and identifies anomalous compounds, and the Contactless Conductivity (CC) unit that detects inorganic parts in the sample.
The latter is the Extant Life Volumetric Imaging System (ELVIS), a multi-microscope system with no moving parts that conducts high-precision searches in a large sample volume at high resolution. ELVIS combines a digital holographic microscope, the Digital Holographic Microscope (DHM), which can identify cells and motion throughout the volume of a sample. It also has two fluorescent imagers – Lightfield Volume Fluorescent Imager (VFI) and the High-Resolution Fluorescent Imager (HRFI) – that use dyes to mark chemical content and cellular structures.
The ELVIS subsystem then relies on machine learning algorithms to detect “lifelike” movement and objects illuminated by fluorescent molecules, whether this is naturally occurring or the result of dyes binding to certain parts of cells. Developed by scientists at NASA JPL and Portland State University, this system will be the first in space capable of imaging cells. It will also be the second instrument system to perform liquid chemical analysis in space, after the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument on NASA’s Phoenix Mars Lander.
Chris Lindensmith, the co-principal investigator of OWLS, also leads the microscope team. “It’s like looking for a needle in a haystack without having to pick up and examine every single piece of hay,” he said. “We’re basically grabbing big armfuls of hay and saying, ‘Oh, there’s needles here, here, and here.'”
In June, after a half-decade of work, the project team began testing its prototype on the salty waters of Mono Lake in California’s Eastern Sierra. Using its built-in software, OWLS found chemical and cellular evidence of life without the help of human intervention. As Peter Willis, the project’s co-principal investigator and science lead, said in a recent NASA press release:
“How do you take a sprinkling of ice a billion miles from Earth and determine – in the one chance you’ve got, while everyone on Earth is waiting with batted breath – whether there’s evidence of life? We wanted to create the most powerful instrument system you could design for that situation to look for both chemical and biological signs of life. We have demonstrated the first generation of the OWLS suite. The next step is to customize and miniaturize it for specific mission scenarios.”
There are many mission configurations that OWLS could be used for in the coming years. One possibility that the engineering team envisions is to use OWLS to sample water from the vapor plumes erupting from Enceladus around its south pole region. Another possibility is to include OWLS as part of the Europa Clipper and Europa Lander missions, which could use it to sample plumes coming emanating from Europa’s icy surface. It could also be fitted on the Dragonfly mission that will launch for Titan in 2027, which could use it to obtain liquid samples from Titan’s methane lakes.
The field of astrobiology has been pretty exciting lately, and it’s about to get a whole lot more so! In the meantime, check out this video of a live NASA panel explaining the OWLS suite and how it will aid in the search for life (courtesy of NASA JPL):
Further reading: NASA