NASA has built a collection of instruments that will search for life in Europa and Enceladus


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 years to come, many robotic and even human missions will fly to Mars to help in the ongoing search for life there. Beyond Mars, outer solar system missions are planned that will explore satellites and bodies with icy exteriors and inner oceans – aka “ocean worlds.” These include Jupiter’s moons Europa and Ganymede, and Saturn’s moons Titan and Enceladus.

Much like 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 we associate with life and biological processes (aka “biosignatures”). To aid in this search, scientists at NASA’s Jet Propulsion Laboratory have developed the Ocean Worlds Life Surveyor (OWLS), a suite of eight scientific instruments for detecting biosignatures. In the coming decades, this suite could be used by robotic probes heading to “ocean worlds” across the solar system in search of signs of life.

The search for traces of life in “ocean worlds”, which takes several years, presents us with enormous challenges. Not only is it a complex task to send probes to the outer solar system and stay in touch with them (despite communication delays). In particular, the probe’s scientific equipment must be able to withstand intense radiation and cryogenic temperatures, while making diverse, independent and complementary measurements that could provide clear and usable indications of biosignatures.

JPL’s OWLS combines powerful chemical analysis instruments looking for the building blocks of life with microscopes looking for cells. Credit: NASA/JPL-Caltech

This is where the OWLS suite comes into play. The new device is designed to take liquid samples, which are then analyzed by eight automated instruments, which would require the work of several dozen people in a laboratory 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 down cells into their component parts and subjects them to several forms of chemical analysis, and one that uses microscopes to look for visual clues.

The former is known as Organic capillary electrophoresis analysis system (OCEANS), which separates a wide range of molecules based on their charge, size and mobility in the presence of an electric field. These molecules then undergo chemical analysis using three different units, including the laser-induced fluorescence (LIF) unit, which looks for amino acids, and the mass spectrometer (MS) unit, which detects organic matter (such as fatty acids) distribution and anomalies identifies 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 performs high-precision searches in a large sample volume with high resolution. ELVIS combines a digital holographic microscope, the Digital Holographic Microscope (DHM), which can identify cells and movements throughout the volume of a sample. It also has two fluorescent imagers – Lightfield Volume Fluorescent Imager (VFI) and High-Resolution Fluorescent Imager (HRFI) – which use dyes to label chemical contents and cellular structure.

The ELVIS subsystem then relies on machine learning algorithms to detect “lifelike” movement and objects illuminated by fluorescent molecules, whether this occurs naturally or is the result of dyes binding to specific parts of cells. Developed by scientists from 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 Microscopy, electrochemistry and conductivity analyzer (MECA) instrument on NASA Phoenix Mars Lander.

Chris Lindensmith, the OWLS co-principal investigator, 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 basically grab big arms of hay and say, ‘Oh, here, here and here are needles.'”

In June, after half a decade of work, the project team began testing their prototype in the salty waters of Mono Lake in California’s eastern Sierra. Using its onboard software, OWLS found chemical and cellular evidence of life without human intervention. As Peter Willis, co-principal investigator and scientific director of the project, said in a recent NASA press release:

“How do you take an ice patch a billion kilometers from Earth and, given the one chance you have while everyone on Earth is waiting with bated breath, determine if there is evidence of life? We wanted to create the most powerful instrument system you can develop for this situation, to look for both chemical and biological signs of life. We 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 years to come. One possibility the engineering team envisions is the use of OWLS to sample water from the Clouds of steam erupting from Enceladus around its south polar region. Another option is to include OWLS as part of the Europe clippers and Europe country Missions that could use it to study plumes emanating from Europa’s icy surface. It could also be mounted on the dragon-fly Mission that will launch for Titan in 2027 and that could use it to obtain liquid samples from Titan’s methane lakes.

The field of astrobiology has been pretty exciting lately, and it’s only going to get a lot more! In the meantime, check out this video of a live panel from NASA explaining the OWLS suite and how it will help in the search for life (courtesy NASA JPL):

Further reading: NASA


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