NASA scientists have developed the tool to detect life in watery jets escaping into space from icy moons like Enceladus and Europa.
Saturn’s moon Enceladus and Jupiter’s moon Europa have long intrigued scientists as prime locations in the Solar System where life could exist. Both have hidden oceans of liquid water with potentially habitable conditions, but reaching these oceans directly through the thick ice is difficult.
Fortunately, moons can bring their oceans to spacecraft. In 2006, the Cassini mission to Saturn discovered plumes of water vapor leaking from Enceladus, which is 500 kilometers wide. Similarly, the Hubble Space Telescope has found intriguing evidence for plumes emanating from Europa, which is much larger at 3,120 km in diameter.
Why is the tool needed to detect life on the moons of other planets?
Now, NASA’s Ocean Worlds Life Surveyor (OWLS) could collect water samples as it flies through the vapor plumes, then search for microorganisms that the geysers might have spewed into space.
Cassini has actually flown through the columns of matter, but neither it nor any other mission in the outer Solar System has been equipped with instruments that can find life to date. Any future mission carrying the OWLS would be different in this respect, he writes Space.com.
However, due to the large distances separating Earth from Jupiter and Saturn, the bandwidth for transmitting data back is small. Therefore, OWLS must collect huge chunks of data, analyze it autonomously to discover life, and then send only the relevant results back to Earth.
“We’re starting to ask questions now that require more sophisticated tools,” he said in a statement Lukas Mandrake, who is an OWLS instrument autonomy systems engineer at NASA’s JPL.
“Are some of these other planets habitable? Is there scientific evidence for life, rather than a hint that it might be there? That requires tools that take in a lot of data, and that’s what OWLS and its scientific autonomy are ready to do,” says Mandrake.
A suite of tools
OWLS is not just a smart instrument, but a suite of eight experiments capable of investigating whether there is life in the samples it collects. Tests with the instrument to detect life in California’s extremely salty Mono Lake, which scientists believe may not be too different from the salty waters of the oceans of Europa and Enceladus, have successfully “discovered” life in the lake from California. So OWLS is ready to “attack” the frozen moons, say its developers.
“We have demonstrated that the first generation of the OWLS suite works. The next step is to customize and miniaturize it for specific mission scenarios,” said JPL’s Peter Willis.
Among the eight instruments at OWLS is the Extant Life Volumetric Imaging System (ELVIS), which is a group of different microscopes developed in association with scientists at Portland State University in Oregon, USA.
What else is the life detection tool equipped with?
Most interestingly, ELVIS’s arsenal of microscopes includes a digital holographic microscope (DHM). It is able to record videos of water samples on a microscopic scale for tens of seconds and then, as the name suggests, turn the video into three-dimensional holographic images.
Machine learning algorithms then set about analyzing the sample’s holographic video: ordinary water particles will simply float lazily or stand still, but more erratic movement will betray any living microorganisms present.
DHM can work in conjunction with OWLS’s Organic Capillary Electrophoresis Analysis System (OCEANS). Capillary electrophoresis is a technique for separating organic molecules (such as the various amino acids, fatty acids and nucleic acids on which life is based) from a liquid using electric fields.
The molecules are then sent to a mass spectrometer, which measures the masses of particles in the sample, and a volume fluorescence imager, which uses dyes to bind these chemical building blocks together. When excited by a laser, the compounds glow, providing a target for DHM to focus on.
When might OWLS be released?
The OWLS development came too late to be included in the European Space Agency’s Jupiter Icy Moons Explorer (JUICE), which launches in 2023, or NASA’s Europa Clipper mission, which launches in 2024.
However, several missions have been proposed to return to Saturn’s Enceladus in the future. Scientists at Johns Hopkins University’s Applied Physics Laboratory have submitted a mission concept called Orbilander to NASA that would function as both an orbiter and a lander on Enceladus.
Then there’s Breakthrough Initiatives’ possible privately funded Enceladus mission. A concept previously rejected by NASA, called the Enceladus Life Finder, could also be revived at some point.
Enceladus is too tempting a target to ignore for long, and when we get back there, OWLS is ready to do its job.