Ocean worlds are on planetary scientists’ minds. More and more, evidence rolls in about the potential habitability of ice-covered bodies like Jupiter’s moon Europa or Saturn’s moon Enceladus. The findings point to heat-driven processes in their subsurface oceans that could support life. Scientists are now beginning to wonder: Could the search for life end on one of these icy satellites?
Assuming humanity does land a spacecraft on Europa or Enceladus, any evidence of life it might uncover would receive heavy scrutiny. In a recent report on a possible landing mission to Europa, scientists devoted multiple chapters to discussing the kinds of evidence they’d need—like finding amino acids and other organic molecules in patterns similar to those in organic matter on Earth.
But even before these signatures can be detected by a probe or scrutinized by researchers in a lab, scientists need an instrument that can take data directly from a hole drilled into an icy surface.
Now scientists at NASA have begun to test such an instrument, a culmination of 20 years of technological development, called the Wide Angle Topographic Sensor for Operations and Engineering, or WATSON. The idea would be to include a WATSON-like instrument on a lander bound for Europa, Enceladus, or even Mars’s polar ice caps, said Rohit Bhartia, a planetary scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., and a WATSON team member.
Bhartia and a group of scientists recently returned from a 2-week field campaign in southern Greenland, where they tested out WATSON in holes they drilled into the Greenland ice cap.
“What we were doing in Greenland has never been performed before,” Bhartia said. “The technology was simply not available.”
Each day of the trip, the team would greet the Greenland morning from their dormitories at the Kangerlussuaq Science Support Facility, which hosts teams of scientists conducting research. They’d load their equipment into a couple of trucks and drive about an hour onto the ice, where they’d spend several hours drilling, looking for new sites to drill, or analyzing boreholes with WATSON.
For Mike Malaska, another WATSON team member and planetary scientist at JPL, the trip was “epically awesome.” It was his first experience conducting field work on a large ice cap.
“It’s hard to put it into words, but you just felt the vastness and largeness of the landscape,” he said. The wind- and Sun-sculpted peaks of ice poked up like shark fins, making the icy scenery look like a “frozen ocean.”
Each fresh snowfall or cloudy sky changed the scenery to dramatic effect, Malaska said. “Every direction we looked it was just an incredible beautiful vastness that couldn’t be captured by a photo; it had to be experienced in person,” he said.
Science on Ice
The researchers set out to study the kinds of signatures life leaves in the ice, like organic molecules or even physical alterations, which will help future scientists evaluate potential evidence for life elsewhere in the solar system, Bhartia said.
Scientists know that microbes on Earth can live under, inside, and around glaciers, but they can’t do any analysis in the field because the technology doesn’t yet exist. Currently, researchers remove an ice core, package it, ship it thousands of kilometers, and study it at a lab bench. Not only can this contaminate the core, but it also leaves out important context about the environment in which the core was found, like how microbes got into the ice: Was it through a subglacial lake? An aboveground fracture?
Enter WATSON, an instrument that can analyze the environment surrounding a core. After the researchers drilled into the ice, they lowered WATSON—a long, silver tube attached to a tripod—into the hole to analyze its walls and hunt for signs of microbes. WATSON contains an instrument called a fluorescence/Raman spectrometer that can detect organic molecules in the ice. It does so by zapping the walls of the borehole with an ultraviolet laser that excites some molecules into a higher-energy state, Malaska said. The molecules then return to their original state, emitting the excess energy as photons. The device collects and measures the energies of those photons to determine what kinds of organic molecules are present on the inner surface of the borehole. It also detects molecules by looking at how much they scatter or change the light of the laser. Other components of WATSON create a visible map of that surface that scientists can overlay with the spectrometer data.
Once it is fully operational, WATSON should be able to rapidly combine these data sets to identify regions of interest within the walls of the borehole. The combined data set will reveal the distribution of the molecules to help scientists conducting these field tests learn more about the many kinds of signatures that indicate the presence of microbial life, Malaska said.
The April campaign was only the first step in testing WATSON, a step Bhartia called “wildly successful.” WATSON functioned as intended—quite a feat, as it was designed, fabricated, tested, and deployed within less than a year, Bhartia said. WATSON generated heaps of data about the organic molecules within the test boreholes. The researchers also collected ice cores from the locations where they drilled, which they will analyze in the coming months at Montana State University in Bozeman. There, the researchers will use the core data to verify WATSON’s data.
The team is currently “feverishly analyzing” their data and preparing for more Greenland field campaigns in 2018 and again in 2019, Bhartia said. If all goes as planned, on those future trips, the researchers will have integrated WATSON with a drill to test the feasibility of the fully operational instrument.
—JoAnna Wendel (@JoAnnaScience), Staff Writer