For
2 weeks on the Greenland ice cap, scientists tested an instrument that might
help us find life on icy moons with oceans beneath their crusts.
A researcher looks over the
Greenland ice cap, a “frozen ocean.” Eleven scientists just returned from a
field campaign testing an instrument that can scrutinize holes in ice for signs
of life. Someday, such an instrument might find its way to Europa or Mars. Credit: NASA/JPL-Caltech/Michael J. Malaska
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.
The idea would be to include a
WATSON-like instrument on a lander bound for Europa, Enceladus, or even Mars’s
polar ice caps.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.”
Frozen Ocean
Mike Malaska said that ice poking
out of the landscape reminded him of waves or shark fins. Credit:
NASA/JPL-Caltech/Michael J. Malaska
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 WATSON instrument analyzes a
drill hole, using fluorescence/Raman spectroscopy to detect organic molecules.
Credit: NASA/JPL-Caltech/Rohit Bhartia
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.
Scientists extracting a core from
the ice. Credit: NASA/JPL-Caltech/Michael J. Malaska
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.
Next Steps
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..
B#23
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