WWW.ASTRONOMY.COM 35
in ice. To that end, Nadeau and her team
have taken their test instruments to
extreme locations in the Arctic. Through
studying microbial life in 100,000-year-
old glaciers, Nadeau is trying to under-
stand what they might be able to see on
Europa. These types of studies are help-
ing her create better computer algo-
rithms to look for life, dead or alive.
“Sometimes cells [in glacial ice] can
survive, but a lot of times they don’t, and
you get dead microbes,” Nadeau says. But
dead microbes can look a lot like inor-
ganic specs of dust, so it’s more challeng-
ing to prove they were once alive.
But how would we get at life below the
surface? Some researchers have proposed
a nuclear-powered drill that could melt its
way down to an area shielded from the
damaging radiation above the ice.
According to recent calculations, pro-
tected locations could exist a foot (30 cen-
timeters) or less below the surface. At
higher latitudes, where the radiation is less
intense, biomaterials could be preserved at
depths as shallow as 0.4 inch (1 cm).
Along with a microscope and poten-
tially a drill, the Europa Lander mission
would carry other instruments, includ-
ing seismometers to investigate subsur-
face structure and spectrometers to
analyze surface material composition.While it’s difficult to speculate
whether life will be found on Europa,
there is certainly cause to think it’s a
habitable place. If the planned and pro-
posed missions stay on track, we may
have an answer within a decade.
Regardless of whether Europa is habit-
able or not, our observations will turn
up new and interesting aspects of the
moon to study.
“If life didn’t arise [on Europa], that
makes life on Earth all the more special,”
Niebur says. “But if we find that life did
arise, that frankly makes the universe all
the more special.”Mara Johnson-Groh, a freelance writer
and photographer interested in topics on
Earth and beyond, is a frequent contributor
to Astronomy magazine.EUROPA CLIPPER,
shown above its target
in this artist’s concept,
is slated to launch in the
2020s. The probe carries
ice-penetrating radar,
a magnetometer, and
more. The mission
hopes to establish
Europa’s habitability
and characterize its
ocean. NASA/JPL-CALTECHTHIS ZOOMED-IN, FALSE-COLOR
view of bands on Europa’s surface shows an area
about 101 by 103 miles (163 by 167 km). Bluer regions
represent purer water ice; red areas indicate water
mixed with contaminants such as magnesium
sulfate and sulfuric acid. NASA/JPL-CALTECH/SETI INSTITUTE