Scientists and engineers on campus and Lab wished NASA's Europa Clipper mission a bon voyage on October 14 as it launched from Earth toward Jupiter's frozen moon, Europa. Hidden beneath Europa's icy crust is an ocean containing twice the amount of water as on Earth, making it an exciting candidate for investigating possible life within our solar system.
Europa Clipper has been in development for over 10 years and will brave the harsh radiation of Jupiter to study Europa's icy surface for clues to the moon's internal processes. The spacecraft carries nine instruments to assess Europa's interior, composition, and geology. One of these instruments with a particular Caltech connection is the Mapping Imaging Spectrometer for Europa (MISE). Jonathan Lunine , JPL's chief scientist, and Bethany Ehlmann , director and Allen V. C. Davis and Lenabelle Davis Leadership Chair of the Keck Institute for Space Studies -both of whom are Caltech professors of planetary science-have both been involved in the development of MISE.
Water is not the only ingredient necessary for life, which also needs sources of chemical energy. MISE will use infrared spectral imaging to make maps of Europa's surface composition, including salts and ices. If Europa experiences a kind of churn that brings ingredients from the interior up to the surface and back down again, this could indicate that there is enough chemical energy to sustain microscopic life.
"There are two ways to freshen the supply of chemical reactants: Implanted materials from Europa's surface ice are cycled down while ocean waters cycle up in icy plate tectonics-like processes to refresh ocean chemistry," says Ehlmann, "or tidal flexing of Europa makes new fractures in its rocky core, supplying fresh rock to react with isolated waters. Maybe both. Either way, the chemical fingerprints of these processes may be in ices that sit on the surface and will be measured by MISE. Most exciting is the possibility that we might find zones of frozen waters from Europa's subsurface ocean that upwell because of icy crust tectonics."
Lunine adds, "The presence of these materials in places where the crust appears to be thin or active, as revealed by other Europa Clipper instruments, will not only reveal the composition of the ocean and whether it could possibly support life but also help guide the decision on where to put a potential future Europa lander to search that material for evidence of life."
MISE is the same type of instrument (an infrared imaging spectrometer) as the High-resolution Volatiles and Minerals Moon Mapper (HVM3) that will be aboard the Lunar Trailblazer mission launching in 2025. Ehlmann is a principal investigator on that mission and plans to develop techniques to map ice on the Moon that also can be used to map ice on Europa.
The MISE technology is part of an "instrument family" built by JPL that previously mapped the Moon's mineralogy , is also on the International Space Station where it is mapping Earth , and, in its next generation, is being optimized to map greenhouse gases.
MISE isn't the only Europa Clipper project of interest on campus. Lunine is also a member of the Clipper's Gravity and Radio Science Team, which will use the radio system on Europa Clipper to measure Europa's gravity field in order to learn more about its interior, such as the depth from the surface to the ocean and the possible topography on its seafloor.
Although the Europa Clipper mission will take six years to reach its destination, the long timespan doesn't bother Lunine and Ehlmann.
"As a planetary scientist, it's good to have curiosity that spans many planets, some of which are nearby and quicker to access for exploration and others that are unique but are farther away," says Ehlmann. "While Clipper makes its way to Europa, we're working on maturing our ice-mapping techniques by investigating past data from the asteroid Ceres and, sometime in 2025, new data from Lunar Trailblazer of ice on the Moon."
Lunine adds, "Six years isn't a long time in exploring the outer solar system. It took Cassini seven years to get to Saturn, and Voyager 2 twelve years to reach its final planetary target, Neptune. During Clipper's cruise, a lot of work goes on to get ready for taking science data and for analyzing the data. The time goes by quickly."
Europa Clipper is managed by NASA's Jet Propulsion Laboratory (JPL), which, in turn, is managed by Caltech for NASA.
