Search for Life: Where Should a Europa Lander Touch Down?

Jupiter’s icy moon Europa is seen in a composite image created by NASA’s Galileo spacecraft. Credit: NASA/JPL-Caltech/SETI Institute Enlarge

If humanity ever launches a life-hunting mission to the icy surface of Europa, the probe should probably touch down on the “chaos terrain” of the ocean-harboring Jupiter moon, a new study suggests.

Europa’s complex chaos regions — which feature numerous cracks, ridges and other signs of geological activity — may offer a way to sample the moon’s huge subsurface ocean of liquid water, which is buried beneath an estimated 60 miles (100 kilometers) of ice, researchers said.

“If you had to suggest an area on Europa where ocean water had recently melted through and dumped its chemicals on the surface, this would be it,” study co-author Mike Brown, an astronomer at the California Institute of Technology (Caltech), said in a statement. [Photos: Europa, Mysterious Icy Moon of Jupiter]

“If we can someday sample and catalog the chemistry found there, we may learn something of what’s happening on the ocean floor of Europa and maybe even find organic compounds, and that would be very exciting,” Brown added.

The scientists, led by Caltech grad student Patrick Fischer, studied the chemical composition of 1,600 locations on the surface of Europa by analyzing observations of the moon made in 2011 using a spectrograph at the Keck Observatory in Hawaii. (Spectrographs break light into its constituent wavelengths and measure the resulting frequencies.)

This work revealed three basic categories of surface material on Europa: water ice, which dominates the satellite; chemicals that result when sulfur and oxygen (which likely originate from eruptions on Jupiter’s volcanic moon Io) react with ice; and a set of compounds that remain unidentified at the moment.

Then, the team overlaid these composition readings on a Europa map constructed with images taken by NASA’s Galileo spacecraft, which orbited Jupiter in the 1990s and early 2000s. They found that the mystery compounds matched up with the distribution of Europa’s chaos terrain.

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