Jupiter Moon: Europa's Surface Was Penetrated By Asteroids, Comets

Even though Jupiter's moon Europa has a hard-frozen surface, it has been dented, scarred and penetrated by comets and asteroids. Also, knowing this might be helpful in learning whether Jupiter can harbor life.

That is, Williams College undergraduate students led by geoscience professor Ronadh Cox recently finished a paper on this finding, which has been accepted by the Journal of Geophysical Research: Planets.

Students led by the professor have been studying Europa's chaos terrain since 2004. They examined the areas that resemble beaches on that moon's crust, which have what appear to be icebergs in hardened slush, as a release confirmed.

One student in 2009, Aaron Bauer, taught himself Fortran (the programming language) in order to look at numerical simulations and test the idea that asteroids or comets might have banged right through the ice on Europa. In that case, they would have opened up the surface to the liquid ocean beneath, and created the chaos terrain, according to the release.

Running the models revealed that the comets or asteroids could have penetrated the ice in several situations. A comet with a diameter of half a kilometer, for instance, can puncture ice with a thickness of five kilometers, for instance. Also, a comet with a diameter of five kilometers could move through to the other side of ice that is 40 kilometers thick. Basically, there's always an impactor (asteroid or comet) that could get through the ice, regardless of ice thickness. In other words, the oceans below the ice were probably often exposed in the long-ago past and possibly in more recent geological time, said the release.

Essentially, the team noted that the punctures would form channels that let astrobiological material move between the crust and the ocean beneath the ice-which could be useful information regarding the moon's potential to hold life forms.

"How Europa's sub-ice surface ocean communicates with the surface, can mass and energy be transferred from the exterior to the liquid beneath and how thick the ice barrier is have been questions at the forefront of research since the Galileo data in the early 2000s revealed the probable existence of a liquid water layer," Cox said in the release. "The research conducted by students about the breaches that occur in the ice could contribute to a better understanding of how they are caused."

The paper was co-authored by Cox and Bauer and will be presented at a November meeting of the Geological Society of America.

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