Listening for an ocean on Europa

Things are crackling on the giant Jovian moon, Europa, and a group of earth-bound
ocean scientists funded by the Office of Naval Research are intrigued… could
Jupiter’s Europa be hiding an ocean of water under that icy surface? A salty ocean…
larger than all the oceans of the earth combined?

The potential for an ocean on Europa makes it one of the best bets in our solar
system for life as we know it.

According to ocean scientists at MIT, it seems that massive ice fractures occur on
Europa daily – about once every 30 seconds as a matter of fact.

Such a phenomenon would generate some very unusual effects, including cracking
sounds that could be used to probe the interior structure of Europa.

Using the same acoustic techniques that Navy ships use to determine water depth
and that seismologists use to probe the interior structure of the Earth, Professor Nick
Makris and his MIT team propose that we start thinking now about deploying an array
of vibration-sensitive acoustic sensors on Europa’s surface.

Terrestrial ice mechanics studies show that the vibrations created when ice fractures
produce sound waves that can penetrate the thick ice layer and propagate for
hundreds of kilometers through the underlying ocean.

Acoustic sensors deployed on the surface of Europa could pick up echoes from the
bottom of the ice layer and the bottom of the ocean. By studying these echoes one
could establish the existence and depth of the ocean as well as the ice layer.

“It’s amazing that research in ocean acoustics may also benefit the search for
extra-terrestrial life,” observes Dr. Jeff Simmen, ONR’s Program Manager for Ocean
Acoustics.

The Office of Naval Research has been in the forefront of ocean acoustics studies for
the last 50 years.

“Such a possibility {deploying an array of vibration-sensitive acoustic sensors on
Europa’s surface} is at least 10 years away,” remarks Makris, “But planning for it has
already begun.” NASA plans a Europa Orbiter mission in 2008, and a Europa landing
mission will follow that.

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For more information on this ONR-funded program, or to interview Simmens or
Makris, call Gail Cleere at 703-696-4987 or email cleereg@onr.navy.mil

Contact: Gail Susan Cleere

cleereg@onr.navy.mil

703-696-4987

Office of Naval Research