UA scientist finds moon's ocean contains water and necessary nutrients

According to new evidence, the conditions on one of Jupiter's icy moons could actually be habitable for life.

Although the surface of the moon Europa is covered in a mile-thick layer of ice, underneath it is a huge liquid-water ocean that is the key to sustaining life on Europa, said Richard Greenberg, a University of Arizona planetary sciences professor, who wrote about his findings in this month's American Scientist.

"The ocean needs to interact with the surface to make it all work," he said. "And it's becoming increasingly clear that the ocean is linked to the surface."

Containing the water and nutrients that are necessary for life, the ocean is significantly affected by large tides caused by the gravitational pull from the enormous Jupiter, Greenberg said.

These tides cause pressure under the surface of the ice, causing cracks and rifts to form. Day after day, these cracks are worked, opening and closing with the changing tides.

"With time, water pushes up into these cracks," said Dereck Urbanowski, an interdisciplinary senior working on the project. "There could be life within that water, which could receive organic material from comets and light from the sun."

Scientists working on the project use high-resolution images from Galileo, a NASA orbiting spacecraft, to learn about the surface of Europa.

Images sent back from the spacecraft show two main types of geologic surface features, cracks and chaotic areas, which are melted areas in the ice that came from warmer water underneath.

Both of these features suggest strongly that Europa's surface interacts with the ocean underneath, Greenberg said.

"Europa is a very new surface, and it is also almost completely covered with criss-crossing ridges and chaos, processes that involve the ocean and are probably a continuing ongoing thing," Greenberg said.

Alyssa Sarid, a physics senior and an undergraduate research assistant on the Europa project, studied these tectonic features on the moon.

"As things are changing on the surface, there is an exchange of nutrients, an exchange of radiation, and more of a chance for exciting things to happen," she said.

"What we see is that 65 million years ago, there was a completely different surface on Europa, which means it's really active, and that's exciting," Sarid said.

"The cracks, opening and closing, can create niches for life to form, and thinner ice has an interaction with the surface and an exchange of nutrients which can help life to grow."

Although the Galileo spacecraft is scheduled to crash into Jupiter in a year, Greenberg has future research projects in store to study Europa, including extensive modeling of the surface and possible exploration.

"If we were able to send a probe down there, we could do a few tests on the water" to see if the oceans underneath contain life, Urbanowski said. "I would love to see it."