The size of ice domes and movement of ice rafts on the surface of Europa, one of Jupiter's moons, are consistent with what one could expect of melting caused by a hydrothermal vent plume, or plumes, in an ocean beneath the ice, say oceanographers John Delaney of the University of Washington and Richard Thomson of Fisheries and Oceans Canada.
Scientists know that Europa has a layer of water on its surface that is perhaps 100 kilometers (60 miles) deep, making it nearly 10 times deeper than any of Earth's oceans. The thickness of the frozen surface continues to be debated.
If hydrothermal vent plumes are contributing heat to Europa's ocean, Delaney and Thomson estimate that the frozen surface of the ocean actually may be 3 to 5 kilometers (2 to 3 miles) thick on average -- instead of the 20 kilometers (12 miles) some have estimated. And it makes it all the more possible that researchers may find microorganisms living in vent fluids on Europa, as they do here on Earth.
Delaney and Thomson's model, the first to take what's known about plume dynamics on Earth and apply them to Europa, was the subject of a paper last year in the Journal of Geophysical Research and a presentation at December's American Geophysical Union meeting.
The possibility of life on Europa will be part of Delaney's presentation, "Volcanoes, Oceans and Life in the Solar System," a lecture that is free and open to the public Jan. 23, 7 p.m., Room 210, Kane Hall. His talk is the second in the "Oceans to Stars Lecture Series" offered by the UW's College of Ocean and Fishery Sciences and School of Oceanography.
Among scientists interested in Europa, a number think tidal forces generated by the gravitational tug-of-war between Jupiter, Europa and neighboring moons Io and Ganymede cause tidal flexing of Europa's icy crust, friction and then melting. Delaney, Thomson and others hypothesize that tidal flexing is at work on Europa's rocky core generating heat and magma.
Delaney says a better understanding of the links between plate-tectonic processes on our own planet and the microbial life that flourishes near faults, fissures, vent structures and beneath the Earth's crust will help us seek life on other planets and moons.
He and Thomson are part of a consortium of researchers from Canada and the United States interested in using 2,000 miles of electro-optical cable -- cable that can carry power, instructions to remote instruments and data sent back from those instruments -- to wire the whole Juan de Fuca Plate off our coast.
The Juan de Fuca is one of a dozen or so major tectonic plates that make up the surface of the Earth. Thousands of instruments, including tiny subs and probes that could be maneuvered by scientists back on land, would be stationed at 30 experimental sites along the cable network as part of Project Neptune.
Abstract of Jan. 23 lecture
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Europa's Ice Crust Is Deeper Than 3 Kilometers, U.Arizona Scientists Find
Tucson - Nov 12, 2001
Impact craters on Europa -- the jovian satellite that scientists say may hide a subsurface liquid ocean -- show that the moon's brittle ice shell crust is more than 3 to 4 kilometers (1.8 to 2.4 miles) thick, two University of Arizona planetary scientists report in Science (Nov. 9 issue).
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