Jupiter's Europa: The Search for an Alien Biosphere (VIDEO)
"There's nothing saying there is life there now. But we do know there are the physical conditions to support it." Richard Greenberg, University of Arizona. world's leading expert on Europa.
Terry Pratchett once described life as a simple, tiny "Yes" being said wherever it could. Extremobiologists among you may have heard of (and been suitably impressed by) organisms clinging to existence under kilometers of ocean and enough pressure to turn you into "Internet reader soup" at the bottom of the sea.
But it seems life always has another trick up its sleeve, and scientists have found bacteria buried in tiny rock fissures hundreds of meters after even the sea itself gives up and stops. A preview, perhaps, of lifeforms elsewhere in our Solar System on places like Mars and Jupiter's Europa and Saturn's moon, Titan.
So, based on what we know about the Jovian moon, parts of Europa's seafloor should greatly resemble the environments around Earth's deep-ocean hydrothermal vents. Experts in marine biology attending the recent annual meeting of the American Astronomical Society’s Division for Planetary Science said they would shocked if no life existed in Europa's oceans.
Richard Greenberg, Principal Investigator in NASA’s Planetary Geology and Geophysics program, has calculated that the ocean may receive about 100 times more oxygen than previous models indicated -- enough to support respiration by three million tons of fish.
Oxygen, generated by charged particles striking water molecules on the moon’s surface, would take 1 to 2 billion years to begin seeping into the ocean, calculated Richard Greenberg of the University of Arizona in Tucson. That delay would have been critical for supporting life because it would have allowed time for primitive organisms to develop the ability to use oxygen.
The most fascinating part of Europa's evolution, says Greenberg, is Europa’s youthful, nearly crater-free appearance, which indicates that the crust is continually resurfaced. Today’s crust is only 50 million years old, even though the moon formed soon after the solar system’s birth 4.56 billion years ago.
Over a period of about 50 million years, a layer of ice 300 meters thick slowly rose from below, gradually covering the moon’s surface and erasing old craters. As a result of this facelift, Europa’s oxygenated layer grew increasingly thick, until after about 1 to 2 billion years the entire ice layer was oxygen-rich. At that point, Greenberg suggests, ice melting at the bottom of the frozen layer began delivering oxygen into the proposed buried ocean at a faster rate than previously estimated, resulting in about 100 times more oxygen in the ocean.
Provided by The Daily Galaxy / sciencenews.org - oceanleadership.org
