Could Life Form on Europa ?

        Jupiter is the largest planet in the solar system, and it harbors dozens of moons. Four were discovered in the 17th century by the early astronomer Galileo Galilei. We caught our first really good glimpses of the moons when the Voyager spacecraft visited them in the 70's and 80's.  Then this year, the Galileo probe reached Jupiter and began studying the moons in depth. All of them were fascinating, but one of them may be exceptionally interesting because it may be a place where life can begin.

       Europa is a big moon, just slightly smaller than Earth's moon with a diameter of 3,138 km. Voyager showed Europa to be an icy world with smooth plains crisscrossed by dark streaky crevices. What was surprising was that there were no craters. Craters occur from impacts and all bodies in the solar system suffered heavy bombardment at one time or another. Our moon is
covered with craters, the Earth has few craters to be found on the surface because years of erosion has covered them up. If Europa has no craters, what process covered them up?

        There must be some processes taking place on Europa that covers up the impact craters. What we believed, and Galileo has confirmed is the apparent presence of an ocean deep under Europa's surface.  The crisscross  lines come from erupting water, either from icy volcanoes, or an ocean under the surface.

      Volcanoes on other worlds are not a new thing. Jupiter's other moon, Io was already known to spew sulfur from multiple active volcanoes. What is driving these volcanoes, something called tidal flexing. Jupiter is a very large world compared to those moons, and they are constantly attracted to the Jovian gravitation. But they are also attracted by earth other's gravitation and this all results in the moons being pulled in several directions at once. Their surfaces actually flex with the strain. And on Europa, water wells up and gushes through the crust.

 
    But where does the possibility of life fit in to this? Until only a few years ago, we believed that life needed to receive energy in one form or another from the Sun. We did not imagine life existing in the deepest depths of the oceans. Then oceanographers on Earth discovered a whole new world, deep under he ocean in the Mid Atlantic Ridge. The ridge is an area of spreading crust, and there are active volcanic vents all along the ridge. And all around the vents are fish, crabs, giant tube worms and other creatures. They feed on microorganisms in the fluids from the volcanoes. As strange as it is to believe, these organism, called thermophylic bacteria, literally thrive in temperatures of 130 degrees F. Life, it seems, can survive in one form or another in very bizarre circumstances!

     Planetary scientists now began to be more open minded about where life could occur. Europa is a hostile place, with temperatures not reaching about -170 degrees F. Still, on Earth, there is a plenitude of bacterial life existing under ice sheets in the Arctic. This and the other information about Europa has sparked interest in the possibility of life there. Currently the Galileo spacecraft is orbiting Jupiter and studying the moons. NASA would like to plan future missions for more detailed studies.