Dan Harlow

Water, water, every where,
And all the boards did shrink ;
Water, water, every where,
Nor any drop to drink.

The very deep did rot : O Christ !
That ever this should be !
Yea, slimy things did crawl with legs
Upon the slimy sea.

About, about, in reel and rout
The death-fires danced at night ;
The water, like a witch’s oils,
Burnt green, and blue and white.

selection from : The Rime of the Ancient Mariner
Samuel Taylor Coleridge, 1817

Is life unique to the Earth? Are we alone in the universe? Many seem to think these are silly questions best left to the domain of science fiction but recently scientists have uncovered many intriguing clues that could erase the homocentric view of the universe much the same way Nicolaus Copernicus proposed the modern heliocentic view.

Europa is the 4th largest moon of Jupiter and is visible with a modest telescope not much more powerful than what Galileo Galilei used back on January 7, 1610 to discover it. In 1979 the Voyager probes took the first detailed images of this little moon and astronomers were puzzled that there were no craters visible. Except for Io the rest of the Jovian moons, Callisto being an extreme example, are heavily cratered but where volcanic activity was the cause of Io’s surface geology, Europa remained something of a mystery. The most reasonable theory was that Europa was basically a giant ice ball, which in and of itself was pretty amazing, and that tidal forces from Jupiter and the larger moons caused the ice to shift and move thus erasing any surface features. This was the common theory until on December 7, 1995 the Galileo Probe entered the Jovian system on it’s 8 year mission.

The Galileo Probe took a series of high resolution digital images of the surface of Europa which gave scientists a better understanding about what was happening. Because of the tidal forces that act upon the moon the subsurface is actually in liquid form - basically it’s an ocean. We can only infer it’s existence because the ice layer above is roughly 5-20 miles thick but based on what we understand about Io, data collected on the orbital resonance taking place in the system and unusual chaos terrain features on the surface we have a good idea that liquid water exists on this frigid moon.

Even more amazing is the possibility of life on Europa similar to what we find in the deepest oceans here on Earth. Giant tube worms, strange clams and shrimp thrive near thermal vents in temperatures and extremes that no other known life on Earth can survive in. The same activity may be taking place on Europa right now and with the aid of “Texas-based Stone Aerospace, the autonomous underwater vehicle Deep Phreatic Thermal eXplorer (DEPTHX)” could provide the tools necessary to explore deep under the ice in the search for life.

Let’s move a little further out into the solar system to another moon, this time in orbit around Saturn. Enceladus is even smaller than Europa at about 500km in diameter but is just as active as it’s larger cousin. The moon orbits within the E-Ring of Saturn which means it is constantly being bombarded with icy particles that keep the surface similar to a fresh snow fall here on Earth. Long ago Enceladus should have swept up all the particles of the E-Ring so something had to be taking place to replenish the supply. In the image above you will notice long, bluish stripes on the surface of the moon. These tiger stripes are basically huge fissures where cryovulcanism is taking place just beneath the surface (most likely due to the similar forces that act on Europa and Io). Each day as Enceladus sweeps up E-ring material, fresh material is spewed out and trails behind the moon.

Closer to home on red Mars the best evidence yet of water on that planet was recently discovered. Orbiting high above the Mars Global Surveyor snapped two photographs; one in August 1999 and another in September 2005 of the same crater rim. Though water has been known to exist on Mars for quite some time it’s abundance nearer the equator had been in doubt until the images revealed a gush of (what is believed to be) water erupting from the ground before freezing upon the surface. Though few believe enough water currently exists on Mars to support indigenous life it does bolster the chances of humans being able to survive on Mars for extended periods of time. The discovery also strengthens the evidence that water was once abundant on Mars and could have supported life.

Let’s head back home to Earth for an equally remarkable discovery. By using seismograms of geologic activity around Eastern China “Michael Wysession, a seismologist at Washington State University in St. Louis, and his former graduate student Jesse Lawrence, now at the University of California, San Diego” have discovered an “ocean” deep inside our own planet roughly the size of the Arctic Ocean. Though not exactly a liquid ocean, the discovery shows how parts of the current ocean floor around China may have sunk thousands of miles until those rocks began to heat up due to the internal pressure of the earth’s core. When the rocks became hot enough the water contained within them evaporated upwards and mixed with the upper layers of mantle. Were it possible to obtain a sample of these rocks you would only be able to see this water in a laboratory but it is still an amazing discovery and reminds us that we know more about the moons of Jupiter and Saturn than we do about our own planet.

Even if we only discover lobsters “scuttling across the floors of silent seas” on a distant moon with so much new evidence it is hard to imagine that we are unique to the universe and that it was created just for our benefit.

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