Lake Vostok and Europa compared
In 1996, Lake Vostok was discovered. Discovered? A lake discovered in a time when it seems like every single inch of the globe has been well documented and put on a map? Yes. But Lake Vostok is special: it is overlaid by about 3,710 meters (12,169 ft) of ice and may be 500,000 to 1 million years old. The water is in a liquid state: how this is possible, no one really knows.
It is far from unique: on the South Pole alone there are some 70 places where ice has covered water in history. But Lake Vostok is a big one: 48 by 224 kilometers (30 by 140 miles).
Scientists are however very hesitant to drill to the depth of the lake and take a sample of its liquid water.
Through computer simulations of the water flow they realized that it might be very well possible that huge quantities of gases like oxygen and perhaps carbon dioxide are dissolved in the water. Next to the obvious danger of contamination of the water by bacteria in present day Earth’s atmosphere, which would render research useless, there is the very real danger of the water being under tremendous pressure and bursting out from underneath the ice, if that cap is breached.
So, what’s the interest in the lake then? Well, the lake has a striking likeness to one of the Jupiter moons, Europa. Europa is also covered with a thick layer of ice, but has a liquid ocean underneath. And the same problems are faced: Europa’s ocean also could be under pressure like a can of soda, and it is also under a very thick layer of ice.
But – more importantly – it could harbor life. So we have the possibility to do research on Europa-like conditions on our own doorstep: that is what really makes Vostok interesting…
As mentioned earlier, nobody’s really sure why Vostok’s water is in a liquid state. We do however know why the water beneath Europa’s caps is in a liquid state: gravitation. The gravitational pull of Jupiter on Europa is enormous. This causes the shape of Europa to be stretched and squashed like a large soapbubble. This constant change in shape causes friction and this friction heats up the moon from the inside out, causing the liquid interior. Now most scientists agree on one of the basic conditions to make any form of life possible: liquid water.
Lake Vostok is deep under the Antarctic ice and not one light particle did ever reach its waters. The same is true about the ocean beneath the icy crust of Europe. Is light a necessity for any form of life to exist? Scientists no longer believe this to be true. In the depths of the Atlantic and Pacific Oceans there is life. And not a little bit of it too: marine biologists Thomas Gold and John Barross think the biomass below the surface of the oceans may be much larger than that on land. It is quite possible that new forms of life still “leak” from sea to land. Barross: “Who knows, the subsurface biosphere may be inoculating' the surface biosphere with new seeds of life. And perhaps, if there's a biosphere beneath the surface here, there might also be one under the surfaces of other planets.”
Special interest is given to the so-called superthermal extremophiles, microbes that can survive many tons of pressure and temperatures up to 130 degrees centigrade. The chemical composition and heat of the water above the “smokers”, volcanic vents on the bottom of the deepest parts in the ocean, would normally prohibit any form of life, but the extremophiles thrive in this acid hell. After the discovery of these record holding survivors, we have been forced to move the barriers around the environment where we deem life possible a great distance. We now know that life is possible at extreme heat and pressure, and that is exactly the sort of environment we hope to in the depths of both Lake Vostok and the ocean of Europa.
Many scientists are practically drooling at the idea of investigating the sub-surface waters of Europa. No other body in the Solar system is a better candidate for harboring life than this Jovan Moon. Its size is practically equal to that of our own moon. Imagery from the Hubble Space Telescope (HST) proved that is has a thin atmosphere containing oxygen, although just enough to fill about three stadiums. These facts, combined with the high probability of liquid water make Europa a desired object of research; so much desired even that the planned Pluto trip was deferred in favor of a drilling expedition to Europa.
While the similarities between Vostok and Europa are obvious, the main difference is this: we can go back to Vostok over and over again. On Europa we only get one chance to get it right…
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