By Mark Aragona
It seems that we don’t have to wander outside of our solar system to find planets that could possibly sustain life. A tiny Saturn moon may just be the place for it. The Cassini-Huygens mission has found that Enceladus, much like Jupiter’s Europa, may have an oceanic layer underneath its surface of ice.
Enceladus is a wonder in itself: a frozen white world, 0.0395 the size of Earth. The moon is the most reflective body in our solar system, reflecting more than 90% of the sunlight that reaches it and leaving the moon with a temperature of -330 degrees Fahrenheit (-201 degrees Celsius). Geysers on its surface shoot out ice particles in great white plumes that feed Saturn’s E ring. Scientists used this very phenomenon to find out what lies underneath the moon’s icy exterior.
In 2008, the Cassini spacecraft dove through Enceladus’s plume trail and found that it was made up of icy water. The real find came when they took a close look at the particles nearer the surface and found salt. In fact, 99% of the solids found in the plume were salt-rich material that resembled the kind found in our own seas. It’s likely that somewhere underneath all that ice, Enceladus has its very own ocean.
There’s more: the spaceship’s instruments have detected negatively charged ions in Enceladus’s icy plume. Professor Andrew Coates of the Cassini mission said: “While it’s no surprise that there is water there, these short-lived ions are extra evidence for sub-surface water, and where there’s water, carbon, and energy, some of the major ingredients for life are present.”
That means that Enceladus is one of three places in our solar system that so far have been found to have negatively-charged ions—the other two are Titan and Earth itself. Here on our own planet, negatively-charged ions are present where there is liquid water in motion, such as streams, waterfalls, and yes, oceans.
The two flybys of the Cassini spacecraft have also shown that Enceladus has an atmosphere. Because the moon is so small that it cannot hold that atmosphere down, scientists speculate that the geysers and ice volcanoes are continuously feeding gas to the surface.
NASA scientists have declared at an Encedalus Focus Group Conference that the Saturn moon “is emerging as the most habitable spot beyond Earth in the solar system for life as we know it.” Meanwhile, the Cassini mission is preparing for another close encounter with this enigmatic world. Here’s hoping that even if they don’t find life, they may at least guarantee a place for it.