Enceladus, Icy Moon Of Saturn, “Could Be Snowing Microbes” Says NASA
Enceladus is just one of 33 moons orbiting Saturn, and one of 146 in our solar system. But if you counted the number of moons that have warm saltwater geysers erupting from the surface, well, that list would be just one. Life-friendly Enceladus has been gaining attention recently due to information from the Cassini space probe that confirmed what scientists were hoping. That the geysers were, in fact, water. What delighted scientists was the discovery that water was full of organic compounds, including propane, ethane, and acetylene.
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"It just about ticks every box you have when it comes to looking for life on another world," NASA astrobiologist Chris McKay told The Guardian. "It has got liquid water, organic material and a source of heat. It is hard to think of anything more enticing short of receiving a radio signal from aliens on Enceladus telling us to come and get them."
The heat source on Enceladus was discovered near the moon's south pole. The Cassini spacecraft measured 15.8 gigawatts of heat in the region, which is more than twice the heat generated by all the hot springs in Yellowstone. The area is geologically defined by four trenches, known as the "tiger stripes." These trenches are generating most of the heat in the region, the source of which is believed to be a combination of radiation and friction. Scientists believe that the moon may have formed a core of radioactive metals that generate heat as they decay. Additional heat is created by a phenomenon known as gravitational tidal forcing. The materials inside Enceladus collide with each other when under the gravitational influence of another celestial body, such as Saturn. Gravitational tidal forcing would also account for the cracks in the surface ice in the southern polar region on Enceladus.
Astrobiology enthusiasts have been calling attention to Enceladus for a while. In 2011, a meeting at the SETI Institute in Mountain View, Calif. called for more support for a mission to Enceladus. McKay attended the meeting and later told Nature that "there is no other environment in the Solar System" that comes close to matching Enceladus for the potential for life. Launching a probe to study Enceladus needs to happen soon, supporters say, because the current position of Jupiter adds a gravitational boost to passing spacecraft that can trim years off the voyage. Jupiter won't return to its current position until sometime in the 2030s.
"The fact that this water is being vented into space and is mixed with organic material is truly remarkable," said McKay. "It is an open invitation to go there. The place may as well have a big sign hanging over it saying: 'Free sample: take one now'."
Carolyn Porco, a planetary scientist for NASA, believes that the type of biology found on Enceladus would be similar to those found deep within the Earth's subterranean volcanic rocks, where microorganisms live off of hydrogen and carbon dioxide. The geysers on Enceladus are what make it especially promising for study, she says, because unlike similar missions that involve a spacecraft touching down on a surface and collecting samples, an Enceladus probe could just fly through the vapors being blasted into space. The same vapors that re-freeze and drift back to the surface.
"It's the most promising place I know of for an astrobiology search," she said, adding, "it sounds crazy but it could be snowing microbes on the surface of this little world."
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