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Sci Tech
Is there a recipe for life on Saturn’s moon Enceladus?
K.S. RAJGOPAL
— Photo: AFP
‘Hot’ finding: New heat maps of the surface show higher temperatures than previously known in the South Polar region
NASA’s Cassini spacecraft tasted and sampled a surprising organic brew erupting in geyser-like fashion from Saturn’s moon Enceladus during a close flyby on March 12. Scientists are amazed that this tiny moon is so active, ‘hot’ and brimming with water vapour and organic chemicals. The findings are reported in the March 26 edition of the journal Science.
New heat maps of the surface show higher temperatures than previously known in the South Polar region, with hot tracks running the length of giant fissures.
The jets themselves harmlessly peppered Cassini, exerting measurable torque on the spacecraft, and providing an indirect measure of the plume density.
Another surprise
Another surprising finding is that the chemistry of Enceladus, what’s coming out from inside, resembles that of a comet. “The spacecraft is using a mass spectrometer, which measures the atomic mass of molecules thereby allowing their identification,” explained Dr. Ralph D. Lorenz, Cassini radar scientist at the Space Department, Planetary Exploration Group, Johns Hopkins University Applied Physics Lab, U.S., in an email communication to this correspondent.
The mass spectrometer saw a much higher density of volatile gases, water vapour, carbon dioxide and carbon monoxide, as well as organic materials, some 20 times denser than expected. To have primordial material coming out from inside a Saturn moon raises many questions on the formation of the Saturn system.
Not a comet
Enceladus is by no means a comet. Comets have tails and orbit the sun, and their activity is powered by sunlight. Enceladus’ activity, however, is powered by internal heat. Enceladus’ brew is like carbonated water with an essence of natural gas.
The dramatic increase in density was evident as the spacecraft flew over the area of the plumes.
New high-resolution heat maps of the South Pole by Cassini’s composite infrared spectrometer show that the so-called tiger stripes, giant fissures that are the source of the geysers, are warm along almost their entire lengths, and reveal other warm fissures nearby.
These more precise new measurements reveal temperatures of at least minus 135 degrees Fahrenheit. That is 63 degrees Fahrenheit warmer than previously seen and 200 degrees Fahrenheit warmer than other regions of the moon.
New data
These new data will help understanding of how the geysers are powered. The high temperatures observed make it more likely that there is water not far below the surface.
“The speed of the gas molecules implies (relatively — as the surface of Enceladus in parts is well below 70K or -200C) high temperatures, perhaps as high as the melting point of water,” noted Dr. Lorenz . Enceladus has got warmth, water and organic chemicals, some of the essential building blocks needed for life. There is quite a recipe for life but the scientists have yet to find the final ingredient, water.
At closest approach, Cassini was only 30 miles from Enceladus. When it flew through the plumes it was 120 miles from the moon’s surface. Cassini’s next flyby of Enceladus is in August. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA’s Science Mission Directorate, Washington.
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