During a flyby of the small moon on March 12th, the Cassini probe detected significant amounts of organic chemicals as it flew through powerful geyser-like jets of ice blasting into space. This active moon appears toÂ be generatingÂ organic chemicals much like the substances found in comets. As Cassini bravely travelled through the plume at a speed of 32,000 mph, it was able to take some indirect measurements of the density of the gas from the surprising amount of torque applied to spacecraft. Fortunately the craft was undamaged as the particles bounced off its bodywork…
Cassini took the daring journey through the plumes of ice crystals and gas at 200 km above the moon’s surface. It came within 50 km of the surface at closest approach, giving mission scientists an unprecedented view of the mysterious satellites northern hemisphere. Images acquired by Cassini showed a vast, ancient region of pits and craters mixed with cracks, with geysers fizzing chemicals into space. Enceladus is located in the densest region of Saturn’s E-ring, possibly indicating there is some relationship between the geyser emissions and ring density.
To discover significant quantities of organic compounds being emitted from the Saturn system is of particular interest to scientists trying to understand how Saturn evolved as the solar system formed.
“A completely unexpected surprise is that the chemistry of Enceladus, what’s coming out from inside, resembles that of a comet, to have primordial material coming out from inside a Saturn moon raises many questions on the formation of the Saturn system.” – Hunter Waite, principal investigator for the Cassini Ion and Neutral Mass Spectrometer, Southwest Research Institute, San Antonio
From measurements by the Ion and Neutral Mass Spectrometer on Cassini, scientists are able to deduce that the moon is highly active, driven by an internal energy source. There is also evidence for tectonic activity on the 500 km diameter body. The gases detected can be likened to the fizz of gas released from carbonated water, with a twist of organic chemicals mixed in. The spectrometer effectively “tasted and sniffed” the gas and was able to get a good idea about what the energetic geysers are spewing into space.
The gases detected, over 20 times more dense than estimated, contained water vapour, carbon dioxide, carbon monoxide, organic compounds and volatile molecules. Quite an explosive mix. The clouds of gas were so dense that the spacecraft felt the force of the emission, creating a torque. From this, some measurements on gas density were possible.
It is thought Cassini was unharmed during the flyby and it will return in August for an even more daring, lower flyby of this strange, gassy moon.
Hello! My name is Ian O’Neill and I’ve been writing for the Universe Today since December 2007. I am a solar physics doctor, but my space interests are wide-ranging. Since becoming a science writer I have been drawn to the more extreme astrophysics concepts (like black hole dynamics), high energy physics (getting excited about the LHC!) and general space colonization efforts. I am also heavily involved with the Mars Homestead project (run by the Mars Foundation), an international organization to advance our settlement concepts on Mars. I also run my own space physics blog: Astroengine.com, be sure to check it out!