Category Archives: Enceladus

Enceladus Flyby

The Cassini spacecraft orbiting Saturn, everyone’s favorite planet (right??), will make it’s closest flyby of Saturn’s tiny, icy moon Enceladus since 2008 at 2:30 EDT today.  The probe will fly over Enceladus’ south polar region at an altitude of 46 miles (74 kilometers) near an area famous for its ice-spewing mega-geysers.  Cassini discovered active cyrovolcanism on Encledadus during its first flyby of the moon in 2005.  It astonished astronomers that a moon so cold and icy could have volcanic activity at all.  Further investigation lead to the discovery of a region in the southern hemisphere known as “the Tiger Stripes” where there are four large rifts in the icy surface.  Below the surface it is believed that there is a local or planetwide ocean of water that is heated far above what is expected of a small icy world so far from the Sun.  Enceladus must must have a hot core just like our own planet that is heated by the friction caused by the gravitational pull of Saturn and orbital resonances from other moons.  Since Enceladus orbits within Saturn’s rings very close to the planet it feels the strong gravitational pull of not only Saturn but of the ring system and the other moons that orbit Saturn.  The south polar region of Enceladus is particularly interesting to astronomers because it shows clear evidence of ongoing geological activity.  The southern terrain is largely free from impact craters which leads us to believe that the surface is being reshaped by the geological forces at work beneath the surface.  Enceladus is one of only three moons where we have seen eruptions; the other two being Jupiter’s moon Io and  Neptune’s moon Triton.

Massive ice geysers around the Tiger Stripes region of Enceladus' south pole suggest the presence of heated liquid H2O Credit: NASA/

The intrigue of the geysers has prompted Cassini’s mission control at the Jet Propulsion Laboratory to carry out a flyby of the south pole region to “taste” the icy vapor with a device called an ion and neutral mass spectrometer.  The data collected from the spectrometer will allow scientists to better understand the composition of the jets of ice and its subterranean source.  Cassini’s composite infrared spectrometer will also be taking pictures of the Tiger Stripes looking for hot spots under the surface similar to the ones recently found detailed in the picture below.

The geological activity and presence of water on Enceladus is extremely exciting for NASA because if there’s water and heat there could also be micro-bacterial life.  A discovery of life on Enceladus would be a massive breakthrough in understanding the picture of the universe and the early stages of life on our own planet as well.  So far it’s the moons, not the planets that are leading the race of potential for life, so I vote to study more moons!

Evidence of subterranean heat below the Tiger Stripes region on Enceladus Credit: NASA/J

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