Cassini Results

Cassini isn't just about pretty pictures. Scientists, presenting at the AGU meeting here in San Francisco today, discussed two recent scientific results from the mission.

The first is the discovery of a cryovolcano on Saturn's moon Titan. Titan's methane atmosphere has long been suspected to be a result of cryovolcanism, perhaps bringing methane from the interior of the moon to the exterior.

Visible data revealed a small rose like feature in an area of Titan called Sotra Facula. The Cassini radar team represented here by Randy Kirk of USGS, decided to take a closer look and map the topography of the area. Using datasets taken by Cassini, he made an animation. "I was shocked when I saw the video... Especially surprised to find not one peak, but a set of them."

Kirk found three conical features and two pits very similar to volcanic calderas. Take a look at the false color image of Sotra, compared with a volcanic ridge in Iceland. As Jeffrey Kargel of the University of Arizona put it, this topographic evidence is very compelling—no other tectonic feature would juxtapose the highest peaks and the lowest pits in one area but a volcano.

This could very well become the first confirmed cryovolcano in the outer solar system. There are two candidate cryovolcanoes on Triton, one of Neptune’s moons. And scientists believe that the geysers emitting from Enceladus are also a result of icy volcanoes.

The second result announced today came from Pontus Brand of Cassini’s magnetosphere imaging team. The magnetosphere is like a magnetic bubble where planets’ magnetic fields interact with the solar wind. Cassini measured hot plasma explosions in Saturn’s magnetosphere. An animation can be seen here.

What’s interesting to the Cassini team is that these explosions seem to be instep with Saturn’s odd magnetic field and radio signals and are believed to be a measure of Saturn’s rotation rate. Unlike other planets in the solar system, Saturn’s rotation and magnetic axis are the same; there is no tilt as there is here on Earth. As Marcia Burton, Cassini Fields and Particles Investigation Scientist, put it into perspective, we care about Saturn’s rotation rate because it can tell us more about the structure of the planet’s interior and its atmospheric winds.

What might Cassini discover next? Cassini’s current mission runs for 7 more years and includes 54 more flybys of Titan and 156 more orbits of Saturn. It might be able to answer some of the new questions these results put forth. What is the substance erupting from Titan’s cryovolcano—water, ammonia, methane, hydrocarbons? Might there be evidence of subsurface life there? What more can Saturn’s magnetosphere tell us? Stay tuned!