All posts for the day December 12th, 2012

Cassini’s Latest Find on Titan

A river and delta system on the surface of Saturn’s largest moon, Titan. Courtesy NASA/ESA.

The hits just keep on coming for the Cassini Solstice mission (a joint effort between NASA and the European Space Agency). This time it has sent back a radar image of what looks like a miniature version of Earth’s Nile River delta. It stretches across more than 400 kilometers (about 250 miles). Some kind of liquid is flowing through it, and scientists suspect that it is following along the boundary of a fault (a crack) in the surface. The river empties out into a Titan sea.

Titan is an interesting place. It’s got liquid flowing across its frigid surface, as well as lakes and small seas. Planetary scientists think the liquid that cycles from surface to the atmosphere and back again contains hydrocarbons such as ethane and methane. That’s not all that weird, really. Early Earth may have had a similar environment before things settled out some 4 billion years ago. What this image, and the many other images and observations about Titan tell us is that this is a lively world — it has activity on its surface, and there’s clearly something going on inside this moon that keeps things bubbling along. It experiences seasons, something that astronomers had not expected to find when they sent the mission.

The Cassini Solstice Mission is one of the great success stories in planetary exploration. It was launched as Cassini-Huygens in 1997 and has been tracing an orbital mission through the Saturn system ever since its arrival in 2004. It finished its initial four-year-long mission in 2008 and has been extended twice to continue exploring Saturn, its moons, and rings. It dropped the Huygens lander to the surface of Titan and that gave us our first in situ look at this once-mysterious moon.

The current mission goes through September 2017 and was renamed Cassini Solstice because it will have observed one complete turn of the seasons by May 2017.  It arrived just after Saturn’s northern winter solstice, hence the name.

Cassini’s greatest hits include the discovery and continual study of jets fountaining away from the moon Enceladus. This tiny world has a deep ocean that is kept warm by tidal heating (created by a tug of war between the gravity of Saturn and its outer moons, with Enceladus caught in the middle). The material spraying out from Enceladus has traces of organic chemicals in it, which suggests that Enceladus could be a place where primitive life could form (or may have already).

Saturn itself continues to be a target for the mission. Planetary scientists hope to use mission data to get a clearer picture of the gas giant’s internal structure, and gather more information about its atmosphere.

Want to know more about Cassini and its explorations? The Cassini Solstice Mission has a marvelous Web site where you can find out about the spacecraft, the science, and see many gorgeous images of the Saturnian system. Check it out!