Now in its eleventh year in orbit around Saturn, the ESA/NASA Cassini spacecraft is delivering new images of Saturn’s moons. It moved to a more equatorial orbit in March, after two years in high orbit above the polar regions. This brings its back in range of Saturn’s moons, and the transition is marked by a stream of new pictures.
In February, Cassini sent back some of the clearest images of Rhea, taken from 30,000 to 50,000 miles away. Rhea is Saturn’s second-largest moon, and had the distinction of being the most heavily-cratered body in the solar system. This is an indication of its great age.
In January Cassini sent back the latest images of Epimetheus, taken from around 1.8 million miles away. The name means “hindsight” and the moon was originally confused with Janus. It was later discovered that though they share the same orbit, Janus and Epithemeus are two distinct objects.
Saturn has 53 known moons and nine more awaiting confirmation. Cassini will remain in equatorial orbit through 2015, during which time it will have several close encounters with Titan, Dione and Enceladus. It will then return to a polar orbit that allows it to study Saturn’s polar regions. The current phase of the Cassini mission is called the Solstice mission. The northern summer solstice on Saturn occurs in May 2017.
Cassini arrived at Saturn just after the northern winter solstice. The extension of the mission allows it to complete the study of the full seasonal cycle: one year on Saturn is 29.7 Earth years, according to Universe Today.
The Cassini-Huygens mission, launched in 1997, was named for the 17th century astronomers who discovered Saturn’s moons. In 2005, the Huygens lander separated from Cassini and landed on the surface of Titan, Saturn’s largest moon. The images and data returned by the mission have transformed our view of the icy worlds of the outer solar system.
The mission will continue until 2017, when it will run out of fuel. It will then fall through Saturn’s rings and into the atmosphere, to burn up like a shooting star.