NASA’s Cassini spacecraft made its closest approach to Saturn’s tiny moon Methone
as part of a trajectory that will take it on a close flyby of another of Saturn’s moons, Titan. The Titan flyby will put the spacecraft in an orbit around Saturn that is inclined, or tilted, relative to the plane of the planet’s equator. The flyby of Methone took place on May 20 at a distance of about 1,200 miles (1,900 kilometers). It was Cassini’s closest flyby of the 2-mile-wide (3-kilometer-wide) moon. The best previous Cassini images were taken on June 8, 2005, at a distance of about 140,000 miles (225,000 kilometers), and they barely resolved this object. Also on May 20, Cassini obtained images of Tethys, a larger Saturnian moon that is 660 miles (1,062 kilometers) across. The spacecraft flew by Tethys at a distance of about 34,000 miles (54,000 kilometers). Cassini’s encounter with Titan, Saturn’s largest moon, on May 22, is the first of a sequence of flybys that will put the spacecraft into an inclined orbit. At closest approach, Cassini will fly within about 593 miles (955 kilometers) of the surface of the hazy Titan. The flyby will angle Cassini’s path around Saturn by about 16 degrees out of the equatorial plane, which is the same plane in which Saturn’s rings and most of its moons reside. Cassini’s onboard thrusters don’t have the capability to place the spacecraft into orbits so inclined. But mission designers have planned trajectories that take advantage of the gravitational force exerted by Titan to boost Cassini into inclined orbits. Over the next few months, Cassini will use several flybys of Titan to change the angle of its inclination, building one on top of the other until Cassini is orbiting Saturn at around 62 degrees relative to the equatorial plane in 2013.