NASA’s Cassini spacecraft is entering the final phase of its mission around Saturn, and the probe will make a flyby of of the weird Saturn moon Hyperion. Mission controllers have stated that the spacecraft will pass the moon at a distance of 34,000 kilometers at approximately 6.36 a.m. PDT (9.36 a.m. EDT) on May 31.
Images from the final mission will be available on Earth in 24 to 48 hours, and scientists hope to capture the other side of the moon, to understand its composition. Currently, only images of an approximate same side have been captured from the irregularly shaped 168 mile (270 kilometers) wide Hyperion, with its signature “spongy” appearance. Hyperion’s evolution has caused rocky impactors to strike the satellite, compressing its surface. The material is lost in space, which leaves a strange pockmarked surface.
However, scientists remain unsure on which side the moon will be facing when Cassini is on a flyby. The moon does not follow orbital dynamics, and is tumbling without control as it orbits Saturn, making it difficult for experts to calculate the object’s spin. The low density of Hyperion decreases its gravity, and scientists believe that this gives the moon a “spongy” appearance. The flyby will not be the closest Cassini has come to Hyperion as the spacecraft had cruised past the moon at a distance of 314 miles (505 km) in 2005.
This will mark the first flyby of several flybys of Saturn’s moons. After Hyperion, Cassini will cruise past Dione at 321 miles (516 kilometers). Then, a daring mission will be Enceladus as the spacecraft will skate across the moon’s icy surface at a distance of only 30 miles (48 km). These series of flybys will mark the beginning of Cassini’s final stage as the spacecraft will move out of Saturn’s equatorial plane. In 2016, the spacecraft will begin a series of deep dives into Saturn’s rings.[ Source ]