CassiniAfter four years orbiting the enormous ringed planet Saturn and flying past its dozens of moons, NASA’s unmanned Cassini probe still hasn’t seen it all. The four successful years thus far included releasing the European Space Agency’s Huygens probe to make the first ever landing on the large moon Titan, discovering (and flying through) water geysers over another moon, and exploring other moons that have puzzled scientists since they were first viewed up close in the early 1980s by the Voyager probes. The mission extension – called the Cassini Equinox Mission – gives Cassini an added two-year lease of life, with a $160 million price tag (the mission so far has cost both NASA and ESA a combined total of $3.3 billion).