Saturn probe’s fiery finale
NASA’s Cassini spacecraft plunged into Saturn on a planned “suicide dive” last week, completing a 20-year mission during which it revealed the ringed planet in astonishing detail and two of its moons as possible locations of extraterrestrial life. Cassini, launched in 1997, made a seven-year journey to Saturn, then spent 13 years streaming back 635 gigabytes of data, including 400,000 photos of a giant planet that has captivated stargazers for centuries. Cassini made a host of stunning discoveries, including a raging hexagonal storm centered on Saturn’s North Pole; lakes of liquid methane on the planet’s largest moon,Titan; and a massive ocean beneath the icy surface of another moon, Enceladus. That ocean, Cassini revealed, periodically spews briny geysers of water out into space—an indication of geothermal heat. Scientists now consider Titan and Enceladus, along with Jupiter’s moons Ganymede and Europa, as prime targets in the search for alien life. “The possibility of life so far from the sun has opened up our paradigm of where you might look for life,” Cassini project scientist Linda Spilker tells Sky &Telescope, “both within our own solar system and in the exoplanet solar systems beyond.” In the final phase of its mission, Cassini flew through Saturn’s ring plane 22 times, sending back data, before its final swan dive. “It may go down as one of NASA’s greatest planetary missions,” Spilker says. “We’ve had a fire hose of data come back over 13 years.”