NASA’s Cassini spacecraft is heading to Saturn’s largest moon Titan for a flyby after capturing some stunning images of the planet’s moon Enceladus, the Jet Propulsion Laboratory (JPL) announced on Wednesday.

The flyby followed a similar mission in which the spacecraft flew over Enceladus, catching an image showing the hazy outline of Titan behind Saturn’s rings, with the dark curve of Enceladus at the bottom, the JPL said.

Other images show Enceladus putting its craggy face forward, exhibiting some of the fractures and cratering that have made the Saturnian moon a favourite of both planetary scientists and outer-planet mission groupies, according to the JPL, which is based in Pasadena, Los Angeles. Cassini finished its flyby of Enceladus on Tuesday, the first leg of its planned double flyby. Cassini passed within about 435 km of the surface.

Cassini’s flyby of Titan will occur in the late evening on May 19 Pacific time, which is in the early hours of May 20 UTC (Coordinated Universal Time). Because of a fortuitous cosmic alignment, Cassini can catch glimpses of these two contrasting worlds within less than 48 hours, with no manoeuvre in between.

The main scientific goal at Enceladus was to watch the sun play peek-a-boo behind the water-rich plume emanating from the moon’s south polar region, the JPL said.

Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume, according to the JPL.

Ammonia has already been detected in the plume, and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon’s interior.

The mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

The JPL, a division of the California Institute of Technology, manages the mission for NASA’s Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

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