Cassini spacecraft will make its final close flyby of Saturn's largest moon Titan on April 21, NASA has said.
During the encounter, Cassini will pass as close as 979 kilometres above Titan's surface at a speed of about 21,000 kms per hour, the US space agency said.
The flyby marks the mission's final opportunity for up-close observations of the lakes and seas of liquid hydrocarbons that spread across the moon's northern polar region, and the last chance to use its powerful radar to pierce the haze and make detailed images of the surface.
The flyby is also the gateway to Cassini's "Grand Finale" – a final set of 22 orbits that pass between the planet and its rings, ending with a plunge into Saturn on September 15 that will end the mission.
During the close pass on April 21, Titan's gravity will bend Cassini's orbit around Saturn, shrinking it slightly, so that instead of passing just outside the rings, the spacecraft will begin its finale dives which pass just inside the rings.
NASA's Cassini spacecraft is in orbit around Saturn for nearly 13 years.