Cassini spacecraft to make last flyby with Saturn's Titan on Saturday

Saturday may be Earth Day here, but for NASA's spacecraft Cassini, it will be Titan Day.

Cassini will make its last up-close flyby of Saturn's mysterious, haze-enshrouded moon Titan this weekend.

This will be "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," NASA said in a statement.

Cassini's radar instrument will look for changes in Titan's methane lakes and seas, and attempt for the first (and last) time to study the depth and composition of Titan's smaller lakes.

The closest approach to Titan is planned for 2:08 a.m. EDT on Saturday. During that encounter, Cassini will pass as close as 608 miles above Titan's surface at a speed of about 13,000 mph, NASA said.

The flyby is also the beginning of the end for Cassini: Once it passes by Titan, its final 22 orbits over the next five months will be between Saturn and its famed rings, ending with a plunge into Saturn on Sept. 15 that will destroy the spacecraft and finish the mission.

“I think it is too early to eulogize Cassini on the occasion of its death, as incineration is five months away," said Jonathan Lunine, the director of the Cornell Center for Astrophysics and Planetary Science, who has worked on the Cassini mission since the 1980s.

"Between now and September, there will be a ton of new science on what’s inside Saturn, how much the rings weigh, and amazing detail on rings, ring-moons and atmosphere," he said.

Launched in 1997, Cassini has been studying Saturn and its moons since it arrived there in 2004. The Cassini mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

“Cassini is the quintessential ‘discovery machine’, unearthing surprises everywhere it has looked in the Saturn system," he said. "I will be sad to see its mission end this fall, but extraordinarily grateful to have been a part of this amazing odyssey from its very beginnings in the 1980s. Cassini sets a high bar for missions yet to come," Lunine said.