On the 11 September 2017, NASA’s Cassini spacecraft made its final flyby past Titan in what the mission engineers are referring to as ‘the goodbye kiss’. This flyby occurred at 7:04 p.m. GMT (3:04 p.m. EDT), and it has provided Cassini with the gravitational nudge necessary to send the spacecraft into Saturn’s atmosphere.
The closest approach Cassini made on the day was at 119,049 kilometres (73,974 miles) above the moon’s surface. However, we will not know what fully occurred until Cassini reconnects with Earth, which is scheduled for 13 September at roughly 1:19 a.m. GMT (9:19 p.m. EDT on 12 September). Images and other scientific data are then expected to begin streaming back to Earth, while the navigators will take this opportunity to ensure the spacecraft is on the correct trajectory.
Cassini has made hundreds of passes over Titan over its thirteen-year voyage, which included 126 precisely targeted encounters. This one is the most important yet, as this goodbye kiss is essential in slowing down Cassini. By slowing down the spacecraft, the altitude of its orbit over Saturn will decrease, directing it into the upper atmosphere. Cassini will then begin to burn up, due to the friction with Saturn’s heavy atmosphere, but this is necessary because it will prevent any potential collisions with Saturn’s other moons. Scientists want to protect the moon Enceladus in particular, as they have been amazed by its subsurface ocean and its signs of hydrothermal activity.
“Cassini has been in a long-term relationship with Titan, with a new rendezvous nearly every month for more than a decade,” said Cassini Project Manager Earl Maize at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This final encounter is something of a bittersweet goodbye, but as it has done throughout the mission, Titan’s gravity is once again sending Cassini where we need it to go.”
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