The planet Saturn
Cassini obtained images of Saturn’s northern hemisphere during the planet’s summer solstice in mid-2017. Photo: NASA

NASA’s Cassini spacecraft made its final flyby of Saturn’s giant moon Titan Monday, four days before its scheduled plunge into the planet.

The spacecraft operated by the Jet Propulsion Laboratory in Pasadena made Monday’s closest approach to Titan at 12:04 p.m. at an altitude of 73,974 miles above the moon’s surface, according to Preston Dyches, a science communications specialist with the laboratory.

The distant encounter is referred to informally as “the goodbye kiss” by mission engineers, because it provides a gravitational nudge that sends the spacecraft toward its plunge that will end in Saturn’s upper atmosphere, Dyches said.

The geometry of the flyby causes Cassini to slow down slightly in its orbit around Saturn. This lowers the altitude of its flight over the planet so the spacecraft goes too deep into Saturn’s atmosphere to survive, because friction with the atmosphere will cause Cassini to burn up.

Cassini is scheduled to make contact with Earth at about 6:19 p.m. Images and other science data taken during the encounter are expected to begin streaming to Earth soon after.

Navigators will analyze the spacecraft’s trajectory following this downlink to confirm that Cassini is precisely on course to dive into Saturn at the planned time, location and altitude, Dyches said.

Cassini is ending its 13-year tour of the Saturn system with an intentional plunge into the planet to ensure Saturn’s moons — in particular Enceladus, with its subsurface ocean and signs of hydrothermal activity — remain pristine for future exploration, Dyches said.

—City News Service

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