NASA’s Cassini spacecraft will make its final close fly-by of Saturn’s moon Dione next Monday when it will come within 474 kilometres of the surface.
New images will be available a couple of days later.
Scientists say gravity data from the fly-by will improve their knowledge of the moon’s internal structure and allow comparisons to Saturn’s other moons.
Cassini’s cameras and spectrometers will collect high-resolution imagery of Dione’s north pole at a resolution of only a few metres. Its Composite Infrared Spectrometer instrument will map areas on the icy moon with thermal anomalies, while the Cosmic Dust Analyzer will keep searching for dust particles emitted from Dione.
The fly-by will be the fifth over Dione in Cassini’s mission around Saturn. Cassini has been orbiting Saturn since 2004. During its time there it has visited a handful of Saturn’s 62 known moons.
Its closest-ever flyby of Dione was in December 2011 when it came 100 kilometres from the surface, providing high-resolution views of the terrain including a system of braided canyons with bright walls.
Scientists also have been eager to find out if Dione has geologic activity, like Saturn’s geyser-spouting moon Enceladus, but at a much lower level.
“Dione has been an enigma, giving hints of active geologic processes, including a transient atmosphere and evidence of ice volcanoes. But we’ve never found the smoking gun. The fifth flyby of Dione will be our last chance,” said Bonnie Buratti, a Cassini science team member at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Cassini later this year will depart Saturn’s equatorial plane and prepare for its grand finale during which it will repeatedly dive through the space between Saturn and its rings.
Bill Condie is a science journalist based in Adelaide, Australia.
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