NASA’s unmanned spacecraft Cassini is all set to whiz past sixth-largest moon of Saturn Enceladus this weekend. It will be probe’s final close flyby of the ocean-bearing moon, NASA said.

Cassini, which entered orbit around Saturn in 2004, will make the flyby at a distance of about 3,106 miles, or 4,999 kilometers, on December 19 at about 9:49 am, as per the US space agency. It will be probe’s final close pass, but it will continue to keep a watch on the natural satellite at a much greater distance, NASA revealed.

The Saturday flyby’s main focus will be to measure the heat coming through the moon’s ice. It may help scientists on earth in understanding the cause behind the plume of gas and icy particles coming from an ocean below the moon’s surface.

If Cassini succeeds in measuring how much warmth Enceladus has, it will reveal several things about geologic activity on the moon, said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory. The scientist hopes the probe’s last close flyby of Enceladus will be a fantastic opportunity to understand the moon.

It will be last the probe’s last and historic encounter, but not the closest one with the moon. Cassini will maintain a safe distance from the surface so that its Composite Infrared Spectrometer instrument could observe heat coming from south polar terrain of Enceladus.

Mike Flasar, CIRS team lead at NASA’s Goddard Space Flight Center, said in a statement, “The distance of this flyby is in the sweet spot for us to map the heat coming from within Enceladus -- not too close, and not too far away. It allows mapping a good portion of the intriguing south polar region at good resolution”.