Cassini set to embark on final five orbits around Saturn

Washington : NASA's Cassini spacecraft is set to embark on a set of ultra-close passes through Saturn's upper atmosphere with its final five orbits around the planet.

Cassini will make the first of these five passes over Saturn at 12:22 a.m. EDT on August 14, NASA said.The spacecraft's point of closest approach to Saturn during these passes will be between about 1,630 and 1,710 kilometres above Saturn's cloud tops.

The spacecraft is expected to encounter atmosphere dense enough to require the use of its small rocket thrusters to maintain stability - conditions similar to those encountered during many of Cassini's close flybys of Saturn's moon Titan, which has its own dense atmosphere.

"Cassini's Titan flybys prepared us for these rapid passes through Saturn's upper atmosphere," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory (JPL) in California.

"Thanks to our past experience, the team is confident that we understand how the spacecraft will behave at the atmospheric densities our models predict," Maize said.

Cassini instruments will obtain data on the atmosphere close to the planet's cloud tops, make detailed, high-resolution observations of Saturn's auroras, temperature, and the vortexes at the planet's poles.

Its radar will peer deep into the atmosphere to reveal small-scale features as fine as 25 kilometres wide - nearly 100 times smaller than the spacecraft could observe prior to its final mission phase, the Grand Finale.