Cassini's Grand Finale: NASA spacecraft all set to commence final five orbits around Saturn

Artist's impression of Cassini making one of its final dives through Saturn's upper atmosphere. (Image courtesy: NASA/JPL-Caltech)

New Delhi: NASA's Cassini mission, which began in 1997, has definitely been a fruitful one owing to all the wonderfully insightful information scientists have managed to glean from it.

The mission, currently in its grand finale phase, is inching toward its graceful finish. At present, the spacecraft is performing flybys of the planet Saturn, making its closest approaches to the rings.

Every new image and data beamed back by Cassini during its last mission has come bearing some evolutionary secret or shows an unpredictable side of the planet or a feature that would have otherwise been impossible to envisage.

Cassini will end its journey in September this year by performing a death plunge into the ringed planet, but there's still some time before that happens and NASA definitely has something huge planned for the spacecraft's remaining days in Saturn's orbit.

On Wednesday, NASA announced that Cassini is all set to commence its five final orbits as a part of its Grand Finale, embarking on a set of ultra-close passes through Saturn’s upper atmosphere.

According to NASA, Cassini will make the first of these five passes over Saturn at 12:22 am EDT Monday, August 14. The spacecraft's point of closest approach to Saturn during these passes will be between about 1,010 and 1,060 miles (1,630 and 1,710 kilometers) 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.

Moreover, other Cassini instruments will 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 16 miles (25 kilometers) wide – nearly 100 times smaller than the spacecraft could observe prior to the Grand Finale.

On September 11, a distant encounter with Titan will serve as a gravitational version of a large pop-down maneuver, slowing Cassini’s orbit around Saturn and bending its path slightly to send the spacecraft toward its September 15 plunge into the planet.

During the half-orbit plunge, the plan is to have seven Cassini science instruments, including INMS, turned on and reporting measurements in near real time. The spacecraft is expected to reach an altitude where atmospheric density is about twice what it encountered during its final five passes.

Once Cassini reaches that point, its thrusters will no longer be able to work against the push of Saturn’s atmosphere to keep the spacecraft's antenna pointed toward Earth, and contact will permanently be lost. The spacecraft will break up like a meteor moments later, ending its long and rewarding journey, NASA reported.