Cassini spacecraft to enter ‘ring-grazing orbit’ around Saturn on Tuesday

Tuesday marks the beginning of the end for NASA’s Cassini mission, as the titular spacecraft will enter a new “ring-grazing” orbit that will bring it to within 5,000 miles of Saturn’s F-ring, the first step in its “Grand Finale” after 12 years of studying the planet and its moons.

According to The Verge, Cassini will be analyzing the particles and gas molecules around the planet’s ring system, while also observing the tiny moons that orbit close to the edges of these iconic features as it prepares for a final plunge into Saturn’s atmosphere next September.

On Tuesday, Cassini will complete one final fly-by of Titan, which Spaceflight Insider said will place it on the correct trajectory for a December 4 encounter with Saturn’s F-ring – the first of 20 planned encounters scheduled to take place, one every seven days, through April 22, 2017.

As Linda Spilker, project scientist at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California, explained in a statement, “We’re calling this phase of the mission Cassini’s Ring-Grazing Orbits, because we’ll be skimming past the outer edge of the rings. In addition, we have two instruments that can sample particles and gases as we cross the ringplane.”

Countdown to the spacecraft’s ‘Grand Finale’ officially underway

During those 20 encounters with Saturn’s ring system, Cassini will circle high above and under the planet’s polar regions, studying a previously unexplored portion of its main rings while using a variety of instruments to directly sample ring particles and nearby faint gas molecules.

According to NASA, during its first two orbits, the spacecraft will pass directly through a faint ring that was created by tiny meteors that struck the moons Janus and Epimetheus. Later flights will see the probe travel through the dusty outer portions of the F-ring, the agency added, while also getting its best looks to date at the moons known as Atlas, Daphnis, Pan and Pandora.

In December, Cassini will begin imaging Saturn’s main rings along their entire with, resolving details smaller and 0.6 miles (1.0 km) per pixel, NASA said. This will allow it to create the best possible complete scans of the rings’ structure, and as the mission continues, it will take a close look at tiny features in the A-ring that may reveal the existence previously unseen moonlets.

Next March, Cassini will travel through Saturn’s shadow, which will allow it to observe the rings backlit by the sun, which scientists at the agency hope will allow it to see dust clouds ejected due to meteor impacts. Then, next April, Cassini (which is running low on fuel) will enter its “Grand Finale” phase, which will culminate with a crash-landing onto Saturn’s surface on September 15, bringing the spacecraft’s two decade long spaceflight to a spectacular conclusion.


Image credit: NASA