Cassini is about to become Lord of the Rings — Saturn’s rings, that is.
The NASA spacecraft, which has been exploring the Saturn system since 1997, has entered into the final phase of its mission, thanks in part to a gravitational nudge from Saturn’s moon Titan.
Engineers have been pumping up the spacecraft’s orbit around the ringed planet this year to increase its tilt respective to Saturn’s equator and rings, according to a NASA statement.
Between now and April 22, Cassini will circle high over and under the poles of Saturn, diving every seven days for a total of 20 times, through the unexplored region at the outer edge of the main rings, NASA said. During these passes, Cassini’s instruments will attempt to directly sample ring particles and molecules of faint gases that are close to the rings. During the first two orbits, the spacecraft will pass directly through an extremely faint ring produced by tiny meteors that struck the two small moons Janus and Epimetheus.
Ring crossings in March and April will send the spacecraft into the dusty outer reaches of the F ring, the outer boundary of the main ring system. Saturn has several other, much-fainter rings that lie farther from the planet. The F ring, NASA said, is complex and constantly changing. Cassini’s images have captured bright streamers, wispy filaments, and dark channels that appear and develop near the ring over the course of hours.
This is the closest to the F ring the spacecraft has ever been – but it will still be more than 4,850 miles from it. This distance will keep the craft and its instruments safe from dust.
“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,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, in a statement.
“In addition, we have two instruments that can sample particles and gases as we cross the ringplane, so in a sense, Cassini is also grazing on the rings.”
In addition to grazing on these rings, Cassini will have the opportunity to observe the small moons that orbit in or near the edges of the rings, including never-before-seen views of Pandora, Atlas, Pan, and Daphnis.
The orbits will put Cassini as close as 56,000 miles above Saturn’s cloud tops.
Cassini’s 20-year mission is drawing to a close because the spacecraft is running low on fuel. During its finale, Cassini will pass as close as 1,012 miles above the clouds as its repeatedly dives through the gap between Saturn and its rings before plunging into the planet’s atmosphere on Sept. 15, 2017.
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