The Cassini probe descends closer to Saturn, beginning a series of plunges into the space between the planet and its rings. The mission ends in September, when the probe will burn up in Saturn's atmosphere.
A joint mission of NASA, the European Space Agency and Italian Space Agency, Cassini was launched on Oct 15, 1997. It reached Saturn's system in 2004, and began returning the first-ever clear and close views of the giant and its moons.
In Nov 2016, the spacecraft began its so-called ring-grazing phase with a series of plunges through the planet's rings.
On April 22, the start of the so-named Grand Finale, "Cassini will leap over the rings to begin its final series of daring dives between the planet and the inner edge of the rings," according to NASA, "after which it will plunge into the upper atmosphere of the gas giant planet, where it will burn up like a meteor, ending the epic mission to the Saturn system."
The space agency notes that during the Grand Finale, "Cassini will collect some incredibly rich and valuable information that the mission's original planners might never have imagined."
Date written/update: 2017-01-04