Cassini has entered its stately death spiral, and the images it’s beaming back from Saturn are second to none. As it starts the Grand Finale, Cassini is taking a long, intense burst of observations designed to beam back as much data from Saturn as we can possibly scrape up, including parsing out an audio recording from flecks of dust smacking into the orbiter’s hull.
“Cassini’s imaging cameras, the Imaging Science Subsystem (ISS), takes advantage of the last opportunity to observe Saturn’s rings at extremely high phase angles while the Sun is hidden behind Saturn, allowing the instrument to survey faint ringlets in the main rings, many of which are difficult to observe outside of this geometry.”
Looking Out at Saturn’s Rings
“No spacecraft has ever been this close to Saturn before. We could only rely on predictions, based on our experience with Saturn’s other rings, of what we thought this gap between the rings and Saturn would be like,” said Cassini project manager Earl Maize, of NASA’s JPL. “I am delighted to report that Cassini shot through the gap just as we planned and has come out the other side in excellent shape.”
Saturn’s hexagonal polar jet stream is no stranger to beauty shots. While the gas giant’s north pole was in shadow for the first part of the Cassini mission, it’s now in full sunlight, which enables Cassini scientists to directly image it in reflected light. But full sunlight there is weak indeed. We can read by it, so to speak — it’s enough to let us study the place — but it’s only about 1 percent of the intensity of sunlight here on Earth.
During Cassini’s last months, it will conduct four dives between Saturn’s surface and its rings. Scientists are calling the region “the Big Empty,” because of the remarkable lack of dust particles or other expected debris. Listen to the song of the Big Empty:
“It was a bit disorienting — we weren’t hearing what we expected to hear,” said Cassini project scientist William Kurth in a statement. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.”
While Cassini is looking backward at Saturn right now, its position and bearing relative to the planet weren’t necessarily a given at the start of the Grand Finale. In the beginning, the Cassini team had its big dish pointed forwards as a sort of ersatz shield against debris. No sense courting damage to the spacecraft now, when the finish line is so near. It’ll be curtains for Cassini on September 15, when the spacecraft finally nosedives into Saturn.
All images: NASA/JPL/Cassini Team
source : https://www.extremetech.com/extreme/248959-cassini-saturn-science-rings