Cassini Completes Its First of 22 Dives between Saturn and Its Rings
published during a waxing crescent moon.
04/28/2017

Cassini embarked on its grand finale yesterday, successfully completing the first of 22 dives between Saturn and its rings. The spacecraft’s historic first pass went according to plan: “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,” said Earl Maize, Mission Project Manager. Plunging between the planet and its rings brought Cassini closer to Saturn than any spacecraft ever before. Cassini was only 200 miles away from the rings’ edges and just under 2,000 miles away from Saturn’s cloudy atmosphere.

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22 orbits. Credit: NASA/JPL

While NASA scientists were confident that Cassini could thread the needle, they were a bit nervous given that no spacecraft has attempted such a feat until now. The area between Saturn and its rings measures roughly 1,500 miles, which might seem plenty big, but we’re talking about space here—nothing is simple or safe. At speeds of roughly 77,000 mph, even tiny ring particles could wreak havoc on Cassini.

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Close-up of Saturn’s atmosphere from Cassini’s first dive. Credit: NASA/JPL-Caltech/Space Science Institute

The spacecraft’s antenna dish served as a shield to ward off any particles, which meant Cassini had to go dark while it passed through. When a spacecraft is out of contact, all scientists can do is cross their fingers and wait. In this case, confirmation of the successful dive took roughly 20 hours. Cassini reestablished contact and began transmitting data and images from the dive just before 3:00 a.m. EDT this morning.

NASA engineers will analyze the data obtained during this first pass both to gain insights about the planet and its rings and to see whether they need to make any adjustments to keep Cassini safe and operational during the next 21 passes. The spacecraft will fly between Saturn and its rings roughly once a week between now and September, with the next plunge set to take place on May 2.

Jim Green, director of NASA’s Planetary Science Division, summed up this success: “In the grandest tradition of exploration, NASA’s Cassini spacecraft has once again blazed a trail, showing us new wonders and demonstrating where our curiosity can take us if we dare.”