There are perks to the graveyard shift. At least, at NASA’s Deep Space Network (DSN) Goldstone Complex in the Mojave Desert. At 2:56 a.m. EDT this morning, the DSN locked on to Cassini’s signal. Five minutes later, the data started coming in. Here’s the first unprocessed image.
During this first dive through the gap between the rings and Saturn’s upper atmosphere, Cassini was just 1,900 miles above the ringed planet’s cloud tops. Here, the air pressure is 1 bar – about the same as we see on Earth at sea level.
Jim Green, the director of the Planetary Science Division at NASA Headquarters in Washington, praised the hardy Cassini spacecraft once more.
“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,” said Green.
The folks making up the Cassini team were anxious watching the first of 22 harrowing dives between Saturn’s innermost ring and its upper atmosphere.
“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. “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.”
These predictions suggested if the spacecraft flew through any ring particles, they would only be the size of smoke particles. Still, Cassini was cruising through this region at speeds approaching 77,000 miles per hour. Even a piece of ring material the size of a smoke particle could do real damage.
But NASA always has a plan to reduce risk. This one involved using Cassini’s high-gain antenna as a shield. It’s shaped like a dish and measures 13 feet across. That also meant the spacecraft wasn’t talking to Earth during the ring-plane crossing, or during its data collection phase. Cassini was on its own for about 20 hours.
Here’s one more unprocessed image captured yesterday.
It’s an epic, but sad start for Cassini. Epic to see such stunning views. Sad because we are officially at the beginning of the end. Cassini’s fate is sealed. The next dive between the 1,500 mile-gap is set for May 2nd. They will continue for another four months. On September 15th, Cassini will take its last dive towards Saturn. It won’t swing back around this time.
Why purposefully crash Cassini? The spacecraft is already running low on fuel, and the mission controllers still want to be able to control it. They don’t want an errant spacecraft possibly crashing on one of Saturn’s wet moons.
Cassini’s Grand Finale serves two purposes. One, gather science data/images never before possible. And two, ensure future missions to study the habitability of moons like Enceladus and Titan aren’t affected.