Department of Climate and Space Sciences and Engineering in the College of Engineering at the University of Michigan


Historic Cassini Mission Ends with Dramatic Dive into Saturn

Posted: September 15, 2017

Historic Cassini Mission Ends with Dramatic Dive into Saturn Final image from Cassini. Image/NASA

After nearly 20 years traveling through our solar system, NASA's Cassini spacecraft embarked on the final stage of its amazing journey: the Grand Finale. 

After an incredible sojourn of exploration that provided close-up views of Saturn and its moons, Cassini was nearly out fuel. In order to preserve the pristine environments of the gas giant's moons, mission scientists took the spacecraft on a series of orbits that brought it ever closer to Saturn with the ultimate goal of deliberately crashing Cassini into the planet.

That moment came this morning at 7:55 a.m. EDT when the control room received the final transmission from Cassini as it entered the atmosphere of Saturn. Soon after, Cassini burned up and disintegrated.

Climate & Space alumnus and WDIV meteorologist Paul Gross wrote two articles this week about Cassini's final days. He interviewed two CLaSP professors who've been a part of the Cassini mission since the beginning, Professor Sushil Atreya and Professor Tamas Gombosi

From the articles: 

NASA's Cassini mission at Saturn to end with a bang

"One of NASA’s most successful and spectacular space research missions is ending after almost 20 years in space. On Friday, NASA's Cassini spacecraft begins the final chapter of its remarkable story of exploration: Its Grand Finale."

"Between April and September this year, Cassini undertook a daring set of orbits that was, in many ways, like a whole new mission. Following a final close flyby of Saturn's moon Titan (which was explored earlier in the mission in great detail by Cassini’s probe, Huygens), Cassini leaped over the Saturn’s icy rings and began a series of 22 weekly dives between the planet and those rings. No other mission has ever explored this unique region. What we learn from these final orbits (which are still underway) will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve." 

NASA's Cassini spacecraft dives into Saturn's atmosphere

"This morning, [the Cassini] mission ends in spectacular fashion, as the spacecraft will be intentionally terminated with a dive into Saturn’s atmosphere.

"The mission’s final calculations predict that loss of contact with the Cassini spacecraft will take place today at 7:55 a.m. EDT. Cassini will enter Saturn's atmosphere approximately one minute earlier, at an altitude of about 1,190 miles above the planet's estimated cloud tops (the altitude where the air pressure is equivalent to sea level on Earth). During its dive into the atmosphere, the spacecraft's speed will be approximately 70,000 miles per hour. The final plunge will take place on the dayside of Saturn, near local noon, with the spacecraft entering the atmosphere around 10 degrees north latitude.

"When Cassini first begins to encounter Saturn's atmosphere, the spacecraft's altitude control thrusters will begin firing in short bursts to work against the thin gas and keep Cassini's saucer-shaped high-gain antenna pointed at Earth to relay the mission's precious final data. As the atmosphere thickens, the thrusters will be forced to ramp up their activity, going from 10 percent of their capacity to 100 percent in the span of about a minute. Once they are firing at full capacity, the thrusters can do no more to keep Cassini stably pointed, and the spacecraft will begin to tumble.

"When the antenna points just a few fractions of a degree away from Earth, communications will be severed permanently. The predicted altitude for loss of signal is approximately 930 miles above Saturn's cloud tops. From that point, the spacecraft will begin to burn up like a meteor. Within about 30 seconds following loss of signal, the spacecraft will begin to come apart; within a couple of minutes, all remnants of the spacecraft are expected to be completely consumed in the atmosphere of Saturn." 


As the spacecraft plunged into the pull of Saturn, it's final act was to transmit the remainder of the images stored on its recorder. NASA has posted these Final Images from Cassini.

But not all of the goodbyes were somber, as evidenced by this operatic send-off

Thank you, Cassini. 


Latest Headlines