Cassini crashes into Saturn, ending 20-year missionSeptember 15, 2017 William Harwood
Dutifully beaming back data to the very end, NASA’s long-lived Cassini probe slammed into Saturn’s atmosphere at some 77,000 mph Friday, blazing like a shooting star as it was ripped apart and incinerated in the final chapter of an enormously successful mission.
Cassini program manager at JPL, Earl Maize, left, and spacecraft operations team manager for the Cassini mission at Saturn, Julie Webster embrace after the Cassini spacecraft plunged into Saturn. Image: NASA/Joel Kowsky.Thirteen years after braking into orbit around Saturn, the end came at 6:32 a.m. EDT, one minute after the spacecraft plunged into the thin-but-discernible extreme upper atmosphere 1,190 miles above Saturn’s cloud tops.
Cassini’s flight computer attempted to maintain the probe’s orientation, firing its thrusters as buffeting built up to keep the spacecraft’s big dish antenna pointed at Earth so it could transmit a final trove of data.
But the thrusters were quickly overwhelmed, the spacecraft lost lock on Earth and began tumbling, according to pre-impact calculations, quickly heating up, breaking apart and melting to vapor, its constituents spreading out and merging with the atmosphere of the planet it spent its life exploring.
Cassini’s final bits of data, traveling at the speed of light — 186,000 miles per second — took 83 minutes to cross the 932 million miles to Earth, reaching NASA’s 230-foot-wide Deep Space Network antenna near Canberra, Australia, at
7:55:46 a.m.At that point, Cassini’s telemetry stream suddenly stopped, confirmation Cassini had met its fiery fate as expected.
“As you just heard, the signal from the spacecraft is gone and within the next 45 seconds, so will be the spacecraft,” Earl Maize, the Cassini project manager at the Jet Propulsion Laboratory, told the flight control team.
“I hope you’re all deeply proud of this amazing accomplishment. Congratulations to you all. This has been an incredible mission, an incredible spacecraft and you’re all an incredible team. I’m going to call this the end of mission.
At 7:55:46 a.m., Cassini’s signal disappeared, indicating the spacecraft had lost lock on Earth as it began tumbling before breaking apart in Saturn’s extreme upper atmosphere. Image: NASA TV.Then, for the last time, Maize said “project manager off the net,” and took off his headset.
Flight controllers stood up from their computer displays, hugged and cheered along with more than 1,500 scientists, engineers, managers, friends and family members gathered at JPL to share Cassini’s final moments.
“I was just overwhelmed with how professional this team is,” said Thomas Zurbuchen, director of the science mission directorate at NASA Headquarters. “During the entire time, this was clearly emotional for everybody. … But everybody was so professional to the very end. It went so fast! It’s all about teamwork with this mission, and it showed in the last seconds.” (...)
https://spaceflightnow.com/2017/09/15/cassini-crashes-into-saturn-ending-20-year-mission/http://www.urania.edu.pl/wiadomosci/koniec-misji-cassini-sonda-zniszczona-atmosferze-saturna-3582.html