But what did you expect? Cassini, their beloved spacecraft, was dead.
Confirmation that the explorer had indeed vaporised as planned in the cloud tops of Saturn was received at the Jet Propulsion Laboratory just before 5am PDT last Friday.
“The signal from the spacecraft is gone, and in the next 45 seconds, so will be the spacecraft,” Earl Maize, Cassini’s programme manager, told the two dozen people in the mission control room in La Canada Flintridge. “Congratulations to all of you. It has been an incredible mission, an incredible spacecraft, and you have been an incredible team.”
He looked around at his colleagues, all wearing matching purple polo shirts embroidered with pictures of Cassini and Saturn.
“Now I’m going to call this end of mission,” he said. “Project manager off the net.”
And just like that, Cassini’s 20-year voyage of exploration was over.
There was hugging, of course, and some tears. Though people came prepared with boxes of tissues, they mostly went unused.
It was like being at a funeral for someone who had lived a long, full life and died peacefully in their sleep at the age of 103.
“I thought I was going to be more sad about the spacecraft, but I’m not,” said Julie Webster, who has worked on Cassini for more than 20 years and served as the mission’s chief engineer. “It did everything we asked of it right until the very end. That’s all you could ever ask of anyone. It was perfect.”
Cassini spent 13 years making jaw-dropping discoveries in the Saturn system, including the first confirmation that the moon Titan had seas of liquid methane on its surface and the revelation that geysers of water ice shoot off the moon Enceladus.
These findings have revolutionised scientists’ understanding of how and where to look for life in the solar system and beyond.
Nasa extended Cassini’s original four-year mission twice. And even in the final seconds before it burned up like a shooting star, the spacecraft gallantly sent back new data from deeper in Saturn’s atmosphere than it had ever been before.
“It was a superb machine in an amazing place, doing everything it possibly could to reveal the mysteries and secrets of our solar system,” Maize said.
More than 5,000 scientists, engineers and support staff from 17 countries worked on the Cassini mission in some capacity since its earliest stages of development in the 1980s. Members of this large extended family congregated on the California Institute of Technology campus in Pasadena early last Friday to celebrate and mourn Cassini’s final moments together.
On the lawn outside Beckman Auditorium, researchers greeted colleagues they hadn’t seen in years and reminisced about the mission.
F Michael Flasar, the principal investigator of Cassini’s Composite Infrared Spectrometer team at Nasa’s Goddard Space Flight Center in Greenbelt, Maryland, has been working on Cassini for nearly three decades and watched the team grow and change as the years passed.
“I like to say this is our claim to immortality,” he said of the mission. “We inspired a new generation, and they’re going to carry on.”
John Barbara, who works on Cassini’s image science subsystem team at Nasa’s Goddard Institute for Space Studies in New York, said it was the daily presence of the spacecraft that would leave the biggest hole.
“I’m going to miss my morning routine of checking my email, drinking my coffee and seeing what Cassini’s been up to,” he said. “It’s been such a part of my life.”
And although Cassini is gone, he knows its discoveries will be part of his 6-month-old son Leo’s life, too.
“As Leo gets older and sees images in his astronomy books, they’re going to be from Cassini,” he said.
Based on models of Saturn’s atmosphere, the Cassini team expected that Earth would lose its connection with the spacecraft at 4:55:16am Pacific time. In reality, the scientists were able to stay in contact until 4:55:39.
“The goal of the engineering team was to make the spacecraft last, and I think you saw this morning that we did,” Webster said. “We got almost 30 seconds longer than predicted.”
Linda Spilker, project scientist for the mission at JPL, said that Cassini made Saturn as familiar to us as our own neighbourhoods.
“Now it’s a small, little world in a telescope again,” she said. “Those details of the rings, those tiny moons struggling to survive — those are all gone, until we go back.”
Both Michael Watkins, JPL’s director, and Thomas Zurbuchen, head of NASA’s science mission directorate, pledged to return to the Saturn system. Titan and Enceladus have emerged as prime candidates in the search for life beyond Earth. Indeed, that’s why Nasa engineers steered Cassini into Saturn, where it was guaranteed to disintegrate without contaminating the moons.
“With today’s end of the mission, we know that these worlds will remain pristine,” Zurbuchen said. “Not only did we do science here at the very end, but we protected science to be done in the future.”
Maize said part of him can intellectualise that Cassini was a robot at the end of its serviceable life. But, of course, there is more to it than that.
“It has been our companion and our dutiful servant for several decades,” he said.
He finished his comments to the Cassini team — and the world — with this eulogy for the spacecraft.
“This morning a lone explorer, a machine made by humankind, finished its mission 900 million miles away,” he said, choking up a little. — Los Angeles Times/TNS
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