NASA’s Cassini plans final fiery encounter with Saturn.
CAPE CANAVERAL, FLA. | After a 20-year voyage, NASA’s Cassini spacecraft is poised to dive into Saturn this week to become forever one with the exquisite planet.
There’s no turning back: Friday, it careens through the atmosphere and burns up like a meteor in the sky over Saturn.
NASA is hoping for scientific dividends up until the end. Every tidbit of data radioed back from Cassini will help astronomers better understand the entire Saturnian system — rings, moons and all.
The only spacecraft ever to orbit Saturn, Cassini spent the past five months exploring the uncharted territory between the gaseous planet and its dazzling rings. It’s darted 22 times between that gap, sending back ever more wondrous photos.
On Monday, Cassini flew past jumbo moon Titan one last time for a gravity assist — a final goodbye kiss, as NASA calls it, nudging the spacecraft into a deliberate, no-way-out path.
During its final plunge early Friday morning, Cassini will keep sampling Saturn’s atmosphere and beaming back data, until the spacecraft loses control and its antenna no longer points toward Earth. Descending at a scorching 76,000 mph, Cassini will melt and then vaporize. It should be all over in a minute.
“The mission has been insanely, wildly, beautifully successful, and it’s coming to an end,” said NASA program scientist Curt Niebur. “I find great comfort in the fact that Cassini will continue teaching us up to the very last second.”
Telescopes on Earth will watch for Cassini’s burnout nearly a billion miles away. But any flashes will be hard to see given the time — close to high noon at Saturn — and Cassini’s minuscule size against the solar system’s second largest planet.
The whole point of this one last exercise — dubbed the Grand Finale — is to prevent the spacecraft, launched in 1997, from crashing into the moons of Enceladus or Titan. NASA wants future robotic explorers to find pristine worlds where life might possibly exist, free of contamination from Earth.
It’s inevitable that the $3.9 billion U.S.-European mission is winding down. Cassini’s fuel tank is almost empty, and its objectives have been accomplished many times over since its 2004 arrival at Saturn following a seven-year journey.
The leader of Cassini’s imaging team, planetary scientist Carolyn Porco, already feels the loss.
“There’s another part of me that’s just, ‘It’s time. We did it.’ Cassini was so profoundly, scientifically successful,” said Ms. Porco, a visiting scholar at the University of California, Berkeley. “It’s amazing to me even, what we were able to do right up until the end.”
Until Cassini, only three spacecraft had ventured into Saturn’s neighborhood: NASA’s Pioneer 11 in 1979 and Voyager 1 and 2 in the early 1980s. Those were just flybys, though, and offered fleeting glances. And so Cassini and its traveling companion, the Huygens lander, actually provided the first hard look at Saturn, its rings and moons. They are named for 17th-century astronomers, Italian Giovanni Domenico Cassini and Dutch Christiaan Huygens, who spotted Titan, the first of Saturn’s 62 known moons.
All told, Cassini has traveled 4.9 billion miles since launch, orbited Saturn nearly 300 times and collected more than 453,000 pictures and 635 gigabytes of scientific data.
On Friday, NASA’s Cassini spacecraft will careens through the atmosphere and burn-up like a meteor over Saturn. NASA hopes for scientific dividends.