Nasa bids Saturn probe Cassini a fond farewell

NASA waited for confirmation yesterday that the Cassini spacecraft had burnt up in the sky over Saturn.

Cassini had been put on a course to plunge through Saturn’s atmosphere and vaporise at the end of its 20-year journey exploring the planet.

Flight controllers at California’s Jet Propulsion Laboratory expected one last burst of scientific data from Cassini, before the radio waves went flat and the spacecraft fell silent. It takes 83 minutes for a signal from it to reach Earth.

While saddened, programme manager Earl Maize said he felt great pride and couldn’t have asked for more from “such an incredible machine”.

The only spacecraft to ever orbit Saturn, Cassini showed us the planet, its rings and moons up close. Perhaps most tantalising, ocean worlds were unveiled by Cassini and its hitchhiking companion, the Huygens lander, on the moons Enceladus and Titan, which could possibly harbour life.

“We’ve left the world informed but still wondering,” Maize said this week. “We’ve got to go back. We know it.”

Cassini was dutiful into the final hours, taking one last batch of pictures before its final job – sampling the atmosphere at the gas giant and sending the data to Earth.

The spacecraft was expected to tumble out of control while plummeting at 122 000km/h. Project officials invited ground telescopes to look for Cassini’s last- gasp flash but weren’t hopeful it would be spotted from a billion miles away.

This grand finalé, as Nasa calls it, came as Cassini’s fuel tank started getting low. Scientists wanted to prevent it from crashing into Enceladus or Titan and contaminating those pristine worlds.

And so, in April, Cassini was directed into the previously unexplored gap between Saturn’s cloud tops and the rings. Twenty-two times, Cassini entered the gap and came out again. The last time was last week.

Maize said all the staff would be on hand “as our faithful traveller from Earth makes its final goodbye”. Their farewells already said, team members planned to raise their glasses in a final salute.

The leader of Cassini’s imaging team, Carolyn Porco, a visiting scholar at the Uni- versity of California, Berkeley, was so involved with the mission for so long that now: “I consider it the start of life, part two.”

Cassini departed Earth in 1997 and arrived at the solar system’s second largest planet in 2004. The European Huygens landed on big moon Titan in 2005. Nothing from Earth has landed farther.

In all, Cassini collected more than 453 000 images and travelled 7.8 billion kilometres. It was an international endeavour, with 27 nations taking part. The final price tag was $3.9 billion (R51.3 bn). – AP