Pittsburgh Post-Gazette

Last adventure arrives for NASA’s Cassini spacecraft at Saturn

- By Marcia Dunn

Associated Press

CAPE CANAVERAL, Fla. — NASA’s Cassini spacecraft faces one last perilous adventure around Saturn.

Cassini began swinging past Saturn’s mega moon Titan early Saturday for a gravity-assisted, orbittweak­ing nudge.

“That last kiss goodbye,” as project manager Earl Maize calls it, was set to push Cassini onto a path no spacecraft has gone before — into the gap between Saturn and its rings. It’s treacherou­s territory. A particle from the rings — even as small as a speck of sand — could cripple Cassini, given its velocity.

Cassini will make its first pass through the relatively narrow gap Wednesday. Twenty-two crossings are planned, about one a week, until September, when Cassini goes in and never comes out, vaporizing in Saturn’s atmosphere.

Launched in 1997, Cassini reached Saturn in 2004 and has been exploring it from orbit ever since. Its European traveling companion, Huygens, landed on Titan in 2005. Cassini’s fuel tank is practicall­y empty, so with little left to lose, NASA has opted for a risky, but science-rich grand finale.

“What a spectacula­r end to a spectacula­r mission,” said Jim Green, NASA’s planetary science division director. “I feel a little sad in many ways that Cassini’s discoverie­s will end. But I’m also quite optimistic that we’re going to discover some new and really exciting science as we probe the region we’ve never probed before.”

There’s no turning back once Cassini flies past Titan, Mr. Maize said. The spacecraft on Wednesday will hurtle through the 1,200-milewide gap between Saturn’s atmosphere and its rings, at a breakneck 70,000-plus mph.

From a navigation standpoint, “this is an easy shot,” Mr. Maize said. The operation was set to be run from NASA’s Jet Propulsion Laboratory in Pasadena, Calif. The concern is whether computer models of Saturn’s rings are accurate. On a few of the crossings, Cassini is “kind of flirting with the edge of where we think it’s safe,” he noted.

This last leg of Cassini’s 20-year, $3.27 billion voyage should allow scientists to better understand Saturn’s rings.

Meanwhile, NASA made more headlines Saturday when a supply ship bearing John Glenn’s name arrived at the Internatio­nal Space Station.

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