An artist’s conception shows the Cassini orbiter zooming through the upper layers of Saturn’s atmosphere, heading for a fiery breakup. (NASA / JPL-Caltech Illustration)
Twenty years after its launch to Saturn, NASA has set the Cassini orbiter on a course for certain destruction on Friday – but there’s a decidedly positive spin to the $3.3 billion mission’s end.
“We’ll be saddened, there’s no doubt about it, at the loss of such an incredible machine,” Cassini program manager Earl Maize said Wednesday during a news briefing at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “But I think all of us are going to have a great sense of pride in .. a little bit corny, perhaps … a ‘mission accomplished.’”
The bus-sized, plutonium-powered spacecraft was launched in 1997 and reached Saturn seven years later. It’s logged 4.9 billion miles, sent back nearly half a million images of the ringed planet and its moons, and transmitted 635 gigabytes worth of scientific data so far.
It’ll continue sending data all the way to the end, when it’s expected to break apart and burn up in the upper levels of Saturn’s atmosphere.
The last batch of imagery, including a picture showing the area of Saturn where the breakup is planned, is being captured today and should be back on Earth tonight.
During the mission’s final minutes, Cassini’s robotic “nose” – known as the Ion and Neutral Mass Spectrometer, or INMS – will be sniffing the molecules above Saturn’s cloud tops.
“One of the most important scientific things that we’re trying to figure out is a concept known as ‘ring rain,’ said INMS science team leader Hunter Waite, a planetary scientist at the Southwest Research Institute.
Waite said scientists have long suggested that water ice particles are falling from Saturn’s rings into the atmosphere. “Ring rain is much more extensive than that. It’s much more complicated. … We’re trying to find out exactly what is coming from the rings and what is due to the atmosphere,” he said. “That final plunge will allow us to do that.”
The probe’s magnetometer and plasma science instruments, as well as the radio science system, will also be collecting data for real-time transmission back to Earth – at a rate low enough to ensure that the data’s received all the way up to the probe’s last gasp.
Cassini’s final signals are due to register at the Jet Propulsion Laboratory at 4:55 a.m. PT Friday, …read more