A robotic spacecraft carrying instruments built at the University of Iowa will plunge into the atmosphere of Saturn and burn up early Friday morning, its final mission after 20 years in deep space.
U-I research scientist Bill Kurth is at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the final commands will be given to Cassini, sending it to its fiery fate. Kurth says the mission’s been a great success.
“I would say it’s more than exceeded all of its goals,” Kurth says. “It originally was planned to be in orbit at Saturn for four years and we’re now in our 13th year.”
It was January of 1990 when Kurth first started drafting plans for the sophisticated instruments onboard to measure radioactive emissions and waves in the ionized gas, called plasma, which surrounds the ringed planet. Since Cassini’s launch in 1997, Kurth says the 22-foot-long, 4,700-pound intrepid space explorer has helped scientists unlock many of Saturn’s mysteries, while revealing new questions for them to ponder.
“We’ve taken advantage of discoveries that we’ve made along the way,” Kurth says, “notably, the existence of geysers coming from the small, icy moon Enceladus.” The mission has brought great progress, he says, in understanding Saturn, its rings, its moons, its months-long storms and its lightning-filled magnetosphere.
The spacecraft’s fuel supply is nearly spent and it is being intentionally sent to its flaming demise. If left to drift in Saturn’s orbit with no way to maneuver, Kurth says it’s possible Cassini’s wreckage could critically alter the environment on one of planet’s 62 frozen moons.
“We would hate to go in 20 or 30 years to look for evidence of life on Enceladus and find some form of life there that, perhaps, came from Cassini should Cassini accidentally crash onto Enceladus and infect it, so to speak, with microbes that might’ve been carried with it from Earth,” he says.
After 27 years of work on the project, which started with building the instruments by hand in an Iowa City lab, Kurth says Cassini’s conclusion brings a combination of feelings — sadness, relief and accomplishment.
“I think the mission will stand out as one of the best NASA has flown,” Kurth says. “I’ve also worked on Voyager so it’s hard to say that anything could top that mission, but Cassini certainly ranks right up there.”
Cassini is now on what’s called a ballistic trajectory, blazing along at 76,000 miles an hour toward Saturn’s atmosphere, where it will be incinerated about 6:55 A.M. Iowa time on Friday.
Audio: Matt Kelley interview with Kurth 7:54.