The Cassini spacecraft went into orbit around Saturn ten years ago, on July 1, 2004 in universal time. Ron Hobbs, a solar system ambassador of the NASA Jet Propulsion Lab, says some of the mission’s most exciting science has occurred quite recently.
Hobbs spoke at the most recent meeting of the Seattle Astronomical Society about Cassini’s decade at Saturn, and notes that recent measurements of the gravitational field of the moon Enceladus have yielded some interesting findings.
“We are very confident that there is body of liquid water at the south pole that extends at least to 50 degrees south latitude on Enceladus,” Hobbs says. “There’s a body of water that’s in contact with rock. We know that some of the ice particles that get shot out into the E-ring have salt and organics in them. This has become on a very short list of places in our own solar system where we might find life.”
Mars and Jupiter’s moon Europa are two others on what Hobbs calls the “astrobiological short list.” Many scientists believe that life on Earth may have originated in hydrothermal ocean vents—a safe haven during the heavy bombardment era—and so it’s reasonable to suspect that life might thrive in similar environments elsewhere in the solar system.
Hobbs calls Cassini “the largest, most complex, and capable spacecraft ever built” and notes that we may owe its existence to persistent Europeans. There was some talk in the mid-’90s that Congress would scrap the mission before it got off the ground because of budget concerns. But the Europeans had already built the Huygens probe that hitched a ride on Cassini in order to do a study of the atmosphere of the moon Titan. Hobbs says word is that protests about the proposed cuts made it all the way to the vice president.
“The fact that we have Cassini, as far as I’m concerned, is in large part due to the fact that the Europeans had the guts to talk to the U.S. government and say, ‘You don’t renege on your promises,’” Hobbs says.
Like the Mars rover missions, Cassini has far exceeded the time allotted for its original scientific mission.
“The plan for Cassini when it arrived in July of 2004 was to study Saturn for four years,” Hobbs notes. “Cassini is still one of the healthiest spacecraft we have anywhere in the solar system. All of its instruments are working great, it’s got fuel.” Nonetheless, Hobbs says he occasionally hears talk that Congress again is considering pulling the plug on the mission. He says that would be a bad idea, as we still have a lot to learn.
The NASA video below gives a preview of the work they’re planning for Cassini over the next four years.