NASA’s Cassini spacecraft flies between Saturn and rings in historic 1st

An artist rendering of the Cassini spacecraft entering orbit around Saturn. The two-story, $3.4 billion spacecraft carrying a load of deadly plutonium will zoom within 725 miles of Earth August 17, 1999 to gain momentum for the final leg of its meandering, seven-year voyage to Saturn. Cassini's return, two years after NASA launched the largest and most expensive unmanned spacecraft ever, poses virtually no risk, mission officials say. The probe will approach Earth at about 35,000 mph. Its speed will increase by about 11,000 mph after the swingby. (NASA)

CAPE CANAVERAL, Fla. — NASA’s Cassini spacecraft ventured Wednesday into the never-before-explored region between Saturn and its rings.

But flight controllers won’t know how everything went until Thursday when they are back in touch with the craft.

Cassini was out of radio contact with Earth as it became the first spacecraft to enter the gap between Saturn and its rings. That’s because its big dish antenna was maneuvered face forward to protect science instruments from potentially damaging particles in the rings. The antenna could sustain minor damage like a small hole and still function properly, according to officials.

“We’re in a waiting period right now,” said Jim Green, director of NASA’s planetary science division. “We won’t know for a number of hours until Cassini gets in a position where it can radio back home, and so that’s one of those things that keeps us on pins and needles.”

If Cassini survives this first round, it will make 21 more crossings before its demise in September. The gap between Saturn’s atmosphere and its rings is relatively narrow: 1,200 miles, or 1,900 kilometers.

“We’re all crossing our fingers saying, ‘Oh, geez, I hope we hear from it’ — and we will,” added guidance and control engineer Joan Stupik.

Launched in 1997, Cassini has been orbiting Saturn since 2004. Because the fuel tank is practically empty, NASA decided on one last dangerous, but science-rich adventure.