NASA announced Thursday morning its Cassini spacecraft was successful in its historic first dive through the gap between Saturn and its rings.

The unmanned Cassini is back in radio contact with Earth after entering the gap Wednesday in the first mission of its kind.

The spacecraft is in the process of beaming back images and data collected during its passage using NASA's Deep Space Network Goldstone Complex in California's Mojave Desert, NASA announced in a written statement.

"In the grandest tradition of exploration, NASA's Cassini spacecraft has once again blazed a trail, showing us new wonders and demonstrating where our curiosity can take us if we dare," said Jim Green, director of the planetary science division at NASA headquarters in Washington, D.C.

Cassini came within 3,000 kilometres of Saturn's cloud tops and within about 300 kilometres of the innermost of the planet's iconic rings.

It zipped through the region at about 124,000 km/h, meaning that if small icy particles floating near the rings had hit a sensitive area of the spacecraft, it could potentially have been disabled.

"No spacecraft has ever been this close to Saturn before. We could only rely on predictions, based on our experience with Saturn's other rings, of what we thought this gap between the rings and Saturn would be like," said Cassini project manager Earl Maize of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"I am delighted to report that Cassini shot through the gap just as we planned and has come out the other side in excellent shape," said Maize.

Cassini captured the images Wednesday on the first of 22 scheduled dives through the gap. (NASA/JPL-Caltech/Space Science Institute)

To protect the spacecraft, its large, dish-shaped antenna was used as a shield by orienting in the direction of oncoming ring particles. As a result, Cassini was out of contact for a period during the crossing.

The spacecraft will make 21 more such crossings, the next of which is scheduled for May 2.

The mission is being referred to as Cassini's "grand finale," the capstone event for the spacecraft, which has been orbiting Saturn for 13 years.

While the 4½-month finale is risky, there's little to lose given the spacecraft's fuel tank is nearly empty and its fatal plunge into Saturn is expected in mid-September.