JPL Experts Jubilant Over Neptune’s Awesome Moon : Voyager 2 Films Ice, Volcanoes

The Voyager 2 spacecraft zoomed past ringed Neptune and completed its tour of the outer solar system today with a long-awaited flyby of the icy moon Triton, beaming back spectacular photos of what jubilant scientists called an “extremely strange and puzzling” satellite.

As the hardy spacecraft raced past Neptune and then Triton, it looked back and photographed the moon as a thin crescent, as if bidding farewell to the known solar system after an epic 12-year, 4-billion-mile mission that carried the probe past Jupiter, Saturn, Uranus, a host of moons and now, Neptune.

“The last few hours have been absolutely thrilling,” said Jancis Martin, a Voyager 2 project member. “The Voyager flight team and science investigators have been literally jumping up and down and shouting with elation.”

‘Exploring New Worlds’

“This is it--we are exploring new worlds!” Jet Propulsion Laboratory astronomer Rich Terrile said. Neptune “is not a gee-whiz, science-fiction, special-effects movie. It’s a real place.”

“This is a historic occasion,” said Lennard Fisk, an associate administrator of the National Aeronautics and Space Administration. “It’s the last time we’re seeing a planet for the first time. We’ve completed the reconnaissance of the planets, except Pluto.”

The Triton photos revealed dormant ice-spewing volcanoes, cliffs and a glacier-like lunar terrain.

As they viewed the photos, scientists who have worked on the project for almost two decades clapped and cheered in the operations room.

Bradford Smith, the team leader, said they had detected swampy ground in the southern half of the moon. “You could walk on it, but it can melt,” Smith said. “The pictures are raising a lot of questions.”

The moon’s distinctly alien landscape was marked by broad, smooth plains and meandering ridges that appeared to separate various types of topography.

Voyager 2 raced a scant 3,000 miles over Neptune’s frigid cloud tops at 8:56 p.m. Thursday, plunging over the northern polar region and dropping behind the planet as seen from Earth.

The 1-ton nuclear-powered spacecraft hit a top speed of about 61,150 m.p.h. at close approach and sailed back into view about 55 minutes later. Four hours after that, Voyager 2 streaked past Triton.

Vigil at JPL

Overnight, hundreds of scientists, journalists and VIPs maintained an excited vigil to witness the culmination of one of the century’s greatest voyages of exploration and to gaze in wonder as the veils of mystery were stripped away from entire new worlds.

Because of Neptune’s vast distance from Earth, radio signals traveling 186,000 miles per second required four hours and six minutes to span the gulf from Voyager 2.

Triton, an exotic moon slightly smaller than Earth’s moon, has a transparent atmosphere and a surface that scientists said is clearly undergoing change, either due to geological forces or from weather.

At 3:40 a.m., spectacular close-up pictures of Triton were received on Earth as Voyager 2 hurtled toward its second flyby in five hours, its final encounter with a body in the solar system.

“We see what’s best described as an extremely strange and puzzling surface,” Smith said. “Triton really is likely to be the star of the show.”