New York

Cassini mission scientists now are poring over hundreds of snapshots made during the spacecraft’s closest-ever flyby of Iapetus, the intriguing walnut-shaped body orbiting Saturn.

Those images show the “yin-and-yang” contrast of its halves and its strange mountain range in great detail. “The images are really stunning,” said TilmannDenk, a Cassini imaging scientist at the Free University in Berlin who began planning the photo shoot seven years ago.

The photographs traveled

1.52 billion kilometers

to reach Earth.

They were

taken from a distance of 1,640 kilometers

from the surface of Iapetus – 100 times closer than Cassini’s 2004 flyby.

Close-ups of Iapetus‘ hemispheres show

a white half resembling snow and another

half as black as tar. The snapshots also show the ridge of mountains

20 kilometers

high along Iapetus‘ equator, which scientists have recently tried to explain.

Iapetus provides us a window back in time, to the formation of the planets over four billion years ago,” said Torrence Johnson, a Cassini imaging team member at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Since then its icy crust has been cold and stiff, preserving this ancient surface for our study.”

A blast of galactic cosmic rays delayed delivery of Cassini’s latest work by several days, but the spacecraft automatically entered into a protective “safe mode” after the event, according to a statement released by NASA. Had the energetic blast arrived a few days sooner, however, the close-up imaging opportunity may have been lost due to the temporary shut-down.

NASA said

is operating normally, and its scientific instruments “are expected to return to normal operations in a few days.”

“There’s never a dull moment on this mission,” said Bob Mitchell, Cassini program manager at JPL. “We are very excited about the stunning images being returned. There’s plenty here to keep many scientists busy for many years.”