Cassini returns images of battered Saturn moon

The pictures show an ancient cratered surface bearing the scars of collisions with many space rocks.
By | Published: March 14, 2013 | Last updated on May 18, 2023
This image was taken March 10, 2013, and received on Earth March 10, 2013 by NASA’s Cassini spacecraft. The camera was pointing toward Rhea at approximately 174,181 miles (280,317 kilometers) away, and the image was taken using the CL1 and CL2 filters. // NASA/JPL/Space Science Institute
Following its last close flyby of Saturn’s moon Rhea, NASA’s Cassini spacecraft captured these raw, unprocessed images of the battered icy moon. They show an ancient cratered surface bearing the scars of collisions with many space rocks. Scientists are still trying to understand some of the curious features they see in these Rhea images, including a curving, narrow fracture, or a graben, which is a block of ground lower than its surroundings and bordered by cliffs on either side. This feature looks remarkably recent, cutting most of the craters it crosses, with only a few small craters superimposed.

Cassini flew by Rhea at an altitude of 620 miles (997 kilometers) March 9, 2013. This flyby was designed primarily for the radio science sub-system to measure Rhea’s gravity field. During closest approach and while the radio science sub-system was measuring the icy satellite’s gravity field, the imaging team rode along and captured 12 images of Rhea’s rough and icy surface. Outbound from Rhea, Cassini’s cameras captured a set of global images from a distance of about 167,000 miles (269,000km).

Data from Cassini’s cosmic dust analyzer were also collected to try to detect any dusty debris flying off the surface from tiny meteoroid bombardments. These data will help scientists understand the rate at which “foreign” objects are raining into the Saturn system.

This was the mission’s fourth close encounter with Rhea. The spacecraft will pass the moon again, but at a much greater distance, in a few years.