The moons of Saturn are fascinating. Recent findings by the space probe Cassini show the diversity of Saturn’s icy moons. Some are marked up with craters; some look dirty; some look like the cleaning lady visits often; one looks like a gigantic sponge from the Pacific Ocean; some are actively spewing debris from their surfaces; and all have one common characteristic. Black stuff.

According to Rosaly Lopes, a Cassini scientist at NASA’s JPL who coordinated 14 technical papers into a special section in the February issue of the journal Icarus, the black stuff that coats the surfaces of Saturn’s moons seems to be evidence of some transport mechanism that has spread the unknown substance around from moon to moon. Perhaps the black stuff has a common cometary origin due to a collision in nearby space.

Roger Clark of the U.S. Geological Survey wrote the lead paper which looked at Saturn’s moon Dione. The black stuff was found to be finely-grained, constituting a thin layer on Dione’s trailing side. Spectrometer readings by Cassini indicate the substance is foreign to Dione. The same type of characteristics are found on Phoebe, Iapetus, Hyperion and Epimetheus as well as Saturn’s F-ring.

Cassini’s next look at an icy moon is a flyby of Enceladus planned for March 12. Cassini will pass by as close as 30 miles (50km) to its surface and within 120 miles (200km) when it passes through Enceladus’ plumes, which have been found to feed into Saturn’s E-ring. The information from this flyby will be very interesting and should provide further information about the origin of the black stuff.