The Cassini mission to Saturn (see Carolyn Porco’s stunning TEDTalk on this mission) today makes its closest flyby yet of Enceladus, a geologically active moon. With its frozen surface and plumes of ice, Enceladus is a fascinating body, and the Cassini probe will be imaging the moon in several areas with many different instruments. From the mission notes:
At 17:40:12 UTC … UVIS will scan across the disk of Enceladus to measure the ultraviolet albedo of the surface and look for oxygen in the environment around Enceladus which may have dissociated from water molecules in the plumes.
The Cassini probe is set to pass through one of Enceladus’ ice plumes as it passes closest to the surface of the moon — flying by at about 70 km, or 50 miles up.