Launched as GRAIL A and GRAIL B in September 2011, the probes were renamed Ebb and Flow by schoolchildren in Montana. The probes operated in almost circular orbit near the lunar poles at an altitude of approximately 34 miles, until their mission came to an end in December 2012. The distance between the twin probes altered a bit as they soared over areas of lesser and greater gravity that were caused by visible topological features on the Moon's surface, such as impact craters and mountains--as well as by masses that were secreted beneath the lunar surface.
Enshrouded in a dense golden hydrocarbon mist, Saturn's largest moon Titan is a mysterious mesmerizing world in its own right. For centuries, Titan's veiled, frigid surface was completely camouflaged by this hazy golden-orange cloud-cover that hid its icy surface from the prying eyes of curious observers on Earth. However, this misty moisty moon-world was finally forced to show its mysterious face, long-hidden behind its obscuring veil of fog, when the Cassini Spacecraft's Huygens Probe landed on its surface in 2004, sending revealing pictures back to astronomers on Earth. In September 2018, astronomers announced that new data obtained from Cassini show what appear to be gigantic, roaring dust storms, raging through the equatorial regions of Titan. The discovery, announced in the September 24, 2018 issue of the journal Nature Geoscience, makes this oddball moon-world the third known object in our Solar System--in addition to Earth and Mars--where ferocious dust storms have been observed. The observations are now shedding new light on the fascinating and dynamic environment of Titan, which is the second largest moon in our Solar System, after Ganymede of Jupiter.
"Since time immemorial, humanity has looked up and wondered what made the man in the Moon. We know the dark splotches are large, lava-filled, impact basins that were created by asteroid impacts about four billion years ago. GRAIL data indicate that both the near side and the far side of the Moon were bombarded by similarly large impactors, but they reacted to them much differently," noted Dr. Maria Zuber, GRAIL principal investigator, in a November 7, 2013 NASA Jet Propulsion Laboratory (JPL) Press Release. Dr. Zuber is of the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts. The JPL is located in Pasadena, California.