Ebb and Flow, NASA’s twin washing-machine sized spacecraft, are making important contributions in an area study similar to the Curiosity rover: providing information taken from places in our solar system to help us understand how Earth and other rocky planets were formed. Except Curiosity has a laser that it uses to shoot rocks so it gets way more press than Ebb and Flow.

At the beginning of fall NASA announced they were waking the twins up after their summer nap. At the time Ebb and Flow were about to start the science phase of the mission after completing the primary phase earlier than anticipated.  On December 17th, just a few weeks shy of the one year anniversary marking their successful placement in orbit around the moon, the extended science phase will come to an end as well.  

Right now the spacecraft are still collecting gravity science but as the 17th draws closer the spacecrafts will begin to operate at lower orbital altitudes above the moon. Then after that I’m not sure what NASA will do with Ebb and Flow.

The GRAIL (Gravity Recovery and Interior Laboratory) mission with Ebb and Flow’s transmission of radio signals have created the highest resolution gravity field map of any celestial body. The data shows scientists that the moon’s gravity field is unique and doesn't resemble that of any terrestrial planet in our solar system.

The unprecedented details about the lunar surface from crust to core NASA was looking for have been provided and the map shows tectonic structures, volcanic landforms, basin rings, crater central peaks, and numerous simple, bowl-shaped craters.

NASA has released some of the results from the primary science mission in a trio of papers in the journal Science.

One of the papers is: “The Crust of the Moon as Seen by GRAIL” and Mark Wieczorek of the Institut de Physique du Globe de Paris is a co-author and a GRAIL co-investigator.

"With our new crustal bulk density determination, we find that the average thickness of the moon's crust is between 21 and 27 miles (34 and 43 kilometers), which is about 6 to 12 miles (10 to 20 kilometers) thinner than previously thought," said Wieczorek, "With this crustal thickness, the bulk composition of the moon is similar to that of Earth. This supports models where the moon is derived from Earth materials that were ejected during a giant impact event early in solar system history."

JPL has created a 35 second video that shows the variations in the lunar gravity field. The video has no background music which led a teacher to ask the agency in the comments to “CONSIDER INSTALLING THAT GOOD NASA MUSIC YOU USE SOMETIMES.” You’ve been warned about the careless JPL production so view at your own risk.