Ebb and Flow, the GRAIL (Gravity Recovery and Interior Laboratory) space probes, completed early their prime mission to study the Moon with great accuracy by measuring its force of gravity. In the course of 89 days, the two spacecraft recorded data on the entire lunar surface for three times using the Lunar Gravity Ranging System on board of both of them.

Many of the measurements targets were accomplished from the analysis of only half the data obtained during the primary mission of the GRAIL spacecrafts. The accuracy with which they have accomplished their mission shows that Ebb and Flow were designed very well.

Over the past two months, the GRAIL spacecraft have also taken over 70,000 photographs of the Moon using their MoonKAM (Moon Knowledge Acquired by Middle school students). In fact, the second mission of Ebb and Flow has a didactic purpose involving American students allowing them to choose the areas to be photographed. All photos were transmitted to Earth and then put online on a website set up for this occasion.

Now the GRAIL spacecraft were placed in a state of hibernation in which their instruments are off. On June 4 there will be a lunar eclipse for which Ebb and Flow are prepared. During their mission, it was verified that they have accumulated enough energy to survive the eclipse.

[ad name=”Google Adsense 468″]

According to the mission schedule, on August 30 the GRAIL spacecraft will be reactivated and their remaining fuel will be used to change their orbit bringing them from an average height of about 55 km (about 34 miles) to just over 22 kilometers (about 14 miles). At that point, Ebb and Flow will start their extended mission that should last until early December making a new measurement of the lunar gravity which should be even more precise than the one just ended.

The educational mission has been extended as well so many other photographs will be taken. Whereas the GRAIL spacecraft will pass just a few kilometers away from the highest mountains of the Moon they could take some really interesting images.

While waiting for the extended mission, at the Jet Propulsion Laboratory in Pasadena, California, the analysis of data already arrived goes on to try to understand in detail what Moon is made of and how it formed. Perhaps some details about the Earth’s history will be discovered as well indirectly.