Stories about space exploration have strong beginnings: the suspense of launch, the big plans for exploration. Those are followed by substantive plot twists, powered by the often-unexpected data that missions send back and the insights they provide into the universe. But stories about space exploration generally don’t emphasize the ending. So what happens when the datastream dies? Some missions, such as Voyager, keep collecting data and journey onward toward interstellar space years longer than anyone expected. But even the most persistent robotic explorers, such as the Mars rover Spirit, eventually rest in peace.
Earlier this month, when the first results from GRAIL, a lunar gravity-mapping mission, were made public, the MIT scientist who heads the mission hinted that the end was near for the twin spacecraft that have been flying in tight formation around the moon, taking their primary data this spring.