Ya got trouble, my friend. Trouble with a capital T and that rhymes with G and that stands for gravity.
A new analysis suggests that when five different spacecraft flew past Earth several years ago, they gained more speed than can be accounted for by Einstein's theory of gravitation.
The unexplained gain in speed is tiny, between 1.8 and 13.5 millimeters per second—only about one-millionth the total velocity of the spacecraft examined. But with radar tracking able to clock spacecraft speeds as small as 0.1 mm per second, that excess is enough to warrant further scrutiny, assert John D. Anderson of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and his collaborators in