A so-called Earth Departure stage and Altair lunar lander would sit atop the core stage and be launched into orbit to meet Orion spacecraft carrying moon-bound astronauts.

This NASA unmanned spacecraft launched Jan. 7, 1998 on a mission to orbit the moon in search of signs of water ice and other minerals in permanently shaded craters at the lunar poles.

But the satellites will arrive with less relative speed than spacecraft making the trip in three days, which means less fuel will be needed to brake and drop into lunar orbit.