NASA has released three photos of human lunar activity ahead of its upcoming GRAIL mission.

NASA's Lunar Reconnaissance Orbiter (LRO) captured images of the Apollo 12, 14, and 17 landing sites. The images were taken from space.

Noah Petro is a member of the LRO project science team and a lunar geologist at NASA's Goddard Space Flight Center.

We can retrace the astronauts' steps with greater clarity to see where they took lunar samples, Petro said in a NASA press release.

The photos come just in time for NASA's GRAIL mission launch.

The purpose of NASA's GRAIL mission is to learn more about the moon's interior structure.

NASA will launch a twin spacecraft Thursday morning, weather pending, on a Delta II launch vehicle from Cape Canaveral, Florida.

Mission objectives include mapping the structure of the moon's crust and lithosphere and placing limits on the size of a possible solid inner core, according to NASA's Web page for the mission.