NASA's Lunar Reconnaissance Orbiter (LRO) captured the sharpest images ever taken from space of the Apollo 12, 14 and 17 landing sites, the U.S. space agency announced Tuesday.

At the Apollo 17 site, the tracks laid down by the lunar rover are clearly visible, along with the last foot trails left on the moon. The images also show where the astronauts placed some of the scientific instruments that provided the first insight into the moon's environment and interior.

"We can retrace the astronauts' steps with greater clarity to see where they took lunar samples," said Noah Petro, a lunar geologist at NASA's Goddard Space Flight Center, who is a member of the LRO project science team.

All three images show distinct trails left in the moon's thin soil when the astronauts exited the lunar modules and explored on foot. In the Apollo 17 image, the foot trails, including the last path made on the moon by humans, are easily distinguished from the dual tracks left by the lunar rover, which remains parked east of the lander.

At each site, trails also run to the west of the landers, where the astronauts placed the Apollo Lunar Surface Experiments Package to monitor the moon's environment and interior. This equipment was a key part of every Apollo mission. It provided the first insights into the moon's internal structure, measurements of the lunar surface pressure and the composition of its atmosphere.

The higher resolution of these images is possible because of adjustments made to LRO's orbit, which is slightly oval-shaped or elliptical. The maneuver lowered LRO from its usual altitude of approximately 31 miles (50 kilometers) to an altitude that dipped as low as nearly 13 miles (21 kilometers) as it passed over the moon's surface. The spacecraft has remained in this orbit for 28 days, long enough for the moon to completely rotate. This allows full coverage of the surface by LROC's Wide Angle Camera. The cycle ends Tuesday when the spacecraft will be returned to its 31- mile orbit.

"These images remind us of our fantastic Apollo history and beckon us to continue to move forward in exploration of our solar system," said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington.