If you're on the moon, watch your step. The lunar surface has clifflike formations called scarps that, according to a team that includes Cornell scientists, may have formed recently -- at least relative to the moon's history.

Using NASA's Lunar Reconnaissance Orbiter (LRO), the researchers have taken the highest-resolution pictures to date of the moon, revealing previously undetected faults, or planar fractures, in all sectors of its surface. The pictures indicate a "young" age of these scarp formations, suggesting the moon's surface contracted within the last 1 billion years, and possibly more recently than that.

The research, published in the Aug. 20 edition of the journal Science, is led by Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian Institution. Cornell researchers, who worked on the image analysis team, included Jim Bell, professor of astronomy; Matthew Pritchard, assistant professor of earth and atmospheric sciences; Peter Thomas, senior research associate in astronomy; and Nathan Williams '11, a science of earth systems major. Other collaborators are from Arizona State University, the SETI Institute, NASA Ames Research Center, Institut für Planetologie, Westfälische Wilhelms-Universität, Münster, Brown University and the Johns Hopkins University Applied Physics Laboratory.

The researchers based their work in part on 40-year-old images taken during the Apollo missions. But less than 5 percent of the moon's surface had been photographed under favorable lighting conditions, and evidence of scarps was restricted to the equatorial zone.

Williams and other team members looked at thousands of LRO images, which are sharp enough to resolve the Apollo landing sites and show the scarps in new detail. The faults show portions of the moon's crust being thrust over another as a result of the moon cooling and contracting throughout its history. This observation, Pritchard explained, may tell scientists about the moon's earthquake and tectonic history.

"So the question is, how many of these faults are there, where are they and how much have they compressed over time? That might tell us something about the initial temperatures in the moon," Pritchard said.

The work is supported by the LRO Project and NASA grants.