Sixteen students in Dennis Mitchell's seventh-grade science class at Evergreen Middle School in Cottonwood, Calif., have discovered a cave on Mars — only the second one to be found in the region, according to ASU News of Arizona State University.

The students made the discovery as part of their project for the Mars Student Imaging Program (MSIP), a component of the university's Mars Education Program, which is run out of the Mars Space Flight Facility on the Tempe campus. The program seeks to involve upper elementary students in Mars research by letting them command a Mars-orbiting camera to answer their own questions about the Red Planet's geology.

The Evergreen middle schoolers were most interested in lava tubes, a common feature both on Earth and Mars.

"The students developed a research project focused on finding the most common locations of lava tubes on Mars," Mitchell said. "Do they occur most often near the summit of a volcano, on its flanks, or the plains surrounding it?"

After examining more than 200 images taken with the Thermal Emission Imaging System (THEMIS), an instrument on NASA's Mars Odyssey orbiter, the students zeroed in on two images in particular, both around the Pavonis Mons volcano region that had yet to be photographed by THEMIS in high resolution.

Sure enough, there were lava tubes. But on one of the two images, the students noticed something peculiar — a small, round black spot. Unlike the usual chain pit crater, which is more common and littered across the Martian surface, this hole was smaller and resembled a relatively straight-sided shaft going straight down into the ground.

Back in 2007, a U.S. Geological Survey scientist named Glen Cushing created a stir among Mars researchers by proposing that anomalous pit craters like the hole discovered by the students are "skylights", where the roof of a cave or lava tube has collapsed.

"This pit is certainly new to us," Cushing told the students. "And it is only the second one known to be associated with Pavonis Mons." He also estimated the cave to be at least 380 feet deep.

Even more exciting for the students, they may get the chance to peer down inside the cave in high resolution, since their discovery has been submitted as a candidate for imaging by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

"The Mars Student Imaging Program is certainly one of the greatest educational programs ever developed," said Mitchell. "It gives the students a good understanding of the way research is conducted and how that research can be important for the scientific community. This has been a wonderful experience."