A NASA spacecraft found seven possible cave entrances on Mars, triggering interest in hunting for other caverns that might be hiding life on the Red Planet, the US space agency said Friday.

While the possible caves discovered are too high in altitude to host life, scientists say caverns elsewhere on the Red Planet could be underground habitats or even one day become shelters for astronauts.

Images from the Mars Odyssey orbiter showed seven dark, nearly circular spots between 100 meters (328 feet) and 250 meters (820 feet) wide on the slopes of the Arsia Mons volcano, located near the planet’s highest peak.

Researchers concluded that the seven circles could be windows to underground spaces after checking their daytime and night time temperatures by using Odyssey’s infrared camera, which checks daytime.

"They are cooler than the surrounding surface in the day and warmer at night," said Glen Cushing of the US Geological Survey‘s Astrogeology Team and of Northern Arizona University, Flagstaff, Arizona.

"Their thermal behavior is not as steady as large caves on Earth that often maintain a fairly constant temperature, but it is consistent with these being deep holes in the ground," Cushing said in a news release from NASA.

Cushing and his team of scientists reported the discovery online in the journal Geophysical Research Letters.

The potential caves are so high that "they are poor candidates either for use as human habitation or for having microbial life," Cushing said. "Even if life has ever existed on Mars, it may not have migrated to this height."

But the discovery of the holes, dubbed "Seven Sisters," has triggered interest in hunting for caverns elsewhere on the planet, NASA said.

"Whether these are just deep vertical shafts or openings into spacious caverns, they are entries to the subsurface of Mars," said co-author Tim Titus of the US Geological Survey in Flagstaff.

"Somewhere on Mars, caves might provide a protected niche for past or current life, or shelter for humans in the future," he said.

Arizona State University operates Mars Odyssey’s Thermal Emission Imaging System, which was used to detect the potential cave entrances.

Odyssey reached Mars in 2001.

Vai: Yahoo News