WASHINGTON, July 19 (UPI) -- U.S. scientists say photos of the moon's surface showing deep holes that may lead to tunnels offer the possibility of underground moon exploration.
Huge pits on the moon, some of them hundreds of feet deep, may be openings to underground tunnels form by rivers of lave, SPACE.com reported Thursday.
"They could be entrances to a geologic wonderland," researcher Mark Robinson at Arizona State University said. "We believe the giant holes are skylights that formed when the ceilings of underground lava tubes collapsed."
Early lunar photographs showed hundreds of long, narrow channels scientists believed could be similar to lava tubes found on Earth.
If they exist, scientists say, they could serve as passages and living spaces for humans.
"The tunnels (could) offer a perfect radiation shield and a very benign thermal environment," Robinson said in a statement.
But scientists aren't ready to go that far yet.
"Hold off on booking your next vacation at the Lunar Carlsbad Hilton," Paul Spudis of the Lunar and Planetary Institute in Texas said. "Many tunnels may have filled up with their own solidified lava."
Viewed though the holes showing up in photographs, the blackness of the enormous pits remains a tantalizing puzzle.
"We just can't tell, with our remote instruments, what the skylights lead to," Spudis said. "To find out for sure, we'd need to go to the moon and do some spelunking."