(Reuters) - As countries and companies rush to build infrastructure on the moon, some researchers are planning to dig under its rocky soil to unlock mysteries about Earth that have eluded scientists since astronauts first stepped foot on its surface a half century ago.

Slideshow ( 3 images )

Scientists theorize that the moon, a quarter the size of Earth and weighing about 80 times less, was formed some 4.5 billion years ago from the remnants of a collision between early Earth and another planetary body, possibly as big as Mars. The pieces of the planetary body orbited the earth before eventually coalescing into the moon we know today.But the oldest rocks found on Earth date back just 4 billion years ago, leaving scientists with a 500 million-year blind spot during the most crucial periods of our world’s formation.

“A lot of that half billion years that we’re missing probably exists on the moon in some form,” says Bill Bottke, at the Department of Space Studies in Boulder’s Southwest Research Institute.

Bottke says fragments of ancient Earth or meteorites that bombarded the lunar surface from other planetary bodies can serve as time capsules of information on how our planet, as well as others in the solar neighborhood, were formed.

“This gives us the opportunity, by understanding the moon, to understand all these other worlds as well,” Bottke said. “This bombardment that’s happening to the early moon...it’s happening to all the planets.”

LAVA TUNNELS

A team at Carnegie Mellon University in Pittsburgh plans to survey a network of underground tunnels carved out by lava that once flowed beneath the moon’s surface. Those could hold untainted materials from the earliest ages of the formation of the moon — and thus the Earth.

“It is the lava tubes that are likely to hold the only pristine materials on the moon,” said William Whittaker, a researcher at Carnegie Mellon. It was too early to say what secrets the materials might divulge as to the moon’s origins, he added.

His team is working on autonomous rovers capable of peering into the tunnels through gaping, football field-sized lunar pits similar to sinkholes found on Earth that caved in from lava flow.

One of Whittaker’s rovers will make it to the moon as early as July 2021 under NASA’s Commercial Lunar Payload Services. The program will seed the development of an eventual moon base by funding a variety of robotic lunar landers to explore the moon’s surface to prepare for humans to arrive.

U.S. Vice President Mike Pence announced on March 26 a goal of putting Americans back on the moon within five years. NASA had previously aimed to return astronauts to the lunar surface by the year 2028, after first putting a “Gateway” station in orbit around the moon by 2024.