Scientists have discovered caves on the moon for the first time.
They say it is at least 100m deep and could be an ideal place for humans to establish a permanent base.
Researchers say this is just one of hundreds of caves hidden in an “undiscovered underground world.”
Countries are racing to establish a permanent human presence on the moon, but they need to protect astronauts from radiation, extreme temperatures and space weather.
Helen Sharman, the first British astronaut in space, told BBC News that the newly discovered cave looked like a good place to set up a base, and suggested that humans could be living in lunar craters within 20 to 30 years.
But, she said, the cave is so deep that astronauts may need to abseil and then use a “jet pack or elevator” to get out.
Lorenzo Bruzzone and Leonardo Carrer of the University of Trento in Italy used radar to penetrate a crater in the rocky plain of Mare Tranquillitatis The opening of the cave was discovered.
Visible to the naked eye from Earth, it is also where Apollo 11 landed in 1969.
The cave has a skylight on the lunar surface that leads to vertical and overhanging walls, as well as sloping floors that may extend further underground.
It was formed millions or billions of years ago when molten rock flowed on the moon, creating a tunnel in the rock.
The closest similar caves on Earth are the volcanic caves in Lanzarote, Spain, Professor Carrel explained, adding that the researchers visited these caves as part of their work.
“It’s really exciting. When you make these discoveries and look at these images, you realize you are the first person in human history to see it,” Professor Carrel said.
When Professors Bruzone and Carrel realized how big the cave was, they realized it might be a good place to build a lunar base.
Professor Karel said: “After all, life on Earth originated in caves, so it makes sense that humans could live in caves on the moon.”
The cave has not yet been fully explored, but researchers hope to map it using ground-penetrating radar, cameras and even robots.
Scientists first became aware of the possibility of caves on the moon about 50 years ago. Then in 2010, a camera on a mission called the Lunar Reconnaissance Orbiter took photos of a crater that scientists believe may be the entrance to a cave.
But researchers don’t know how deep the caves are or whether they could collapse.
The work of Professors Bruzone and Carrel has now answered this question, although there is still much work to be done to understand the overall scale of the cave.
“We have very good images of the surface – with a resolution of up to 25 centimeters – and we can see the Apollo landing sites – but we know nothing about what’s going on below the surface.” Francis, coordinator of the Planetary Caves Theme Group at ESA Francesco Sauro told BBC News.
This research may also help us explore caves on Mars in the future, he said.
This could open the door to finding evidence of life on Mars, because if it did exist, it would almost certainly be inside a cave, protected from the elements on the planet’s surface.
Lunar caves may be useful to humans, but scientists also stress that they could help answer fundamental questions about the history of the moon and even the solar system.
The rocks within the caves are not damaged or eroded by space weather, so they can provide an extensive geological record from billions of years ago.
The research was published in the scientific journal Nature Astronomy.
Cartography: Gerry Fletcher
