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Almost 55 years after the launch of Apollo 11 – the first mission to land humans on the moon – scientists have discovered evidence of a large cave system near the landing site of those astronauts.

Using radar images taken by NASA’s Lunar Reconnaissance Orbiter spacecraft in 2010, researchers were able to determine that huge pits found in images of the Moon may actually be “windows” to large caves and tunnels that lie below the lunar surface.

They could be incredibly valuable to future astronauts hoping to settle on the moon, acting as a convenient shelter for a lunar base.

The cave is accessed via a pit in the well-explored Mare Tranquillitatis (Sea of ​​Tranquility). It is a large basin made mostly of basalt. Neil Armstrong and Buzz Aldrin landed in this region on July 20, 1969.

While Mare Tranquillitatis probably won’t be the first place humans try to settle on the moon, the existence of one cave makes the existence of others highly likely, so scientists now expect there to be others in places more suitable for human habitation.

Mare Tranquillitatis is not the scientists’ first choice for a human base because it does not contain any of the other important ingredients necessary for survival. There is no ice on the lunar equator, and therefore no easy access to water for astronauts to drink, produce oxygen, and split it for rocket fuel. This makes the equator great for landing and visiting, but a poor choice for setting up camp.

However, ice is likely to exist at the lunar poles, thanks to the shadow that protects it from the sun’s harsh rays. So the poles are our first choice to start colonizing the moon as it reduces the amount of water we have to take with us.

The vent studied here is known simply as the Mare Tranquillitatis Pit, and is one of about 200 known vents on the lunar surface. It was first photographed in 2010 and was suspected to be a pit leading into a cave or tunnel system, but until now there was no way to confirm this.

In an article published in Natural astronomy, Leonardo Carrer of the University of Trento, Italy, and colleagues report evidence that this pit does lead to a cave below and possibly to a larger system of tunnels and canals. The Mare Tranquillitatis crater is about 100 meters (330 ft) wide, with steep walls that extend down between 130 and 170 meters, making it the deepest known lunar crater.

By reanalyzing the radar data and using computer simulations to reconstruct the pits, the scientists were able to determine that some of the radar reflected back to the satellite came from an underground cave conduit that was at least tens of meters long. This suggests that the Mare Tranquillitatis pit leads to an accessible cavern beneath the surface of the moon.

An exciting prospect

This discovery is incredibly exciting, not least because it is a promising potential site for future lunar shelters and bases. In addition to providing natural shelter from harmful cosmic rays, the cave system also provides a stable temperature.

The temperature of the lunar surface fluctuates greatly over a period of weeks due to the lack of an atmosphere to retain heat. During the lunar day, temperatures can soar to 121°C (250°F) in sunlight, then drop to -133°C (-208°F) after nightfall. The shade of an underground cave system is expected to regulate the temperature to be much more consistent, making building shelter in them much easier.

Likewise, small asteroids often crash into the Moon due to the lack of atmospheric shielding. Being in a shelter that is sturdy enough to survive an impact is important. The cave provides the perfect solution for this.

While having a cave to shelter in could reduce the amount of materials we need to take to the moon to begin settling there and have a long-term human presence, there are still some hurdles to overcome.

For example, the walls of the pit are a sheer drop and are over 100 meters high, meaning that future explorers will need to find a safe way to descend into the caves and climb up when exploring the surface.

This can take the form of ladders or more complex systems similar to jetpacks. Fortunately, however, the lower lunar gravity means that this problem is less severe than it would be on Earth. The structural integrity of the caves will also need to be assessed before we move.

The survey also revealed that the underground system could be between 30 to 80 meters (98 to 262 ft) long and about 45 meters (148 ft) wide. This will make it big enough for several “moonhouses”. The floor also appears flat enough to build on without serious work or preparation.

The most likely reason for moon caves is that they are old lava tubes. These are tunnels that formed when the Moon was still volcanically active millions of years ago. Flowing lava can form a continuous and hard crust, forming a roof over the still flowing lava flow. A cavity then exists after the lava stops flowing.

Even better than the cave at Mare Tranquillitatis would be the discovery of other similar structures near each of the lunar poles. Then the astronauts will have the best of everything – shelter from the harsh conditions of the Moon and access to the water ice that exists in the shadowy craters of the lunar poles. This would be an excellent chance to reduce the cost and difficulty of establishing the Moon for an extended period of time.

The fact that we can spot them from space also allows us to plan missions to exploit these natural refuges. This could mean that future astronauts live in volcanically formed caves on the moon.

This article is republished from The Conversation under a Creative Commons license. Read the original article.