Using years of surface temperature data, scientists have identified caves with comfortable conditions for humans. Permanent research bases could be built in them.
Because the Moon has no atmosphere, its temperature fluctuates greatly: during the lunar day the satellite heats up to 127 degrees Celsius and during the lunar night it cools down to minus 173 degrees. In this case day and night alternate about once a month - every 354 hours (14 Earth days and 18 hours). Such conditions make it difficult to build and maintain a permanent base, so scientists are actively seeking more favourable conditions on the satellite.
Using data from the Lunar Reconnaissance Orbiter (LRO), a team of American planetary scientists have discovered that temperatures in shaded areas of caves on the moon are always kept at a comfortable level for humans - about plus 17 degrees.
Despite the earth's satellite's long history of exploration, the caves were only discovered in 2009 by Japan's Kaguya Satellite, also known as SELENE. The question immediately arose: Can people use these natural shelters to protect themselves from cosmic rays, solar radiation and micrometeorites?
Caves are not craters. According to study leader Tyler Horvath, a PhD student at the University of California, Los Angeles, 'about 16 of the more than 200 caves discovered are probably collapsed lava tubes.
Lava tubes are formed from lava rivers when the upper layer solidifies and the lava underneath continues to flow. They are also found on Earth. On the Moon, such tubes are traces of former volcanic activity. Photographs of two of the most famous caves show the edge overhanging the bottom and there are strong indications that a larger cave is hiding in the depths.
To determine the temperature at the depths of the caves, researchers examined data from the Diviner thermal camera, which has been measuring the temperature of the moon for more than 11 years. In this data, they detected a strong temperature difference in the caves of the Sea of Tranquillity, near the equator, and the more southerly Sea of Dreams.
Comparing the data with the results of thermophysical models, the scientists found that while the daytime floor temperature in the caves reaches plus 147 degrees, the temperature in the permanent shade stays around plus 17.
According to the authors of the work, "if there is a larger cave in the depths, it too may maintain a comfortable temperature along its entire length, fluctuating by less than one degree throughout the lunar day". Of course, it is impossible to confirm the presence of such caves without closer examination.
Temperature is one of the many problems to be solved by the architects of lunar bases. Ideally, such bases would exist almost independent of Earth, providing themselves with water, food, oxygen, materials and fuel.
