On the Moon, astronauts will need protection from a different set of hazards. They’ll have to contend with cosmic and solar radiation, meteorites, wild temperature swings, and even impact ejecta. The Lunar Reconnaissance Orbiter (LRO) has found hundreds of lunar ‘skylights,’ locations where a lava tube’s ceiling has collapsed, making a natural opening into the tube.
The International Space Station is only about 300 miles high. That gives the ISS some protection from cosmic rays. Cosmic rays are positively charged particles moving at relativistic velocities. Alpha radiation consists of some of the same positively charged particles, and is the type of radiation that Putin has used to assassinate opponents. He used polonium which emits alpha radiation. Those particles are big and slow, and can be stopped with a piece of paper. When a person ingests polonium, the radiation attacks the person from the inside, with nothing stopping the particles.
Cosmic rays are moving at nearly the speed of light. Shielding with lead, as one might use to block Superman’s vision, doesn’t work because the particles hit lead atoms and knock them free. Those heavier atoms would act like shrapnel.
Hydrogen atoms are good for shielding from cosmic rays, so water, ice or plastic works, but you need a lot of it, on the order of several meters. A lunar lava tube would provide meters of rock and would be excellent shielding.
On the Moon, astronauts will have to contend with the temperature swings. Earth’s natural satellite is a world of temperature extremes. One side of the Moon is in direct sunlight for half of the time, and surface temperatures reach as high as 127 degrees Celsius (260 °F.) The side that’s shrouded in darkness sinks as low as -173 °C (-280 °F.)
The Moon is a world of temperature extremes only on the surface. Apollo astronauts did experiments with thermal conduction on the surface of the Moon. Go down half a meter, and the temperature is a constant temperature of about -4 °F. It gets colder than that in Ohio.
Because the Moon has no atmosphere, heat is not conducted through convection, but only from radiation from the lunar surface to the -450 °F of space and through conduction through Moon rock. A lava tube on the Moon be -4 °F. An enclosure that is insulated from the floor of the cave would lose very little heat.
China’s future plan, after successful exploration, is a crewed base. It would be a long-term underground research base in one of the lunar lava tubes, with a support center for energy and communication at the tube’s entrance. The terrain would be landscaped, and the base would include both residential and research facilities inside the tube.
This is likely to be every nation’s plan. China has 30 million people living in caves, so maybe the idea doesn’t seem as novel to them.
Vincent was a new engineer hired into our Paris office. To get some field experience, he was sent down to Madrid to work with me on the Vetrotex project.