Even without water reuse, humanity could build a pretty serious base at the Moon’s south pole, according to a new study. However, this decision will have very serious consequences. Moreover, the most likely path to developing lunar bases in general would require significant consumption of water on the Earth’s natural satellite.

American researchers calculated the water consumption for a large lunar base with an area of ​​​​five hectares and a staff of 100 people. Moreover, despite the usual approach to such issues, they made calculations based on the assumption of systematic release of used water resources, excluding the reuse of water. The text of the work can be viewed on Cornell University’s preprint server.

Lunar base projects were developed in the 1950s and 1960s, but they were normally very modest. For example, the Soviet project of the “Zirka” lunar base in the 60s consisted of nine blocks of 73 cubic meters each (about 660 cubic meters in total) for 12 crew members. So in terms of volume, the base will be slightly smaller than the modern ISS, where there are more people. Of course, the project envisaged the “circular” use of water: at that time the Moon was believed to be practically waterless.

In the 21st century, there was first a theory predicting the presence of large amounts of water in the form of ice on the Moon, and then specific observations (e.g. radar observations) showing the presence of water ice at the poles of the Earth satellite. . It turns out that there is no urgent need to save water. Moreover, with the large amount of water ice, it is possible to create much larger bases in Selene than was thought half a century ago.

A new study by American researchers estimates the amount of water at a base to be 500 x 100 meters per 100 people. At the same time, the authors deliberately rejected not only the obligatory reuse of water, but also its economy in general: they calculate per capita consumption based on earthly indicators of water consumption in the average American household (375 liters per person per day). According to calculations, the bulk of the water will still fall not on people, but on agricultural needs (greenhouses with plants), which are inevitable for a self-sustaining colony.

According to new calculations, the easiest way to extract water from lunar ice is to use automatic “thermal drills” with a capacity of 10 kilowatts each. In total, about 6.5 thousand such exercises will be needed.

Since there is no atmosphere on the Moon, the ice beneath the regolith layer immediately turns into water vapor when heated. Researchers proposed collecting it with a special awning stretched over the workplace of thermal drills that heat the regolith. The water vapor is then piped from the awning into the cistern, where the vapor condenses into liquid water.

Scientists then analyzed the base’s water consumption. It turns out that even if all the oxygen necessary for breathing were obtained not from greenhouses, but due to electrolysis of lunar water, only 0.3% of the water needs of the entire base would be used for this. A significant amount of water will need to be spent on greenhouses. Researchers determined the space needed to support the people there was 370 square meters per person. These are very large indicators taken from the productivity of agricultural greenhouses on Earth. The calculations raise serious doubts: in the BIOS-3 experiment in the USSR in the 1970s, it was established that an area of ​​​​less than 150 square meters is enough to provide oxygen and food for a person.

Scientists estimated the base’s total water needs at 105,000 tons per year; This turned out to be quite sufficient for extraction from lunar ice in the presence of heat sources with a capacity of 65 megawatts (thermal). This is not a huge value: a Russian icebreaker reactor has several times more thermal power. At the same time, the source of such heat is not taken into account in the study. Moreover, researchers proceed from the option of power supply of the base at the expense of solar radiation.

They therefore thought it reasonable to locate the base near the Shackleton-de-Herlach ridge, which is almost at the South Pole. The top of the ridge is almost always illuminated by sunlight, and around it there are zones of endless shadow, where the temperature of the soil is always around minus 250 degrees. Scientists believe that it makes sense to place solar panels in high places and melt water ice in low areas.

There are many unclear parts of scientific work. For example, the total volume of the base (including non-hermetic) is very large – up to 300 thousand cubic meters. A base like this is too big for 100 people.

After all, the idea of ​​a moon base on the surface raises questions. The truth is that today the moon landing is planned with only one landing system: Elon Musk’s Starship. Its closed volume is about 900 cubic meters, which is larger than the ISS or the Soviet base of the Zirka lunar project. Each Starship can accommodate up to 40 people on a long-haul flight. To accommodate 100 personnel, it makes much more sense to land a series of such ships near the Moon’s south pole, since serial costs are estimated at several hundred million dollars, which is not much. Instead of building a huge base there, the total size of which exceeds 300,000 cubic meters.

As mentioned above, according to the experience of the Soviet BIOS-3, 150 cubic meters of hermetic space per person, including living and laboratory premises, is enough to provide people with oxygen and food. Thus, even with a permanent base for 100 people on the moon, it is easier to deliver 16 Starships than to build structures the size of a large skyscraper.

However, the part of the study that recommends collecting water under the awning during thermal storms looks quite interesting. It was traditionally assumed that water ice was cut from the regolith and then transported to melting points. This is how water is extracted in winter in some regions of Yakutia (other methods are difficult due to permafrost in winter). But the physical work of breaking up water ice at minus 250 degrees will be quite difficult. As we have written many times before, space machines without human guidance cannot handle complex work on the surface of other celestial bodies. And the astronaut will have to spend a lot of time and effort. Melting ice with heat seems like a simpler option.