Yesterday, the lander of the Chinese probe “Chang’e-5” successfully separated from the orbital module and started landing on the Moon. It must collect and deliver samples of lunar soil to Earth. This is the next stage of an ambitious program, the ultimate goal of which is a permanent base on the satellite. Roscosmos and NASA are also planning “lunar cities.” About what will be the first human settlement outside of our planet is in the material.
To leave, to return
The last time humans landed on the Moon was 48 years ago. Then, on December 14, 1972, American astronaut Eugene Cernan, after walking on the lunar surface, said: “We are leaving as we came, and with God’s help, we will return.”
Over the past few years, several countries have declared their readiness to resume lunar programs. The Moon is attractive for several reasons. First, as an Outpost for flights to other planets in the Solar system-it is easier to start from it than from Earth.
Secondly, as a source of minerals-primarily helium-3: it can be used to produce thermonuclear fuel.
Third, on the Moon’s far side, scientists plan to place a radio telescope protected from earth’s interference. And with its help, they discover the cosmic microwave background, which they hope to reconstruct the events of the “dark ages” of the Universe-the first few hundred million years after the Big Bang.
And last, perhaps most important, the Moon’s base should become an experimental testing ground for testing technologies for human migration to other planets.
Therefore, in the coming years, we will inevitably witness the Earth’s satellite’s active development. But it is too expensive to send heavy missiles there every time. Today, no space agency will finance the sending of crews, as in the Apollo program. Everyone is inclined to create permanent bases — first in the Moon’s orbit and then on its surface. But this is not an easy task.
Zone of increased competition
The first problem is related to the fact that all participants in the “Moon race” are aimed at the same locations and resources. Thus, discussions are still mostly not about the science but the legal and commercial aspects of the issue.
So, in all lunar projects, the permanent base’s location is defined in the area of the South Pole of the Moon. However, it is technically easier to make Shuttle flights to and from the orbital station from the Equatorial zone.
But in the South Polar Region, the so-called cold traps are concentrated-permanently shaded areas where there is ice necessary to get water. Also, it is never dark here, so you can continuously recharge the solar panels. On the rest of the Moon’s surface, the night lasts for two weeks.
Despite the 1967 Treaty on principles governing States’ activities in the exploration of outer space, or, as it is more commonly called, the outer space Treaty, the use of space resources is not regulated by international law.
There is, however, an Agreement on the activities of states on the Moon and other celestial bodies, adopted by a resolution of the UN General Assembly in December 1979. Still, any country has not ratified it with its own lunar program. Moreover, on April 6, 2020, US President Donald Trump signed an Executive order approving the commercial development of resources by the United States on the moon and planets of the Solar system. And this only increases the tension.
Water-the “oil of space”
The location of the lunar base depends primarily on the location of potential sources of water, which is necessary for all operations to ensure human life on the moon — for General needs, drinking and growing food, obtaining oxygen for breathing and hydrogen for rocket fuel.
For a long time, the moon was considered absolutely waterless. This view was reinforced after scientists examined samples delivered to Earth by the Apollo mission astronauts.
But in 2018, evidence emerged that there are significant reserves of water ice at the bottom of the craters. This gave a second wind to lunar programs.
Developers of settlement projects suggest that mirrors can be fixed on craters’ edges and direct sunlight to shaded areas. The heated ice will turn into steam, which will go through a pipeline to an electrolysis plant, where it will be split into hydrogen and oxygen. Another option of extraction of water in the craters with an earth-moving combine harvester is equipped with a heating device for the ice’s evaporation.
Experts estimate that there are up to ten billion tons of ice in the traps near the South Pole. For comparison, to provide water and oxygen to a base where four people live, it will take several tens of tons of water per year.
In addition to large shaded areas, scientists have identified many small cold traps, up to a centimeter in diameter, most in the circumpolar regions. Based on NASA’s Lunar Reconnaissance Orbiter data, the researchers estimated that up to forty thousand square kilometers of the lunar surface could be covered in water ice.
More recently, the SOFIA stratospheric Observatory’s infrared telescope detected signs of molecular water in the illuminated areas. According to scientists, its recorded spectral signature indicates the presence of ice filling the voids between the grains of minerals in the lunar soil. If the discovery is confirmed, the list of places to build the base will expand significantly.
Oxygen from the regolith
The composition of the lunar soil-regolith-includes iron and other elements: silicon, aluminum, manganese, and calcium. According to scientists, all this is potentially available for extraction, as well as oxygen, which is 43 percent in the regolith. And by combining oxygen with hydrogen taken from other sources or delivered from Earth, you can get water.
However, it takes a lot of energy to extract oxygen from oxides and silicates. Scientists suggest using giant mirrors that focus sunlight on the shell of a small reactor. For the moon dust to decompose, the temperature in it must be brought to 900 degrees Celsius. Also, the oxygen separation reaction requires catalysts-hydrogen and carbon, previously brought from Earth. And even under all these conditions, it will take years for the facility to generate enough water fuel to send just one Apollo-sized spacecraft into lunar orbit.
Despite all the difficulties, the European Space Agency (ESA) has already allocated funds to finance the project of extracting oxygen from regolith. The implementation will be handled by the British company Metalysis. The company’s specialists, along with scientists from the University of Glasgow, said that they extracted 96 percent of oxygen from artificial lunar soil during the experiment on Earth, turning the rest into useful metal powders.
Improvement of the living environment
Unlike Earth, the moon does not have an atmosphere and a magnetic field, so the lunar base structures must protect the inhabitants from cosmic rays, solar radiation, and a stream of meteorites.
The first option is to cover the erected shelters with a multi-meter layer of lunar soil. The second option is to place the base in a rock, canyon, or cave. As such a natural shelter, scientists once proposed a lava tunnel under the Marius hills in the Central part of the Ocean of Storms. The walls are planned to be built using 3D printing by sintering regolith particles.
Recently, American scientists from the University of Arizona published a project to build a lunar base from blocks obtained by melting regolith using a focusing solar reflector. The authors’ experimental device with an area of ten square meters burned a hole in a steel plate six millimeters thick in ten seconds.
The researchers calculated that in three years, using such a device, the robotic line will produce regolith blocks that will be enough to build a base with a total area of two thousand square meters.
And later, they suggest using the reflector to illuminate residential premises and greenhouses, where you can plant greens, cabbage, and potatoes. As part of a closed ecosystem, plants will process organic waste and convert carbon dioxide into oxygen for respiration.
Astronauts on the International space station are already eating leafy greens grown on Board using the hydroponic method. According to scientists, the “space” salad in quality and useful components is not inferior to the earth.