What percentage of asteroids contain valuable resources
There is a gold rush atmosphere in space
The involvement of private companies such as Space X or Blue Origin has spurred space travel. Even ambitious goals are considered. Some companies are already dreaming of mining valuable raw materials on asteroids.
NASA plans to send people back into space beyond Earth orbit. First it should go to the lunar orbit, then to the earth's satellite itself and finally to Mars. And ESA is also considering a base station on the moon. Wouldn't it be practical if there were a supply of necessary raw materials in space that could be tapped directly on site instead of constantly having to deliver supplies from the earth? Because that is what makes manned space missions so expensive.
In fact, there is an abundance of gravel in the solar system that could hold some resources ready. The asteroids left over from the formation phase of the solar system probably contain similarly valuable materials as the earth, albeit in a different composition.
Landing on an asteroid
For decades, visionaries have pondered using these cosmic rocks as a source of raw materials. They expect immeasurable wealth from it. With recent developments in space, such plans seem to be becoming more tangible. A few days ago, the Hayabusa 2 spacecraft successfully dropped a lander on the asteroid Ryugu; The previous Hayabusa mission had already proven that it is possible to take a soil sample from an asteroid - albeit in very small quantities - and bring it back to Earth. Another probe, Osiris-Rex, is currently heading for the asteroid Bennu.
So far, such missions to asteroids have been relatively expensive. Usually only large space agencies can afford them. In the future, however, innovative production processes such as 3-D printing are likely to make the construction of satellites and space probes cheaper. The private space sector has also recognized this. In the past six years, three companies have been founded with the aim of using resources from space economically.
When it comes to asteroid mining, precious metals such as gold or platinum first come to mind. Perhaps the most important resource asteroids have to offer is water. "We do not necessarily have to rely on the extraction of water from asteroids, but such an infrastructure would be an advantage," says Andreas Hein. The scientist at the Ecole Centrale in Paris examines future scenarios and novel technologies for their feasibility and profitability. "Water is not only essential for life, it also provides one of the simplest fuels and is also very suitable as a protective shield against cosmic radiation," explains Hein.
In a certain class of asteroids, this raw material is likely to be available in large quantities. Even ordinary rock can contain up to 30 percent water in bound form. Estimates for the so-called C asteroids assume a water content of around 8.5 percent. They also contain higher concentrations of volatile substances, carbon compounds and organic materials. They are covered by a regolith layer, the material inside these asteroids is rather loosely packed.
In a study commissioned by NASA, the company Transastra investigated how water could be extracted from these asteroids. Among other things, the researchers developed a method with which a special mirror system is supposed to bundle sunlight and direct it onto the asteroid. The resulting heat would to a certain extent hollow out the asteroid and at the same time allow volatile substances such as water to evaporate. Experiments on asteroid-like materials have shown that this can work.
This is how the mining of natural resources on asteroids could begin
In space, the released water vapor would then be captured in a kind of inflatable balloon that envelops the asteroid, condensed again by a cooling system and finally stored as ice. According to the present study, up to 120 megatons of water could be obtained in this way within a few months. This could be transported to orbit near the moon with a supply chain from smaller satellites and stored there in a corresponding module as a fuel base. This process, known as “optical mining”, would be much more cost-effective than machining an asteroid with a robotic hammer or drill or with a laser. According to the study, this is what makes the breakdown of water profitable in the first place.
Detlef Koschny from the ESA's Department for Space Assessment says it will perhaps be easier to say in five years whether the asteroid mining will actually come and when. “It's a bit like nuclear fusion. I don't really believe in asteroid mining myself yet. But I think it's great that there are companies that are investing there. "
It doesn't work without a preselection
Asteroid exploitation technology may gradually mature. But there are other hurdles as well. An asteroid has yet to be found in a favorable orbit close to the earth, the composition of which promises a rich yield. So far, the exact nature of very few asteroids is known. These celestial bodies can be roughly classified by optical or infrared observations. For example, the C asteroids covered by a regolith layer appear rather dark. The objects in the S-Class, on the other hand, which are rich in silicates and metals from the platinum group, for example, reflect more light and therefore look brighter. In only one case, a meteorite could be assigned to a specific asteroid and thus its composition could be determined. Ultimately, certainty about this can only be obtained through on-site investigations, as is currently being carried out by Hayabusa 2 on the asteroid Ryugu and soon also by Osiris-Rex on Bennu.
"For example, you could send mini-satellites, so-called cube-sats, to individual asteroids, which then explore their properties," says Hein. These are more cost-effective than missions like Hayabusa 2 or Osiris-Rex. Planetary Resources has such mini satellites in its range. At the beginning of the year, the company first sent a probe into Earth orbit in order to test, among other things, an imaging method that can be used to detect water.
Even before the researchers or the companies extract large amounts of water from an asteroid and make it usable for space travel, they could, however, use very similar methods to tap the moon themselves. The ESA, for example, wants to investigate by the year 2025 as part of the Isru mission (“in-situ resource utilization”) how water and oxygen can be sensibly extracted from the materials on the moon's surface.
The call of platinum
Far more daring are the considerations to bring certain raw materials from asteroids to Earth, such as rare metals of the platinum group. It is estimated that these materials are 10 to 100 times as abundant in asteroids as they are on Earth.
Mining platinum, however, would be much more difficult than water. In order to extract such compounds from the asteroid material, it would first have to be melted at very high temperatures. How this can be done in space is simply not known today.
Nevertheless, Hein takes up this case in his studies, in which he examines the topic of asteroid mining for the first time under ecological criteria: According to this, from a purely environmental point of view, the degradation of water on asteroids is worthwhile as soon as the amount of water to be transported from the earth to the orbit near the moon exceeds the mass of the carrier satellite exceeds. According to his calculations, the limit for platinum is much smaller delivery quantities. Since the mining of platinum is very energy-intensive, corresponding amounts of CO are generated2. "We were very surprised that the balance becomes more favorable once a certain amount of space has been extracted," says Hein.
Everyone on their own?
In addition to the technological and economic feasibility, another question remains: Who do the resources on such celestial bodies belong to? Everyone or nobody? The currently valid agreement, the Space Treaty from 1967, does not yet specifically regulate the question of resource extraction on celestial bodies. The 1979 lunar agreement also remains vague in this regard. "There is a lot to suggest that the extraction of raw materials should be possible," says Stephan Hobe, head of the Institute for Air and Space Law at the University of Cologne, "but only under certain conditions." These conditions are still very controversial today, for example the question of whether one has to share the income.
Some states are currently trying to create investment incentives for companies in the space sector with new legal regulations, especially for resource extraction in space. Luxembourg and the United States are currently the only countries that have given national permits for the extraction of resources, says Hobe. The United Arab Emirates may soon follow suit.
Regulating the mining rights is clearly beyond the competence of a single state. There is therefore an intense debate within the United Nations about how to deal with national powers. That must always happen as an international joint act, says Hobe. "I'm sure that those who see it differently will fall on their stomachs with it."
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