In recent years, there has been an interest to create and develop technology that can collect and use the raw materials from asteroids. With increasing scarcity of Earth’s resources and our growing innovation in the field of space exploration, various companies have begun to consider how asteroid mining could feasibly work to harness new resources from space.
Asteroids are like mini-planets that were formed at the same time as the planets in our solar system. They are mainly composed of mineral and rock, and are most often found in the inner part of our solar system. Asteroids can be quite big, which makes them possible destinations for mining activities. The largest ones, sometimes called “planetoids”, can be almost 1,000 km across (imagine an asteroid that covers the distance from London to Prague or Seattle to San Francisco). However, even relatively small asteroids can cause significant impact on bodies in the solar system. For example, from Earth we can see the impact craters on the moon that are caused by asteroids. Even the asteroid that caused the extinction of the dinosaurs and around 75% of all species on Earth 66 million years ago measured only 10 to 15 kilometres across. Despite its size, the asteroid’s collision with Earth released energy a billion times that of the atomic bombings of Nagasaki and Hiroshima in World War II.
Asteroids exist in the millions and there is even an asteroid “belt” that lies between the orbits of Mars and Jupiter that contains a particularly large concentration of asteroids. Meteoroid is the term used for small asteroids less than 1 meter in diameter. Of the roughly 50,000 that have entered the atmosphere and hit the Earth (we then call it a meteorite), it is estimated that nearly all of them came from this asteroid belt.
Asteroids are often categorized for what they are made of and there are certain types that would be useful for us if we were to mine them. For example, C-type (carbon-type) asteroids carry lots of water. If we wish to collect water, comets may also be a valuable mining destination because these are much like dirty snowballs, made of dust, rock, and ice. Although not a mineral for mining, water could help support longer missions through space. The liquid hydrogen and oxygen could be broken down from water to be used as fuel. Water in the form of super-heated vapour can also be used as a propellant for spacecraft. C-type asteroids can also contain important elements used in fertilizer that could help grow food on these longer missions into space, such as organic carbon and phosphorus. Although they do not have much water and are less common, M-type (metal-rich) asteroids contain valuable metals. They contain high amounts of nickel, cobalt and even valuable metals like platinum and gold. C-type asteroids can contain smaller amounts of metals as well.
There are several uses that the mined materials from asteroids could be used for. It could be returned to Earth for use here or it could even be processed on a spacecraft to make propellant for the journey to Earth or elsewhere in space. “In-situ resource utilization” is a term used to describe the use of resources that are collected on-site. The valuable resources from asteroids offer new applications of conducting work in space that is in-situ, including on spacecraft or on other celestial bodies. For example, using them to make a the structures for a permanent base on the moon or Mars.
Material could be extracted from an asteroid in several different ways. The surface of the asteroid may be scraped or drilled. Larger extractions could involve constructing a mine from which material is taken out from a shaft. Since much of the material we want to collect is metal, magnets could also be used to gather them. If mining were to take place in-situ, a hole could be drilled that would then have hot fluid or gas put into it. The metal we want to remove would then melt or react with this heat that will allow it to be extracted. One challenge of these activities is that because they are small compared to planets, asteroids do not have a strong gravitational field. This means that any drilling activity would release dust clouds and small particles, which could complicate activities or damage equipment.
A big challenge that exists in the interest of asteroid mining is how far we must travel to collect this material. It is likely that mining would take place on asteroids that are closer to Earth, but these objects are still very far away. This raises the question of whether or not it is economically worth travelling to collect this mined material in the first place.
Today, there are missions to collect asteroid samples to help us prepare for future mining projects and to help us better understand these objects and how they relate to how our solar system and life formed. For example, NASA launched the OSIRIS-Rex mission in 2016, which plans to to return a sample from the “Bennu” asteroid in 2023. Aiming to study the asteroids organic material, the spacecraft will use a robotic arm to collect the sample from the asteroid that has a diameter comparable to the height of the Empire State building. The Japanese space agency has already collected an asteroid sample of dust grains from its Hayabusa mission, which returned in 2010, and has since launched the Hayabusa2, which hopes to collect a larger sample from its asteroid for return in 2020. According to the Japanese Aerospace Exploration Agency (JAXA), the spacecraft successfully rendezvoused with the asteroid on June 27, 2018 (pictured below). Evidently, these missions take generous time to travel to the asteroid, collect a sample, and to return it. It is for this reason that the in-situ use of asteroid resources is being strongly considered for its applications.
Image of the Ryugu asteroid taken from roughly 22 kilometres (14 miles) away by the Hyabusa2 space probe on June 26, 2017.
Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST
Deep Space Industries is a private American company that was founded in 2013 with the aim of extracting resources, particularly water, from C-type asteroids. The company is developing the technologies needed to conduct asteroid mining activities. For example, DSI has developed an electrothermal propulsion system that uses water as a propellant, which is a valuable technology that could make use of the water extracted from asteroids. Refuelling technology such as this will allow for the conception and development of longer missions into space.
Another American company, Planetary Resources, also hopes to develop its asteroid mining technology. Founded in 2010 , this company hopes to launch several satellites in the near future to collect data about near-Earth asteroids for the future design and construction of commercial asteroid mines in space.
There has also been a legal debate about whether asteroid mining should be allowed to happen at all. The United Nations “Outer Space Treaty” of 1967 has banned countries from appropriating, taking or seizing other space bodies (like other planets, moons and asteroids). However, there is not currently an international legislation that has set out the rules about the ownership of minerals, metals, or other resources that may be found there.
In 2015, the United States past the “SPACE Act” (Spurring Private Aerospace Competitiveness and Entrepreneurship), which recognizes the rights of American companies to engage in the exploration and extraction of space resources from asteroids and other celestial bodies. This includes water and minerals but does not include biological life. The act specified that the extraction of any resources does not mean that the United States is asserting exclusive rights or jurisdiction over the ownership of the body that is being collected from. A second country has since followed the same legislation. In 2017, the government of Luxembourg passed a bill that gives companies the rights to space resources that they extract from asteroids or other celestial bodies. As of March 2018, these are the only two countries to establish legal frameworks that secure property rights for space resources.