On Asteroid Mining

Ethan Wong

December 6th, 2024

Just a few days ago, Earth experienced a brief jumpscare (not really) with asteroid 2020 XR, which flew by Earth at roughly 2.2 million kilometers from the surface. While leaning toward the categorization of larger asteroids–300 to 700 meters in length–such a sighting isn’t so bad when compared to other asteroids that will make a closer appearance in the future; 99942 Apophis will be just above 30,000 kilometers from the surface when it strolls past the planet in 2029. 

A collision between a significantly large asteroid and the Earth threatens the planet’s life and stability. However, these massive astronomical bodies harbor a variety of valuable resources for society–some of which will be used up if humans are not careful. While it's improbable that the Earth’s metal reserves will deplete themselves for now, rarer metals will continue to become increasingly scarce and expensive due to the increasing production of technology. Metal is non-renewable, and given society’s current dependence on it, we must find other means of maintaining the Earth’s metal supply.

Currently, NASA is studying 16 Psyche (without intent to extract metallic material), one of the most metallically-rich asteroids, and popular among the science community for the potential wealth it harbors. This asteroid yields an estimated 10,000 quadrillion dollars if completely stripped apart for its material. While asteroids like 16 Psyche can hold an abundance of attractive and valuable metals, even smaller asteroids can possess accessible resources that could benefit society.

In “Physical Characterization of Metal-rich Near-Earth Asteroids 6178 (1986 DA) and 2016 ED85,” researchers Juan Sanchez, Vishnu Reddy, William Bottke, Adam Battle, Benjamin Sharkey, Theodore Kareta, Neil Pearson and David Cantillo found that 6178 (1986) DA itself exceeded worldwide reserves in iron, nickel and cobalt in 2020; these three metals made up over 99% of the asteroid. Other metals, such as Gold and Platinum, made up less than 1% of the asteroid’s composition. Yet, their combined market valuation was showcased at over 3 trillion dollars–that is, if all the Gold and Platinum in the asteroid were to be completely extracted, which is an incredibly difficult task.

Despite the abundance and value of asteroids’ compositions, asteroid mining hasn’t been a huge priority for large space companies due to other ongoing initiatives, and because of its expensive, time-intensive work for little gain. But space companies have still taken samples from asteroids. In 2016, NASA launched the OSIRIS-REx spacecraft on a 7-year mission to collect asteroid samples to return to Earth. While NASA originally intended to return 60 grams of the asteroid regolith, the mission collected around 121 grams from the asteroid Bennu in 2020, which is a tremendous amount. The estimated funding for this project, according to the Planetary Society via Forbes, was over 1 billion dollars. Japan’s Hayabusa2 also delivered samples to Earth from asteroid Ryugu, a C-type asteroid (the most common, contains water), over a 6-year mission starting in 2014. 

However, while the big names haven’t discussed any big plans for an asteroid mining initiative, a start-up company called AstroForge has. Just recently founded, they are currently working to extract valuable metals and minerals from M-Type (contains nickel, iron, cobalt, gold; made of mostly metals) asteroids–in pursuit of platinum group metals–and return them to Earth. With NASA spending over a billion dollars on one mission, and its highest sample retrieval of less than 200 grams, it's safe to call AstroForge’s plan an immense challenge. As of now, the company has launched two missions, and is working toward launching their third in 2025, which will feature the Vestri spacecraft landing on an asteroid and studying its metallic composition. However, being relatively new, there have been no plans for asteroid mining, collection and return journey yet. 

So how would mining asteroids even work? 

As discussed above, asteroid sampling has been the closest equivalent. During the Hayabusa2 mission, asteroid samples were retrieved by detonating an explosive package on the asteroid's surface, allowing the Hayabusa2 spacecraft to subsequently obtain underground material from the resultant crater. This small carry-on impactor (SCI) was engineered to experience an explosive charge of 2 km/s, and Japan acquired around 5 grams through multiple samplings. However, asteroid mining with this method is impractical. For one, a much larger explosion would result in high-velocity reactionary debris, posing a threat to the spacecraft (and mining equipment), while also potentially losing valuable material in the process.

NASA’s method of asteroid sampling involves a simple “touch and go” mechanism (TAGSAM): a robotic arm lowers the body of the mechanism onto the surface of an asteroid, and nitrogen gas is ejected onto the surface to capture small dust and rocks of the asteroid which are then stored in the mechanism. While safer and faster than an explosion, it would take thousands of spacecraft and many more TAGSAM arms to make asteroid mining a reality. And even then, funding and launches become an obstacle. This method is most likely impractical as well.

So circling back to the initial question: how can asteroids be mined? Location is essential to asteroid mining, as spacecraft fuel is costly and takes up space; as a result, near-Earth asteroids serve as the best places to start mining before the asteroid belt. The actual asteroid mining process would most likely involve human miners and robotics. These miners would drill and dig up asteroid material, yet would need to be anchored to the asteroid’s surface due to its extremely low (practically non-existent) gravitational pull. Additionally, miners would need storage compartments for the asteroid material, which would have to be sent down by a small spacecraft, or somehow be tied down similar to the miners. If the asteroid is moving/rotating fiercely, it might not be the best location. 

Returning these collected chunks of asteroid back to Earth is a big challenge in asteroid mining. A popular proposal is to keep the resources in space to help build equipment, acting as In-Situ Resource Utilization (ISRU) for any possible space missions in the future. The biggest usage of this idea would involve turning the water from C-type asteroids into hydrogen and oxygen for rocket propulsion and human consumption. An asteroid mining colony in space has also been a popular idea, yet it will likely never happen until a civilization is established on Mars.