C-Type Caverns: Space Mining for the 21st Century

In Posts, Space by Joshua Miller1 Comment

Reading Time: 4 minutes

Earth is making quick use of its most sought-after elements.  Elements like phosphorus, indium, gold, and platinum form the mainstay of the modern age, from pollution regulating catalytic converters to the flashy iPhone in your pocket.  With the ever-expanding use of electrical devices, some sources estimate a 50 – 60 year period remains until our deposits are sapped dry.  A dearth of this magnitude would not only be devastating to our way of life but could entirely halt the innovation of new technologies.  Luckily, with the increasing reliability of space launches, and the discovery of material-rich near-earth asteroids, space may soon be truly open for business.

When scoping out potential targets for mining operations, there are a variety of factors to consider.  In the initial stages of planning, it is necessary to consider the type of asteroid and the materials within it.  Three main types have been classified.  The first and most common is known as C-type asteroids, which have plentiful storages of water, carbon, and phosphorus.  While not likely to be of much use in terms of profit, the water has the potential to be converted into hydrogen and oxygen, making C-type asteroids into pit stops towards longer and more involved missions.

The second type is S-type asteroids, which are likely to make up the bulk of early mining operations due to the multitude of precious metals like gold and nickel found in them.  However, the third and rarest type, the M-type, is the most sought after in terms of raw materials.  Approximately 8% of asteroids deserve this classification, but with good reason, as they can contain up to 10 times the amount of metal than found in S-types.

Perhaps the most costly and limiting aspect of a space mining venture is the fuel required to get to a suitable asteroid.  Several asteroids have been identified as “easily recoverable objects” yet still would require almost as much change in velocity as a trip to the Moon.  Not to mention that, unlike the Apollo missions, the sole purpose is to add as much weight to the return vessel as possible.  Numerous methods can be applied to ensure that the cost is trimmed.  For instance, levying the orbital pull of the moon through flybys can reduce the amount of fuel required to reach an asteroid, but considerably increases the travel time.

Others have noticed the benefit of refining the materials directly on the asteroid, resulting in less deadweight to lug back to Earth, but runs the risk of requiring multiple trips to transport machinery and might be too complex to justify such actions.  The last option would be to simply establish a mining colony on the Moon, which has been proven to be rich in certain rare-earth elements and helium-3, a possible future energy source.  However, a 1984 treaty known as the Moon Agreement severely limits the extent to which any country can maintain mining rights on the lunar surface.

Despite the slew of difficulties, humans have been trying to successfully mine in space since at least the 1980s.  A study produced by NASA in 1980 titled Advanced Automation for Space Missions provided the framework for an automated and self-replicating factory on the Moon.  Starting with an initial seed of machinery and other tools, an estimated 80% of materials required to copy the seed could be mined directly from the Moon, with more complex parts requiring imports from Earth.  While mostly theoretical in nature, there are a few companies actively planning their first steps into this largely unrealized field.  The two main players are Deep Space Industries and Planetary Resources.

Deep Space Industries was founded in 2013 with a heavy focus on turning water from C-type asteroids into fuel for deeper missions.  There is a four-stage process outlined by the company to break into the market of space.  The first step begins with prospecting, with a satellite concept known as the Prospector-1 looking at potential asteroids for resources such as water and valuable metals.  The next step will use the data gathered from the Prospector-1 to extract and transport resources.  An already developed water thruster known as Comet will be used to counteract the added weight and provide valuable fuel for the trip home.

The next step, however, does not return to Earth but instead returns to processing ships in near-Earth space to act as a refinement center.  These mobile factories act as an intermediary to divide the entire process into manageable chunks.  Finally, from the processing centres, materials are sent to manufacturing centres.  The unique thing about Deep Space’s plans for the materials is that the materials are never brought back to Earth.  By building additional space structures in microgravity, larger and more complex projects are able to be completed, without the drawback of requiring fuel to get into orbit.

Planetary Resources has a similar plan, but with a much narrower scope with regards to its future endeavours.  Starting with the planned launch of multiple copies of the Arkyd-301 spacecraft in 2020, the company is looking into mapping out the asteroids of space first.  The Arkyd-301 is capable of measuring the water content of pre-determined asteroids.  Along with this, each satellite employs the use of burrowing mini-probes to get a closer and more developed picture of the asteroids composition.  After the initial stages of collecting data and choosing suitable mining locations, currently, undeveloped satellites are planned to make the journey into collecting and transporting valuable resources back to Earth.

As of right now, NASA is conducting its own project on asteroid sampling.  The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, or better known as less jumbled OSIRIS-REx is currently en route to asteroid 101955 Bennu, and has been since September 2016.  Tasked with collecting approximately 60 grams of material from the asteroid to provide details on the formation of the Solar System and possible organic compounds with the potential of forming life, it will be the first spacecraft from the United States to return asteroid samples.  While its 2023 arrival is a long ways away, it marks the first steps towards physical analysis of asteroids, and potentially the catalyst for further exploration and subsequent mining.

Despite being an extremely risky gamble that seems more science fiction than science at the time, asteroid mining is poised to not only bring about a bountiful future but perhaps our only future.

Joshua Miller
Joshua Miller is a student in the Computer Science and Aerospace Engineering programs at the University of Michigan. With a long-held appreciation for space and learning, he is actively invested in the future of technology both on Earth and beyond, seeking out the stories that fly under the radar of mainstream attention.


  1. Nice article Josh! I never heard of or thought about space mining until now. It’s a very interesting concept!

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