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How to Mine an Asteroid | Part 2

Now that we have an idea as to why we should mine an asteroid, the next question on the list must be to answer how we might go about doing so?

If you have not read the previous article, I highly recommend reading it before you continue with this one as it will help you to better understand the things we will be talking about in this article. Now lets us continue by discussing the various ways by which we can mine an asteroid.

Before we jump into the topic, let us first understand how we (or a mining company) might find an asteroid with the proper resources. This is because an investment without the possibility of a good return would simply be a waste of money, time and resources.

Asteroid Prospecting

Asteroid Prospecting is a means by which asteroids are identified, cataloged, and assessed for the value of their minerals and resources. At the initial stage, this would mostly be done using ground-based telescopes and a few space missions – such as NASA’s Galileo and Dawn crafts.

After the initial assessments, we can send robots to the NEO asteroids in order to confirm their size and composition. They will also help to identify whether the asteroid is rocky, metallic, or carbonaceous, along with the actual abundance of minerals present in the asteroid.

The probes will also help to estimate the structure of the asteroids, as being apparent “rubble piles” of loose fragments, or made of solid; non-fractured rock and metal. Some missions may be used to bring back actual samples of asteroid material for analysis.

As described in the previous article, two criteria’s must be met for the asteroid to be feasible for mining

  • The asteroid has to be near the earth’s orbit or it must be small enough that we can bring it close to our orbit
  • The asteroid must have something precious in it.

As per the recent news, on December 8, 2020, “The Japanese space agency, JAXA, has successfully retrieved a 16 kg capsule that is hoped to contain flecks of an asteroid. The capsule landed in Australia’s remote outback following a six-year mission by the $250m Hayabusa 2 mission to retrieve samples from the asteroid Ryugu.”

Mining an Asteroid

Let us say that an asteroid got the attention of the owner of a mining company. Here is how they might go about mining it and getting the resources to Earth:

Bringing the Asteroid Close to Earth

About 12 asteroids with a diameter ranging from 2 meters to 20 meters were identified in 2013, which can be mined using present-day technology by bringing them closer to Earth and reducing their orbital velocity. This can be done by a process called aerobraking or using the drag created by Earth’s atmosphere to slow down the path of an incoming object. Or in Laymen’s terms using big rockets to push the asteroid. Think of it as towing a car.

These asteroids are called Easily Retrievable Objects (ERO) and can help to vastly minimize the transportation costs of bringing the resources to Earth by shortening the distance between the Earth and the asteroid.

After Bringing them close

After bringing the asteroids close to Earth’s orbit, they can be mined in the following ways.

  1. Surface Mining: Surface mining is similar to the primitive method used by human beings to collect precious metals like gold. In this process, a machine would go and pick up the pile of valuable rubble by either scooping or actively grabbing it from the surface of the asteroid. There is strong evidence to suggest these piles of stones and pebbles could harbor a ton of precious minerals and metals. In addition to this, we can also use Magnets to pick up minerals with magnetic properties.
  2. Shaft Mining: Shaft mining is the process by which a shaft can be used to dig straight down into the surface until you reach the desired depth. This process can also lead to dust clouds forming because an asteroid’s gravity cannot pull the debris of Peebles and dust produced by the mining process (Breaking of rocks) back to the ground. These dust clouds can be collected with a large canopy to ensure that they don’t escape into space and can further be organized at a later date.

Both these operations would require an immense amount of fuel. So, For this, the water-rich elements on the asteroids can be heated, and its vapor can be stored as fuel. This can be done by using a simple vessel to hold the heated vapor.

Processing the Mined Materials

Lets us now explore the process by which the mined materials from the asteroids can be processed.

Processing the materials on site (On the asteroid)

This refers to taking an entire ore processing plant (the equipment needed to take a piece of ore and extract metals out of it) to the asteroid and processing the collected materials on the asteroid itself. Initially, this might be expensive because you would have to carry large equipment onto the asteroid. However, the idea behind this is that the elements mined from the asteroids in the future will be able to pay for the high initial cost of setting up everything.

Processing the materials on Earth

An alternative to building a mining base on the asteroid would be to bring all the collected materials back down to Earth for further processing. The idea behind this is to let all the stuff fall into the Earth’s atmosphere and catch them mid-way using rockets. However, there are inherent problems associated with this process.

First is the fact that things that fall into the Earth’s atmosphere tend to break apart after hitting it, and, in most cases, big objects burn off before reaching the stratosphere. To protect them from burning off, we would need to send large cargo rockets to the sky. This is why this process will be much more expensive than setting up an entire processing unit on the asteroid. Because setting up a station on the asteroid would be a one-time investment allowing reusability.

For example: Mining a ton of high-grade gold ore can give us about 2 grams worth of gold. Even if there is a large deposit of gold on the asteroid we want to mine, it is safe to assume that the cost of transporting 2 grams of gold will be a lot less expensive than transporting a ton of gold ore back to Earth. Remember, in space, transportation is the highest cost we need to minimize.

Compare that with taking a sizeable 10-ton processing plant with all the chemicals and processing equipment on to the asteroid itself and sending materials back after they have been processed. This seems a much cheaper and efficient method because we save on fuel costs and other transportation charges.

Hence, we can conclude that making a one-time investment in taking the processing plant to the asteroid is a much better alternative. We can load the processed metals into a rocket and ensure a safe landing. This is also safer because we can control where the materials land, which is more challenging with larger things like an entire load of unprocessed ore. Surely we don’t want a 10-ton ore landing on top of our home.

In the upcoming articles, we will explore the economic impacts and technological advancements in asteroid mining, the socio-environmental changes that it might bring, and much more.


New Class of “Easily Retrievable” Asteroids Discovered

L. Wilson; K. Keil; S. J. Love (1999). “The internal structures and densities of asteroids”. Meteoritics & Planetary Science34 (3): 479–483. Bibcode:1999M&PS…34..479Wdoi:10.1111/j.1945-5100.1999.tb01355.x.

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