Mining on the asteroid

Mining an Asteroid is very different than mining on Earth. This is because we have to account for the following:

1. Microgravity
2. No atmosphere
3. Ore Collection
4. Location of Ore Processing unit

Microgravity

Due to Microgravity, escape velocity on an Asteroid is really low. For example, the escape velocity on Asteroid Ryugu is 38cm/s, which is 1/30,000 of Earth’s escape velocity 11.2km/s. This is a big problem for two reasons: 

1. Moving about: First, moving about on the Asteroid itself is a problem. Wheel based rovers like Curiosity won’t work in a microgravity environment. The Japanese mission Hayabusa, which went to Ryugu, created a rover which hops instead. They had to take care of the force applied for hopping otherwise the rover can fly off the Asteroid. They had to program the whole hopping sequence from start to finish because they were worried that the rover would fly off the Asteroid.
2. Mining itself: Second, in a microgravity environment of an Asteroid, any downward force applied on the Asteroid can send you flying off the Asteroid. This is due to Newton’s 3rd law. Mining tools used on Earth will not work because they use too much downward force.

No Atmosphere

This is mostly a good thing. Most Asteroids are covered with loose rocks, dust and debris called Regolith. This happens because of extreme temperature difference between the Sun facing and non-facing sides, which breaks the rocks into Regolith. Since there is no atmosphere or wind, thick layer of Regolith is just lying on the Asteroid, making the mining easier because the Regolith can just be picked up off the surface of the Asteroid. The lack of Atmosphere means the Regolith doesn’t get blown away as it would on Earth.

Ore Collection

Ore collection on the Asteroids can be done in the following ways:

1. Sifter: this can be something that just picks up the loose Regolith on the Asteroid.
2. Break parts of the Asteroid: This may need to be done on an asteroid which doesn’t have loose Regolith. The challenge is that applying any downward force can send the mining equipment flying off the surface of the asteroid. 

Location of Ore Processing Unit

Depending on the quality of the ore, the yield of useful minerals may vary anywhere from 10-90%. In most cases, it may not make sense to transport the unprocessed ore back to Earth for processing because of large $/Kg transportation costs. It is desirable to process the ore as much as possible on the Asteroid itself.

Usually, ore processing requires heating to temperatures of thousands of degrees, processing this in space will require specialized equipment that can use solar power to achieve this.