Like Earth, planetary bodies like the Moon, Mars, asteroids and comets contain substantial deposits of valuable resources. This has caught the attention of researchers and industry, with hopes of one day mining them to support a space economy.
But establishing any kind of mining industry off Earth will be no small feat. Let’s see what we’re up against.
Use of on-site resources
When you think of off-Earth mining, you can imagine extracting materials from various bodies in space and bringing them back to Earth. But this is unlikely to be the first commercially viable example.
If we wanted to establish a permanent human presence on the Moon, as NASA proposed, we would need to resupply the astronauts who live there. Resources like water can only be recycled to a certain extent.
At the same time, resources are extremely expensive to launch from Earth. As of 2018, it cost around A$3,645 to launch a kilogram of material into low Earth orbit and more to launch it higher, or to the Moon. Materials mined in space are likely to be used in space, to help save on these costs.
Harvesting needed materials on-site is called “in-situ resource utilization”. It can involve anything from mining ice to collecting soil to building structures. NASA is currently exploring the possibility of building buildings on the Moon with 3D printing.
Mining in space can also transform satellite management. Current practice is to deorbit satellites after 10 to 20 years, when they run out of fuel. A big goal of space companies like Orbit Fab is to design a type of satellite that can be refueled using thrusters collected in space.
Even for low-Earth-orbiting satellites, the energy needed to reach them from the Moon is less than that needed to reach them from Earth.
What resources are there?
When it comes to off-Earth mining opportunities, there are some resources that are abundant and valuable. Some asteroids contain large amounts of iron, nickel, gold, and platinum group metals, which can be used for construction and electronics.
Lunar regolith (rock and soil) contains helium-3, which could become a valuable resource in the future if nuclear fusion becomes viable and widespread. British company Metalysis has developed a process that can extract oxygen from lunar regolith.
Ice is expected to exist on the Moon’s surface, in permanently shadowed craters near its poles. We also think there is ice under the surface of Mars, asteroids and comets. This could be used to support life, or be split into oxygen and hydrogen and used as a propellant.
How would we mine in space?
My (Michael) Ph.D. thesis involved testing how exploration techniques would operate on the Moon and Mars. Our other work included economic modeling for ice mining on Mars and computer modeling on the stability of tunnels on the Moon.
Some proposals for off-Earth mining are similar to on-Earth mining. For example, we could mine lunar regolith with a bucket wheel excavator or mine an asteroid using a tunnel boring machine.
Other proposals are more unknown – such as using a vacuum-like machine to pull regolith up a pipe (which has had limited use in excavations on Earth).
Researchers from the University of New South Wales Sydney and the Australian National University propose the use of biomining. In this, bacteria introduced into an asteroid would consume certain minerals and produce a gas, which could be harvested and collected by a probe.
Huge challenges remain
Our work at the Australian Space Engineering Research Center at UNSW involves finding ways to reduce risks in a space resources industry. Needless to say, there are many technical and economic challenges.
The same launch costs that have made so many eager to start mining off Earth also mean that getting mining equipment into space is expensive. Mining operations will have to be as light as possible to be profitable (or even viable).
Also, the further away something is from Earth, the longer it takes to reach it. There is a delay of up to 40 minutes when sending a command to a Mars rover and finding out if it was successful.
The Moon only has a 2.7 second delay for communications and may be easier to mine remotely. Near-Earth objects also have Earth-like orbits and occasionally pass by Earth at distances comparable to the Moon. They are an ideal candidate to mine as they require little energy to reach and return.
Off-Earth mining would need to be mostly automated or remotely controlled, given the additional challenges of sending humans into space – such as needing life support, avoiding radiation, and extra launch costs.
However, even mining systems on Earth are still not fully automated. Robotics will need to improve before asteroids can be mined.
While spacecraft have landed on asteroids multiple times and even retrieved samples – which were returned to Woomera in South Australia during the Hayabusa 1 and 2 missions – our overall success rate for landing on asteroids and comets is low.
In 2014, the Philae lander sent to comet 67P/Churyumov/Gerasimenko fell into a ditch during a failed landing attempt.
There are also environmental considerations. Mining in space can help reduce the amount of mining needed on Earth. But that is if off-Earth mining results in fewer, rather than more, rocket launches, or if the resources are returned and used on Earth.
While collecting resources in space may mean not having to launch them from Earth, more launches could inevitably follow as the space economy grows.
Then there is the question of whether the proposed mining techniques will even work in space environments. Different planetary bodies have different atmospheres (or none), gravity, geology, and electrostatic environments (for example, they may have electrically charged soil due to particles from the Sun).
How these conditions will affect off-Earth operations is still largely unknown.
But the work is in progress
While it’s still early days, several companies are developing technologies for off-Earth mining, space resource exploration, and other uses in space.
The Canadian Space Mining Corporation is developing the infrastructure needed to support life in space, including oxygen generators and other machinery.
The American company OffWorld is developing industrial robots for operations on Earth, the Moon, asteroids and Mars. And the Asteroid Mining Corporation is also working to establish a market for space resources.
Article by Michael Dello-Iacovo, casual scholar, UNSW Sydney and Serkan Saydam, Off Earth Mining, Future Mining, Mining Systems, UNSW Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.