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Early evidence suggests that there are trillions of dollars’ worth of minerals and metals buried in asteroids that come close to the Earth. These include phosphorus, antimony, zinc, tin, lead, indium, silver, gold and copper. The mining of resources contained in asteroids, for use as propellant, building materials or in life-support systems, has the potential to revolutionize exploration of our Solar System.
Scientists infer that a small platinum-rich asteroid, just 200 meters in length, could be worth $30 billion. In response, it has been suggested that platinum, cobalt and other valuable elements from asteroids may be mined and sent to Earth for profit, used to build solar-power satellites and space habitats, and water processed from ice to refuel orbiting propellant depots. Asteroid 2011 UW158, which sailed at a distance of 1.5 million miles from Earth in July 2015, was worth an estimated $5 trillion in platinum.
Number of technological and economic hurdles will also need to be overcome. To make this concept a reality, we need to increase our knowledge of the very diverse population of accessible Near Earth Asteroids (NEA). Some of these are the high launch and transportation costs of spaceflight, inaccurate identification of asteroids suitable for mining, and in-situ ore extraction challenges. Economic costs extremely large, according to one the starting cost of asteroid mining to be $100B.
Challenges of Asteroid mining
A White Paper “Answers to Questions from the Asteroid Miners” presented at the European Planetary Science Congress (EPSC) 2017 in Riga on Tuesday 19th September by Dr JL Galache and Dr Amara Graps.
The White Paper covers questions surrounding the need for asteroid surveys in preparing for mining missions, the asteroid’s surface and interior, implications for astrobiology and planetary protection and other questions relating to policy and strategy for developing a roadmap for advancing asteroid in-space resource utilisation.
A number of knowledge gaps were identified: the asteroid miners need access to a map of known NEAs with an orbit similar to the Earth so that they can fine-tune their selection of potential targets. Many objects are – as yet – undiscovered, or very little is known about them, so there is also a need to develop a dedicated NEA discovery and follow-up programme.
Galache explains: “NEAs are usually discovered when they are at their brightest, so our best chance of studying them is by immediately following up detections with further observations to characterise their shape and spectral properties. That needs good quality, relatively large, dedicated telescopes that are available at short notice. We don’t have reliable access to these facilities right now.”
Further studies are needed to understand the link between meteorites and asteroids, and to share data more widely about the composition of meteorites so that more accurate simulant asteroid soils, or “regolith”, can be created. This is important for understanding which asteroids hold which resources, and for preparing for the practical side of a mining mission, such as landing and extraction of material.
“Aside from samples returned from a handful of missions, the only way we can study the composition of asteroids is by analysing light reflected from their surfaces, or by examining fragments that have landed on Earth in the form of meteorites,” says Graps of the University of Latvia and the Planetary Science Institute, Tucson, Arizona. “Both these techniques have limitations. Spectral observations come from the ‘top veneer’ of the asteroid, which has been space weathered and subjected to other kinds of processing. Meteorites are crucial, but they also lack part of the story: fragile constituents of primitive material contained within asteroids may be lost during atmospheric entry. At the moment, our mapping of types of meteorites back to the different classes of parent asteroid is not that robust.”
Three quarters of known asteroids are classed as Carbonaceous or “C-type”, dark, carbon-rich objects. However, most NEAs are from the Silicaceous “S-type” class of asteroids, which are reddish-coloured stony bodies that dominate the inner Asteroid Belt. For asteroid miners looking for water to use in rocket fuel or life support systems, being able to identify the class of asteroid is vital. Carbonaceous chondrite meteorites have been found to contain clay minerals that appear to have been altered by water on their parent body. While these meteorites are thought to be derived from sub-classes of C-type asteroids, there is not an exact match with any single spectral class.
A short-cut to understanding an NEA’s composition could be to identify where in the Solar System they formed and look at the characteristics of their “orbital family”. Thus, another knowledge gap is the link is between the dynamical predictions of where an NEA originates and its actual physical characterisations.
Information is also sparse on the size of grains at the surface of the asteroid. The asteroids Eros and Itokawa have similar spectral signatures and reflectiveness, but rendezvous missions show that they have very different regolith properties. NEAR Shoemaker showed that Eros is covered in fine dust, while Hayabusa revealed that the surface of Itokawa has chunky blocks tens of centimetres in diameter. Comprehensive knowledge of regolith properties at asteroids’ surface and subsurface will be vital for developing strategies for landing and extracting materials. However, as yet, no mission has explored how asteroid regolith might vary with depth.
“Results from ESA’s Rosetta mission showed that the surface of comet 67P/Churyumov Gerasimenko is much denser than its interior. It may be that we’ll find the same thing if we dig down into the regolith of NEAs. But at the moment, we just don’t know,” said Graps.
More work also needs to be done to understand the dynamics of granular material in low-gravity. Studies suggest that granular material can behave as a solid, a liquid or a gas in this environment. This behaviour will be particularly important for asteroids that are rubble-piles, as spacecraft trying to land or drill into these could easily destabilise regolith causing granular flow or avalanches.
Asteroid Mining solution approaches
There are three options for mining:
- Bring raw asteroidal material to Earth for use.
- Process it on-site to bring back only processed materials, and perhaps produce propellant for the return trip.
- Transport the asteroid to a safe orbit around the Moon, Earth or to the ISS. This can hypothetically allow for most materials to be used and not wasted. Along these lines, NASA has proposed a potential future space mission known as the Asteroid Redirect Mission, although the primary focus of this mission is on retrieval.
The fruits of space mining will be used initially in orbit rather than brought to Earth. There is scope for converting metals into components for spacecraft using 3D printing and robotic techniques. Manufacturing in orbit from materials available in space promises to be more economical than making things on Earth and lifting them into orbit.
Asteroid prospecting
Before asteroid mining can begin, there is the necessity of “asteroid prospecting.” In short, asteroids will first need to be identified, cataloged, and assessed for the value of their minerals and resources.
In 2012, NASA commissioned a project called Robotic Asteroid Prospector (RAP) intended to assess the feasibility of asteroid mining. They identified four different classes of asteroid mission that would be possible using conventional technology (or what is already in the process of being developed).
These included prospecting, mining/retrieval, processing, and transportation. Prospecting, the logical first step, involves studying and scoping out asteroids that would provide good economic returns.
Technology requirements
Once the prospecting is finished and the infrastructure created, the process of mining can begin. Fleet of mining robots and haulers would need to be built, capable of extracting ore and resources from Near-Earth Objects (NEOs) and hauling them back to Earth. A series of orbital platforms where vessels can dock, offload ores and other resources, and refuel, would also be needed.
There are several possible techniques that can be used, ranging from the more basic to the highly futuristic. These include surface mining, where minerals could be removed by a spacecraft using scoops, nets, and augurs. Shaft mining is another possible means, where spacecraft equipped with drills bore into asteroids to extract the materials within. Applying heat to asteroids and then collecting the ores or ices as they melt away is another possible method, as is chemical disassociation
The construction and maintenance of this infrastructure will involve a process known as in-situ resource utilization (ISRU). This involves using locally-harvested materials for manufacturing necessities like a propellant, components for orbiting platforms, oxygen, and even other spacecraft. This would not only simplify mining operations, but it would also lead to dramatically lower costs.
“Asteroid mining techniques will need to adapt to the low-gravity environment. Possible solutions include cancelling out action-reaction forces by digging in opposite directions at the same time, or by producing a reaction force, such as by strapping a net around the asteroid for robots to grab onto while they dig,” says Galache. “It’s a challenge! But answering the questions posed in this White Paper will be an important first step.”
Steam-propulsion is another method that has been proposed for asteroid mining. In this case, robotic spacecraft would harvest the oxygen in water ice to manufacture propellant, giving them a degree of self-sufficiency and the ability to mine indefinitely.
Grappling
Asteroids are massive tumbling targets with unstructured physical properties, and new grappling technologies will be needed to capture either a small asteroid or a boulder from a larger asteroid. Grappling systems are ranked as a high priority because they enable the physical capture of small asteroids and asteroid-sourced boulders, the attachment of said objects to robotic spacecraft, and the capture of free-flying spacecraft, says NASA.
Grappling technology would thereby support the transport of asteroids from their natural orbit to a lunar orbit, the human collection and return of samples from a boulder in lunar orbit, orbital debris mitigation, the protection of Earth from small planetary bodies, and the assembly of large spacecraft in orbit for future exploration missions.Potential commercial uses include securing boulder-sized asteroid samples for detailed sampling or processing in commercial space resources operations and securing dead satellites for return, disposal, salvage, or repair.
NUST MISIS Scientific-Educational Center for Innovative Mining Technologies
“We have already created a technical device allowing us to imitate the lunar soil. This soil is fundamentally different from the Earth’s. The main difference is that even with the same mineral composition, this soil will build up a strong electric charge, which will cause it to stick on wheels, compromise the safety of electronics and so forth. Today we already have the possibility of conducting tests in conditions close to those of the Moon’s environment,” said Pavel Ananyev. Moreover, we are currently developing an automated drilling rig, which will be necessary for exploration missions on natural objects in space.
“One more important area of focus at NUST MISIS is flash smelting: evaporation, separation and crystallization of soil and rock for obtaining metals (powders) for 3D printers in space. Using flash smelting, scientists can extract metals directly and thus bypass mining, enrichment and processing, which is important, since we cannot afford to build the same complex metal-processing facilities in space that we have on Earth.”
ESA and GomSpace sign contract for M-ARGO mission to develop miniaturized electric propulsion system
GomSpace’s subsidiary in Luxembourg and the European Space Agency (ESA) have signed a contract of $446,000 for the Phase A design of the Miniaturized Asteroid Remote Geophysical Observer (M-ARGO) mission.
Under the contract GomSpace will be in charge of preliminary design of the mission, spacecraft and implementation planning. A “12U” CubeSat spacecraft configuration is envisioned for the mission, packing in beyond state-of-the-art advancements in miniaturized technologies including communication, instrumentation, electric propulsion and operational autonomy to be demonstrated in the deep space environment.
Expected launch of the mission is in 2023, subject to funding of the implementation phase, and it will be the first nanosatellite ever to rendezvous with an asteroid and perform close proximity operations over an extended period for identification of in-situ resources.
“The M-ARGO technology demonstration mission is intended as an enabler of a potential future operational capability for highly cost-effective in-situ resource exploration of the accessible Near-Earth Object (NEO) population using a fleet of deep space CubeSats,” says Roger Walker, Head of ESA’s Cubesat Systems Unit. The NEO population now has more than 20,000 largely uncharted asteroids and the M-ARGO capability will be able to access the nearest 100 or more in terms of propellant needed to achieve a rendezvous.
NEOs are interesting not only for scientific exploration, but also for the potential of future long-term exploitation of minerals and other useful materials mined from asteroids. In addition, NEOs pose a threat for potential collisions with the Earth, requiring the need for further understanding of their physical properties for future planetary defense purposes. Nanosatellite technology will allow future cost-efficient exploration of these objects in significant numbers.
“Activities like M-ARGO allow us to develop our internal capabilities and technologies to new levels – not only to the benefit of science and exploration, but also to build competitive advantage for the commercial markets,” said GomSpace CEO Niels Buus.
Reflecting on the recently announced deep space projects, (Hera’s CubeSat to perform first radar probe of an asteroid and ESA and GomSpace sign contract to adapt and improve smallsat subsystems for deep space), Niels said: “With these orders we are very satisfied to have built significant momentum for space exploration capabilities – positioning us well to serve ESA – and other institutional customers – on future high-profile long duration missions.”
. The work will be supported by the scientific-technological university, Politecnico di Milano in Italy, providing expert support on deep space mission analysis and navigation of low thrust trajectories associated with electric propulsion. A contract is open to further European cooperation, and to maximize the outcome of the mission a scientific committee on asteroid mining is being set up to consolidate the scientific requirements and propose the most suitable instruments for the mission.
GomSpace’s subsidiary in Sweden and ESA have signed a contract to develop a miniaturized electric propulsion system suitable for small spacecrafts going on interplanetary missions. “This is an important step in expanding our propulsion capabilities. Providing such small spacecraft with its own propulsion capability of this caliber will significantly reduce the cost to perform interplanetary missions. Furthermore, such a propulsion capability will also find several applications on the commercial market in Earth orbits as well,” says CEO, Niels Buus, from GomSpace.
The project will expand GomSpace’s propulsion capabilities to span both cold-gas technology for station-keeping, collision avoidance and maneuvering as well as electric propulsion technology for orbit changes, e.g. for safely disposing of spacecraft after the end of a mission.
