Asteroid Mining Could Draw on Carbon-Rich Asteroids

Just a few years ago, asteroid mining was one of the most talked-about ideas in space exploration. As the commercial space industry expanded quickly, the prospect of commercialising space appeared to be drawing close.

The concept of deploying platforms and spacecraft to rendezvous with and mine Near-Earth Asteroids (NEAs), before taking their materials to space-based foundries, seemed as ambitious and plausible as transporting commercial crews to Mars.

Following extensive speculation and the collapse of several ventures, however, such ambitions were pushed aside until technology could advance and other essential milestones were met first.

Asteroid mining and carbon-rich asteroid research

Even so, the vision of asteroid mining and the “post-scarcity” future it might enable has endured. Alongside the need for more infrastructure and technical progress, scientists must carry out further work to establish the chemical composition of small asteroids.

In a recent study, a group led by researchers at the Institute of Space Sciences (ICE-CSIC) examined samples from C-type, or carbon-rich, asteroids, which make up 75% of known asteroids. Their results indicate that these bodies may represent an important source of raw materials and could offer opportunities for future resource extraction.

Dr Josep M. Trigo-Rodríguez, a theoretical physicist at Barcelona’s Institute of Space Sciences (ICE) and Catalan Institute of Space Studies (IEEC), led the team.

His collaborators included PhD student Pau Grèbol-Tomàs, also of ICE and IEEC; Dr Jordi Ibanez-Insa of Geosciences Barcelona; Professor Jacinto Alonso-Azcárate of the Universidad de Castilla-La Mancha; and Professor Maria Gritsevich of the University of Helsinki and the Institute of Physics and Technology at Ural Federal University.

Their research is described in a paper due to appear on 2 January in the Monthly Notices of the Royal Astronomical Society (MNRAS).

Carbonaceous chondrites and asteroid composition

Carbonaceous chondrites, also known as C chondrites, regularly reach Earth, although scientists seldom recover them for examination. They account for only 5% of all meteorites, and their fragile composition means they frequently break apart and are lost. Most recovered examples so far have been discovered in desert environments, including the Sahara and Antarctica.

ICE-CSIC’s Asteroids, Comets, and Meteorites research group, headed by Trigo-Rodríguez, studies the physicochemical characteristics of asteroids and comets. The group also serves as the international repository for NASA’s Antarctic meteorite collection.

For the new study, the researchers chose and characterised asteroid samples before Professor Jacinto Alonso-Azcárate at the University of Castilla-La Mancha examined them using mass spectrometry.

The analysis established the detailed chemical composition of the six most prevalent categories of C chondrites. This provides useful evidence about whether extracting resources from them could become possible. Trigo-Rodríguez said in a Spanish National Research Council (CSIC) press release:

"The scientific interest in each of these meteorites is that they sample small, undifferentiated asteroids, and provide valuable information on the chemical composition and evolutionary history of the bodies from which they originate.

"At ICE-CSIC and IEEC, we specialize in developing experiments to better understand the properties of these asteroids and how the physical processes that occur in space affect their nature and mineralogy. The work now being published is the culmination of that team effort."

Understanding how much material asteroids contain is crucial because they are extremely heterogeneous. Although they are generally divided into three groups - C-type (carbonaceous), M-type (metallic) and S-type (silicaceous) - they are also categorised according to their spectral properties and orbits.

Asteroids are also effectively leftover material from the Solar System’s formation, and their composition has been strongly shaped by an evolutionary history spanning about 4.5 billion years. Determining their exact make-up is therefore necessary for identifying where various resources, including water and ores, may be found.

Resource extraction in microgravity

The team’s findings suggest that mining undifferentiated asteroids, thought to be the parent bodies of chondritic meteorites, is far from practical. However, the study identified an asteroid type containing abundant olivine and spinel bands as a possible target for mining operations.

The researchers also said that water-rich asteroids containing high levels of water-bearing minerals should be prioritised. For now, they stress that more sample-return missions are needed to confirm the identities of parent bodies before mining can become a reality. Trigo-Rodríguez said:

"Alongside the progress represented by sample return missions, companies capable of taking decisive steps in the technological development necessary to extract and collect these materials under low-gravity conditions are truly needed. The processing of these materials and the waste generated would also have a significant impact that should be quantified and properly mitigated."

In their view, this will mean creating large-scale collection systems and techniques for extracting resources in microgravity.

"For certain water-rich carbonaceous asteroids, extracting water for reuse seems more viable, either as fuel or as a primary resource for exploring other worlds," said Trigo-Rodríguez.

"This could also provide science with greater knowledge about certain bodies that could one day threaten our very existence. In the long term, we could even mine and shrink potentially hazardous asteroids so that they cease to be dangerous."

Grèbol-Tomàs added:

"Studying and selecting these types of meteorites in our clean room using other analytical techniques is fascinating, particularly because of the diversity of minerals and chemical elements they contain. However, most asteroids have relatively small abundances of precious elements, and therefore the objective of our study has been to understand to what extent their extraction would be viable.

"It sounds like science fiction, but it also seemed like science fiction when the first sample return missions were being planned thirty years ago."

In any event, the potential advantages of asteroid mining are substantial, explaining why the subject attracted so much attention over the previous decade. Beyond precious metals, many asteroids contain water ice that could be used to produce fuel for deep-space expeditions, as well as water for drinking and crop irrigation.

This could lessen dependence on resupply flights from Earth and allow robotic and crewed missions to become more self-sufficient. Moving mining and manufacturing activities into cislunar space and the Main Asteroid Belt would also reduce the environmental effects these industries have on Earth.

Although public interest in asteroid mining has declined during the past decade, many organisations continue to investigate and develop the required technologies. Space agencies such as NASA and JAXA have likewise completed sample-return missions, revealing much about both the scientific value and material riches that asteroids may hold.

In the near future, China’s Tianwen-2 mission will rendezvous with an NEA and a comet in the Main Asteroid Belt. A space-based resource industry may still be many decades away, or longer, but plenty of groups are ready to be involved from the outset.

Further reading: CSIC, MNRAS

This article was originally published by Universe Today. Read the original article.