Asteroid mining has received a lot of attention, both as a possible way of addressing resource shortages and as a way of reducing the environmental impact of mining on Earth. While it is assumed that asteroid mining is still a far-off dream, the recent Planetary and Terrestrial Mining Science Symposium may suggest otherwise.
While the main focus of the Symposium was lunar mining, the session focused on asteroid mining showed that there was real possibility in extracting resources from asteroids using recognizable technology in the near term.
Two of the presentations, by MDA’s Cameron Dickinson and by Trans Astronautica (TransAstra) Corporation’s Joel Sercel, showed us that asteroid mining may be closer than we thought, more accessible than we thought, and maybe even a bit easier than we’d thought.
Resources on Bennu
Dr. Cameron Dickinson’s presentation was on the OSIRIS-REx mission to asteroid Bennu. Bennu is a B-type near-Earth asteroid with an orbit that takes it comparatively close to Earth, getting as close as 480,000 km annually in late September.
If Bennu was barren, it would likely remain little more than a curiosity. Dickinson said that one of the OSIRIS-REx mission’s most important findings was confirming that, no, it’s far from barren. Dickinson said that they took extensive measurements during OSIRIS-REx’s two years at the asteroid making it the most heavily surveyed object in the solar system. The Canadian’s OSIRIS-REx Laser Altimeter he worked on “laid down around three billion shots across the surface.” They found a lot of resources.
Their most immediately important finding may be that Bennu has a lot of water. Based on the analyses done by scientists involved in the OSIRIS-REx mission, more than 1% of Bennu may be made of water, and it could be well more than 1% water. Despite Bennu’s comparatively small size, over .7 megatonnes of water might be available for extraction.
As we pointed out in our earlier article from PTMSS and lunar mining, water is one of the most important resources in space: not only can it be used to sustain life, but it’s easily turned into efficient and lightweight rocket engine propellant. While some launch companies rely on methane instead — notably including SpaceX — it’s widely expected that most companies will rely on these water-based propellants. Considering how important water is in space and how much water is on Bennu — Dickinson estimated it would be worth $2.8 trillion at current prices — Bennu could become a key source for cislunar propellant, and could even serve as a “gas station” for travel within cislunar space.
It may also be comparatively easy to access. Dickinson explained that the composition of Bennu is remarkably loose and porous. It was so simple to get materials for their sample acquisition with a simple blast of gas that they ended up ejecting far more material than they were expecting, and left a larger crater than they were planning. Even Bennu’s boulders only have the consistency of what Dickinson called “a charcoal briquette.” Dickinson said that this would mean that extracting resources from Bennu could be even more straightforward than one might have hoped.
Dickinson says that it’s likely that Bennu is also rich in iron, nitrogen, carbon, and sulfur, among other resources. Carbon could be especially important for companies like SpaceX which rely on methane based propulsion. Companies like SpaceX that rely on methane can manufacture it given sources of carbon, hydrogen and oxygen. While SpaceX head Elon Musk has expressed skepticism about asteroid mining, SpaceX’s reliance on methane as fuel may lead them to become key cislunar customers for Bennu’s resources. The difficulty and expense of lifting resources from Mars and Earth, and the lack of carbon in lunar regolith, may make Bennu a sorely needed source of propellants.
So, no, Bennu is far from barren. The asteroid could have tremendous economic value. Dickinson said that the yield from only the first metre of Bennu could theoretically top $300 billion, and even a very conservative estimate of the yield from the asteroid’s top layer would be $30 billion. He followed that up by saying that the more likely and reasonable yield from the asteroids top metre would be 30 billion, which is still impressive considering its comparative accessibility to Earth — and its comparative value as a source of resources in space that don’t need to be launched from Earth, Mars, or the Moon.
This points to the tremendous potential of asteroid mining: while B-type asteroids are comparatively rare, Bennu is still just one asteroid of the tens of thousands in near-earth orbits. Dickinson gave a specific reference to another presenter during the session, TransAstra, which was demonstrating one way that resources might be extracted from these thousands of asteroids.
TransAstra’s Apis asteroid miners
The presentation by TransAstra’s Joel Sercel focused on demonstrating their asteroid harvesting technology. The “Apis” (Asteroid-Provided In-Situ Supplies) system consists of several distinct sizes of semi-autonomous drones.
Fitting the Apis name, each of the asteroid mining drones is named after a type of bee. The desktop-sized “Mini Bee” would handle small asteroids and asteroid chunks. The midsize “Honey Bee” would be the size of a communications satellite, handling asteroids and chunks up to 10m in diameter. The largest — the “Queen Bee” — would process asteroids and chunks of up to 40m in diameter, and TransAstra produced a video simulating a Queen Bee in action.
(Sercel mentioned other drones for transportation and logistics called “Worker Bees”, but gave no further details.)
Each of the “Bees” work similarly, using a technique called optical mining. The drones approach an appropriately-sized asteroid and envelop it in a flexible bag. After the bag is shut using a mechanical zipper, the reflectors on the outside of the drone channel light into the drones interior, which then focuses the concentrated light on the asteroid to break it up and vaporize the useful volatiles. The Bee then separates the volatiles from the solids, stores the volatiles as ice separately from the solid byproducts, and returns both to a depot for further processing.
Sercel estimated that up to 80% of the water in the asteroid could be extracted this way. He said that the water would be “dirty water” and would need further refinement and purification, but also said that the dirty water would still work as propellant for the drones’ “omnivore” solar powered thruster. If Apis works as expected, the drones will only require propellant to reach the asteroid. Once they’ve finished mining the asteroid, they can use the asteroid’s “dirty water” as propellant in order to return with their prize.
TransAstra is aiming to demonstrate this process during an upcoming rideshare, where they’ll be launching both a prototype MiniBee and a 50cm simulated asteroid that the MiniBee will capture and process. TransAstra has received both NASA and private sector funding, and are using that funding to test the omnivore thruster, demonstrate and refine the optical mining concept, and rapidly iterate on terrestrial versions of Mini Bee components. Their goal is to refine and improve the Mini Bee’s components, and to “reduce these components to TRL 4-5” in preparation for building and launching the space-ready Mini Bee and its simulated asteroid in the near future.
This is only one of many possible approaches from many asteroid companies. But these two presentations show us two things: that asteroid mining might be closer than we might have expected, and may be more lucrative than we’d ever imagined.