Asteroid Mining for Earth will fail

But Asteroid Mining will still be hugely successful

ArsTechnica recently wrote about AstroForge, an asteroid mining startup, raising $45M. I’m skeptical about it ever being economical to mine asteroids in order to return materials to earth. Not only will it be incredibly expensive, but the business model suffers from its own success. The typical argument points out that a single asteroid can contain billions or trillions of dollars of some precious metal like Gold or Platinum, but ignores the fact those metals are “precious” because of their rarity. In the case of Platinum, if you spend $10B to mine and return $30B in platinum from an asteroid, it seems like a hugely profitable venture. But $30B in platinum is 1,000 tons, and the entire world production of platinum is less than 200 tons per year. So your $30B melts away as your massive surplus crashes prices.

What most are missing in the article is that basic math/physics indicates costs are likely always be prohibitive for asteroid mining, as long as earth as the destination customer. But asteroid mining will clearly be incredibly economically successful, for the space based economy itself.

We can have a good idea that once fully optimized decades hence, future fully reusable chemical rocket based launch systems inspired by Starship will decline in cost to approach launch prices of $5M for 100 tons into orbit. This is based on the assumption that with far higher cadence spreading out operational costs across far more flights (and expected increase in reusability lifetimes and time between maintenance) it will start to get close to the commercial passenger aviation model where fuel costs are roughly 20% of the ticket prices.

That's a roughly $50/Kg tax to pay for LEO's 9 km/sec to move only a few hundred kilometers from earth (by comparison I pay $5/Kg for a cross country flight today). So everything that is brought into orbit will always be expensive, just far less so than it was during our previous lifetime ($80,000/Kg on Shuttle, currently $2,000/Kg on a Falcon Heavy).

But once in LEO, things get far cheaper. To go 225 million km away to land on Mars from LEO is nominally 9 km/sec, but with aerobraking really only around 5-6 Km/sec. But once in space you get to use solely vacuum optimized engines to increase ISP significantly, and because the rocket equation essentially exponentially increases fuel mass requirements, meaning going from LEO to Mars can require as little as 1/4 as much fuel as it took just to get to LEO.

But still paying LEO tax on that fuel makes it very expensive. But while valuable metals are relatively rare in asteroids, the building blocks of chemical rocket fuels, water and carbon based (organic) chemicals, are relatively common, Water has been found even on stony asteroids in low quantities. So making methane and LOX should be doable on most asteroids by processing outgassing from heating carboniferous rocks to high temperatures with power supplied by power generated by solar panels at far higher effective rates than on earth, unimpeded by night or atmosphere. Unfortunately the round trip deltaV to most near earth asteroids is over 8 km/sec, so on the surface the NEA tax is as high as the LEO tax. But this is deceiving for several reasons.

First, you only pay the tax one way for the mining/fuel production equipment sent to the asteroid (and to be hosted there permanently slowly reducing raw materials to fuel),so again about a quarter of the cost of getting the equipment to orbit. And once producing fuel from a NEA, the fuel needed to ship your production back to LEO is essentially free. In fact the fuel itself can be incredibly cheap when it gets to LEO if automated mining/production machinery can be built. The costs of making all the machinery on earth (mining, production, and automated shipping tankers), launching them to space and sending to the NEA are your fixed costs, your only variable costs are maintenance of the tankers and production equipment.

Its estimated are at least 1,000 NEAs over a KM in size, which should mass at least a half trillion tons each. There is actually an earth crossing “armor” classification dead comet named 3552 Don Quixote estimated to contain 20 trillion tons of water alone. But more easily accessible asteroids such as 101955 Bennu have water and veins of carbonate minerals, and it has a mass of 70M tons despite only being 500 meters in diameter.

So if it cost ten billion dollars to manufacture and ship an automated fuel production system to a NEA and it produced a million tons of Methalox before maintenance/replacement is required, your total costs would be $10,000 per ton of Methalox, versus a minimum cost of of $50,000/ton launched from earth. Note: I've obviously simplified and skipped over a great many problems that have to be solved in the production process in this analysis. Most importantly its quite likely that humans will be needed to operate and frequently maintain the equipment, adding to your costs. But you can see there is a lot of margin to pay for that.

But I think this shows that even in the most optimistic near future where launch costs plummet to $50/kg from todays cheapest $2,000/kg, it will be far cheaper to mine asteroids for the fuels needed to power our exploration and expansion into deep space and the rest of the solar system.

For just one potential example, at $50/kg a passenger ticket for a single person to low earth orbit could decline to roughly $10,000 each, but tickets from LEO to Mars using NEA generated fuels can be a fraction of that cost. The cost of food/life support on the long trip might be higher than the fuel costs. Or not given the trip can be done in less than 45 days with chemical rockets if fuel is cheap and plentiful at the LEO refueling depots.

Once the new "oil rush" in space is well underway with multiple NEA's supplying tens of thousands of tons of methalox to LEO based launch platforms, the infrastructure for supplying LEO based manufacturing systems with other raw materials from NEAs such as iron, aluminum, silica, etc should rapidly grow out of it. There is no reason to lift heavy metal frames, plates and glass from earth paying that LEO tax on every Kg, when they can be manufactured at an NEA and cheaply shipped back to LEO far less expensively. Using NEA metals/silicates to build the heaviest mass parts of your spaceships and habitats will greatly reduce the costs of space expansion and increase the supply of materials for it.

Once that happens, earth launch capacity will evolve to be mostly used for us meat-bags and for specialized high tech components such as electronics, fiber materials, and plastic materials that are difficult to make in space. Over time anything that can be produced in space will replace earth based production because shipping earth production to LEO cannot be competitively priced with the LEO DeltaV tax.

So the future of asteroid mining will be almost entirely for those who live and work in space. Little of its output will make it to earth. But it will significantly increase the resources available for and reduce the costs of traveling to deep space destinations like Mars, building space stations, space ships and will make the space based economy functional, even prosperous.

.