How to build a lunar mass driver – Casey Handmer's blog

Skip to content

Search

Search for:

Casey Handmer May 2026

What?

Elon has recently (late 2025, early 2026) been talking about building many terawatts of orbital AI compute and launching some components from Moon factories with a mass driver. This is an old idea, enabled by the Moon’s relatively low gravity and lack of an atmosphere. See, for example, The Moon is a Harsh Mistress and The High Frontier.

The fundamental problem with The High Frontier is that the set of products that can be made in space and sold on Earth while making money is very limited, due to the sheer cost and difficulty of accessing space. In general, they are observations and communication, which in both cases distributes the product using radio waves, which are much cheaper than physical return of artifacts from space.

In 2019, I wrote that Starlink was likely to be incredibly lucrative and I’m happy to see this is the case, with over $10b in revenue last year. Space AI takes this business model and ramps it up to 11. Why? Starlink has already established that converting a space solar photon into an electron and using it to relay bits of information around the world is extremely profitable. Space AI is a great way to vastly increase both the total demand for space data bits as well as the value per bit, as the tokens encoded by these bits have already proven to have stupendous economic value and apparently unlimited demand.

Why?

Starship promises a near future with launch costs to LEO of perhaps $100/kg. With electric propulsion, large quantities of cargo, including solar powered AI can be positioned anywhere in cis-Lunar space for an incremental cost beyond that. For AI hardware, most of the cost is in the GPU/TPU die, which contributes almost no mass, while most of the mass is in the solar panel and radiator, which cost (relatively speaking) almost nothing.

Here’s a spreadsheet I put together last year with some basic first-principles analysis. At even $500/kg, launch cost is only 5% of the total satellite deployment cost, so a lunar mass driver is unlikely to drastically improve the economics of space-based AI, by reducing launch costs.

It’s also unlikely to have low start up costs!

Instead, we must look to a future where Starship costs stop falling from experience and economies of scale and rise to unaffordable levels, perhaps comparable to the Shuttle’s $50,000/kg, because of a constraint on launch capacity.

In my spreadsheet, I estimate that one Starship can deliver about 15 MW of solar power to orbit. Last year, China produced over 1 TW of solar photovoltaic panels. Supposing we weren’t constrained by chip fabrication and Starship was fully operational, it could launch 1 TW to orbit per year with just 67,000 launches, or one every 8 minutes.

This might seem like a lot, but the world currently sustains about 100,000 commercial flights per day! In a world where SpaceX can turn around a launch site in an hour, only seven or eight pads would be necessary to keep up with this rate of launch, requiring a fleet of perhaps 10 boosters and a few hundred Starships.

Nor would this launch rate defeat our global oil production. One Starship launch consumes roughly 10,000 barrels of oil (equivalent), and the world currently consumes 100 million per day. So 67,000 launches per year is less than a week of the world’s current supply of oil. It may require a few gas pipelines in Texas to be upgraded, and of course by the time this happens solar synthetic fuel will be a recognized and mature technology.

There has been some speculation about damage to the upper atmosphere of the Earth caused by huge launch volumes.

In any case, we’re talking about a launch volume of hundreds of thousands of Starships per year, or more than 10 million tonnes of cargo per year, with a total launch revenue of about a trillion dollars – equivalent to about six weeks of the global oil and gas industry!

The lunar mass driver must transcend this scale.

What does the lunar mass driver drive?

The Moon is made of rocks. Primarily volcanic rock, similar to Earth basalts. As ores go, they are not preferred sources of metals on Earth. Though they contain nearly every metal – the net present value of the metal in 1 tonne of basalt is about $1300 vs the $20 price as crushed gravel – they’re mixed together and generally considered energetically infeasible to extract. We’re working on this at Terraform but the energy demand is a fact of life.

In one model, the lunar mass driver fires raw rocks into Lunar orbit, to be processed in space using copiously available space solar power. In another model, moon rocks are pre-processed to increase their metal content, or even converted into finished products, before launch. Blue Origin has demonstrated a process to convert Lunar regolith (dirt) into a functioning solar panel, but it’s not clear what the energy return on energy invested for this process would...