2022-04-04 8 min read


Notes, 2022-04-04.

The use of resources around us – to create tools, harvest energy, and grow food – has been integral to human existence from our very beginnings as a species. We use (and use up) resources at hand: clean air and water, wild plants and animals, and more advanced resources, like rare-earth metals and hydrocarbons (the latter of which should now clearly stay in the ground). While we take the availability of these resources for granted, hundreds of generations of our ancestors worked to learn the skills needed for their extraction and use.

In aerospace, in situ resource utilization (ISRU) is the use of locally available resources for the manufacturing of fuel, food, and objects outside the atmosphere of our exceptionally cushy home planet. For example, using Martian or Lunar regolith (the top layer of loose material on celestial bodies that have a solid rock subsurface) as a manufacturing material to make shelters. While significant R&D has gone into ISRU techniques, very few have actually been demonstrated in space… but that is starting to change. With NASA & ESA’s Artemis program returning to the Moon, and the China National Space Administration’s program hot on their heels, local resources like the scarce water frozen in shadowed lunar craters will soon become valuable, and likely contested, resources.

If we want people to live in space long-term, we have to do it sustainably. Space is unforgiving to poor planning – if your oxygen recycling system leaks, if you run out of fertilizer for growing food, if you don’t have enough fuel, that’s it. Like resources on Earth, resources in space are not infinite and require progressively more energy to obtain and transport as the most accessible sources are consumed. And despite the click-generating false dichotomy that plays investment in space against investment on Earth, there’s a symbiotic relationship between the two. A solar-powered Sabatier process that converts CO2 to CH4 (methane) can be used on Earth or Mars, and splitting water into hydrogen and oxygen has applications for both Earthly energy storage and propellant generation on the Moon. Like counter-top microwaves and integrated circuits developed for Apollo, or Earth observation satellite data which provide the foundation for tracking climate change, we believe ISRU will continue the long history of space exploration benefitting life on Earth… even as we expand beyond it.

- Andrew Cantino & Ben Lachman

The most clicked link from last week's issue (~10% of opens) was a collection of buildings that show the breadth of shipping-container architecture. In the Members' Slack, the #tools channel has been buzzing with advice on the best order of operations to remove a stripped bolt and the best way to keep a CNC router's racks and pinions greased. Also, advice for picking up some very nice clothespins.

Planning & Strategy.

Making & Manufacturing.

Maintenance, Repair & Operations.

Distribution & Logistics.

  • A self-sustaining presence on Mars would require 100% ISRU, just as we do here on Earth. This would mean the production of both raw materials and high-complexity products like semiconductors and pharmaceuticals, outlined in this meta-analysis of the hypothetical colonization of Mars.
  • SpaceX’s Starship, a fully reusable launch system designed for high launch rates (maybe even multiple times per day), would dramatically reduce costs for getting things into space – it could reasonably decrease current launch from ~$2,000/kg to $200/kg, and SpaceX is targeting < $100/kg. Given these reductions, launching fuel and material from Earth for use in cislunar space is likely to remain cost-effective for a while. This paper estimates that propellant production costs on the Moon would have to be $4,000-$8,000/kg to be economical when compared to launching from Earth on current commercial launch vehicles. Starship only makes these economics more Earth-favorable, so we’re unlikely to see fuel tankers launching from the Moon for refueling cislunar spacecraft anytime soon.

Inspection, Testing & Analysis.


  • However, there is one thing that might be worth harvesting in space for use on Earth: Power. China, Japan, the EU, the UK, and the US (Caltech, Air Force, among others) are all exploring the feasibility of building solar power stations in orbit that would beam energy to the ground using either microwaves or lasers. It sounds crazy, but at scale, it could provide much-needed baseload power that is otherwise usually provided by gas or coal plants, and for which we have no great alternative without either a grid-scale energy storage breakthrough or a change in public opinion around nuclear power (we support both!).
  • Why are concentrations of useful metals found in only some asteroids (about 5% of those that are near Earth)? During the formation of the solar system, heavy, iron-loving (“siderophilic”) elements sank into the molten cores of newly-formed protoplanetary bodies. Over time, these protoplanets either merged or were broken apart through titanic collisions. Metallic asteroids are fragments of these shattered protoplanetary cores, enriched in valuable platinum-group elements. NASA’s upcoming Psyche mission will explore one of these fragments, a particularly large metallic asteroid in the main asteroid belt between Mars and Jupiter. (Expect to see frenzied media reports about NASA visiting an asteroid worth $10,000 quadrillion.)
  • And where did lunar water come from? The solar wind and comets.
  • Of course, humanity’s use of resources on Earth has always been ISRU, and while all mass on Earth is originally space material, some of it was delivered a bit more recently. Early human metalwork often used meteoric iron, like a dagger found in the tomb of King Tutankhamen. A recent study used nondestructive two-dimensional chemical analyses and found the classic Widmanstätten pattern on the blade’s surface, which “implies the source meteorite of the dagger blade to be octahedrite”. The preservation of the pattern through forging suggests that the dagger was manufactured by low-temperature (< 950 °C) processes, while calcium impurities in the golden hilt hint at a calcium-based plaster adhesive, putting the dagger’s likely origin in Anatolia, not Egypt.

    If you want to make your own meteoric tooling, you can buy chunks of the massive Campo del Cielo iron meteorite. Or, you could build a meteorite-hunting drone and then extract platinum from space rocks from the relative safety of your garage.

An entrance to one of the Undara lava tubes in Queensland, Australia.

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