This is Part One of a three-part series on space-based manufacturing and logistics.
In the past, I assumed that serious, ‘at scale’ manufacturing in space wouldn’t start until several decades in the future — with the possible exception of 3D printing of repair/replacement parts in space. Recently, it is looking like we might start to see some commercial space-based manufacturing within the next decade, starting at a relatively small scale but potentially ramping up quicker than expected.
Manufacturing a Giant Telescope Lens in Space
A year before the Hubble Space Telescope (HST) was launched in 1990, scientists started exploring what the next space-based optical telescope should look like. 32 years later, those discussions came to fruition with the launch of the James Webb Space Telescope (JWST) in December 2021. It is an engineering marvel, pushing the limits of remote autonomous technology in a self-assembling, self-adjusting, super-accurate scientific instrument that successfully deployed itself while traveling almost a million miles from the nearest human. While en route to where it is permanently deployed (in a halo orbit at the L2 Lagrange point),1 it unfolded itself and then adjusted its 18 hexagonal 1.4m (4’ 7”) primary mirrors, which are adjustable in 6 spatial degrees of freedom to within 10 nm (about 1/2,000,000th of an inch) of accuracy.2 The lens is about 25 m2, about six times larger than the surface area of the Hubble Space Telescope’s 4.5 m2 primary lens.
Unsurprisingly, there are already discussions underway about what the next space-based optical telescope will be. One challenge is how to create a lens that is at least 125 m2 (>40 feet in diameter), while still maintaining an accuracy of ±10nm or better. A self-unfolding array of mirrors gets very unwieldy at that size. One line of thinking is to manufacture the lens from scratch in space. This may sound like science fiction, but it is a serious proposal. In the zero gravity of space, liquids eventually settle into nearly perfect spheres due to the effects of surface tension free from the pull of gravity distorting the shape of the liquid. The idea is to create a sphere of liquid polymer or some other liquid that can be hardened (with UV light, heat, or other means) once it has become perfectly spherical. The Fluidic Telescope Experiment (FLUTE), a collaboration between NASA’s Ames Research Center, the Goddard Space Flight Center, and the Technion-Israel Institute of Technology, has conducted a series of experiments first underwater, then in parabolic flights, and later this year3 at the International Space Station (ISS) where they will create a small proof-of-concept lens.
This envisioned next-generation space telescope is an extremely specialized, one-of-a-kind project with a budget of billions of dollars. Therefore, it is dubious to say it is an indicator that we are ready for a surge in space manufacturing. But there are other reasons to think space-based manufacturing’s time may be drawing near. In the past, the cost of getting things and people into space has made manufacturing in space economically infeasible. Launching things into Low Earth Orbit fell from the initial price of about $1,000,000/kg on the Vanguard 1 rocket (launched in 1958) to about $85,000/kg in the early space shuttle, to staying stuck at about $10,000/kg during the decade of 2000-2010. Even at those prices, only rare or very special commodities or machines make it into orbit and back. Such economics don’t enable mass manufacturing in space. However, with the privatization of launch vehicles, the price has fallen to under $1,000/kg (with the SpaceX Falcon Heavy) and may approach $100/kg before the end of this decade.4 Looking further out (decades from now), space elevators5 may provide a path to $1/kg launch prices and possibly even lower in the long run, though these elevators would require huge leaps in material sciences and new technology developments.
Figure 1 – Estimated Launch Cost Per Kg for LEO Payloads (logarithmic scale, inflation-adjusted to 2000 $)
While Figure 1 neatly fits our narrative, it oversimplifies the variation between different launch vehicles, as well as glosses over our uncertainty about the actual rate of decline in future launch costs. Figure 2 below provides a more complex view of past launch costs over time, based on data from the Center for Strategic and International Studies’ Aerospace Security Project. It shows that there has been and will continue to be a wide range of launch costs, depending on the vehicle size and other factors, and the drop in launch costs is not quite as dramatic as the cherry-picked launch costs in Figure 1 imply.
Figure 2 – Cost of Space Launch for LEO Payloads, Various Launch Vehicles, in 2021 Dollars
Nevertheless, launch costs have dropped to their lowest levels ever over the past decade, and the expectation is that launch costs per kilogram will continue to decline. With these falling launch costs, we are starting to get into an era where the economics of space-based manufacturing might make sense for some specialized materials and components.
Why Manufacture Anything in Space?
Even though the cost of launching into space has been plummeted, it is still about 50 to 1,000 times more costly to launch cargo into low earth orbit than to ship freight from one side of the planet to the other using standard ocean and ground transport.6 So why would anyone manufacture anything in space, given those ultra-high transportation costs? Space-based manufacturing holds promise for some very specific needs because it has some attributes that are difficult or virtually impossible to simulate on earth:
- Zero-gravity — The weightlessness in space eliminates convection and sedimentation, enabling immiscible materials7 to be intermixed and remain mixed. Weightlessness also enables the growth of much higher-quality and larger crystals compared to those grown under the influence of gravity. As mentioned above, zero gravity allows the creation of near-perfect spheres.
- Ultraclean vacuum — The near-perfect vacuum of space allows the creation of ultra-pure materials and parts, including the use of vapor deposition to build up objects in layers, free from defects. It is sort of like the perfect cleanroom for ‘free’ (i.e., once you get there).
- Extreme heat and cold — In space, sunlight can be concentrated in a controlled way to create extreme heat. In the shade in space, objects will automatically cool to near absolute zero temperature, without requiring any of the highly specialized cryogenic refrigeration equipment needed to attain those temperatures on Earth. The extreme temperature gradients can be used for various purposes, such as to produce strong, glassy materials.
Materials or components that have a high value-to-weight ratio, and require any of these capabilities, are candidates for manufacturing in space. In Part Two of this series, we examine some specific examples of manufacturing applications being considered or pursued, including ZBLAN optical fibers, biomanufacturing, construction of large structures, space-based farming, drugs, microfabrication, carbon nanotubes, and perfect spheres.
1 The L2 Lagrange point is a point in space about 930,000 miles from the Earth, on the opposite side of the Earth from the Sun. Due to the combined gravitational pull of the Earth and the Sun at that point, objects that remain fixed at the L2 point automatically orbit the Sun in exactly the same period as the Earth, even though they are further away from the Sun. Thereby they maintain that same relative position on the opposite side of the Earth from the Sun. — Return to article text above
2 On March 16, 2022, NASA announced it had completed the alignment of the JWST’s optics. Lee Feinberg, optical telescope element manager for JWST said “The optical performance of the telescope is absolutely phenomenal — as good, if not better, than our most optimistic predictions.” Marshall Perrin, JWST deputy telescope scientist added “The images are focused together as finely as the laws of physics allow. This is as sharp an image that you can get from a telescope of this size.” — Return to article text above
3 The equipment for the experiment at the ISS was launched on April 8, 2022, with the Ax-1 mission. NASA said the experiment will take place “in the first half of 2022”. — Return to article text above
4 Elon Musk has predicted costs approaching $10/kg for launching cargo into LEO aboard the SpaceX Starship. Many observers are highly skeptical of that aspirational number, but some believe a cost approaching $100/kg might be feasible within a decade. — Return to article text above
5 Space elevators are a hypothetical planet-to-space transportation system comprised of a space tether — i.e., an extremely long cable, anchored to the surface of the planet and extending out into space, out beyond geostationary orbit, with a large counterweight attached at the orbiting end of the cable in space. The centrifugal force of the counterweight orbiting the planet keeps the cable aloft. Launch vehicles would repeatedly climb up and down the tether by mechanical means, rather than by rocket propulsion. No known material is strong enough to build the space tether that could withstand Earth’s gravity. Proponents of Earth-based space elevators envision material scientists inventing stronger materials to make such space elevators feasible. Materials already exist that are strong enough to be used for a space tether on the Moon. It is conceivable that a Moon-based space elevator may be built and used to prove out the concept and economics. — Return to article text above
6 The least expensive current launch option, the Falcon Heavy, costs about $1,000/kg of payload. Shipping from China to the US has historically cost around $1-$2/kg when supply and demand were balanced. (Prices have been higher recently due to higher demand, but we expect eventually for demand and supply to come back into balance.) Coast-to-coast shipping in the US has historically been about $10-$12/kg for rail and about $50-$60/kg for trucks. Sources: Bureau of Transportation Statistics Average Freight Revenue per Ton-Mile and https://www.freightos.com/freight-resources/ocean-freight-explained/ — Return to article text above
7 E.g., examples of immiscible liquids include oil and water, molten silver and lead, pentane and acetic acid, gasoline and water, and methanol and hydrocarbon solvents. — Return to article text above
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