While SpaceX and Blue Origin tend to dominate the headlines, a new wave of private companies is quietly forging the future of orbital launch. Many of them are introducing radical, ground-up innovations to the aerospace sector. This article, part of our ongoing series on these industry trailblazers, focuses on one of the most ambitious: Relativity Space.
Today’s launch proved Relativity’s 3D-printed rocket technologies that will enable our next vehicle, Terran R. We successfully made it through Max-Q, the highest stress state on our printed structures. This is the biggest proof point for our novel additive manufacturing approach…. pic.twitter.com/9iaFVwYoqe
– Relativity Space (@relativityspace) March 23, 2023
Founded in 2015 by Tim Ellis and Jordan Noone, Relativity Space set out to achieve something unprecedented: building an entire orbital rocket using 3D printing. This meant moving beyond just printing engine parts to printing the primary structure, fuel tanks, and oxidizer tanks. To pull this off, the company recruited top experts in metal additive manufacturing to develop the massive machines and novel processes required to build a structure of this scale.
Originally based in Los Angeles, the company moved to its current Long Beach, California headquarters in 2020. Notably, Relativity maintains an incredibly transparent culture. Instead of relying on hype, they openly share their concrete progress and technical hurdles with the public.
Terran 1
Relativity’s debut vehicle, the Terran 1, stood 34 meters tall. It was a two-stage rocket fueled by liquid methane and oxygen, powered by nine Aeon-1 engines on the first stage and a single vacuum-optimized Aeon-1 on the second. Designed to carry up to 1.5 tons to Low Earth Orbit (LEO) or 900 kg to Sun-Synchronous Orbit (SSO) at $12 million per flight, the vehicle made its historic first launch in March 2023 from the Cape Canaveral Space Force Station.
Although a second-stage ignition failure prevented the rocket from reaching orbit, the test was largely hailed as a massive success. The first stage performed flawlessly, successfully enduring the extreme aerodynamic stresses of Max-Q. For a radically new rocket architecture, proving the structural integrity of a 3D-printed airframe in flight was a monumental achievement. Furthermore, reaching orbit on a maiden flight is historically rare, and in-flight ignition of a liquid-fuel engine in a zero-gravity vacuum is notoriously difficult to simulate on the ground.
Why 3D Print a Rocket?
Traditionally, rockets are assembled from thousands of separate components—flat metal plates, machined blocks, and cast parts. Each must be meticulously measured, fitted, and welded or bolted together to prevent leaks and structural failures. It is an incredibly labor-intensive, slow, and expensive process.
3D printing allows engineers to consolidate hundreds of individual components into a single, highly complex printed part, perfectly replicated every time. For example, according to Relativity, a traditional engine injector might consist of 1,000 individual parts and take nine months to build. Relativity prints theirs as a single piece in just two weeks, at a tenth of the cost.
Why Isn’t Everyone Doing It?
If the advantages are so clear, why isn’t the rest of the manufacturing industry doing it? The answer is production volume.
3D printing is far too slow for mass-producing millions of consumer goods like cars or appliances. For high-volume manufacturing, investing in custom molds and stamping presses is much more cost-effective. However, rockets are built in very small quantities and are highly experimental, requiring constant adjustments. This makes the aerospace industry uniquely suited to the flexibility of 3D printing.
So why haven’t legacy aerospace companies copied Relativity’s approach? Put simply: the immense R&D required. Relativity had to pioneer proprietary printable aluminum alloys and build the world’s largest metal 3D printers, known as Stargate. It took years of trial and error – generating what CEO Tim Ellis called “piles of melted metal” – to perfect the process.
While legacy providers and organizations like NASA’s JPL successfully use metal additive manufacturing for small, complex engine or probe components, printing an entire rocket airframe carries a level of risk and developmental delay that most traditional companies are unwilling to take on.
The Engineering Details
By mass, 86% of the Terran 1 was 3D printed. This allowed Relativity to print the propellant tanks and the rocket’s primary structure as a single continuous piece, eliminating thousands of traditional joints and welds.
The Aeon-1 engines also featured fully printed regenerative cooling channels (which heat the propellant while cooling the engine nozzle), a historically difficult component to manufacture without leaks. To further reduce part counts, the engines utilized autogenous pressurization. Instead of relying on heavy, separate tanks of inert gas (like helium), the heated propellant gas is fed back into the main tanks to maintain pressure. While historically rare for first-stage boosters (used notably on the Space Shuttle and Titan 34D), autogenous pressurization is now being used or considered for next-generation heavy lifters like Starship, SLS, and New Glenn.
The Future: Terran R
Having proven their manufacturing concept with Terran 1, Relativity Space is now pivoting entirely toward a much larger prize: the Terran R. Slated for the near future, this fully reusable, 3D-printed heavy-lift vehicle is designed to surpass the payload capacity of the Falcon 9, marking the next giant leap for additive manufacturing in space.
Note: While this article is originally from 2021, it received a small update in 2023 to report on the first flight of Terran 1.
More info
Relativity Space’s official website: https://www.relativityspace.com/
Video about Relativity Space, from Veritasium:
First launch of the Terran 1:
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