Relativity Space’s first 3D-printed rocket booster passes initial tests
Relativity Space CEO Tim Ellis said the startup’s first 3D-printed “Terran-1” rocket booster had already completed some significant testing after arriving at its Florida launch pad last month.
Terran-1 is an expendable two-stage launch vehicle that when first assembled will be approximately 33 meters (110 ft) high, 2.3 meters (7.5 ft) wide and weigh 9.3 tonnes (~20,500 lbs) empty. Fueled by liquid oxygen and methane (methalox) and powered by nine small Aeon engines, the first Terran thruster will produce approximately 90 tonnes (~200,000 lbf) of liftoff thrust. In total, the rocket is designed to initially launch up to 1.25 tonnes (~2750 lbs) into low Earth orbit, with plans to expand to 1.5 tonnes (~3300 lbs) in the future. SpaceX’s Falcon 9, for context, is 3.7 meters (12 feet) wide, 70 meters (~230 feet) tall, likely weighs around 30 tons (~65,000 lbs) dry, and can launch 22, 8 tons (~50,250 lb) to LEO in an expandable configuration. Just one of its nine Merlin 1D booster engines produces about as much thrust as the entire Terran-1 first stage.
Although tiny by comparison, Terran-1’s booster is still a relatively large and powerful rocket, and testing it poses significant challenges. Instead of building a custom test bed elsewhere, Relativity elected to perform nearly all of the first-stage qualification tests on its LC-16 pad at Cape Canaveral Space Force Station (CCSFS).
This plan increases the risk of the rocket damaging Relativity’s only available launch pad, significantly delaying launch preparations, but it also has the potential to save time by acting as a launch pad shakedown. Basic concrete features and foundations aside, LC-16 was essentially a blank slate when Relativity arrived, so qualifying the pad – which is practically brand new and recently installed – is no small feat in and of itself.
Relativity’s first Terran-1 flight hardware performed surprisingly well. The smaller, single-engine upper stage underwent a comprehensive program of periodic tests, including a full duration static fire – shortly before shipping to LC-16. The first Terran-1 booster, meanwhile, left Relativity’s California factory and arrived at LC-16 to begin its own qualification tests in early June.
On June 28, CEO Tim Ellis revealed that the thruster had already completed “pneumatic proof testing” and passed its “first thruster loading” test less than a month after arriving at LC-16. That would be fast for the first prototype of any new orbital-class rocket, but Relativity’s Terran-1 has an extremely unique feature that makes that speed even more impressive: by mass, the vast majority (85%) of the rocket was made with 3D printing. Indeed, most of Terran’s airframe and tanks are just giant, continuous welds that have been precisely manipulated into cylinders, domes, and the like. While the rough surface finish leaves something to be desired and likely reduces the overall efficiency of the rocket airframe, Relativity says the composition of the metal in its printed structures is nearly identical to a more traditionally fabricated component.
Relativity’s ultimate hope is that the technical foundations it lays will allow it to manufacture complex, high-performance rockets with minimal human intervention, drastically reducing production costs. One day, the descendants of these semi-autonomous factories could even be used to build rockets and other complex machinery and infrastructure on Mars or other extraterrestrial destinations.
However, the company must first begin successfully launching the Terran-1 rockets and fully prove the concept. Next, Relativity will likely perform a full wetsuit rehearsal, a launch simulation in which the rocket is loaded with propellant and pressurized for flight. Once this step is complete, Relativity will attempt one or more static fire tests, culminating in a multi-minute static fire or “mission cycle”.