There are companies that are 3D printing rocket parts, even rocket engines, but Relativity Space, a startup that just received $35 million in investor funding, aims to 3D print entire rockets autonomously, on Earth and on Mars. To do so requires not just thinking outside the box, but reinventing the box itself, which is why Relativity Space developed a new metal 3D printing technology and the largest metal 3D printer the world has yet known.

Relativity Space has completed the 100th hot fire test for its 3D-printed Aeon rocket. (Image courtesy of Relativity Space.)

To learn more about the Stargate 3D printer and the startup’s plan for 3D printing rockets, we spoke to Relativity Space CEO and co-founder Tim Ellis.

Building a Team of Rocket Scientists

Ellis explained that the concept for a startup that 3D prints rockets was born from work that he and his co-founder, Jordan Noone, were performing at two of the leading private space companies. At Jeff Bezos’s Blue Origins, Ellis was a development engineer operating under extremely tight development timelines.

“We very quickly realized that the only way to possibly meet those timelines was to use metal 3D printing for some of the rocket engine parts,” Ellis said.“I ended up doing the first metal 3D printing at Blue Origin. Then when I went back to join full time, I ended up starting the metal 3D printing division at Blue as well.”

Meanwhile, Noone was at SpaceX, working Elon Musk’s 3D-printed rocket engine, where he saw the same benefits that Ellis had. “We just really thought it was inevitable in the future for a whole product to be 3Dprinted,” Ellis explained. “We thought, instead of just 3D printing part by part—there are 100,000 parts or so in a rocket—if we were able to 3D print the whole thing, that that would be the future.”

The next step of obtaining the initial funding would prove much easier than one would think. The first week that the two started the company, they emailed Mark Cuban and asked for an investment, and within five minutes, they received a reply offering $500,000. Relativity Space has since raised $45 million to date in the last two years or so.

Building the World’s Largest Metal 3D Printer

Ellis said that, in order to build an entire rocket, it would be necessary to build the world’s largest metal 3D printer, since what existed on the market did not meet the team’s needs. Since Relativity was made up of people who’d worked on metal 3D printing and rockets, they believed they had what it took to make a 3D printer.

Featuring three industrial robotic arms, Stargate is the largest metal 3D printer in the world. (Image courtesy of Relativity Space.)

The result is called Stargate, a hybrid directed energy deposition system that relies on three industrial robotic arms that work together using collaborative robot path planning software written by the startup. Two arms feature high-powered lasers, also developed in-house, that can work on the same part, while a third arm utilizes a mill that can perform the necessary machining work to add details and finish the part. This will be key as the startup establishes its process for autonomously creating rockets and rocket parts.

Thanks to a Lawrence Livermore National Laboratory scientist that Relativity now has on its team, the print heads melt an aluminum feed wire that is, according to Ellis, three times stronger than off-the-shelf aluminum alloys typically used for creating rocket structures. It’s also specially designed for the 3D printing process so that it prints faster and with fewer flaws than those alloys, Ellis said.

Thanks to a milling arm, it’s possible to get fine details and limit post-processing. (Image courtesy of Relativity Space.)

“Long term, Relativity’s core mission is to create an entirely new process for building and flying rockets, so everything from materials to the supply chain and factory [enterprise resource planning] software and how you design and build rockets,” Ellis said.

The architecture for Stargate is extensible in such a way that the size or number of the robotic arms can be increased as the company builds out. Because the system is not limited by a vacuum gas chamber, its size is essentially limited by the size of the room Stargate is in. “Literally, it’s a few inches away from the walls on either side and the ceiling,” Ellis laughed.“If we had a bigger building, we could just have a bigger enclosure and the print volume would be larger.”

Building 3D-Printed Rockets

So far, Relativity has 3Dprinted six different versions of six different designs of the Aeon rocket that they are working on. The team also performed its 100th engine test, featuring a full-scale combustion chamber nozzle igniter.

The startup has also 3Dprinted structural components, including a full-scale fuel tank for the rocket upper stage measuring 7 feet in diameter and 14 feet in height. Relativity plans to continue integrating more components into the engine, such as the turbo pump, as it performs more tests.

By early 2019, Ellis plans to put together a large printed tank structure and rocket structure, plus the engine, to perform a combined test. If the team achieves this, it would be the first 3D-printed rocket ground test in the world.

Building the Future of Space

The ultimate goal for Relativity Space is not just to speed up and reduce the cost of manufacturing rockets, but to automate the process such that it would be possible to print the first rocket on Mars. In the process, the startup believes it can provide a return to its investors in a number of ways.

For instance, Relativity is seeing a lot of demand for its technology in the small satellite sector. Its first rocket, dubbed the Terran 1 (as opposed to Martian?), could send 1,250kg payloads to low Earth orbit (LEO) for $10 million, which is two to three times less expensive than alternative methods. Rather than send large school bus–sized satellites into space with a much larger rocket, Terran 1 would take a cluster of mini fridge– or small car–sized satellites into LEO.

Given the flexibility and benefits of an autonomous rocket factory, it’s also clear that something like Stargate could be used in other industries. Though Ellis wouldn’t comment on the company’s plans for making other industrial products, he did say that “if you’re 3D printing and making goods on another planet, you’re also probably making other industrial products and infrastructure there, too, which means that what you want to do there does help make the same factory on the Earth able to make a wide range of products.”

To help get Relativity Space to the stars and beyond, the startup also formed a first-of-its-kind partnership with NASA, in which the space agency is giving Relativity a 20-year lease on its E-4 facilities at Stennis at cost. Whereas the startup previously had access to an existing test stand for the past two years, it will now be able to have 24/7 management over a 25-acre test complex to develop and test its first launch vehicle.

“We’re the only startup that has done a deal like this at all, which really helps with legitimacy with customers,” Ellis said.

With its recent $35 million investment, Relativity Space is on track to get Terran 1 into orbit in 2020 before performing commercial services in early 2021. To do so, the company will hire 28 new employees, expand its facilities from 10,000 square feet to around 40,000 square feet and create the second version of Stargate. The path from now until first launch may prove to be as exciting as the launch itself.

To learn more about Relativity Space, visit the company website.