Relativity Space

Relativity Space

Relativity Space

Relativity Space

Relativity Space

Even in an era during which the aerospace industry faces significant disruption from myriad new competitors, Relativity Space stands out. The company, led by a pair of twenty-somethings who used to work for Blue Origin and SpaceX, seeks to 3D print rocket engines and the boosters themselves, reducing the number of parts in an orbital rocket from 100,000 down to fewer than 1,000.

Founded in late 2015, Relativity remained in stealth mode until last year, but now it is starting to come out of the shadows. And in doing so, the California-based company is revealing some pretty outsized ambitions. One day, in fact, the company intends to 3D print a rocket on Mars for a return trip to Earth. "We have a pretty broad long-term vision," Tim Ellis, a co-founder of Relativity, admitted in an interview with Ars.

Before it reaches Mars, of course, Relativity must first successfully 3D print a rocket on Earth. Ellis said Relativity is making good progress toward that goal, having already printed engine components for test firings. (The company has performed more than 85 engine tests of various kinds to date). Now, the company has taken a key step toward conducting a lot more engine test firings.

NASA deal

Relativity announced Wednesday that it has signed a 20-year partnership with NASA's Stennis Space Center for an exclusive lease of the 25-acre E4 Test Complex in Southern Mississippi. The four test stands on the site will allow Relativity to develop and test enough engines to build 36 rockets a year, and the agreement includes an option for the company to eventually expand its footprint at the site to 250 acres.

Ellis said this is the first Commercial Space Launch Act agreement that Stennis has signed—under these agreements, NASA locations with launch-related facilities can share them with the private sector. Kennedy Space Center has used similar agreements, such as the deal allowing SpaceX to use Launch Complex-39A. The Stennis agreement allows Relativity to test 24 hours a day, seven days a week, Ellis said, and tap into site utilities and contract labor as needed. The company values the partnership at $30 million.

Unlike SpaceX, which built engine-test facilities in McGregor, Texas, or Blue Origin, which has a test site in West Texas, Ellis said he sought the partnership with NASA to avoid similar infrastructure costs. "With this partnership, we really don't have to reinvent the wheel," he said. "Because we have exclusive use of the site, we don't have to ask for permission when we want to test."

The hardware

Relativity is deep into development of its Aeon 1 rocket engine, which uses a mixture of oxygen and methane fuels. The Aeon engine has a modest vacuum thrust of about 19,500 pounds, less than one-tenth that of a Merlin 1D engine used in SpaceX's Falcon 9 rocket. It's also nearly four times more powerful than the small Rutherford engines that power Rocket Lab's smaller Electron rocket.

The key thing about the Aeon engine is not so much its raw performance but its lack of complexity. Ellis said the engine could be printed in fewer than 20 days, which accelerates the development and testing cycle. Moreover, the Aeon engine has just 100 parts, compared to a few thousand for most other engines.

For its first rocket, Relativity plans to integrate nine Aeon engines into the first stage of its Terran rocket, with a single-engine upper stage. The Terran booster will hit what the company believes is a sweet spot between smaller rockets under development by Rocket Lab (and others) and the much larger Falcon 9. It has a planned capacity to deliver 1,250kg to low-Earth orbit and a per-launch cost of $10 million.

Ellis said a test flight is presently planned for late 2020, with commercial launches beginning in 2021. (As always, rocket development schedules are subject to delay). There appears to be a healthy market at this price point, as Relativity has secured more than $1 billion in commitments for future orders provided it can become operational on a reasonable schedule.

Long-term vision

The company has a clear long-range vision that, ultimately, all rockets will be 3D printed because the highest cost today is human labor. "We really feel like that, extrapolating into the future, if we could 3D print 90 to 95 percent of the components of a rocket, we will have a launch vehicle that would be very disruptive," Ellis said. "Fundamentally, this is the cheapest possible rocket."

Before starting Relativity, Ellis interned and then worked at Blue Origin, helping to develop the company's powerful BE-4 rocket engine. He pushed the business case for bringing 3D printing of metals into the production process. Relativity's cofounder, Jordan Noone, worked at SpaceX on the SuperDraco thruster program used for the company's Crew Dragon spacecraft.

Both Ellis and Noone were interested in 3D printing and felt as though two of the most cutting-edge companies in aerospace—Blue Origin and SpaceX—weren't pushing the technology far enough. So they founded Relativity. They believe that 3D printing not only has the potential to dramatically reduce costs but also will allow them to iterate new designs quickly and scale to much larger vehicles.

So far, Ellis said, the gamble is paying off. Building and 3D printing an engine has been, he says, "a little bit easier than expected." The metals they are using for engine chamber parts, based on their strength and grain structure, are actually 20-percent stronger and have higher ductility than similar alloys not printed using the 3D process.

Automation has allowed Relativity to remain a very lean company—it still has just 17 full-time employees at a time when it is beginning to perform full-scale and flight-weight engine tests. Turbopumps will be added to the engine tests this year for a much more flight-like configuration. Ellis said Relativity will probably expand to about 45 people by the end of this year, as it scales up production.

Listing image by Relativity Space