WASHINGTON — Relativity, the startup company developing small launch vehicles using additive manufacturing technologies, announced March 21 an agreement with NASA’s Stennis Space Center to take over one of its test stands.

The company said it reached a Commercial Space Launch Act agreement with Stennis that gives the company exclusive use of the E-4 Test Complex at the Mississippi center for the next 20 years. That complex includes four cells for engine tests as well as 15,000 square feet of office space over 25 acres, with an option to expand to 250 acres.

Relativity had already been using another Stennis test stand, E-3, for tests of its Aeon 1 engine, with more than 85 tests performed to date. Taking over the E-4 complex will allow the company to expand its test activities, including qualification and acceptance testing of as many as 36 of its Terran small launch vehicles a year.

“We just recently got the keys handed over to us for it,” said Tim Ellis, chief executive and co-founder of Relativity, in an interview. The first activity for the new complex, he said, will be to build a test stand for second stage holddown engine tests.

Relativity will continue to use the E-3 test stand, which it uses under an earlier Space Act Agreement with Stennis, while building up the facilities at the new complex. “The plan is to use them both in parallel,” he said. “While we’re building up E-4 we will be continuing to test on E-3.”

In addition to the next test complex at Stennis, Relativity has doubled its space at its Los Angeles headquarters. “With the space we have now, we can produce full second stages quite readily,” he said. In the future, he said, the company will develop a single manufacturing facility that would allow it to produce the Terran rocket “at rate,” but the company hasn’t decided where that facility will be located.

Terran is designed to place up to 1,250 kilograms into orbit at $10 million a launch. Relativity plans to make extensive use of additive manufacturing technologies to reduce production costs and to scale up production. “We’re hoping to disrupt 60 years of aerospace manufacturing,” he said.

The company has not yet announced any deals for the rocket, which is scheduled to make its first test flight in late 2020 and enter commercial service in early 2021. Ellis, though, said there’s significant interest in the rocket given its performance and cost.

“We’re seeing massive interest” in the vehicle, he said. “It’s very competitive on a cost-per-satellite basis.” Potential customers, he said, are also interested because the additive manufacturing approach offers the potential to scale up production and produce more reliable vehicles with less human labor involved, while also offering the ability to make changes to individual vehicles for customers, such as different payload fairing sizes.

The new test complex and vehicle development plans will also lead to hiring more employees. Ellis said Relativity has 17 employees, but expects to grow to 45 by the end of the year. The company recently hired its first Stennis-based employee, the E-4 test site director, and will be hiring more people to work there as well as in Los Angeles.

In addition to his work at Relativity, Ellis was named last month to the Users Advisory Group that will advise the National Space Council. While Ellis attended the Feb. 21 meeting of the National Space Council where he and the other members of the group were formally announced, he said the paperwork making their membership official is still being finalized.

He said he was nominated by his company’s board of directors to provide the perspective of a venture-backed startup in the space industry. “Our hope is to really influence and see tangible action and tangible benefits that would that benefit all space startups,” he said.