WASHINGTON — Relativity Space, a startup developing small launch vehicles using 3D-printing technologies, announced March 27 a $35 million funding round led by a venture fund making its first space investment.

The Series B funding round is led by Playground Global, a venture fund established in 2015 by a group that includes Andy Rubin, a former Google executive that led development of the Android mobile operating system. The fund is focused on “software-based” hardware startups.

In an interview, Tim Ellis, chief executive and co-founder of Relativity, said he was attracted to Playground Global given its technical expertise. “They’re extremely technically complex,” he said of the firm. “They’re all about developing rule-breaking and future-looking technologies.”

Relativity has emphasized such technologies in the development of its Aeon 1 engine, currently undergoing testing at NASA’s Stennis Space Center, and its Terran 1 launch vehicle. The company has been developing 3D-printing technologies that will ultimately allow the company to produce most of the rocket through additive manufacturing versus traditional production techniques, with the promise of significant cost savings.

“They believe in the vision of what we’re trying to do in disrupting 60 years of aerospace tradition,” Ellis said. “They’re on board, and we’re all very excited to build this future.”

Jory Bell, vice president of product development of Playground Global, will join Relativity’s board. “Relativity is shaking up an industry that hasn’t experienced this level of innovation in decades,” he said in a statement. “We are excited to be a part of a company that is taking a radical approach and we believe Relativity brings significant value to the aerospace ecosystem.”

“They are makers and engineers to the core in addition to being very smart VCs,” Ellis said of Playground. “That combination is extremely rare in Silicon Valley.”

Relativity’s previous investors all joined the Series B around. They include Social Capital, the VC firm that led the Series A round, as well as the Y Combinator Continuity Fund and billionaire Mark Cuban. “That’s a huge sign of support and buy-in,” Ellis said of the decisions of earlier investors to participate in this round.

The funding will enable continued development of the Aeon engine and Terran rocket. The company announced March 21 an agreement with NASA Stennis to take over the E-4 Test Complex at the Mississippi center, with plans to build up capabilities there for testing of the rocket’s second stage. The timing of the agreement and the funding round were coincidental, Ellis said.

Relativity is starting to look at potential launch sites for Terran 1, whose first launch is currently scheduled for late 2020. “We’re planning to have a launch site under contract by the end of the year,” he said, adding the company is looking at “the usual suspects” among those sites, but declined to name any specific facilities.

The company also has what it says is more than $1 billion in letters of intent and memoranda of understanding for launches, although none have yet been converted into firm contracts. Those potential customers, Ellis said, are spread among “big public commercial companies” as well as government agencies around the world. The larger size of the vehicle compared to other small launchers under development — it is designed to carry up to 1,250 kilograms into low Earth orbit — has helped get “initial traction” among potential customers.

Ellis said that Relativity will need to raise additional capital in the future in order to complete development of Terran, but did not disclose estimates of how much or when.