The Long Beach, California-based company's 110-foot-tall (33.5m) Terran 1 rocket, which is 85 per cent made of 3D-printed parts, lifted off on its debut flight around 11:25 p.m. EDT (03:25 GMT on Thursday) from a launchpad at Florida's Cape Canaveral Space Force Base.
Roughly 80 seconds into the flight at an altitude of nearly 10 miles (16km) above the Atlantic ocean, the rocket reached peak aerodynamic stress as it ascended toward space at 1,242mph (1,999km/h), passing a key objective of the test mission.
Upon reaching space, the rocket's second stage engine appeared to briefly ignite but failed to achieve thrust, ultimately failing to reach orbit.
"While we didn't make it all the way today, we gathered enough data to show that flying 3D-printed rockets is possible," said Arwa Tizani Kelly, Relativity's test programme manager, on the company's live video stream.
Relativity's launch was intended to validate the company's supposition that its rocket's 3D-printed structure can withstand the forces of a launch off Earth.
Image credit: Relativity
The Terran rocket's inaugural launch had been postponed from early March, after concerns were raised about fuel temperatures. Dwindling "propellant thermal conditions" in the rocket's second stage during a three-hour launch window on 8 March ultimately forced the cancellation, the company said.
Relativity is one of a number of US rocket start-ups competing to meet the growing demand for cheap launch services. It is betting on the cost savings it expects to achieve using giant, robotic 3D-printers to simplify its rocket production lines.
Rival space firms are mostly focused on lowering costs by building rockets designed to be reuseable, such as the Falcon 9 boosters produced by Elon Musk's SpaceX.
"The launch that we're preparing for is an opportunity to demonstrate a whole bunch of things all at once," Josh Brost, Relativity's senior vice president of revenue, told Reuters ahead of the 8 March attempt. Brost called the Terran 1 rocket "by far the largest 3D-printed structure that's ever been assembled."
The use of 3D-printers, Brost said, allows Relativity to hasten much of its manufacturing processes and more easily make changes to improve the rocket's design if needed after it flies, eliminating the need for a complex supply chain that would otherwise slow down rocket enhancements.
"First launches of new rockets are notoriously prone to have different reasons that they need the scrub," Brost said. "So it would not be at all unlikely for us to even need a couple of attempts to get through the countdown and lift off for our inaugural launch."
While the expendable Terran 1 is built to carry 2,755 pounds (1,250kg) of satellites to low-Earth orbit, waning demand for that class of launch vehicle has led Relativity to develop a larger, 3D-printed reusable rocket - the Terran R - that it expects to fly in 2024.
Driving the demand for new rockets are the so-called mega-constellation plans by companies such as SpaceX, OneWeb and Jeff Bezos' Amazon to deploy tens of thousands of internet-beaming satellites to low-Earth orbit in the next few years.
SpaceX flies its own heavy-lift rockets to get its Starlink network into orbit, while Amazon and OneWeb plan to use similar large rockets from various launch companies for their own satellites. OneWeb will launch its next-generation satellites on Relativity's Terran R, the two companies announced in 2022.
Relativity has approximately $1.65bn-worth of launch contracts secured for both its rockets, with the bulk of that revenue attributable to the larger Terran R.
While market demand for rockets like Terran 1 has weakened, Brost said the rocket's upcoming flights will inform how Terran R is engineered and that the company "continues to talk to people about both vehicles."
