WASHINGTON — Relativity Space scrubbed a launch of its Terran 1 rocket March 11 after two last-minute aborts for technical issues.

A first launch attempt during a three-hour window was aborted at 2:42 p.m. Eastern, at T-0.5 seconds. The rocket’s nine Aeon 1 engines had already ignited when the abort was called.

Relativity said on its launch webcast that the abort was triggered by a violation of launch commit criteria, but was not more specific. It later tweeted that a “a corner case in the stage separation automation” a few seconds before scheduled liftoff caused the abort.

 The company recycled for a second launch attempt at 4 p.m. Eastern, at the end of the launch window at Cape Canaveral’s Launch Complex 16. That countdown halted at about T-45 seconds, scrubbing the launch for the day. The company later said the abort was caused by fuel pressure in the upper stage that dropped too low.

The March 11 scrub came after propellant temperature issues postponed an initial launch attempt March 8. The company said during the March 11 webcast that a faulty ground valve, since fixed, caused the problem during the earlier launch attempt. The company did not report any propellant temperature issues in the latest attempt.

Relativity has not announced a new launch date for the mission, which it calls “Good Luck, Have Fun.” The company explained it waited three days between launch attempts to condition the liquid natural gas it uses as fuel for the rocket. That is primarily methane, but includes some butane, ethane and propane, according to Arwa Tizani Kelly, technical program manager for test and launch at Relativity, during the webcast.

Methane boils off faster than the other compounds. “If we were to offload and then reload those same propellants after a scrub, our methane composition would be off,” she said. “Instead, we bring in fresh propellants, and the fuel then needs some time to level off to the right compound mix before we make another launch attempt.”

This is the first mission for Terran 1, a rocket that Relativity manufactured primarily using 3D-printing technologies. The mission does not carry a payload and is primarily a technology demonstration of the vehicle, including testing if those additive manufacturing techniques are suitable for a launch vehicle.

Tim Ellis, chief executive and co-founder of Relativity, tweeted before the first launch attempt that he hopes the launch at least gets through maximum dynamic pressure, or Max-Q, about 80 seconds after liftoff, when stresses on the vehicle peak. “But the key inflection in my mind is surpassing Max-Q,” he wrote. “We have already proven on the ground what we hope to prove in-flight – that when dynamic pressures and stresses on the vehicle are highest, 3D printed structures can withstand these forces. This will essentially prove the viability of using additive manufacturing tech to produce products that fly.”

Terran 1 is also testing technologies for its larger, reusable Terran R rocket. The company has $1.65 billion in launch contracts from several customers, including OneWeb, for that vehicle, which could start launching as soon as 2024.

The Terran 1 launch was one of two scheduled for March 11, neither of which took place. Rocket Lab postponed a launch of its Electron rocket from Wallops Island, Virginia, earlier in the day, citing strong upper-level winds. The company has not announced a new date for the “Stronger Together” mission carrying two Capella Space radar satellites. The company has airspace restrictions for the launch daily through March 17.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...