After two failed attempts on Saturday, a California-based aerospace company has opted to postpone the launch of the world’s first 3D-printed rocket.

Relativity Space’s Terran 1 booster was scheduled to lift off at 4 p.m. ET from the Cape Canaveral Space Force Station in Florida, but with 45 seconds left in the countdown, ground controllers called off the attempt. About an hour earlier, the rocket suffered a separate last-minute abort after the booster engines ignited.

It’s unclear what caused Relativity’s launch controllers to be pulled, and the company has yet to announce a new launch date and time.

“Based on initial data review, the vehicle is in good condition. More information to follow about the cause of abortions today. Thanks for playing”, the company said in an update on Twitter.

The company’s first takeoff attempt on Wednesday was canceled after a problem with propellant temperature was detected in the rocket’s second stage. Relativity has not said whether Saturday’s miscarriages were related to the same problem.

The Terran 1 test flight represents a big step for Relativity Space and, if successful, would be a significant milestone for the space technology industry. The company has said 3D printing could make it cheaper to build rockets and make space capsules and other components for missions to the Moon and Mars.

Rockets with 3D-printed parts have flown into space before, but Relativity’s booster is the first to be made almost entirely with 3D printing.

About 85% of the rocket’s mass, including its nine engines, was 3D printed, according to the company. Relativity said it aims for future versions to be 95% 3D printed and completely reusable.

Relativity Space was founded in 2015 and is based in Long Beach, California. The Terran 1 rocket is designed to carry up to 2,756 pounds to low Earth orbit. Company officials have said that its 3D-printed boosters will offer a relatively low-cost option for launching small commercial satellites into space.