By Joey Roulette

WASHINGTON (Reuters) -The U.S. Federal Aviation Administration wrapped up a technical investigation into SpaceX's April test launch of its giant Starship rocket, saying in a Friday statement that the company must implement dozens of corrective measures before flying the vehicle again.

The April 20 launch of SpaceX's Starship Super Heavy rocket from Texas pulverized its launchpad upon liftoff and ascended 25 miles (40.23 km) before exploding roughly four minutes into its flight, as it was attempting a crucial demonstration to reach space for the first time.

The FAA, which regulates launch site safety, closed its review on Thursday of SpaceX's technical investigation into the launch mishap, according to an FAA safety official's letter sent to SpaceX that day.

The letter and the FAA statement on Friday cited "multiple root causes" of the Starship failure and 63 corrective actions to take before launching the rocket again.

"The closure of the mishap investigation does not signal an immediate resumption of Starship launches at Boca Chica," the agency said, referring to SpaceX's sprawling Starship launch site in south Texas.

The FAA probe's closure puts SpaceX one step closer to getting Starship in space for the first time - a major, long-sought testing milestone before the company can use the reusable rocket for commercial satellite missions and human landings on the moon for NASA.

It was unclear whether SpaceX had already implemented some of the corrective actions, which will impact Starship's next launch timeline. The agency's mishap report was not made public.

SpaceX must also obtain a modified FAA license to launch, which entails a sometimes-lengthy review of the Starship's flight trajectory, accident probabilities and other factors affecting nearby public safety.

"Starship is ready to launch, awaiting FAA license approval," Elon Musk, SpaceX CEO and founder, wrote in a Tuesday post on X, the social media site previously known as Twitter that Musk also owns.

In the letter on Thursday, the FAA official summarized some of the corrective actions as being hardware changes on Starship to prevent leaks and fires and reinforcing the rocket's launch pad to prevent a storm of kicked up debris and sand.

Debris kicked up by the April 20 liftoff sparked fresh environmental concerns over SpaceX's Boca Chica launch site, which is at the center of a lawsuit from environmental groups accusing the FAA of inadequately reviewing the site's impact to nearby nature preserves.

SpaceX has vowed to install a large metal plate on the launchpad to mitigate the debris field from Starship's liftoff.

In the weeks after the test launch, Musk said Starship had deviated from its planned trajectory during ascent and that a destruct command was triggered some 40 seconds later than it should have to blow up the rocket.

That automated destruct command is one of multiple "safety critical systems" that SpaceX must test before attempting another launch, the FAA official wrote in the letter.

(Reporting by Joey Roulette; Editing by Chizu Nomiyama, Mark Porter, Josie Kao and David Gregorio)