(Reuters) – A SpaceX Falcon 9 rocket blasted off from Florida on Friday on a satellite-delivery mission that was to involve an attempt to make a return landing at sea.

There was no immediate word from Elon Musk’s privately owned Space Exploration Technologies on whether the first stage of the rocket returned intact to a landing platform floating in the Atlantic Ocean off Florida.

The rocket, carrying the 12,613-pound (5,721 kg) Boeing-built satellite, lifted off from Cape Canaveral Air Force Station at 6:35 p.m. EST/2335 GMT. The launch, which had been delayed four times since Feb. 24, marked the second of more than 12 SpaceX flights expected this year.

The Beoing-built satellite is owned by Luxembourg-based communications network operator SES SA.

SpaceX was aiming to deliver the satellite as high as 24,233 miles (39,000 km) above Earth and still have enough fuel to land the first stage of the Falcon rocket on a platform floating about 400 miles (645 km) off Florida’s coast.

In December, a returning Falcon 9 rocket successfully touched down on a ground-based landing pad in Florida, an unprecedented milestone in Musk’s quest to develop a cheap, reusable booster.

The rocket flying on Friday was traveling too fast to return to land, prompting SpaceX to try the ocean landing, though the company sought to lower expectations.

“Given this mission’s unique … profile, a successful landing is not expected,” SpaceX said in a statement before the launch.

(Reporting by Irene Klotz from Cape Canveral; Editing by Steve Gorman, Chris Reese and Leslie Adler)

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