Defying a bleak weather forecast, a SpaceX Falcon 9 rocket blasted off from Cape Canaveral Air Force Station Friday to send a Dragon cargo capsule on its way to the International Space Station.

“The rocket flight was perfect as far as we could tell,” SpaceX chief executive Elon Musk told reporters after launch.

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The Dragon capsule, loaded with about 5,000 pounds of science gear and supplies for the station crew, is due to arrive on Sunday.

The rocket lifted off at 3:25 p.m. EDT, ending a series of delays caused by unrelated technical issues. Clouds and rain threatened to postpone Friday’s launch as well, but skies cleared in time for the launch attempt.

“Mother Nature is providing a window of opportunity today,” NASA mission commentator Michael Curie said shortly before liftoff.

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Mother Nature was not as kind to the seas, which Musk believes were too rough for the rocket’s first-stage to splash down intact, the goal of an engineering test conducted as part of Friday’s launch.

SpaceX is working to recover and reuse its rockets to cut cost.

“We didn’t really expect this stage to come back — obviously we had some hope of course. Overall, I think the data is much more important here,” SpaceX vice president Hans Koenigsmann told reporters.

SpaceX Falcon Rocket to Test Landing Legs

After the rocket’s first stage separated from the upper-stage and Dragon capsule, it re-lit some of its engines to brake its descent back to Earth and position it for an attempted vertical touchdown on the ocean (before gravity takes hold and topples the rocket on its side.)

The rocket also included four deployable 25-foot long landing legs for stabilization.

Results of the test are pending.

Before the end of the year, SpaceX hopes to evolve its test flights so that a Falcon returns on land.