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Trevor Mahlmann for Ars

Trevor Mahlmann for Ars

Trevor Mahlmann for Ars

12:45pm ET Thursday Update: A Falcon 9 rocket launched on Thursday from Florida, delivering its Dragon spacecraft into orbit. The first stage then made a safe landing on a drone ship stationed in the Atlantic Ocean. The company's webcast ended without any coverage of the second stage's six-hour coast to demonstrate a capability for an unnamed customer.

This was the tenth Falcon 9 launch of 2019. Overall the rocket has now launched 76 times. Sometime in 2020, among rockets in active service, the Falcon 9 will almost certainly become the U.S. booster with the most launch experience, surpassing the Atlas V. That rocket has launched 80 times, with one more mission scheduled for later this month—a test flight of Boeing's Starliner spacecraft.

Original post: At Kennedy Space Center in Florida on Thursday morning, the countdown clock is again ticking toward a launch of the Falcon 9 rocket.

On Wednesday, poor weather scrubbed the first attempt to launch the cargo mission to the International Space Station. Winds in the upper level of the atmosphere were above the acceptable level for a safe launch, and seas near the drone ship stationed offshore, Of Course I Still Love You, were too rough to ensure the rocket's first stage could make a stable landing.

And so SpaceX reset the launch to its backup date of Thursday, at 12:29pm ET (17:29pm UTC). Weather conditions along the Florida coast are more sedate as of Thursday morning, but meteorologists will still need to send up a weather balloon to provide in-situ data about conditions in the mid and upper levels of the atmosphere.

As for the rocket and its NASA-sponsored payload, a fully laden Dragon spacecraft, all appears to be ready for launch. This will be a typical supply mission for NASA, the 19th such flight that SpaceX has made to ferry food, supplies, and scientific experiments to the orbiting laboratory. But there is one interesting aspect of the first stage landing, which will take place offshore rather than at a landing site on the Florida coast.

Asked about this earlier this week, SpaceX's director of Dragon mission management, Jessica Jensen, said the rocket's upper stage is slated to fly a "thermal demonstration" for another, unnamed customer. To put this second stage into the proper orbit for this demonstration, the first stage will need to burn longer and will not have the fuel needed to return to the coast. Jensen declined to provide additional information, and this indicates the customer may be the US Air Force, seeking some kind of assurance about the rocket's performance for a future classified mission.

Weather permitting, a webcast for today's launch should go live about 15 minutes before the instantaneous launch window opens.

Listing image by SpaceX webcast