Update September 7th, 10:12AM ET: After launching the X-37B to orbit, SpaceX’s Falcon 9 rocket also stuck another landing at the company’s ground-based landing site at Cape Canaveral, Florida. This marks the 16th successful landing of a Falcon 9 post-launch and the seventh successful landing on solid ground. SpaceX’s live coverage of the mission ended at landing and did not show the deployment of the X-37B, likely due to the fact that its mission is classified.

Original Story: A hurricane barreling toward the Florida coast isn’t stopping SpaceX from launching its Falcon 9 rocket today. The company is slated to launch the US Air Force’s mysterious X-37B spaceplane into orbit sometime this morning or early afternoon from NASA’s Kennedy Space Center. The timing may work out, since Hurricane Irma isn’t slated to reach Florida until this weekend, but it’s possible weather may delay the mission until after the storm passes.

This launched, dubbed OTV-5, is a big one for SpaceX. It’s the company’s second time launching a national security payload and the first time launching the Boeing-built X-37B, which has only ever gone into space on top of Atlas V rockets built by the United Launch Alliance. Air Force secretary Heather Wilson confirmed during a hearing in June that the plane would fly on SpaceX’s Falcon 9 for the first time and ULA CEO Tory Bruno later tweeted that his company was not given the opportunity to submit a bid to launch the vehicle for this mission.

This will be the fifth flight of the X-37B

This will be the fifth flight of the X-37B, but the details of the mission are vague. The Air Force says the vehicle will be carrying small satellites for this trip, as well as testing out experimental technologies for space. A special payload called the Advanced Structurally Embedded Thermal Spreader will also be on board, meant to try out a new vibrating heat pipe. And the X-37B is going to a higher inclination orbit than usual — or a much more tilted orbit in relation to the equator. But ultimately, the X-37B’s main mission is classified and kept secret.

Also, it’s unclear how long the reusable vehicle will remain in orbit this time around. On its last trip to space, the spaceplane stayed in orbit for nearly two years before landing at Kennedy Space Center in May, without much of a heads up from the Air Force. It’s possible it could be an additional few years before the X-37B comes back down to Earth again after this launch.

But first, the spaceplane has to get to space, and conditions are fairly iffy today, according to Patrick Air Force Base. Hurricane Irma will be around 900 miles away from Kennedy Space Center during the SpaceX launch, so it shouldn’t pose too much of a threat to the mission. However, a front is passing through the area today and it’s expected to stall on top of Central Florida, creating a higher chance of storms and thick clouds in the afternoon. As of now, there’s about 50 percent chance that conditions will be favorable.

SpaceX has a long launch window from 9:50AM ET to 2:55PM ET

Fortunately, SpaceX has a long launch window from 9:50AM ET to 2:55PM ET, during which the Falcon 9 can take off. Weather will supposedly be better in the morning as opposed to the afternoon, making a earlier launch more likely. But if the Falcon 9 doesn’t get off the ground today, it may have a hard time launching before Irma makes it to Florida. There’s a backup launch date available on Friday, but weather conditions are expected to worsen by then as Hurricane Irma will be closer to the coast. The approaching storm in combination with the decaying weather front could cause winds that will strengthen throughout the course of the day.

And once Irma passes, it’s unclear how quickly launches will be able to resume from Kennedy Space Center. All of the facility’s buildings built after Hurricane Andrew in 1992 are supposed to withstand winds between 130 and 135 miles per hour. And last year, KSC was spared substantial harm when it was hit by Hurricane Matthew and experienced winds up to 107 miles per hour. However, Matthew still caused millions of dollars in damage.

For now, though, the mission is still on for today. The Air Force’s 45th Space Wing, which supports launches out of Florida, started hurricane preparations early so that personnel would be available to support the launch. SpaceX even plans to do a Falcon 9 rocket landing after take off too, sending the vehicle to the company’s landing port located off the Florida coast.

SpaceX’s coverage of the event is set to begin 10 minutes before liftoff. Check back towards the beginning of the launch window to see if this mission happens before Irma reaches the coast