SpaceX launches X-37B ahead of Hurricane Irma

The Air Force's X-37B Orbital Test Vehicle mission 4 lands at NASA 's Kennedy Space Center Shuttle Landing Facility Fla

Elon Musk's rocket company Space X is set to launch its Falcon 9 rocket amidst the looming threat of a hurricane in Florida.

The launch window is long, from 9:50 a.m. EDT to 2:55 p.m. The main goal today was getting the reusable X-37B - also known as the Orbital Test Vehicle (OTV) - into orbit.

The flight is the fifth time one of the Air Force's two X-37B spaceplanes, each about one-quarter the length of one of NASA's retired space shuttle orbiters, has rocketed into space.

SpaceX has launched the Air Force's super-secret space shuttle. For comparison, the space shuttles were 122 feet (37 m) long, with 78-foot (24 m) wingspans.

The X-37B is the first uncrewed space plane for the USA, and is designed for reusability at a reasonable cost. Given the top-secret nature of the X-37B's [spying] mission, there's little that we know about its orbit or what it could possibly be carrying aboard.

Publicly, the Air Force says the X37-B is a testing platform for advanced technologies for spaceflight, but few details have ever been provided. On all four previous flights, the X-37Bs rode atop United Launch Alliance Atlas V launchers.

Like the space shuttle, the X-37B launches vertically and comes to back to Earth horizontally, in a runway landing. We also don't know how long the X-37B will stay in orbit, although its last mission was almost two years in length (270 days to be exact). The last mission, which ended in May, spent a record-breaking 718 days in space. The booster's return to SpaceX's landing zone at Cape Canaveral Air Force Station was broadcast live.

The SES 11/EchoStar 105 spacecraft has been delivered to Cape Canaveral from its Airbus Defense and Space factory in Toulouse, France.

Today's launch is going to be the last for a while from the Kennedy Space Center.

Hurricane Irma is not due to make landfall in Florida until the weekend, but adverse weather conditions surrounding the storm system left mission control with just a 50/50 chance of success.