https://techcrunch.com/2017/09/07/watch-spacex-launch-the-u-s-air-forces-secretive-x-37b-spaceplane-live/

SpaceX is set to launch the U.S. Air Force’s X-37B spaceplane into orbit today, with a launch window that opens at 9:50 AM ET (6:50 AM PT). The Boeing-built uncrewed spaceplane most recently completed a two year orbital mission before returning to Earth in May, and it’s going back up hopefully this morning, though weather conditions are looking only 50 percent favorable ahead of launch, with SpaceX hoping to get the launch off the ground ahead of hurricane Irma’s arrival.

This is another first for SpaceX – the first launch of the X-37B, which has run four missions previously but always launched atop a United Launch Alliance Atlas 5 rocket. SpaceX gained its U.S. military payload certification in 2015, and the USAF is hoping to diversify its orbital test vehicle launch capabilities with SpaceX with this launch, provided everything goes smoothly.