|Operator||U.S. Space Force|
|Mission duration||1 year, 5 months and 1 day|
|Spacecraft type||Boeing X-37B|
|Launch mass||5,400 kg (11,900 lb)|
|Power||Deployable solar array, batteries|
|Start of mission|
|Launch date||17 May 2020|
|Contractor||United Launch Alliance|
|End of mission|
|Landing site||Shuttle Landing Facility|
|Perigee altitude||388 km (241 mi)|
|Apogee altitude||404 km (251 mi)|
USA-299, also referred to as Orbital Test Vehicle 6 (OTV-6), is the third flight of the first Boeing X-37B, an American unmanned vertical-takeoff, horizontal-landing spaceplane. It was launched to low Earth orbit aboard an Atlas V rocket from SLC-41 on May 17, 2020 and remains in orbit. Its mission designation is part of the USA series.
The spaceplane is operated by the United States Space Force, which considers the mission classified and as such has not revealed the objectives. However an unclassified secondary satellite, FalconSat-8, was deployed from the X-37B soon after launch.
OTV-6 remains in orbit as of May 2021.
A rideshare payload for the United States Air Force Academy, FalconSat-8, was deployed from the X-37B a few days into the mission. The satellite provides a platform for the Academy's Cadet Space Operations Squadron to test various technologies.
Onboard experiments include: