The Boeing X-37B OTV's fourth mission is now complete

USAF’s ‘Secret’ Spaceplane Returns

posted by Paul Fiddian | 08.05.2017

X-37B Completes Longest Orbit Yet

The Boeing X-37B Orbital Test Vehicle's fourth space mission - a historic two-year-long deployment - is now complete.

The USAF’s state-of-the-art Boeing X-37B unmanned spaceplane is back on Earth after two years out in orbit.

A ‘secret’, 24-month-long mission, it ended at 0747hrs on 7 May when the pilotless technology demonstrator touched down at Florida’s Kennedy Space Center, using the same runway as had its Space Shuttle predecessors.

With all previous X-37B OTV (Orbital Test Vehicle) landings having occurred at California’s Vandenberg Air Force Base, this was a first-time event within its programme overseen by the USAF’s Rapid Capabilities Office. Details of what the latest X-37B OTV mission entailed are ‘classified’ but the type’s role generally involves ‘risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies’, according to the USAF.

Boeing X-37B Launch

Longest Space Mission

Lasting 718 days, this was the X-37B’s longest space mission yet and it set a new standard for unmanned reusable spacecraft. Designated ‘OTV-4’, it followed the OTV-1, OTV-2 and OTV-3 missions. The spacecraft’s first flight (OTV-1), lasting 10 months, began in April 2010. Its next sortie – a 15-month deployment – started the following April, then came the 22-month-long-OTV-3. With OTV-4 now over – completion of which means the X-37B’s now spent a combined 2,085 days aloft – OTV-5 is scheduled to start before the end of 2017.

“The hard work of the X-37B OTV team and the 45th Space Wing successfully demonstrated the flexibility and resolve necessary to continue the nation's advancement in space”, comments Air Force Rapid Capabilities Office director, Randy Walden. "The ability to land, refurbish, and launch from the same location further enhances the OTV's ability to rapidly integrate and qualify new space technologies."

"The landing of OTV-4 marks another success for the X-37B program and the nation," adds Lieutenant Colonel Ron Fehlen, the X-37B programme manager. "This mission once again set an on-orbit endurance record and marks the vehicle's first landing in the state of Florida. We are incredibly pleased with the performance of the space vehicle and are excited about the data gathered to support the scientific and space communities. We are extremely proud of the dedication and hard work by the entire team."


Carried into space by an Atlas rocket, the X-37B OTV has a launch weight of 11,000 pounds. Only around 25 per cent Space Shuttle-sized, it has a 29-foot three-inch fuselage length and its wing span is one inch short of 15 feet.

Power is supplied by Gallium arsenide solar cells that feed lithium-ion batteries. It’s these that help this very advanced design orbit Earth at an astonishing 17,426 miles per hour.

Main X-37B image copyright/courtesy USAF
Text-embedded X-37B photo courtesy of ULA via Boeing


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