US space plane completes two-year secret mission


- After 718 days on orbit, the U.S. Air Force's fourth X-37B mission concluded and returned to Earth for an automated landing at Kennedy Space Center's Shuttle Landing Facility - the first time the secretive spaceplane has touched down on the historic runway.

Image: The U.S. Airforce's X-37B Orbital Test Vehicle mission 4 after landing at NASA's Kennedy Space Center Shuttle Landing Facility in Cape Canaveral, Florida, U.S., May 7, 2017.

It was the fourth mission for the X-37B, with a fifth scheduled for later this year.

The space plane sent a sonic boom that rattled east-central Florida before 8 a.m., waking residents from their weekend slumber.

"Technologies being tested in the program include advanced guidance, navigation and control, thermal protection systems, avionics, high temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, advanced propulsion systems, advanced materials and autonomous orbital flight, reentry and landing."

But the Air Force says it has two main objectives: Conduct operating experiments that can be returned to and further studied on Earth, and test reusable spacecraft technologies to support "America's future in space". "This mission once again set an on-orbit endurance record and marks the vehicle's first landing in the state of Florida". The Air Force relocated the programme in 2014, taking over two of NASA's former shuttle-processing hangars. According to CBS News this is the second mission for this specific X-37B craft.

"Today marks an incredibly exciting day for the 45th Space Wing as we continue to break barriers", Air Force Brig.

Among the few payloads known to have been launched on OTV-4 was an XR-5A "Hall" thruster, an electric device that ionizes and accelerates a noble gas to produce thrust.

Sunday's landing was the X-37B's first in Florida.

The X-37B measures about 29 feet long and has a almost 15-foot wingspan, and weighs 11,000 pounds when launched.

This took was a practice run, working on opportunities for the X-37B to approach the Kennedy Space Center, with the Range holding a space for several return opportunities before weather became a major factor for what turned out to be a false landing attempt. He said that the ability of the OTV to land and launch from the same place is ideal to develop new space technologies.

The total time reached in space by the four flights reaches 2085 days now.

The shuttle that landed Sunday had been in orbit for more than 700 days, the Air Force said.