The US Air Force’s X-37B has successfully returned back to Earth on Friday morning, landing at Vandenberg Air Force Base in California at 9:16am GMT. Also known as the Orbital Test Vehicle 1 (OTV-1), its maiden voyage involved 220 days on orbit, conducting experiments and testing its systems, before carrying out the first autonomous re-entry and landing in the recorded history of the US space programme.
Launched on an United Launch Alliance (ULA) Atlas V 501 rocket late on April 22, 2010, the X-37B’s full mission outline was kept secret by the US Air Force, with updates on its position only occasionally noted by sky watchers – who had pre-empted the vehicle’s return as it lowered its orbit over recent days.
That return occurred without a hitch, as it fired its orbital maneuver engine in Low Earth Orbit (LEO) to perform an autonomous re-entry before landing at the Californian runway – which required a large amount of work to host the vehicle’s return.
In the event it was required, the Edwards Air Force Base landing strip provided a back-up runway, the destination for shuttle orbiters when the Kennedy Space Center (KSC) Shuttle Landing Facility (SLF) is unavailable due to weather constraints.
The X-37B is the newest and most advanced re-entry spacecraft. Managed by the Air Force Rapid Capabilities Office (AFRCO), the X-37B program performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies.
“Today’s landing culminates a successful mission based on close teamwork between the 30th Space Wing, Boeing and the Air Force Rapid Capabilities Office,” said Lt Col Troy Giese, X-37B program manager from the AFRCO. “We are very pleased that the program completed all the on-orbit objectives for the first mission.”
OTV-1’s de-orbit and landing mark the transition from the on-orbit demonstration phase to a refurbishment phase for the program. A second flight is already in the planning for sometime in 2011.
The X-37 was developed by Boeing, originally as part of a NASA programme. In 2004, the Defense Advanced Research Projects Agency took over the programme, and in 2006 the US Air Force began development of the X-37B derivative for military applications.
Originally scheduled for launch aboard a Space Shuttle, the X-37B was moved to a Delta II in the aftermath of the Columbia accident. In this configuration the Delta II would have flown without a payload fairing, which raised concerns over the aerodynamics of the vehicle and led to the decision to launch on the larger Atlas V.
The X-37B is 8.9 metres (39 feet and 3 inches) long, has a wing span of 4.5 metres (14 feet and 11 inches), and stands 2.9 metres (9 feet and 11 inches) high. It has a mass at launch of about 5,000 kilograms (11,000 pounds). The spacecraft is powered by lithium ion batteries, which were recharged in orbit by gallium arsenide solar arrays.
It was launched from Launch Complex 41 at the Cape Canaveral Air Force Station by the ULA Atlas V AV-012, which was the first Atlas to fly in the 501 configuration – featuring a five metre diameter payload fairing, no solid rocket motors, and a single-engine Centaur upper stage.
Images via USAF.