Satellite Technology Feature Article
U.S. Air Force X-37B Unmanned Spaceplane Returns to Earth After 469 Days
By Doug Mohney, Contributing Editor
On June 16 at 8:48 AM EST, the second X-37B Orbital Test Vehicle (OTV) returned to earth after a whopping 469-day "experimental" test mission.
Launched from Cape Canaveral Air Force Station, Fla. on March 5, 2011, the X-37B successfully landed at a Vandenberg Air Force base runway. Beyond that, the U.S. Air Force and spaceplane builder Boeing (News - Alert) aren't saying a whole lot.
The X-37B program is "demonstrating a reliable, reusable unmanned space test platform for the Air Force," according to Boeing's June 16 statement. "Its objectives include space experimentation, risk reduction and concept-of-operations development for reusable space vehicle technologies that could become key enablers for future space missions."
So what exactly did OTV-2 accomplish on its 496 day mission? It "tested the vehicle design further" over the first 220-day mission conducted with OTV-1 and "tested additional capabilities." The Air Force or Boeing is otherwise not saying exactly what OTV-2 may or may not have had in its payload bay. Speculation is the pair of spaceplanes have been or will be used to carry various experiments and/or prototype sensors into orbit and/or used as recyclable satellite platforms.
Put into orbit by an Atlas V, the X-37B is designed for autonomous reentry and landing operations at an airstrip. The unmanned vehicle is 8.9 meters long, has a wingspan of 4.5 meters and is 2.9 meters high. It has improved thermal protection over the Space Shuttle and a payload bay of about 2.1 meters by 1.2 meters.
In orbit, the vehicle deploys gallium arsenide solar cells to provide operational power and charge lithium-ion batteries.
OTV-1, the first vehicle, is scheduled for a second launch later this year. The launch will demonstrate further reusability and sustainable operations, but there's no word on what its payload will contain – given the Air Force's penchant for secrecy around the two previous missions, there probably won't.
Speculation of X-37B capabilities has run from on-orbit inspection of satellites to repair and/or refueling of friendly spacecraft and the ability to disable unfriendly ones. One report said the second X-37B mission had stalked China's Tiangong-1 in orbit, closing in to gather more information on the rendezvous target and orbiting space lab.
With a pair of X-37Bs, the U.S. Air Force could run a continuous set of R&D flights for new spacecraft payloads, testing instruments that could be flown – or reflown – on a more permanent basis as hosted payloads on commercial satellites. In an emergency, the X-37Bs could be used as reusable satellites, servicing as gap-fillers for some Low Earth Orbit (LEO) missions until a replacement satellite could be built and launched.
Edited by Braden Becker