On Dec. 11, 2012, ULA launched the third mission to deliver a secretive and controversial U.S. Air Force “mini-shuttle” into orbit as part of the Air Force’s X-37B program. The vehicle, known as the X-37B Orbital Test Vehicle (or OTV), has been on orbit (as far as we know) ever since, and this week NASA announced that the last two remaining space shuttle orbiter processing facilities (or OPFs) at the agency’s Kennedy Space Center in Florida will now be used to process the reusable unmanned space plane for its future missions.
“Kennedy is positioning itself for the future, transitioning to a multi-user launch facility for both commercial and government customers, while embarking on NASA’s new deep-space exploration plans,” said Kennedy Center Director Robert Cabana. “A dynamic infrastructure is taking shape, designed to host many kinds of spacecraft and rockets.”
NASA utilized three OPFs to support processing the agency’s now-retired space shuttle fleet over the course of the 30-year space shuttle program, but the agency has been hard pressed to find a mission requirement for the facilities since the last shuttle landed in 2011. Boeing is already leasing former OPF-3 to manufacture and process their CST-100 spacecraft, and now Boeing is also performing construction upgrades in OPF-1 and OPF-2 on behalf of the X-37B Program, with the upgrades expected to be completed in December.
Described as “the United States’ newest and most advanced re-entry spacecraft,” the OTV’s close resemblance to the shuttle is misleading. In orbit, it deploys an array of gallium arsenide solar cells, which, when combined with power from a set of lithium-ion batteries, have thus far enabled it to remain aloft years longer than the any shuttle mission. Its payload bay measures 7 feet long and 4 feet wide and can house a payload weighing between 500-660 pounds. An advanced avionics suite and airframe, together with electromechanical actuators and autonomous guidance controls, has focused the OTV’s mandate onto “risk reduction, experimentation, and operational concept development for reusable vehicle technologies in support of long-term developmental space objectives.”
Its thermal protection materials are impressive … and so are their acronyms: Toughened Uni-piece Fibrous Refractory Oxidation-resistant Ceramic (TUFROC) tiles line the leading edges of the wings, instead of the reinforced carbon-carbon used on the shuttle, whilst highly durable Toughened Uni-piece Fibrous Insulation (TUFI) impregnated silica tiles and Advanced Conformal Reusable Insulation (CRI) blankets cover the airframe.
Like the Soviet-era Buran vehicle, the OTV has the capacity to land autonomously on a runway at either Edwards or Vandenberg Air Force Bases in California. The X-37B Program has also conducted testing at KSC’s Shuttle Landing Facility to demonstrate that landing the vehicle at the former shuttle runway is a technically feasible option.
The X-37B currently circling the Earth on the OTV-3 mission has been doing so now for over 650 days. Its launch marked the first occasion on which an OTV has ever been used for a second mission. It previously flew for 224 days in April-December 2010, and a sister ship flew the OTV-2 mission for 15 months from March 2011 until mid-June of 2012.
It is not known how long OTV-3 will remain in orbit, and its precise mission objectives remain heavily classified.
— Written by both Ben Evans and Mike Killian.
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