It circled the Earth in obscurity for more than half a year, now the semi-secret X-37B OTV 5 space plane has been conclusively identified by amateur satellite observers in a circular orbit around 355 Kilometers in altitude. The orbit’s inclination at 54.5 degrees is much different from previous OTV missions and in part responsible for the craft remaining undiscovered for so long.
X-37B, conducting its fifth orbital flight, lifted off from Launch Complex 39A at Florida’s Kennedy Space Center on September 7, 2017. In the typical secrecy surrounding the Air Force’s X-37B program, the launch was shown until separation of the protective payload fairing and confirmation of successful orbital insertion was provided a short time later but operational aspects of the mission like the craft’s operating orbit, intended mission duration and specifics on the payloads it carries were not disclosed.
Given the hush-hush nature of its missions, X-37B is a target of intense observation by the amateur satellite community and the orbital dynamics of all four prior OTV missions were closely watched. Typically, the spacecraft was spotted in orbit within a few days after launch; however, there were several cases where observers lost track of the spacecraft due to unexpected orbital maneuvers.
X-37B OTV 5 proved to be a tougher nut to crack as it was clear from the outset that the spacecraft would operate from a different orbit than its predecessors: “The fifth OTV mission will be launched into, and landed from, a higher inclination orbit than prior missions to further expand the X-37B’s orbital envelope,” the U.S. Air Force Rapid Capabilities Office said in a statement before the craft blasted off atop Falcon 9.
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What the spacecraft might be up to in this type of Low Earth Orbit, some 50 Kilometers lower than the International Space Station, is pretty much unknown. As with the previous X-37B flights, only very few details on the OTV 5 mission are being shared with the public and most of what resides in the vehicle’s 2.1 by 1.2-meter payload bay will remain secret.
One payload on the OTV 5 mission that was publicly acknowledged is the Air Force Research Laboratory Advanced Structurally Embedded Thermal Spreader that will test experimental electronics and oscillating heat pipe technologies over a long-duration space flight. Three oscillating heat pipes are part of the package to evaluate the technology for future applications in space as it could offer lighter and less expensive thermal control solutions for satellite missions. The goal of the OTV-5-mounted experiment will be to evaluate the technology’s initial thermal performance and monitor it over an extended period to assess long-term degradation.
The Air Force also said the OTV 5 mission hosts small satellite ride shares to demonstrate greater opportunities for rapid space access; however, no additional objects have been cataloged under the OTV 5 mission’s international designator 2017-052 up to this point.
