US Air Force's X-37B preparing for next space flight

The US Air Force's strange little space plane, the experimental X-37B, is preparing for its sixth mission. Dubbed the Orbital Test Vehicle (OTV), little is known about its mission, apart from that the Pentagon claims it exists to test new technology. According to a rocket launch schedule, one of the Air Force's two remotely piloted X-37Bs will blast off on its next mission atop an Atlas V rocket on May 16 from Cape Canaveral Air Force Station on Florida's Atlantic coast. As for the details about its mission, your guess is as good as ours. The last flight, launched in September 2017, lifted the Advanced Structurally Embedded Thermal Spreader II, an experimental heat pipe used for managing temperature flows, for testing. When the last OTV touched down in October 2019, it had been in orbit for 779 days. The box truck-sized space plane operates at altitudes ranging from 110 to 500 miles up. However, part of the X-37B's mission is simply development of reusable space plane technology, according to the Air Force. The tech is being pursued by a variety of nations as well as private firms like Virgin Galactic. "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," the Air Force adds.

The US space agency NASA once operated the Space Shuttle, which the X-37B somewhat resembles and to which it operates similarly, but those craft have all been retired. The X-37 was originally developed by NASA in the late 1990s, but the program was handed over to the Defense Advanced Research Projects Agency (DARPA), a Pentagon tech lab, in 2004, at which point it became classified, according to Space.com. Its first flight was in 2010.

Secrecy Tightens for X-37B

The recent landing of the latest X-37B robot spaceplane mission has been less visible to outsiders than any previous mission. The US Air Force has released photos of the spacecraft taken soon after its return. They show that the vehicle seems to be in fairly good condition after its longest flight ever, which extended for well over two years. The photos also show that the spacecraft has no visible features that would distinguish it from other spacecraft launched in this program, and in some ways make it hard to know exactly which one of the identical X-37B vehicles was used on this mission. We can probably judge that the mission was successful, but we are still not entirely sure of what the spacecraft was doing in orbit. Analysts have been speculating on the program for years, and have never been successful in penetrating the veil of secrecy surrounding the project. While the project itself is an amazing feat of technology, kudos must be extended to the team behind the scenes, who have managed to keep so much under wraps for so long. The existence of X-37B is no secret, and much has been officially released into the public domain. But there is an ongoing trend of tightening secrecy for the X-37B. In the past, we were given detailed images of the spacecraft being encapsulated in its payload fairing for launch, and then treated to nice video and images of its landing. That changed for recent missions, when pre-launch imagery of the spacecraft was not released. At the time, this analyst speculated that something had changed with the hardware, and this needed to be concealed.

The theory was that some form of instrument or sensor target had been added to the interface between the spacecraft and its launch vehicle, which would be used in some sort of interactions between the X-37B and the final launch stage shortly after launch.

The fact that the US Air Force had no problems with releasing full views of the spaceplane after landing suggested that any sensitive parts were on the rocket and not the X-37B itself.

This time, it's different. Admittedly, we still have photos of the spacecraft after landing, but they are far more restricted than ever before. The US Air Force Web site and an affiliated site contain just two images of the latest landing. No video of the landing has been released, either, which is also a departure from earlier trends.

Curiously, the images do not give any proper views of the rear of the spacecraft. By not showing certain things, the USAF is hinting that something unusual is there.

What could it be? This analyst suggests that some sort of calibration target is pasted to the rear of the X-37B. It was presumably photographed by sensors on the rocket soon after the spaceplane separated from it. This suggests that cameras or other sensors are being tested for close inspections of other satellites. T

hat being said, this analyst does not believe that any X-37B mission has ever made a close inspection of any foreign satellite, despite speculation elsewhere.

An alternative theory could be that there is a mounting bracket for a sub-satellite that was deployed from X-37B at some point in its mission. Such a satellite would be very small, and would presumably be in close proximity to the spaceplane. Thus, it could be hard to track or detect it.

What really lies at the rear of the spacecraft? We may never know until this program is declassified, and we could be waiting a long time for that.