Popular Mechanics (South Africa)
Machines:
Inside the US Air Force’s X-37B spy plane.
WITH ITS bullet shape and stubby wings, the US Air Force’s X-37B Orbital Test Vehicle looks like the little brother of NASA’s classic Space Shuttle orbiter. But the comparisons end there: The X-37B is built to spend months and even years in orbit, carrying out classified missions for America’s military space programme.
In the 1990s, NASA needed a cheaper option to boost spaceplane readiness. The Space Shuttle couldn’t lower its payload-to-orbit costs, and it took months to refurbish between flights. The agency’s solution? An unmanned spaceplane (a vehicle that moves like an aircraft in our atmosphere and like a spacecraft in space), which would require less thrust and a smaller rocket to send it into space. Without a crew, it could spend as long as the mission needed in low-Earth orbit before coming home.
NASA and the Air Force simultaneously planned similar craft, but after a few fits and starts – including the lone X-40A that Boeing built for the military – NASA let the Pentagon’s Defense Advanced Research Projects Agency (DARPA) take control. DARPA’s X-37, an Approach and Landing Test Vehicle, eventually gave way to the sequel: a fully capable vehicle with heat-resistant tiles and a propulsion system that would fulfill the mission profile of an unmanned spaceplane.
Boeing’s X-37B went to space for the first time in 2010. The two X-37B spacecraft have carried out a total of five missions, racking up 2 866 days in orbit. The fifth mission, OTV-5, was in orbit for more than 700 days.
At 8.8 m long and 2.7 m wide, the X-37B has a wingspan that stretches almost 4.6 m and has a launch weight of 4 990 kg, excluding the booster rocket. The spaceplane is powered by gallium arsenide solar cells with lithiumion batteries, and has thrusters for orbit manoeuvring and de-orbiting, but it has no engines to travel long distances in space, or for powered flight through the atmosphere.
So it can push itself down into Earth’s atmosphere for a landing but can’t, for example, travel to a higher geosynchronous orbit or place itself on a path to the Moon.
The X-37B’s payload bay measures 2.1 m by 1.2 m – the size of a truck bed. What makes it unique among current spacecraft is its ability to take cargo loads into space and return them to the
engineers who built them on Earth. As an Air Force platform, it’s natural to think of the X-37B as an exotic weapon system. Some even speculate it could be used to snatch enemy satellites for study.
In reality, the X-37B’s most likely mission, per the space policy non-profit Secure World Foundation, is as an ‘on-orbit sensor platform and technology test bed’. The X-37B could allow the Air Force to test upcoming tech bound for the next generation of spy satellites.
Even if the X-37B carries out missions that aren’t the stuff of spy novels, its unpredictability still drives the enemies nuts. Former Secretary of the US Air Force Heather Wilson recently said the X-37B ‘can do an orbit that looks like an egg and, when it’s close to the Earth, it’s close enough to the atmosphere to turn where it is’.
That means when the X-37B is out of sight from adversaries on the other end of the Earth, it can dip down into the atmosphere by using its wings and manoeuvring its thrusters. This increases drag, slowing down the spaceplane to prevent it from popping up on a predictive schedule.
Imagine that the Chinese military has located the X-37B in space and is guiding satellites to get a closer look. If the US gets wind of the operation and spots the approaching Chinese satellites, it could order the X-37B to change its orbit – ideally over South America, the opposite end of the Earth from China. The X-37B would simply fail to show up at the designated time, forcing the Chinese to reacquire the spacecraft and start all over.
Although more capable spaceplanes are almost certainly in development, they’re unnecessary for deploying most space-based weapon concepts. The X-37B gets the job done – even if we don’t actually know what that job is.