U.S. Air Force spaceplane tests fuel-saving techniques in orbit
The unmanned X-37B spaceplane, operated by the United States Air Force, has been in orbit for over a year. Although its tests are classified, the Pentagon has indicated that it is exploring the potential of aerodynamic braking. This technique offers fuel savings and allows for dynamic manoeuvres, including potential combat, in space.
The Boeing X-37B is a small, unmanned spaceplane. It was tested in 2010 after earlier assessments of the X-37A variant. The X-37 B has been engaged in classified missions in Earth's orbit for several years.
The vehicle is just under 9 metres long and has tiny wings with a wingspan of about 5 metres. Weighing nearly 5,000 kilograms, the spaceplane features a payload bay of slightly more than 2,000 litres in space.
The X-37B spaceplane is noteworthy for the duration of its missions. It stayed aloft for 908 days in a record-breaking flight, even though its initial official specification stated its autonomy at 270 days. This was incorrect; the current X-37B mission has lasted over a year. What has the spaceplane been doing for so long in orbit?
Aerodynamic braking in space
Among the tasks undertaken is the exploration of aerodynamic braking capabilities. This involves leveraging the resistance generated by the Earth's atmosphere at high altitudes—above the notional boundary of space.
Even when atmospheric gases are extremely sparse, the aerodynamic drag they produce can be harnessed. In the case of the X-37B, this is meant to facilitate a rapid orbital transition to a lower orbit without using an engine, thereby preserving valuable fuel.
Dynamic space operations
These tests are intended to assess the feasibility of swiftly discarding the mission module's carrier. Previously jettisoned at high orbital altitudes, these modules contributed to space debris, circling the Earth for decades.
Current NASA guidelines stipulate that space debris should not remain in orbit for more than 25 years, but the ongoing X-37B tests aim to reduce this period to just five years. During this time, the mission module is anticipated to descend sufficiently due to atmospheric resistance to combust in the atmosphere.
In addition to the official rationale, experts suggest that these tests could have potential military applications. According to reports, the Pentagon's "dynamic space operations" could facilitate manoeuvres, allowing, among other things, the inspection or elimination of hostile satellites.
