To what ends might the United States Department of Defence have developed an unmanned, highly-manoeuvrable ‘spaceplane’? Why have its lengthy missions – lasting as long as two and a half years – been so shrouded in secrecy? And what are China’s intentions for its rival vehicle? These questions and more underpin speculation around the dangers of an unfolding spaceplane race.
The US X-37b space drone, conceived by NASA and Boeing in the late 1990s, was taken up as a classified project of the US government’s ‘Space Force’ in 2004. At around nine metres long and four-and-a-half wide, the bus-sized vessel is launched by rocket but can land independently on conventional runways. Its significant cargo bay, however, rarely pictured open in any publicly-available images since its maiden flight in April of 2010, leaves uncertainty about the drone’s internal capacities, and its possible functions.
This secrecy has fuelled questions about the X-37b’s military capabilities – questions which have not been dampened by the minimal official communications issued about the X-37b’s purposes, despite the heavily publicised spectacle of its launches.
A common official line for early flights – offering that the vehicle functioned as a contained test site for the viability of new satellite materials – justified extended missions with a need to examine these materials’ resilience over time. That this testing could not take place in the established International Space Station (ISS), however, implied secrecy, and added to the questions that have accompanied each of the space drone’s launches. Among other omissions, commentators have remarked on the absence of requisite UN notification and thus proper transparency for satellites the X-37b has released in flight – an unusual divergence from international space norms with which the United States usually seeks to demonstrate public compliance.
But it is in the months since the X-37b’s most recent departure, in late December 2023, that attention to its purposes has come to a head. The use of the highly powerful SpaceX Falcon Heavy rocket for the plane’s launch – rather than the Falcon 9 rocket used for 2020’s launch – has prompted questions: why might its engineers need the plane to orbit at the altitudes this higher-powered rocket could propel it to? These queries remain unresolved by formal statements regarding its still ongoing flight, which poses extended experiments into the atmospheric viability of plant seeds as the mission’s innocuous purpose.
In the absence of trustworthy information, it is of little surprise that curious minds have sought clues to intentions for the X-37b. In February 2024, Tomi Simola – an amateur satellite tracker from Finland – spied the spacecraft in one of his regular sky captures after weeks of collaborative effort by fellow online tracking enthusiasts. Based on this, Harvard astrophysicist Jonathan McDowell remarked that the ‘unusual elliptical orbit’ of the plane appeared similar to that of US Space Force satellites used for detecting ballistic missiles in flight. McDowell speculates that the X-37b’s current mission could be about testing a powerful infrared ‘early-warning’ sensor used to detect such missiles – but stressed that this was only speculation. Indeed, without proper transparency, only such speculation is possible. Read more
While the launch is being presented as a step forward for the civil space industry – with Virgin’s commercial space ambitions being heavily promoted – the rocket will launch two military satellites (that we know about) alongside commercial ones: Prometheus-2 and Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE). The mission is being led by RAF Squadron Leader Matthew Stannard.