The US Space Force’s (USSF’s) secretive Boeing X-37B Orbital Test Vehicle (OTV) – a highly classified, unmanned, reusable spaceplane – has returned to Earth after successfully completing its sixth operational mission, during which the platform beat its own previous flight duration record by remaining in orbit for 908 days before landing.
This milestone mission came to an end at 0522hrs (local time) on November 12, after the spaceplane had successfully deorbited and landed at NASA’s Kennedy Space Center Shuttle Landing Facility on Merritt Island in Florida. Having started life as a NASA project in 1999, the X-37 programme was handed over to the US Department of Defense (DOD) in 2004 and was managed by Air Force Space Command until 2019, when it was subsequently passed on to the USSF. In total, two X-37Bs have been produced, with the first completing its maiden orbital flight in 2010. The two spaceplanes have since been used to carry out lengthy space missions, but its latest 908-day orbital flight – which was launched via an Atlas V 501 rocket from Cape Canaveral at 1314hrs (local time) on May 17, 2020 – sets a new personal record for the X-37B.
Given that the X-37B programme is officially classified, very little light is shed on the purpose of its missions or what the platform did during its orbital flights. However, US Air Force (USAF) and USSF officials have noted that a variety of scientific experiments were conducted during the type’s latest mission. Gen Chance Saltzman, the USSF’s Chief of Space Operations, said: “This mission highlights the Space Force’s focus on collaboration in space exploration and expanding low-cost access to space for our partners, within and outside of the Department of the Air Force (DAF).”
Known as OTV-6, this mission marked the first time a service module – in this case a ring attached to the rear of the spaceplane – had been used, which helped expand the number of experiments that could be hosted by the platform during a mission. Prior to its landing, the service module was successfully separated from the spaceplane, which is a necessary move due to the aerodynamic forces the X-37B experiences upon re-entry. “In the coming weeks, the service module will be disposed of in accordance with best practices,” the USSF said in a statement.
The X-37B’s OTV-6 mission also hosted and conducted experiments with the Naval Research Laboratory’s Photovoltaic Radiofrequency Antenna Module. In which, the module successfully harnessed solar rays outside of the Earth’s atmosphere and aimed to transmit power to the ground in the form of radio frequency (RF) microwave energy. The X-37B also deployed the FalconSat-8 small satellite, which was developed by the Air Force Academy in partnership with the Air Force Research Laboratory (AFRL), in October 2021.
In addition, multiple NASA experiments were carried out during OTV-6. The X-37B was fitted with thermal control coatings, printed electronic materials and candidate radiation shielding materials as part of Materials Exposure and Technology Innovation in Space (METIS-2). After spending 908 days in space, NASA scientists will now leverage the data collected on the materials and compare their observed effects against ground simulations to validate and improve the precision of space environment models. Another NASA experiment aimed to investigate the effect of long-term space exposure on seeds, with scientists interested in the seeds’ resistance and susceptibility to space environment-unique stresses, such as radiation. This experiment will help inform space-based crop production for future interplanetary missions and the establishment of permanently inhabited bases in space.
Commenting on the platform and its capabilities, Lt Col Joseph Fritschen, the X-37B Program Director at the DAF’s Rapid Capabilities Office, concluded: “The X-37B continues to push the boundaries of experimentation, enabled by an elite government and industry team behind the scenes. The ability to conduct on-orbit experiments and bring them home safely for in-depth analysis on the ground has proven valuable for the [DAF] and scientific community. The addition of the service module on OTV-6 allowed us to host more experiments than ever before.”