U.S. Space Force Will Use Aerobraking to Change X-37B Orbit

Published on: October 10, 2024 at 7:44 PM
Artist rendering of the X-37B conducting an aerobraking maneuver using the drag of Earth’s atmosphere. (Courtesy graphic by Boeing Space)

The innovative use of aerobraking will allow the X-37B to efficiently and safely dispose of the service module, using minimal fuel thanks to decades of experience of the scientific community conducting space missions.

The U.S. Space Force announced that its X-37B Orbital Test Vehicle spacecraft, currently in orbit as part of the OTV-7 mission, will perform a series of innovative maneuvers known as aerobraking. This technique, which uses the drag of Earth’s atmosphere to change a spacecraft’s orbit, will be used for the first time on the X-37B to safely dispose of its service module components in accordance with recognized standards for space debris mitigation

OTV-7 is the fourth flight of the second X-37B, which was launched last year for the first time aboard a Falcon Heavy rocket instead of the Falcon 9 used for OTV-5 and the Atlas V used for the other missions. The X-37B has been in orbit since Dec. 28, 2023, conducting radiation effects experiments and testing Space Domain Awareness technologies in a highly elliptical orbit, supported by the Air Force Rapid Capabilities Office.

The aerobrake maneuver will allow the X-37B to change orbit using minimal fuel, demonstrating a more efficient solution. After completing the aerobrake maneuver, the X-37B will continue its testing and experimentation objectives before returning safely to Earth, as it has done on its six previous missions.

Secretary of the Air Force Frank Kendall emphasized the significance of this maneuver, stating, “This new and efficient series of maneuvers demonstrates the Space Force’s commitment to achieving breakthrough innovation while conducting national security missions in space.”

The decision to perform the aerobrake maneuver was based on the previous six successful X-37B missions, as well as decades of lessons learned from the scientific community conducting missions to the Moon and Mars.

Chief of Space Operations Gen. Chance Saltzman commended the team for their efforts, stating, “This maneuver, the first of its kind with the X-37B, is an incredibly important milestone for the United States Space Force as we look to expand our capabilities and capabilities to operate in this challenging domain. The success is a testament to the team’s dedication and perseverance.”

The X-37B Orbital Test Vehicle (OTV), the Air Force’s unmanned, reusable space plane, landed at Vandenberg Air Force Base at 5:48 a.m. (PDT) June 16. OTV-2, which launched from Cape Canaveral Air Force Station, Fla., March 5, 2011, conducted on-orbit experiments for 469 days during its mission.  (Image credit: Boeing)

Innovation and Experimentation in Space

The Department of the Air Force, in partnership with the United States Space Force, launched the seventh mission of the X-37B Orbital Test Vehicle (OTV-7), also known as USSF-52, on Dec. 28, 2023. OTV-7, the fourth mission for the second X-37B built, was placed in a highly elliptical orbit (HEO) at an inclination of 59.1°.

The mission, classified as secret by the U.S. Space Force, is intended to test and experiment with a wide range of technologies. These include operating the reusable spacecraft in new orbital regimes, testing space domain awareness technologies, and investigating the effects of radiation on NASA-provided materials.

One of the experiments aboard OTV-7 is NASA’s “Seeds-2,” which studies the effects of space radiation on plant seeds during long-duration spaceflight. This experiment builds on the successes of previous experiments and will help prepare for future crewed space missions.

Gen. B. Chance Saltzman, Chief of Space Operations, called these experiments “game-changing” and noted that the X-37B continues to provide the United States with the knowledge needed to improve current and future space operations. He also highlighted the USSF’s commitment to innovation and defining what is possible in the space domain.

William D. Bailey, Director of the DAF RCO, praised the collaboration with industry, particularly Boeing, to create a more responsive, flexible and adaptable testing platform. The collaboration between government and Boeing teams has led to streamlined processes and the adaptation of evolving technologies, allowing the United States to learn a great deal about operating and returning from a space environment.

The X-37B Orbital Test Vehicle, or OTV, is an experimental test program to demonstrate technologies for a reliable, reusable, unmanned space test platform for the U.S. Air Force. (U.S. Air Force photo courtesy of Boeing)

X-37B, A Spacecraft Shrouded in Mystery

The X-37B Orbital Test Vehicle (OTV) is an experimental program designed to demonstrate technologies for a reliable, reusable, unmanned space test platform for the United States Air Force. The X-37B is operated by the United States Space Force and serves as a test platform for new technologies and experiments.

The primary goals of the X-37B are twofold: to demonstrate reusable spacecraft technologies for America’s future in space, and to operate experiments that can be returned to Earth for examination.

Based on NASA’s X-37 design, the unmanned OTV is designed for vertical launch to low Earth orbit altitudes where it can perform long-duration space technology experiments and tests. Commanded from the ground, the OTV autonomously reenters the atmosphere, descends, and lands horizontally on a runway.

Technologies 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 U.S. Air Force began work on the X-37 in 1999 as a test project with NASA and, in 2004, the program was transferred to DARPA, which completed the ALTV portion of the X-37 program in 2006, performing a series of captive-carried and free-flight tests.

DARPA successfully validated the flight dynamics and extended the flight envelope beyond the low-speed/low-altitude tests previously conducted by NASA on the X-40A, a scaled-down version of the X-37 developed by the AFRL. NASA’s X-37 Orbital Vehicle was never built, but its design was the starting point for the Air Force’s X-37B Orbital Test Vehicle program.

There are currently two operational X-37B spacecraft and a single X-37A. The most recent mission, OTV-6, launched on May 17, 2020, and spent 908 days in low Earth orbit, setting a new endurance record that surpasses its previous record of 780 days in orbit, set in 2019 at the end of the OTV-5 mission.

OTV-6 was also the first mission to introduce a service module attached to the rear of the vehicle, expanding the number of experiments that can be accommodated during a mission. The service module successfully separated from the OTV prior to landing. In the weeks following OTV-6’s landing, the service module was disposed of “in accordance with best practices.”

The X-37B has flown more than 1.3 billion miles and spent a total of 3,774 days in space, as of 2022, conducting experiments for government and industry partners with the ability to return them to Earth for evaluation.

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Stefano D'Urso is a freelance journalist and contributor to TheAviationist based in Lecce, Italy. A graduate in Industral Engineering he's also studying to achieve a Master Degree in Aerospace Engineering. Electronic Warfare, Loitering Munitions and OSINT techniques applied to the world of military operations and current conflicts are among his areas of expertise.
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