After more than nine months in an unusual, highly elliptical orbit, the US military’s X-37B spaceplane will soon begin dipping its wings into Earth’s atmosphere to lower its altitude before eventually coming back to Earth for a runway landing, the Space Force said Thursday.
The aerobraking maneuvers will use a series of passes through the uppermost fringes of the atmosphere to gradually reduce its speed with aerodynamic drag while expending minimal fuel. In orbital mechanics, this reduction in velocity will bring the apogee, or high point, of the X-37B’s orbit closer to Earth.
Bleeding energy
The Space Force called the aerobraking a “novel space maneuver” and said its purpose was to allow the X-37B to “safely dispose of its service module components in accordance with recognized standards for space debris mitigation.”
While the reusable Boeing-built X-37B spaceplane is designed to land like an aircraft on a runway, the service module, mounted to the rear of the vehicle, carries additional payloads. At the end of the mission, the X-37B jettisons the disposable service module before reentry. The Space Force doesn’t want this section of the spacecraft to remain in its current high-altitude orbit and become a piece of space junk.
“Once the aerobrake maneuver is complete, the X-37B will resume its test and experimentation objectives until they are accomplished, at which time the vehicle will deorbit and execute a safe return as it has during its six previous missions,” the Space Force said.
The Space Force has identified mobility in orbit as a key focus for its next-generation space missions. This would allow satellites to more freely move between altitudes and orbital inclinations than they can today. Commanders don’t want a spacecraft’s movements to be constrained by the amount of fuel it carries, allowing satellites to “maneuver without regret.”
Space Force leaders have discussed in-orbit refueling, more efficient propulsion technologies, and other ways to achieve this end. Aerobraking is another way to lower a spacecraft’s orbit without using precious propellant.
“This first-of-a-kind maneuver from the X-37B is an incredibly important milestone for the United States Space Force as we seek to expand our aptitude and ability to perform in this challenging domain,” said Gen. Chance Saltzman, the Space Force’s chief of space operations.
Hellbound and Down 