Universal

• Momentum dumping in minutes instead of hours
• Full automation of the process
• Increased payload capacity or reduced satellite mass
• Extended satellite service life

• Higher payload mass
• Reduced total spacecraft mass
• Cost savings of several million USD per spacecraft

• No deposition of fuel combustion byproducts on optical surfaces

• All currently known methods of kinetic moment unloading have limitations in terms of operational conditions.

• Methods based on the use of Earth's external physical force fields (gravitational or magnetic) are limited by distance from Earth and may require extended periods of time to be effective.

• For spacecraft in high orbits, such as geostationary (GEO), and interplanetary missions, the only viable method of unloading reaction wheels and control moment gyros remains the use of reaction-based systems.

• However, reaction-based unloading imposes significant and often insurmountable constraints on spacecraft, due to the need to carry a limited supply of reaction mass onboard.

• For low Earth orbit (LEO) space stations, replenishing this supply introduces major technical complexities and considerable financial costs. For spacecraft in high Earth orbits, around other celestial bodies, or in deep space, the reaction mass cannot be replenished at all.

• The Ensintron-1 concept is based on transferring the accumulated angular momentum from electromechanical momentum wheels or control moment gyroscopes (CMGs) to a spherical rotor, whose center of mass is suspended in vacuum using a magnetic levitation system.
• Electromagnets are installed on the rotors of the spacecraft’s orientation wheels or — in the case of CMG unloading — on the rotors of dedicated unloading wheels.
• The spherical rotor is positioned between the unloading wheels in such a way that their axes of rotation intersect at a calculated point — the center of mass of the spherical rotor.
• Momentum is dumped from the wheels through the interaction of the rotating electromagnets’ magnetic fields with secondary electromagnetic fields induced on the surface of the spherical rotor.
• The system includes cooling elements in case of rapid or high-intensity unloading of momentum wheels or CMGs — for example, when used on heavy or super-heavy spacecraft.
• To perform momentum unloading, the spacecraft is rotated into a specific orientation in which the angular momentum vectors of the unloading wheels and the spherical rotor become oppositely directed.
• During this maneuver, the axis of rotation of the spherical rotor remains fixed in space, and its angular velocity remains constant.
• This is possible because the rotor is held in a contactless magnetic suspension, effectively decoupling its mass, angular momentum magnitude, and direction from the spacecraft. As a result, the spacecraft rotates around the suspended rotor as if the rotor were not physically present at all.
• When unloading CMGs, their stored angular momentum is first transferred to the unloading wheels, and the orientation of the spacecraft can be arbitrary during this process.
• This concept represents a foundational technology, demonstrating the possibility of momentum dumping without expending propellant or relying on external physical fields. However, the device requires the development of specialized momentum wheels with integrated electromagnets.
• For practical implementation, improvements are needed to increase system reliability and simplify the design. These improvements are already underway, and additional patent applications have been submitted to extend and refine the original concept.

• The Ensintron-2 concept is based on transferring angular momentum from the spacecraft’s electromechanical momentum wheels (or control moment gyroscopes) to a gimbal-mounted momentum wheel that acts as an astatic gyroscope with an electrically controlled rotor.
• To prevent the gimbal lock effect during unloading of inertial actuators, the outer gimbal frame is installed inside the spacecraft body in such a way that its axis of rotation is not aligned with any of the spacecraft’s orientation axes.
• As with the Ensintron-1 concept, the spacecraft is rotated into an unloading position using its inertial actuators (IMA) along all three axes. The critical threshold of angular momentum that triggers unloading is chosen below the absolute limit to ensure a reserve in case of momentum growth during spacecraft maneuvering. Rotation around any given axis is achieved by accelerating or braking the corresponding momentum wheels or by moving the gimbal frames of the CMGs that control that axis. These maneuvers generate gyroscopic moments that also rotate the spacecraft around the remaining axes. Special control algorithms govern these coordinated movements.
• When a momentum wheel accelerates or decelerates, it generates a torque that causes the spacecraft to rotate. This rotation continues until the momentum wheel returns to its initial angular momentum. The spacecraft’s orientation can be stopped at any desired angle, during which the angular momentum vectors of all inertial actuators — as well as the total resulting vector — change direction in accordance with the spacecraft’s rotation.
• To perform unloading, the spacecraft is rotated to a position where the angular momentum vectors of the actuators (along the axis being unloaded) and the gimbal-mounted momentum wheel are collinear.
• During this maneuver, the gimbal-mounted wheel preserves the magnitude and direction of its angular momentum vector, adjusting its orientation within the gimbal. The gimbal’s outer frame is hinged to the spacecraft body, allowing this spatial preservation. Once the spacecraft reaches the unloading orientation, the inner and outer gimbal frames are locked (arrested), and angular momentum is transferred from the inertial actuators to the gimbal wheel.
• Depending on the alignment of the momentum vectors, the wheel either accelerates or decelerates:
• If the vectors are aligned, the wheel gains speed.
• If they are opposed, it slows down or reverses direction.
• The alignment and direction of momentum vectors — and the corresponding spacecraft rotation — are selected so that at the end of the unloading cycle, the gimbal wheel does not exceed its maximum speed and still maintains enough momentum to preserve its spatial orientation after the gimbals are unlocked.
• Once unloading is complete, the gimbals are released, the spacecraft returns to its operational orientation, and the momentum wheel continues free-spinning with a stable angular momentum vector until the next unloading cycle.
• This technology enables rapid unloading, with duration limited only by the onboard power supply capabilities.
• The Ensintron-2 concept is technologically mature, reliable, and based on existing hardware components. The device is compact and lightweight, comparable to a single-axis IMA, and it can be installed anywhere on board the spacecraft