Nanosatellite Orbit Control via Pulsed Ablative Thrusters
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Solution Overview
Problem
Nanosatellites in low Earth orbit face challenges in maintaining formation-flying configurations due to gravitational and drag perturbations, requiring frequent orbital correction maneuvers, which is impractical with conventional chemical propulsion systems given their mass and volume constraints.
Innovation Solution
A unified attitude-and-orbit control system using pulsed ablative thrusters (PATs) integrated into the spacecraft body, with attitude sensors and processing systems to calculate and apply corrective torques, allowing for efficient and precise thrust vector control without additional momentum wheels, thereby maintaining line of sight and formation flying for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemical propulsion systems are used for orbital correction maneuvers, then orbit control can be achieved, but the mass and volume requirements become impractical for nanosatellites
Solution Approach 1:
The patent replaces conventional chemical propulsion systems with pulsed ablative thrusters that use electrical discharge to ablate material from the spacecraft body itself. This substitution eliminates the need for separate propellant tanks and chemical fuel systems, dramatically reducing propulsion system mass and volume while maintaining orbit control capability through controlled material ablation from the spacecraft structure.
2Measurement precision
If separate attitude control systems (e.g., momentum wheels) are used, then attitude control precision is improved, but power, mass, and volume penalties increase
Solution Approach 1:
The patent merges the attitude control function with the propulsion system by using the same pulsed ablative thrusters for both orbit correction and attitude control. The thrusters are positioned at spacecraft extremities and controlled to produce both translational acceleration for orbit maintenance and rotational torque for attitude control, eliminating the need for separate momentum wheels or reaction wheels and reducing overall system mass.
3Reliability
If continuous thrust is used for orbit maintenance, then orbital precision is maintained, but power consumption increases
Solution Approach 1:
The patent employs periodic pulsed thrusting rather than continuous thrust to maintain orbital precision. The pulsed ablative thrusters are activated in discrete intervals to provide corrective impulses that counteract gravitational and drag perturbations. This periodic action achieves the same orbital maintenance effect as continuous thrust but with significantly reduced average power consumption, as the thrusters operate at high power only during brief pulse intervals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables prolonged maintenance of nanosatellite formation flying and orbit control with reduced power, mass, and volume requirements, enhancing thruster performance by utilizing pulsed thruster actuation and distributing firing across multiple thrusters, thus extending propulsion system lifetime.
Implementation Method 1
pulsed ablative thrusters (PATs) on at least one of the spacecraft body orientations
Implementation Method 2
pulsed ablative thrusters (PATs)
Data Source
AI summary
Systems and methods for orbit and attitude control of nanosatellites are provided. A spacecraft can be equipped with a plurality of pulsed ablative thrusters (PAT), mounted on at least one of the spacecraft body orientations. The PATs are integrated with the spacecraft structure. The actual spacecraft attitude is measured by a sensor and compared with the desired thrust direction. In order to reduce attitude errors, a control system is used to determine the firing sequence of thrusters. During maneuvering the thrusters are continuously being fired. To conserve energy a thrust switch control is utilized, selecting a single PAT to be fired each pulse. The result of this operation is that the attitude of the spacecraft is adjusted continuously. Therefore, thrust deviation from a selected path can be minimized during orbital maneuvering.