Autonomous Spacecraft Deorbiting With On-Board Burn Calculation
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Solution Overview
Problem
Existing systems for deorbiting spacecraft rely on ground-side systems and two-way communication, leading to latency and reduced confidence in deorbit burn calculations due to transmission errors and other factors, which complicates the selection of a landing site and calculation of efficient deorbit paths within a time window.
Innovation Solution
An autonomous on-board system that uses computing devices and sensors to select a target landing site, determine a burn solution, and execute a deorbit maneuver by calculating an estimated time of ignition and burn velocity vector, allowing for real-time or near-real-time calculations and increased confidence in the deorbit process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground-side systems and two-way communication are used for deorbiting, then the spacecraft can receive external guidance and control, but latency and transmission errors reduce confidence in deorbit burn calculations
Solution Approach 1:
The spacecraft performs autonomous deorbit operations by independently selecting landing sites, calculating deorbit paths, and determining burn parameters using on-board sensors and computing systems, eliminating reliance on ground-based control and communication
Solution Approach 2:
The system pre-calculates multiple deorbit paths and landing site options before the deorbit maneuver, allowing the spacecraft to quickly select and execute the optimal path without time-consuming ground-based calculations
2Measurement precision
If ground-based systems calculate deorbit paths, then complex computations can be performed, but communication latency and transmission errors increase the time needed and reduce confidence
Solution Approach 1:
The spacecraft's on-board computing system independently performs all deorbit path calculations and landing site selections using sensor data, eliminating the need to transmit sensitive calculation data to and from ground systems where transmission errors could occur
Solution Approach 2:
The system transitions from ground-based to space-based computation, moving the computational capability from the ground dimension to the orbital dimension where real-time autonomous decision-making is possible
3Productivity
If the spacecraft must select a landing site and calculate deorbit path within a time window, then the deorbit can be completed efficiently, but the complexity of coordinating these functions increases system complexity
Solution Approach 1:
The on-board computing system performs multiple functions including sensor data processing, landing site selection, deorbit path calculation, and burn parameter determination within a single integrated autonomous system, reducing the need for separate specialized subsystems
Solution Approach 2:
The system combines landing site selection and deorbit path calculation into a unified autonomous process that simultaneously optimizes both functions, allowing the spacecraft to efficiently determine the optimal deorbit trajectory and target location together rather than as separate sequential steps
Data Source
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AI summary
In an example, a method for deorbiting a spacecraft is described. The method includes selecting a target landing site for deorbiting the spacecraft. The method includes determining a range target and a velocity target for reaching a predicted atmospheric entry location. The method includes determining a back-propagated orbit state estimate of the spacecraft. The method includes comparing the back-propagated orbit state estimate to a known orbit state of the spacecraft to determine that the back-propagated orbit state estimate has converged with the known orbit state. The method includes calculating based on determining that the back-propagated orbit state estimate has converged with the known orbit state, (a) an estimated time of ignition for a propulsion system of the spacecraft and (b) an estimated burn velocity vector of the propulsion system using the range target and the velocity target. The method includes performing a burn pulse by the propulsion system.