Autonomous Spacecraft Deorbit Burn Targeting Without Ground Latency
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Solution Overview
Problem
Existing systems for deorbiting spacecraft rely on ground-side communication, leading to latency and reduced confidence in deorbit burn calculations due to transmission errors and other factors, making autonomous on-board deorbiting challenging.
Innovation Solution
An autonomous on-board system that selects a target landing site and calculates a deorbit burn solution using on-board sensors and computing systems, determining a range target, velocity target, and back-propagated orbit state to converge with the spacecraft's known state, allowing for real-time accurate burn pulse execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground-side communication systems are used for deorbiting spacecraft, then two-way communication allows for centralized control and calculation, but latency and transmission errors increase the time needed to calculate deorbit burn targets and reduce confidence in the resulting burn instructions
Solution Approach 1:
The spacecraft performs deorbit burn calculations autonomously using on-board sensors and computing systems. The system determines range targets, velocity targets, and back-propagated orbit state estimates independently without requiring ground-based calculation, thereby eliminating communication latency and transmission errors while maintaining high confidence in the burn instructions.
Solution Approach 2:
The patent introduces an on-board autonomous deorbit targeting system as an intermediary between the spacecraft and ground systems. This intermediary performs real-time orbital mechanics calculations and burn target determination locally, replacing the traditional ground-based calculation pathway and eliminating the need for time-consuming two-way communication for critical deorbit computations.
2Productivity
If ground-side systems are used for deorbiting, then centralized control is maintained, but communication latency reduces productivity in executing deorbit maneuvers
Solution Approach 1:
The spacecraft autonomously determines deorbit burn targets using on-board sensors and computing systems. The system performs real-time orbital state estimation, range and velocity target calculation, and burn parameter determination without ground intervention, thereby eliminating communication latency and significantly increasing the speed of deorbit maneuver execution.
Solution Approach 2:
The autonomous system continuously monitors orbital parameters and pre-calculates deorbit burn targets within a predetermined time window. By performing these calculations in advance and in real-time without waiting for ground communication cycles, the system eliminates latency and enables immediate execution of deorbit maneuvers when conditions are favorable.
3Measurement precision
If autonomous on-board systems are implemented for deorbiting, then real-time accurate burn pulse execution is achieved, but device complexity increases
Solution Approach 1:
The on-board computing system performs multiple functions including orbital state estimation, sensor data processing, range and velocity target calculation, and burn parameter determination. By consolidating these previously ground-based functions into a single multi-functional on-board system, the patent achieves high measurement precision while managing complexity through functional integration rather than proliferation of separate systems.
Solution Approach 2:
The system continuously compares back-propagated orbit state estimates with actual orbital parameters and adjusts burn target calculations in real-time. This feedback mechanism ensures high accuracy in burn calculations by constantly verifying and refining the orbital state estimate, compensating for any drift or uncertainty without requiring overly complex hardware.
4Reliability
If autonomous deorbiting is implemented within a predetermined time window, then confidence in the deorbit process increases, but the difficulty of detecting and measuring orbital parameters increases
Solution Approach 1:
The system combines multiple sensor inputs and orbital measurement data into a unified back-propagated orbit state estimate. By merging sensor measurements with orbital mechanics models and continuously reconciling them through back-propagation, the system achieves high confidence in the deorbit process while managing the complexity of orbital parameter detection through integrated data fusion rather than separate measurement systems.
Data Source
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.