Phobos Quasi-Satellite Orbit Tracking With Three-Body Feedback Control
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Solution Overview
Problem
Conventional orbital design approaches for missions to Mars, particularly involving Phobos, are complex due to the unusual orbital characteristics of Phobos and the multi-body dynamics in the Mars-Phobos system, making fuel-efficient transfer orbits challenging to plan and track.
Innovation Solution
The use of a three-body assumption in orbital design, specifically the circular restricted three-body problem (CR3BP), allows for the identification of quasi-satellite orbits and distant retrograde orbits, which are leveraged to generate fuel-efficient transfer orbits using a processor-based system that includes a transfer orbit generator and feedback stabilization controller to manage delta v commands for thruster control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional two-body conic orbit structure is used for Mars orbital design, then orbital design simplicity is maintained, but orbital design accuracy and fuel efficiency deteriorate due to Phobos's unusual orbital characteristics and multi-body dynamics
Solution Approach 1:
The patent changes the fundamental parameters of the orbital design approach by transitioning from a two-body conic model to a three-body model that includes Phobos's orbital characteristics around Mars. This parameter change allows the system to account for Phobos's unusual orbital features (fast orbital period, low altitude, high eccentricity) while maintaining computational tractability through the circular restricted three-body problem framework.
Solution Approach 2:
The patent introduces quasi-satellite orbits (QSOs) and distant retrograde orbits (DROs) as intermediary orbital structures that facilitate transfer between initial and target orbits. These intermediary orbits serve as stable transfer pathways that leverage the three-body dynamics of the Mars-Phobos-spacecraft system, providing both precision and fuel efficiency without requiring complex real-time trajectory adjustments.
2Use of energy by moving object
If multi-body dynamics are incorporated into orbital design, then orbital transfer fuel efficiency is improved, but computational complexity and trajectory prediction difficulty increase
Solution Approach 1:
The patent segments the complex three-body orbital transfer problem into distinct phases: (1) defining the circular restricted three-body problem framework, (2) identifying quasi-satellite and distant retrograde orbit families, (3) computing transfer trajectories between these orbit families, and (4) implementing feedback stabilization control. This segmentation allows each phase to be addressed with appropriate mathematical tools while maintaining overall system manageability.
Solution Approach 2:
The patent implements feedback stabilization control mechanisms that continuously monitor and adjust the spacecraft's orbital parameters to maintain the desired trajectory. This feedback approach compensates for the complexities of multi-body dynamics by using real-time or predicted orbital information to correct deviations, thereby achieving fuel-efficient transfers without requiring overly complex open-loop trajectory designs.
3Measurement precision
If Phobos's unusual orbital characteristics are fully accounted for, then orbital tracking accuracy is improved, but orbit determination difficulty increases
Solution Approach 1:
The patent performs preliminary computation of Phobos's orbital elements and the resulting quasi-satellite and distant retrograde orbit characteristics before the actual orbital transfer and tracking phases. By pre-calculating the expected orbital paths and using these as reference models, the system can achieve high tracking accuracy during execution without needing to perform complex real-time measurements and calculations.
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
This approach enables efficient and stable transfer of spacecraft between Phobos orbits, minimizing fuel consumption and accounting for the unique gravitational influences in the Mars-Phobos system, thereby overcoming the complexities of conventional two-body conic orbit designs.
Implementation Method 1
generating a fuel-efficient transfer among orbits in the Mars-Phobos system, that leverages multi-body dynamics on the spacecraft using a three-body assumption
Data Source
AI summary
A method and system for activating thrusters of a vehicle for trajectory-tracking control of the vehicle. A transfer orbit generator to generate a transfer orbit for the vehicle from an initial orbit to a target orbit, and a feedback stabilization controller. Compute the target orbit for the vehicle about the celestial body. Compute a free trajectory with patch points along the free trajectory using a free trajectory module, each patch point includes a position and a velocity. Determine a feedback gain at each patch point using a feedback gain module, wherein a state penalty function at each patch point is set to match a state uncertainty function at the same patch point. Apply the feedback gain at each patch point to map the position and the velocity at each patch point to delta v commands, to maintain the target orbit using a feedback stabilization controller.