Mars Capture Navigation via Hybrid Celestial and Radio Velocity
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Solution Overview
Problem
Current deep space navigation methods, particularly for the Mars capture phase, face challenges in achieving continuous, autonomous, and high-precision navigation due to limitations in ground radio technology, such as visible arc constraints and radio delay, which hinder real-time accuracy.
Innovation Solution
A navigation method combining celestial velocity measurements performed by a probe with ground radio measurements using an extended Kalman filter, incorporating observation equations for distance and radial velocity, and dynamic equations accounting for Mars' gravitational and perturbation forces, along with the use of a B-plane error ellipse to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground radio measurement is used for deep space navigation, then navigation coverage can be achieved, but navigation accuracy and real-time performance are limited due to visible arc constraints and radio delay
Solution Approach 1:
The patent combines ground-based radio measurement with space-based celestial velocity measurement into a hybrid navigation system. The ground radio provides baseline positioning while the celestial velocity measurement instrument on the probe autonomously measures radial velocities of celestial bodies, merging both measurement systems to achieve higher accuracy and real-time performance without being constrained by radio delay alone.
Solution Approach 2:
The probe performs autonomous celestial velocity measurement using its own onboard instrument to measure the radial velocities of celestial bodies relative to the probe. This self-service capability allows the probe to independently obtain navigation data without relying solely on ground-based measurements, reducing the impact of radio delay and improving real-time navigation capability.
2Measurement precision
If autonomous celestial velocity measurement is added to ground radio measurement, then navigation accuracy is improved, but system complexity increases
Solution Approach 1:
The celestial velocity measurement instrument on the probe serves multiple functions: it measures the radial velocities of celestial bodies for navigation, and can also be used for attitude determination and scientific observation. This multi-functionality reduces the need for separate dedicated instruments, thereby limiting the increase in system complexity while achieving improved navigation accuracy.
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 method effectively improves navigation accuracy by integrating ground ranging, velocity measurement, and celestial autonomous velocity measurements, meeting the high precision requirements of deep space exploration through clear engineering steps and improved state estimation.
Implementation Method 1
the distance and the radial velocity between the ground station and the probe are measured by the ground station to obtain observations ρ, ρ̇
Implementation Method 2
the radial velocity between the specified star and the probe is independently obtained by the probe, to obtain an observation ρ̇ Sun
Implementation Method 3
a kinetic differential equation (including Mars two-body gravitation, Mars gravitational field J2 perturbation, Mars three-body perturbation, major planet three-body perturbation, solar radiation pressure perturbation) is established according to the dynamic environment in Mars capture phase
Implementation Method 4
solar radiation pressure perturbation
Data Source
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Figure 3~4
AI summary
The invention provides a navigation method for Mars capture phase based on the combination of celestial velocity measurement and ground radio. The method comprises the following steps: obtaining the distance between the probe and the ground through radio ranging of a ground station; obtaining the radial velocity between the probe and the ground station through radio Doppler velocity measurement of the ground station; obtaining the radial velocity between the probe and a star by the probe through navigation sensor for autonomous velocity measurement; obtaining the position and velocity estimations of space-ground combined navigation through the extended Kalman filter (EKF). Compared with the navigation solely relying on the terrestrial radio, the autonomous celestial observation of the probe is added in the method of the invention, so that the navigation accuracy can be effectively improved.