Planet Ephemeris Translation Software

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Description

The Planet Ephemeris Translation Software is a flight software module that converts a planet state message into a standard ephemeris message format. This translation enables planetary bodies to be represented in the same coordinate framework as spacecraft and other objects, facilitating relative navigation calculations, visibility analysis, and interplanetary trajectory computations. By default, the module is configured to track Earth, but it can be connected to any planetary body in the solar system.

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Example Use Cases

• Interplanetary Navigation: Provide planetary ephemeris data for trajectory calculations during deep space missions.
• Relative Position Computation: Enable relative position and velocity calculations between spacecraft and planetary bodies.
• Eclipse Prediction: Support eclipse and occultation analysis by providing planetary position in ephemeris format.
• Gravity Assist Planning: Provide planetary state data for flyby trajectory design and analysis.

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Module Implementation

The Planet Ephemeris Translation Software is a Software component that extracts position and velocity data from a Planet State Message and outputs it in ephemeris format.

State Extraction

The planetary position and velocity are extracted directly from the input message:

$${\mathbf{r}}_{B/N}^{\mathcal{N}}={\mathbf{r}}_{P/N}^{\mathcal{N}}$$ $${\mathbf{v}}_{B/N}^{\mathcal{N}}={\mathbf{v}}_{P/N}^{\mathcal{N}}$$

where:

• ${\mathbf{r}}_{P/N}^{\mathcal{N}}$ is the planet position relative to the inertial origin
• ${\mathbf{v}}_{P/N}^{\mathcal{N}}$ is the planet velocity relative to the inertial origin

Default Configuration

The module automatically connects to Earth’s planet state message from the Solar System during initialization. This can be overridden by connecting a different planet’s state message to the input.

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Assumptions/Limitations

• The position and velocity are copied directly without transformation; both messages use the same inertial reference frame.
• The module defaults to Earth if no planet state message is explicitly connected.
• Planetary rotation state and physical parameters are not included in the ephemeris