Account for Earth Orientation Parameters

[ChristopherRabotin]

High level description

Earth Orientation Parameters (EOPs) are used to describe the orientation of the Earth's axis of rotation with respect to its orbit around the sun. These parameters are necessary for satellite orbit determination and prediction, as well as for precise positioning on the Earth's surface. EOPs include parameters such as the Earth's nutation and polar motion, which are affected by factors such as the Earth's tides and the gravitational pull of the moon and the sun.

This is required for interplanetary orbit determination.

Relevant links:

• https://www.iers.org/IERS/EN/DataProducts/EarthOrientationData/eop.html
• AstroPy implementation https://docs.astropy.org/en/stable/utils/iers.html

Requirements

• Nyx shall support the inclusion of Earth Orientation Parameters (EOP) in the orbit determination process.
• Nyx shall provide a way to specify the EOP data to be used in the orbit determination process.
• Nyx shall provide a mechanism for interpolating the EOP data to match the epochs of the observations being used in the orbit determination process.
• Nyx shall provide a mechanism for applying the EOP data to the observations and state estimates during the orbit determination process.
• Nyx shall provide a mechanism for propagating the EOP data uncertainty through the orbit determination process.

Test plans

• Verify that the EOP data can be loaded and accessed by Nyx
• Check that the EOP data is used to accurately transform the position of an object from an Earth-fixed frame to a celestial frame
• Test the accuracy of the EOP data by comparing the resulting position of an object in the celestial frame with independent sources of EOP data
• Test the handling of EOP data with gaps or irregularities, such as missing data or sudden changes in the EOP data
• Test the performance of Nyx with large datasets of EOP data to ensure it can handle the computational load efficiently.

Design

This is the design section. Each subsection has its own subsection in the quality assurance document.

Algorithm demonstration

If this issue requires a change in an algorithm, it should be described here. This algorithm should be described thoroughly enough to be used as documentation. This section may also simply refer to an algorithm in the literature or in another piece of software that has been validated. The quality of that reference will be determined case by case.

API definition

Define how the Nyx APIs will be affect by this: what are new functions available, do any previous function change their definition, why call these functions by that name, etc.

High level architecture

Document, discuss, and optionally upload design diagram into this section.

Detailed design

The detailed design *will be used in the documentation of how Nyx works.

Feel free to fill out additional QA sections here, but these will typically be determined during the development, including the release in which this issue will be tackled.