Satellite Orbit Control Using Predicted Ephemerides During GPS Outages

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Solution Overview

Problem

Satellites face positioning errors due to GPS outages, which can lead to inaccurate orbit determination and control, particularly in small satellites used for earth observation, where errors exceeding 500 m may be unacceptable.

Innovation Solution

A ground-based orbit determination method generates auxiliary data using tracking data from GNSS, SLR, or radar measurements, predicting future ephemerides, and transmitting this data to the satellite for its attitude and orbit control, allowing precise position knowledge even during GPS outages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GPS receiver is used for satellite positioning, then positioning accuracy is improved, but system reliability deteriorates during GPS outages

Engineering Contradiction:

Improvepositioning accuracyVSAvoidsystem reliability during GPS outages

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The ground segment performs preliminary orbit determination and generates predicted ephemerides data before GPS outages occur. This pre-computed auxiliary data is stored and ready for use when GPS signals are unavailable, allowing the satellite to maintain positioning accuracy without real-time GPS measurements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Predicted ephemerides data acts as an intermediary between ground-based tracking systems and on-board orbit propagators. This intermediate data product allows the satellite to bridge the gap when direct GPS measurements are unavailable, maintaining the positioning function through a substitute information source.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If internal orbit propagator is used during GPS outages, then system autonomy is improved, but positioning accuracy deteriorates over time

Engineering Contradiction:

Improvesystem autonomy during GPS outagesVSAvoidpositioning accuracy over time

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The ground segment performs preliminary orbit determination using tracking data and generates predicted ephemerides data before GPS outages occur. This pre-computed auxiliary data is stored and ready for use when GPS signals are unavailable, allowing the satellite to maintain positioning accuracy without real-time GPS measurements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from ground-based tracking data to continuously update and refine the predicted ephemerides. This feedback loop ensures that the auxiliary data remains accurate and current, compensating for the lack of real-time GPS feedback during outages.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12441488B2Auxiliary data for controlling a satellite

Publication Date: 2025.10.14 ICEYE OY

AI summary

The present disclosure relates to a method of generating auxiliary data for controlling a satellite travelling in orbit around Earth, the method comprising: receiving tracking data for the satellite; applying an orbit determination algorithm including: estimating an orbit for the satellite based on the tracking data; and predicting, based on the estimated orbit, future ephemerides data of the satellite; generating auxiliary data comprising predicted future ephemerides data; and transmitting the auxiliary data to the satellite for use in the satellite's attitude and orbit control.