European Space Agency

Satellite Ephemeris Estimator -Satellite Ephemeris Estimator for LEOP, Geostationary orbital move, MEO and LEO satellites.


Objectives of the project:
  • With a simple, light and low cost system, to study and prove that it’s possible to estimate accurate ephemeris with a fully passive ranging method for:
    • LEOP: from the start of the launch to the final position of the satellite;
    • Orbital move for Geostationary satellite: when a satellite changed its longitude position;
    • MEO: for satellites in Medium Earth Orbit;
    • LEO: for satellites in Low Earth Orbit.
  • When it’s possible, to give expected accuracy of the system;
  • To confirm the architecture of the system.


To find which parameters the system shall process for an accurate satellite’s ephemeris, then to define hardware and software architectures. With system definition, to define accuracy assessment.


With very simple, light and low cost stations, even transportable, the system will be able to estimate orbits with high accuracy.


This product or system will provide :
  • Satellite ephemeris,
  • Maneuver early alert,
  • Measurement for ephemeris estimation (in this case ephemeris processing will be done by the customer).

System Architecture

Architecture of the system will be based on several passives small stations.


From standard orbits, study of parameters drift, range. Overall system software modelization for simulation.
From these parameters, statistical study to define which parameters can be processed
Architecture definition for hardware and software modules.

Current status

Feasibility study showed that passive ranging applied to LEO/MEO/LEOP and orbital move satellites is possible and give accurate ephemeris restitutions.

Phase 1, feasibility and definition step, of the product development is over.

Status date

Tuesday, February 19, 2019 - 07:53