European Space Agency

ELCOGEO (Impact of electric propulsion on the collocation of geostationary satellites)


The project objectives are:

  • To define collocation requirements and station keeping strategies for geostationary satellites,

  • To develop a software tool and a GNCDE-compatible template in MATLAB,

  • To execute simulated test scenarios.


During the last decade, electric propulsion has become a good alternative to traditional chemical satellite propulsion, also for large and small GEO platforms. Two of the most promising technologies are Ion Gridded Engines and Hall Effect Thrusters due to their high specific impulse compared to chemical thrusters.

The project provides all the elements needed to assess, design and test a collocation strategy based on electrical propulsion for geo satellites.


The two main software products of the project are:

  • A tool to design collocation strategies based on electrical propulsion,

  • A simulator to test the strategy.
The two elements will run in an integrated environment called GNCDE that provides also a series of other features: I/O data management, Montecarlo simulation, covariance analysis, visualization functions, statistical analysis among the others.

Even if the tool is executable on a stand-alone basis, the integrated characteristics of the environment provide additional benefits.

The user will be able to design and test a collocation strategy with accurate models for environment, satellite and IGE and HET propulsion


The main features of the projects include:

  1. A review of existing models for perturbation, satellite and electrical propulsion leading to a selection of models,

  2. Collocation and station keeping requirements will be defined,

  3. A software tool will be developed, re-using internal experience and using the results of the previous phase for the modelling part. The tool will permit the definition of the collocation strategy for geostationary satellites,

  4. A software simulator will be developed that will permit to simulate and test the result of the tool developed in previous step,

  5. All the new software developments will be done in Matlab/Simulink.


The project is organised in 3 steps:

  1. In the first step, perturbation, satellite and electrical propulsion models are studied and a selection is performed on the models to be used. The length of this phase is approximately 4 months.

  2. In the second one,  requirements for collocation and station keeping for electrical propulsion systems are identified. The length of this phase is approximately 3 months.

  3. In the third and final step, acquired knowledge is used to produce a new tool for collocation manoeuvre calculations and strategy definition. Additionally, a simulator will be developed in order to test the designed strategy. The length of this phase is approximately 5 months.

Current status

A set of activities have been performed:

  • A deep literature collection and review both for perturbation, satellite and electrical propulsion models using internal and external documentation,

  • A review of existing internal software models, including routines for manoeuvre calculation, perturbation models and satellites and propulsion models,

  • The results achieved so far have been already documented and are being revised.

Status date

Thursday, May 8, 2008 - 09:01