Copyright ESA-P. Carril Europe’s fifth Galileo navigation satellite, one of two delivered into a wrong orbit by VS09 Soyuz-Fregat laun...
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| Copyright ESA-P. Carril |
The satellite has reached its new target orbit and its navigation payload has been successfully switched on. The revised and more circular orbit means the fifth satellite’s Earth sensor can be used continuously, keeping its main antenna oriented towards Earth and allowing its navigation payload to be switched on.
The fifth and sixth Galileo satellites, launched together on 22 August, ended up in an elongated orbit travelling up to 25 900 km above Earth and back down to 13 713 km.
The targeted orbit was circular, inclined at 55 degrees with a semi major axis of 29,900 kilometers. The satellites went in to an elliptical orbit, with excentricity of 0.23, a semi major axis of 26,200 km and inclined at 49.8 degrees.
A total of 11 manoeuvres were performed across 17 days, gradually nudging the fifth satellite upwards at the lowest point of its orbit.
As a result, it has risen more than 3500 km and its elliptical orbit has become more circular.
The commands were uploaded to the satellite via an extended network of ground stations, made up of Galileo stations and additional sites coordinated by France’s CNES space agency.
In the current orbit, it will now overfly the same location on the ground every 20 days, against a normal Galileo repeat pattern of every 10 days, effectively synchronising its ground track with the rest of the Galileo constellation.
The same recovery manoeuvres are planned for the sixth satellite, taking it into the same orbital plane but on the opposite side of Earth.
The decision whether to use the two satellites for Navigation and S earch And Rescue (SAR) purposes as part of the Galileo constellation will be taken by the European Commission based on the test results.
The Aug 22 anomaly occurred during the flight of the launcher's fourth stage, Fregat, designed and produced by NPO Lavochkin.
The Independent Inquiry Board formed to analyze the causes of anomaly, found a shortcoming in the system thermal analysis performed during Fregat stage design which led to a cascading failures.
Galileo is Europe’s own global satellite navigation system. It will consist of 30 satellites and their ground infrastructure.
The definition phase and the development and In-Orbit Validation phase of the Galileo programme were carried out by the European Space Agency (ESA) and co-funded by ESA and the European Union.
This phase has created a mini-constellation of four satellites and a reduced ground segment dedicated to validating the overall concept.
The four satellites launched during the IOV phase form the core of the constellation that is being extended to reach Full Operational Capability (FOC).
The FOC phase is fully funded by the European Commission. The Commission and ESA have signed a delegation agreement by which ESA acts as design and procurement agent on behalf of the Commission.
The ESA is an intergovernmental organisation, created in 1975, with the mission to shape the development of Europe’s space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world.
ESA has 20 Member States: Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom, of whom 18 are Member States of the EU. Two other Member States of the EU, Hungary and Estonia, are likely soon to become new ESA Member States.
Source: ESA/Arianespace
