London-based mobile satellite operator Inmarsat has sent out an RFI for a replacement satellite for its Inmarsat-4 spacecraft.
The move, which is still at a very early stage, reflects the company’s intention to change its satellite procurement policy…
London-based mobile satellite operator Inmarsat has sent out an RFI for a replacement satellite for its Inmarsat-4 spacecraft.
The move, which is still at a very early stage, reflects the company’s intention to change its satellite procurement policy and purchase spacecraft through rolling replacements rather than ordering a new three satellite constellation each time.
Inmarsat ordered the I-4 constellation from EADS Astrium in a US$700m deal back in May 2000. The first two satellites were launched in March and November of 2005, with the final satellite, F3, launched in August 2008.
In addition to ordering a replacement satellite, Inmarsat’s L-band constellation is set to be significantly bolstered with the launch of Alphasat. Also known as Inmarsat-4A F4, it is the largest European telecommunications satellite ever built.
Due to be launched by an Ariane-5 rocket on 25 July and located at 25E, Alphasat is the result of a public–private partnership between the European Space Agency, the French space agency CNES and Inmarsat. Indeed, it is the largest PPP that ESA has undertaken with a total cost of approximately €598m (US$783m).
The UK-based satellite operator is investing €283m (US$370m) in Alphasat, funded in part by a €225m 8-year senior secured term loan the company secured from the European Investment Bank. ESA said it has contributed €168m to the project, while UK-based regional development agencies provided a further €50m in funding. CNES has also invested in Alphasat’s development.
The high-powered satellite, which is roughly the size of a British double-decker bus, is being constructed by Astrium (prime payload contractor and co-prime platform manufacturer) and Thales Alenia Space (co-prime on the bus) under a joint ESA contract.
The Inmarsat L-band payload utilises an advanced digital signal processor developed by Astrium that doubles the spectrum efficiency of the standard I-4 satellites and will provide increased capacity to handle more than 750 channels in the L-band. The spacecraft can support in excess of 400 such spot beams although Inmarsat currently anticipates using 212.
The spacecraft also contains four technology demonstration payloads (TDPs) developed through ESA’s ARTES (advanced research in telecommunications systems) programme. These are a laser communications terminal, an advanced star tracker, an environment effects facility to monitor the GEO radiation environment, and a Q-V Band communications experiment to assess the feasibility of these upper frequency bands for future commercial applications.
ESA stated that testing these TDPs is one the main objectives of the project, though the predominant one is the in-orbit validation of Alphabus. The space agency sees the bus as hugely important in enabling the European satellite manufacturers to maintain their competitiveness.
So far no Alphabus-based satellites have been ordered but ESA and Astrium stated that there were several prospects in the pipeline.
