Airbus Defence and Space

A communications satellite with vision

The height of sophistication: Alphasat

Alphasat, the most sophisticated commercial satellite ever built, is currently being prepared for an end of July launch aboard an Ariane 5.

Designed and built by Airbus Defence and Space for Inmarsat, the leading provider of global mobile satellite communications services and the European Space Agency (ESA), Alphasat embodies three outstanding achievements in a single programme. Not only does it comprise in excess of 200 spot beams, with digital beam forming capability, but it marks the first flight of Europe’s new high capacity satellite platform Alphabus and is also equipped with four technology demonstrator hosted payloads for ESA.

Radio frequency tests on Alphasat in an anechoic chamber in Airbus Defence and Space’s Toulouse facilities.

Radio frequency tests on Alphasat in an anechoic chamber in Airbus Defence and Space’s Toulouse facilities.

Indeed, it is the number of spot beams and the digital beam forming capability which denote Alphasat’s high level of technological refinement. The payload makes best use of the limited spectrum available in L-band to efficiently manage numerous communications with maximum flexibility in both frequency and beam power allocation according to users’ throughput requirements. The eight integrated processors, developed by Airbus Defence and Space, are the key elements of this payload.

The new, high capacity Alphabus platform being flown for the first time on Alphasat is the most powerful platform on the market. It is capable of conducting missions with a satellite launch mass of up to 8,800 kg, a payload power of up to 22 kW and a payload mass up to 2,000 kg.

Artist’s impression of Alphasat.

Artist’s impression of Alphasat.

Of the four Technological Demonstration Hosted Payloads being carried by Alphasat for ESA, one is a Tesat-built laser communications terminal which is a precursor to the operational system for EDRS (European Data Relay System).

Moving towards a new generation of mobile technologies

The Airbus Defence and Space-primed Alphasat satellite and payload incorporate an impressive number of innovations developed in Europe.

These new technologies will enable Alphasat to manage communications across Europe, Asia, Africa and the Middle East with ease and deliver extra capacity – Alphasat is capable of handling over 750 L-band channels with enhanced quality, which is especially beneficial for satellite telephone users. As a result of more efficient utilisation of the spectrum, the satellite will guarantee communications in areas with no terrestrial infrastructure, in particular in crises and humanitarian emergencies. This will enable governmental authorities to maintain contact with scattered populations, and secure voice-data transmission of crucial importance for sectors such as the press, marine transport, and the oil and gas industry, to name but a few.

Alphasat will enable its operator Inmarsat, the world leader in the satellite-based mobile communications domain, to provide its customers with enhanced services by increasing available capacity, improving communications quality and reducing down-time.

Integrated processors

One of the eight integrated processors on board Alphasat.Airbus Defence and Space’s eight advanced digital integrated processors are a core element of the leading-edge geomobile L-band communications payload, allowing allocation of capacity with an unprecedented flexibility through digital channelisation and beamforming. It represents a major step forward in payload operational capability and commercial competitiveness.

The Integrated Processor (IP) developed for the Alphasat mobile mission is the latest evolution of Airbus Defence and Space’s Digital Signal Processors product line – a technology that, for space applications, only a very few companies in the world are able to master. It is based on Airbus Defence and Space Next Generation Processor modular technology, which can be applied for other applications such as broadband and military missions.

The primary function of Alphasat’s IPs is the routing and combining of channels to the desired beam. They are the key elements for the generation of spot beams and associated channel gain. This provides Alphasat with maximum flexibility in both frequency and power allocation to beams to meet traffic demands.

The eight large processors weigh around 250 kg and use the latest electronics technology to work in parallel on board Alphasat. The Digital Processing Module in each Integrated Processor includes 17 large ASICs (core computers) which contain all of the complex digital processing for routing and beam forming, providing Alphasat with a processing capacity which is unprecedented on board a commercial satellite: it can perform more than 10 trillion calculations per second!

A communications satellite with vision

The Alphasat programme, truly European in scope, is a real benchmark for cooperation: the satellite was designed and built under a public–private partnership framework between Inmarsat and ESA through an industrial contract between Inmarsat and Airbus Defence and Space; many industrial partners throughout Europe contributed to the programme, backed by ESA and national space agencies.

Alphasat is the first satellite to be based on the new high capacity European satellite platform Alphabus.

Alphabus platform.

Alphabus platform.

The most powerful platform on the market, Alphabus is Europe’s response to increasing market demand for larger communications payloads for delivery of better, faster direct-to-home TV broadcasting, digital audio broadcasting, broadband access and mobile services. Alphabus has been developed jointly by Airbus Defence and Space, lead partner, and Thales Alenia Space with a large team of well-established industrial collaborators all over Europe.

The Alphasat mission will provide in-orbit demonstration of the Alphabus platform, an important milestone for product commercialisation for future high capacity communications missions.


With Alphabus, the European industry is extending its communications satellite range significantly beyond the capabilities and capacities of existing platforms. Alphabus is now available on the commercial market to accommodate missions requiring payload power of up to 22 kW and payload mass of up to two tonnes.

The ultra-advanced technology developed for Alphasat is the basis for the next generation of telecom satellites in Airbus Defence and Space’s product line and puts Airbus Defence and Space in fine fettle for future programmes, both civil and military.

TelecommunicationsAlphasat I-XLCommunicationsMobile phone