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Large Platform Mission (LPM)

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The Large Platform Mission (LPM) is a programme developed under the European Space Agency’s (ESA) Advanced Research in Telecommunications Systems (ARTES)’ programme with the aim of establishing a high-power, large-satellite class platform in geostationary orbit, enabling advanced communications payloads and hosted technology demonstrations. 

In the early 2000s, the satellite telecommunications market began increasingly demanding larger payloads: more power, larger mass, more flexible payload architectures. The LPM programme was a result of ESA’s recognition that Europe needed to field a generic large-platform bus that could accommodate payloads in the 12–18 kW (and potentially up to around 25 kW) power class, to remain globally competitive. 

The project was structured around three key strands: pre-development of enabling technologies; the design and qualification of the bus platform. named Alphabus, and a demonstration mission, named Alphasat, to validate the platform and hosted payload concept. 


The Alphabus platform

At the heart of the LPM is the bus architecture, Alphabus. Designed by European industrial partners, including EADSAstrium (now Airbus Defence and Space) and Thales Alenia Space, in cooperation with ESA and the Centre National d’Etudes Spatiales (CNES), Alphabus was aimed at meeting high mass (a payload up to around 1,400 kg) and very high power (initially 12–18 kW, with growth potential toward 22–25 kW) telecommunication missions. 

From a technical perspective, this required advanced subsystems: larger solar arrays (capable of tens of kilowatts of power), enhanced thermal control (to manage more dissipation from large payloads), high-performance propulsion and attitude control systems, and modular “hosted‐payload” interfaces. For example, one of the pre-development tasks addressed in LPM was the need for improved thermal-analysis tools to cope with large panel structures and capillary two-phase loops for heat transport. 


The Alphasat mission: Demonstration in orbit

The first major flight of the Alphabus platform was the Alphasat satellite, launched on 25 July 2013 from Europe’s Kourou spaceport. 

Alphasat carried a state-of-the-art communications payload operated by commercial operator Inmarsat, along with hosted technology-demonstration payloads developed via ESA’s ARTES programme and the German Aerospace Center (DLR). 

These included:

An advanced laser-communications terminal at 1064 nm for geostationary Earth orbit (GEO)- to low Earth orbit (LEO) optical links.
A Q/V-band communications experiment to explore very high-frequency satellite communication bands
An advanced star tracker and an environmental radiation sensor payload to monitor spacecraft effects in GEO


The mission served a dual role: commercial service provision through Inmarsat (now Viasat) and technology maturation of European large‐satellite capabilities. For example, Alphasat’s L-band communications payload supported more than 750 mobile communication channels and was designed for a mission lifetime of around 15 years. 


Technical highlights of the Large Platform Mission (LPM)

High-power payload accommodation
supporting payloads up to around 22 kW or more, enabling very high-throughput communications.
Hosted payload flexibility
Alphasat demonstrated the value of embedding smaller technology demonstration experiments alongside a major commercial payload, thereby sharing launch/operational costs and gaining flight heritage.
Advanced thermal management
with large panel sizes and high-power dissipation, new thermal-control tools (capillary loops, standardised modules) were developed under the LPM.
Digital payload flexibility
for example, Alphasat’s digital integrated processors allowed re-allocation of capacity in L-band via digital channelisation and beamforming.


Impacts and market positioning 

The LPM programme was intended not only to demonstrate technical capabilities but also to strengthen Europe’s competitiveness in the global GEO-telecommunications market. The European industry believed large satellites (above around 6 tonnes) would account for around 30 % of the geostationary-satellite market around 2010. 

By developing Alphabus and demonstrating it via Alphasat, the programme sought to ensure European independence, reduce the competitive gap, and provide an alternative to non-European platforms. 

Alphasat remains in operation, and its hosted-payload programmes have been extended, with the Alphasat hosted-payload programme being extended in 2016. 

The LPM programme has matured into a reference model for large European telecommunications satellites, and the Alphabus platform is now offered commercially. The success of this approach has helped Europe position itself for next‐generation telecom platforms and high-throughput satellites.

The hosted‐payload concept validated through Alphasat enables ESA and industry to embrace both commercial and institutional architectures as well as technology demonstration opportunities aboard large platforms.

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CONTACT

Michael Witting


ESA’s European Space Research and Technology Centre (ESTEC)

Keplerlaan 1

2201 AZ Noordwijk, The Netherlands

+31 625158619

Michael.Witting@esa.int

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Advanced Research in Telecommunications Systems (ARTES)

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