SES Astra/Redu Space Services EDRS phase 0 study

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The project aims to study Data Relay Satellite capability.

The ESA Programme related to Data Relay Satellites (EDRS) is a major opportunity for the development of satellite telecommunications in Europe and throughout the world. The evolution of EDRS services will bring unrivalled data distribution channels for the future high data-rate missions and systems under development. Examples of missions and systems under development are launcher tracking and scientific missions, GMES, PROBA, dual-use and other national and European earth observation missions.

The project targets the definition of an ESA DRS mission. From a technical standpoint, the project contributes to identifying and consolidating the requirements of an efficient EDRS solution which includes suitable payloads and frequency bands. From a business standpoint, the project intends to identify the various business and governance options that may exist for providing DRS services to institutional and commercial customers.

In order to achieve a complete and effective examination of the issues, challenges, and perspectives of EDRS, the various elements that this EDRS Phase 0 study addresses cover technical as well as business aspects. This project consists of a series of five Work Packages (WP) defined for the Study. These are, Market Study WP1, Technical Study WP2, Regulatory Study WP3, Business Plan Analysis WP4 and Operational Scheme Study WP5.

Taking the Market Study (WP1) as an input, the Technical Study calculates options for the appropriate satellite and payload that can accommodate the EDRS mission. Trade-offs as well as different solutions (dedicated satellite vs. piggy-back payload) have been explored, in an iterative process with the Business Plan Analysis.

Depending on the type of mission under consideration, the Regulatory Study will also be essential in order to make sure that the proposed solution can actually interoperate in a frequency-coordinated way with neighbouring satellite operators. Once the main options have been examined from a technical and business point of view, the operational architecture and concept will be studied in WP5.




The expected benefit brought by the project is to provide a complete and effective examination of the issues, challenges, and perspectives of EDRS.


Market Study
The market study shows that the market for DRS services does not yet exist. Nonetheless, direct research in the market place for downstream application service providers indicates a growing requirement for improving data timeliness. A concept highlighted in reports produced by Vega and Euroconsult. This can be achieved by a variety of means. On the ground, by improving reception and connectivity arrangements. In space, both on board the satellite and by using the inter-satellite links of a DRS system.

There are indications from the upstream providers of commercial EO services, based in the USA, that the provision of an alternative service to TDRSS could be attractive in meeting the emerging requirement for real-time or near-real-time services. This is particularly being driven by governments in Europe, the US, and elsewhere in the world due to growing environmental and security issues. However, commercial organisations are in no position to kick-start the market for DRS services. The market is still unclear. By adopting a stage-by-stage approach described elsewhere in this Phase 0 approach, ESA will achieve its DRS aims while limiting its risk. A commercial operator will also have a valuable platform for development of a new international market area.

Technical Study
Based on its experience in designing commercial satellite missions, SES has looked at the EDRS concept with the spirit to keep it as cost-efficient and as technically simple as possible. This will make it advantageous for both ESA and SES. Therefore, SES has only looked at transparent architectures for both optical and radio-frequency inter-satellite links.

When investigating the details of each type of ISL, the optical option looks the most efficient in terms of throughput available, with a higher mass and power consumed, and a much higher cost per terminal. The K-band ISL probably provides the most cost-, mass-, spectral- and power efficient options with well-known technologies. The disadvantage is probably the accommodation constraints that could appear depending on the commercial host satellite.

Concerning the S-band ISL, when considering the types of applications foreseen (launchers with omni-directional antennas), the accommodation requirements of a 2m or larger reflector are very demanding compared to the lower throughput achievable. This is mainly due to the narrow spectrum available. It is debatable whether all host candidates could host a S-band ISL without substantially de-scoping the main commercial missions.

SES investigated two EDRS hosted missions that seem to be reasonable with respect to the accommodation constraints and the potential foreseen demand. These options should be studied in more details in the future based on feedback from potential users and customers.

Concerning the operational aspects, using the experience accumulated on Artemis in the Redu station makes sense. The constraints that need to be studied in more detail in the following studies are the impact of customers requesting the ISL resources simultaneously, ensuring availability of service with probably prioritisation of certain customers compared to others and probably from the telecommunications network aspects.

Regulatory Study
EDRS presents a challenge from a regulatory standpoint as it will undoubtedly need to have dedicated adequate frequency bands as well as orbital positions allocated. In this project, a review is made of ITU frequency and orbital slot filings available to ESA for such an EDRS program.

Regulatory study in this project reflects the Phase-0 stage. The emphasis was put on a collection of comprehensive information rather than focusing on a particular scenario. Key Frequency Coordination issues that will need to be addressed by ESA for putting services into the EDRS are identified as well as issues specific to the EDRS topology. Considering that the scope of the EDRS concept in the Phase-0 is quite broad, this study is as generic as appropriate for setting the landscape.

Business Plan Analysis
The EDRS concept consists of relaying information from platforms such as LEO/MEO satellites, aerial vehicles or launchers directly to ground stations, headquarters or processing centres in Europe or vice-versa through a geostationary satellite. The purpose of this work package is to explore, analyse and recommend the EDRS System, which makes most sense from a business perspective including business viability aspects. A DCF methodology was used to analyse two distinct approaches from the point of view of profitability:

  • Piggy back payload on a commercial satellite,
  • Dedicated EDRS satellite launched and operated by an independent satellite operator.

The business model takes into account the initial capital expenditure as well as all recurring operating expenses. It weighs these costs against the identified third party market demand to assess the minimum revenues to support investment decision, and in turn the minimum funding commitment to maintain profitability of the EDRS operating entity.

Operational Scheme Study
The objective of this study is to provide an analysis of the operational scheme of a data-relay mission aboard a geostationary satellite in the frame of a phase 0 study sponsored by the European Space Agency. It deals with the definition of the operational requirements of such a system, from the ground segment point of view. The proposed operational scheme is based on market requirements outlined in the Work Package 1 report, and on the proposed architecture outlined in the Work Package 2 report.

A high quality level of EDRS operations was delivered from Redu RSS/SES, based on the extensive experience of both Artemis (Data Relay Satellite) and ECS (geostationary Satellite) Control.

Current status

The project is finished and the study report was delivered and accepted by ESA.

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