Airbus Defence and Space

AstroTerra puts itself on the map

The AstroTerra programme, encompassing the Spot 6 and 7 satellites, will enhance Airbus Defence and Space Services’ leading role in the field of high-resolution remote sensing services and ensure continuity from 2012 onwards. In a fast-growing market, its GEO-Information Services division has put together a portfolio of Earth observation services which is both dynamic and at the cutting edge of technology.

Is it better to wait for events to unfold or to make things happen? If a football club is on a winning streak, should it stick with the same successful team or boldly change some of its key players to prevent complacency creeping in? For seven and a half years, the Spot 5 satellite has been the centre of the Spot Image ‘solar system’ and the company’s business has gravitated around it. The satellite’s performance has enabled the company to acquire an 80% share of the market for two-metre range resolution satellite imagery. To ensure long-term continuity in high-resolution data while competition gets ever tougher and new players enter the market, Airbus Defence and Space decided to take the bull by the horns and launch a new project, AstroTerra, in 2007. This aims to put the satellites Spot 6 and Spot 7 into orbit in 2012 and 2013, respectively. The two satellites and the receiving stations are designed to deliver 1.5 metre ortho imagery (geometrically corrected aerial photographs) to users.

Just like their predecessors, the new satellites will focus on applications in the fields of cartography, defence, agriculture and deforestation and geology studies, as well as the distribution of telemetry data to the existing network of more than 40 Spot 4 and 5 receiving stations around the world. “We are facing some serious competition, especially from the US, so it was essential for us to move forwards,” says Philippe Ghesquiers, AstroTerra Programme Director. “Our goal is to reinforce our existing customer base by ensuring service continuity and tying down major agreements for longer periods – for example, contracts of at least five years as opposed to the one-year and three-year contracts we had for Spot 5. This is a key issue for us,” he emphasises. The first step in this direction was achieved in September 2010, with a ten-year partnership signed with the Russian research and development centre ScanEx.

The proactive nature of the AstroTerra programme is also evident in its new business model: this is the first time in the Earth observation industry that a private company has funded all the costs of developing a system of this kind. “We looked into the possibility of a Public–Private Partnership (PPP), but governments at the moment are keen for companies to provide all the funding themselves,” says Philippe. Responsibility for the operational phase has shifted heavily towards Airbus Defence and Space. It will be taking charge of the system management activities (which are handled by the French space agency CNES for the Spot 5 programme) as well as supplying the complete ground station and the satellite command and control system.

Airbus Defence and Space will also benefit from close links to the Pléiades constellation and the TerraSAR-X and TanDEM-X radar satellites. “The Spot 6 and 7 and Pléiades 1 and 2 satellites will operate in the same orbit, as a true constellation, combining a twice daily revisit capability with an ingenious range of resolutions. The day-to-day use of this constellation will be coordinated with the commercial operations of TerraSAR-X and TanDEM-X, which are managed from Germany by Airbus Defence and Space GEO-Information Services, in order to ensure we can offer the best all-round service,” Philippe adds. Lightweight and agile “A decade ago we simply couldn’t have built the same type of satellite,” says Michel Siguier, AstroTerra Project Manager at Airbus Defence and Space Satellites. The search for innovative solutions focused on three key goals: high resolution (two metres), broad coverage (60 kilometre swath width) and a longer lifecycle (up from five to ten years). “The biggest technical challenge was working within such a tight timeframe and cutting the satellite’s launch mass by more than two thirds compared to Spot 5, from 2.7 tonnes to 800 kilos. Miniaturisation was crucial, especially when it came to the instruments; we moved into entirely new territory with many of these, including a new detector,” Michel enthuses.

Once again, Airbus Defence and Space has reaped the benefits of its expertise in silicon carbide technology, which allows it to produce optical and structural elements from the same material, thereby reinforcing the satellite’s intrinsic stability. “That industrial capacity enabled us to propose an optimum solution for the Spot 6 and 7 optical instruments, offering the expected high level of performance at best cost and in the required short schedule,” says Michel. The design of the ground segment facilities and their operations have also been optimised to take maximum benefit from the accessible network of polar stations. “That approach will basically enable us to increase the number of daily mission plans from one to six per day for each satellite, which means we can program the type of images that are required on a just-in-time basis,” he adds.

A further significant improvement is the ability to record stereo images in a single pass, a feature that relies on enhanced spacecraft agility, as he explains: “With Spot 5, if the satellite were above Toulouse and you wanted an image of Montpellier, for example, you would have to activate a mechanism that moved the mirror. With Spot 6 and 7, instead of moving the instrument you will be moving the whole satellite. So we will be able to take images of the Earth from one angle and then move the satellite to take images from a different angle – and it is those two perspectives that give you single pass stereo capabilities.” The result is a ‘stereo satellite’ that will enhance the surround quality of Airbus Defence and Space’s remote-sensing services.

SPOTGeoinformation Services