Painting Earth’s Palette

Jörg Schwartz

Although it may look like a big blue marble from outer space, Earth is a truly multicolored orb. And a new multispectral geographic information system (GIS) is on its way to check it out.

At the Baikonur space centre in Kazakhstan, a DNEPR rocket roared into space this past summer carrying a satellite system from RapidEye AG. The system, composed of five identical Earth observation satellites, represents the start of a commercial GIS that will be able to obtain more than 4 million square kilometres of high-resolution multispectral image data per day – with the ability to reach any point on Earth every day.

With multispectral data spanning the visible to near-infrared parts of the spectrum – and offering high-resolution detail – the satellite constellation offers the ability to observe and differentiate land cover, to assess vegetative conditions and to distinguish human-scale ground features in a single data set. It is expected that the high repetition rate of the data will have strong benefits in environmental monitoring, landscape architecture and disaster management.

Commercial benefits

Beyond the scientific, there is the promise of commercial benefits for end users such as agricultural insurers, who must forecast or report crop damage. In fact, one investor in RapidEye is Vereinigte Hagelversicherung (United Hail Insurance), the largest German agro-insurance company. In addition, entities such as the European Union, companies that trade in agricultural commodities and farm corporations that rely on precision crop management are likely benefactors of the new source of data.

The satellite system enables data acquisition by employing multispectral imagers developed by Jenoptik subsidiary Jena-Optronik of Jena, Germany, one of which is used in each satellite. The imagers cover the Earth’s surface continuously line by line using the push-broom principle; i.e., building up an image using a linear array without using electromechanical components. This enables precise data acquisition of an ~75-km-wide strip of land with a pixel size of 6.5 m out of 630 km. It operates in five spectral channels, covering the wavelength range from the visible to the near-infrared and providing pin sharp multispectral and high-resolution images.

Jena-Optronik received the order for the development and production of the multispectral imagers from MacDonald, Dettwiler and Associates Ltd. (MDA) of Richmond, British Columbia, Canada, the prime contractor for the RapidEye constellation, in 2004.

Shown is the Jena Spaceborne Scanner multispectral camera for the RapidEye constellation.

Looking forward, Jena-Optronik says that it will build on and develop the technology as a member of the core team of other Earth observation projects, such as Sentinel-2 for optical Earth observation and Sentinel-3 for observation of the oceans, both within the European Earth observation GMES (Global Monitoring for Environment and Security) programme. Furthermore, a proprietary imaging radiometer, METimage, is planned as a German contribution to future operational Earth observation platforms in polar orbits of EUMETSAT Post-EPS, the European Organisation for the Exploitation of Meteorological Satellites Polar System.

Components are assembled for the RapidEye constellation system.