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Satellite Constellations for Environmental Monitoring


The Disaster Monitoring Constellation

The Disaster Monitoring Constellation (DMC) consists of several similar satellites orbiting in a configuration that enables a daily revisit for most points on the Earth’s surface. If a historical record going back farther than 2002 is important, DMC has it covered: the DMC spatial resolution and placement of its three spectral bands were designed to match up well with Landsat TM. The satellites were built by Surrey Satellite Technology Ltd (SSTL), and are currently operated for various international governments by DMC International Imaging. The constellation currently includes AISAT-1 (Algeria), BilSAT (Turkey), NigeriaSAT-1 (Nigeria), UK-DMC (United Kingdom), Beijing-1 (China), UK-DMC2 (United Kingdom), Deimos-1 (Spanish commercial), NigeriaSAT-2 (Nigeria), and NigeriaSAT-X (Nigeria).

This NigeriaSat-1 image of New Orleans, USA in 2005 shows an area affected by Hurricane Katrina. New Orleans is visible in the centre. Dark areas in the city indicate flooding, and at full detail (not shown here) it is possible to see which streets are submerged.

Data from DMC sensors have been used to monitor the effects of the Indian Ocean Tsunami in December 2004 and Hurricane Katrina August 2005, in addition to many other disasters. The RapidEye constellation consists of five satellites which, like the DMC constellation, were designed and implemented by SSTL (this time subcontracted to MacDonald Dettwiler and Associates ). Each satellite carries an identical sensor, designed and implemented by Jena Optronik, which measures five visible and near infrared bands at 5 m spatial resolution. The sensors include a unique red edge band that make RapidEye data appropriate for monitoring changes in chlorophyll content. Consequently, RapidEye data can be used to monitor vegetation health, distinguish different species of vegetation, and monitor protein and nitrogen content in vegetation.

NigeriaSat-1Image of Katrina aftermath

RapidEye imagery before and after alumina plant accident in Hungary
Natural-color RapidEye imagery of Kolontár, Hungary, before and after an alumina plant accident in which a dam holding back a reservoir of caustic sludge failed catastrophically, resulting in flooding of nearby towns and villages. Source: RapidEye.