Approach to solve remote sensing tasks with small satellites

Kurzfassung

There is an increasing need for cost effective Earth Observation (EO) missions to meet the information requirements of an almost ever growing range of applications. This is perhaps most clearly seen in the many current moves for international co-operation in the field of environment where measurements from Earth Observing satellites are an essential element. This is especially so where we need to acquire, analyze and use data documenting the condition of the Earth’s resources and environment on a long-term (permanent) basis. The paper touches briefly some reasons for pursuing the small satellite concept. The paper focuses then on the application areas in the field of operational Earth observation. It is shown that the wide application range from mapping to global climate, for instance disaster warning and support, agriculture, forestry, atmosphere, weather and climate, ice and snow, mapping and GIS applications, land use and cover change, implies very different requirements concerning ground sample distance, spectral resolution, and temporal resolution. Even within a specific application area the spectrum of requirements is wide spread. In order to improve the actual situation of a given application, the following general approach may be used when we restrict ourselves to single tasks to be addressed only: Starting from the status quo, a new quality can be achieved when analysing the needs/requirements and combining them with the possibilities of small satellites which can be conducted relatively quickly and inexpensively and therefore providing increased opportunities for access to space. The spacecraft bus and the instruments can be based on optimised off-the-shelf systems, with little or no requirements for new technology, or on new high technology systems. This general approach needs to be applied to specific tasks of the diverse application areas mentioned. The forest fire task is selected from the application area of disaster warning and support to describe the approach in more detail. In this context, the micro-satellite BIRD (Bi-spectral InfraRed Detection) is used to describe a possible small satellite system for detection and quantitative characterisation of high-temperature events like vegetation fires on the Earth surface. Both the global change scientific community and the fire fighting authorities demand new and dedicated space-borne fire observation sensors with resolution of 50-100 m for local/regional monitoring and of a few hundred metres for global observations that would be able to detect fires from a few to a few tens of square metres and to estimate quantitatively variables such as location, temperature, area, energy release, associated aerosol and gaseous emissions. BIRD was successfully piggyback launched by an Indian Polar Satellite Launch Vehicle (PSLV-C3) in a circular sun-synchronous orbit with an altitude of 572 km.