Special satellites are being developed to monitor the Earth from orbit. Typical applications include weather and environmental monitoring, mapping and geology. In partnership with the firm OHB-System AG in Bremen, the Steinbeis Research Center for Optimization, Control and Adjustment Control has developed a mathematical software tool to optimize resource planning for these satellites. Both partners were honored with the Löhn Award 2008 for the project – one of three to receive the award this year.
OHB-System AG in Bremen is an SME specializing in astronautics and security. It is probably most famous for its radar reconnaissance satellite system SAR-Lupe, developed and manufactured in Bremen. Small satellites are used for civilian purposes to monitor the environment, recording volcanic eruptions, floods, and shipping accidents, or directly measuring water, soil and air quality.
Optimizing satellite constellations and operating times is vital to every successful mission. The sort of parameters that have to be optimized mathematically include photography schedules and satellite orbits around target areas, as well as communication schedules with ground stations and data relay satellites.
In partnership with OHB-System AG, the Steinbeis Research Center for Optimization, Control and Adjustment Control in Bremen has developed a software program which uses innovative mathematical techniques to analyze and optimize satellite constellations used in global monitoring. The software optimizes each satellite’s orbit in a constellation with respect to different target areas. This takes a variety of factors into account, such as different sensors’ field of vision, communication with ground stations, and the differing needs of each target area. The system also optimizes satellite operating schedules based on mathematical factors such as target area priorities, monitoring modes, time lags between photography and ground station contact, ground station positions, and multiple activation and deactivation points per orbit. Limiting factors include the finite amount of photographic memory, the position of the sun, limited battery power, and restrictions in reactivating the satellite. No product on the market is able to automatically optimize satellite constellations and operating schedules. The new software is the first to automatically determine the precise maximum observable area. Previous methods often took weeks or even months to arrive at an acceptable solution.
Not only is the new solution more userfriendly, it is 200 times faster at performing calculations and optimizing satellite schedules online. It thus significantly outperforms Satellite Tool Kit, American software already used worldwide. Mathematicians at the Steinbeis Research Center successfully applied special strategies to measure precise areas and run simulations, combining overlaps to form complex polygons. They also used sequential quadratic programming methods to optimize the non-linear problems.
One thing is clear: both partners can expect financial success. GMES (Global Monitoring for Environment and Security) is a joint initiative of the European Commission and European Space Agency. The European network provides analysis and forecasting services in the areas of emergency management, land monitoring and ocean monitoring. Vital to this work? Usable data.
Prof. Dr. Christof Büskens
Steinbeis Research Center Optimization, Control and Adjustment Control (Grasberg)
stz1118@stw.de