Formation ﬂying has brought flexibility to complex space systems. It allows achieving and even surpassing the functionality of a big single satellite with multiple small satellites simpler in design and cheaper in manufacturing. Multi-satellite formations have numerous applications such as precise measurements of Earth’s gravity and magnetic field and its dynamics, atmospheric sampling, distributed antenna platforms and apertures for imaging etc.
One of our projects is focused on control of formation flying satellites. The control is needed when a certain orbital configuration has to be deployed, maintained or reconfigured and possible collisions have to be prevented. In the study various control approaches are considered such as impulsive control, differential drag control, and continuous control by low thrust propulsion. All algorithms are tested on a benchmark problem, which is to maintain a formation of small satellites with sunlight reflectors that in appropriate lighting conditions can produce graphical images in the sky.
Another venue our group explores is how to employ tethers for formation keeping. Three dimensional satellite formations are often discussed in connection with multipoint measurements needed for atmospheric, geodetic or plasma physics studies. To simplify control strategies and to minimize fuel consumption, tethers can be used to maintain desired relative positions of satellites in the formation flying.