Ricerc@Sapienza

Most of the current formation flying systems are
intended to work in a single, stable orbital configuration
acquired shortly after the launch. However, the formation flying
concept lends itself to be used in a flexible manner, by
introducing the possibility of changing the relative
configuration of the platforms, i.e. to reconfigure the formation.
Instead of maintaining a single relative geometry, the change in
configuration helps to achieve multiple objectives. Several
examples of missions gaining from a reconfiguration capability
have been already identified (as some space-based distributed
telescopes, the TPF – Terrestrial Pathfinder, and variable
aperture/geometry radar missions), and it is expected that the
concept will be increasingly applied in the future. Obviously, the
reconfiguration has to be achieved by minimizing the control
effort, by approximately distributing such an effort in a uniform
manner among platforms, and – above all – by ensuring the
safety of the maneuvers, avoiding any risk of collision. Within
such a range of constraints, reconfiguration moves as an
optimization process, opening the path to several ways to tackle
the problem. This paper investigates a solution based on the
Pontryagin Maximum Principle, looking primarily to the
reduction of the required control effort. An important asset of
this solution is its applicability to eccentric orbits, which are
especially appealing for some of the astronomical missions
interested to the reconfiguration opportunity. The proposed
solution is described in theory and then applied in simulations
of several mission scenarios – at different altitude ranges and to
different configurations – to show its potential applicability and
advantages.