Formation reconfiguration optimization for the IRASSI space interferometer

Abstract

The IRASSI mission, aimed at studying pre-biotic conditions in Earth-like planets, is composed of five free-flying telescopes operating around the Sun-Earth L2 point. To address the challenge of finding suitable relative positions in three-dimensional space which satisfy science goals over long periods of time, a reconfiguration procedure has been devised. The method assigns optimized post-maneuver positions of the individual telescopes for the next to-be-observed target. A mesh-adaptive direct search algorithm is selected for the optimization and two cost functions are analyzed: a fuel-based and a ΔV-based one, both pursuing a balanced use of these resources across the fleet. The effect of simulation variables such as initial wet mass and fuel mass balance, thruster settings and cost-function weighting parameters is evaluated with respect to overall used fuel and fuel balance, ΔV and ΔV balance and maneuver duration. Results show that for wet-mass-imbalanced cases, cost functions should be tuned differently for optimal fuel and ΔV management. This is not necessarily the case for homogeneous or fuel-mass imbalanced cases. The analysis also suggests that the ΔV-based function produces more consistent optimal ΔV-balancing potential across different sets of initial conditions and shows less variability in individual maneuvers than the fuel-based function.