Line of Sight Alignment Algorithms for Future Gravity Missions

Abstract

Laser interferometry is viable candidate to microwave interferometry as it exploits bet- ter performances in terms of range measurements. Preliminary studies on future gravity missions show that, before addressing their metrology target, these laser terminals of- ten require an intermediate alignment and signal acquisition phase whose complexity can vary according to instrument's layout and the environmental constrains. The line of sight alignment algorithms here presented are designed to autonomously perform spatial scans through laser beam pointing corrections and, if necessary, laser frequency tunings in order to overcome initial pointing and frequency errors. The laser beam guidance algorithms an- alyzed use randomly generated pointing and/or continuous curve patterns while frequency changes (if necessary) are operated through Piezo-electric and thermal tuning. The al- gorithms here presented are tailored for a two-satellite-based heterodyne interferometer and have been tested through numerical simulations. Nevertheless, being the formulation parametric allows the algorithm's to be readapted for a di�erent mission concept.