Feasibility study of a moon sensor for satellite attitude determination

Abstract

ENGLISH ABSTRACT: The purpose of this study was to investigate the feasibility of a moon sensor as an alternative or supplemental sensor to supply attitude information to a satellite. The visibility of the moon was evaluated with regards to that of the sun from a satellite (i.e. the feasibility of the moon sensor is compared to that of a sun sensor). An algorithm was developed to calculate the center of the moon, regardless of phase or rotation, to offer increased accuracy of the center of the moon. The accuracy of this algorithm and the possible error margins were evaluated and discussed in both ideal and actual test cases. The sensor was implemented on embedded hardware. The conclusion of the feasibility analysis was that the sensor would function well as a supplemental sensor (e.g. in conjunction with a sun-sensor) rather than as an alternative sensor. The accuracy of the moon center algorithm was satisfactory for attitude deterrnina tion. This sensor could thus be seriously considered for use on a future satellite.

AFRIKAANSE OPSOMMING: Die doel van die studie is om die lewensvatbaarheid van 'n maan-sensor, as alternatiewe of aanvullende sensor, om oriëntasie data aan 'n sateliet te verskaf, te ondersoek. Die sigbaarheid van die maan en die sigbaarheid van die son is met mekaar vergelyk, vanaf 'n sateliet (m.a.w. die uitvoerbaarheid van 'n maan-sensor is vergelyk met dié van 'n son sensor). 'n Algorittne is ontwikkel om die middelpunt van die maan, ongeag van fase of rotasie, te bereken om verhoogde akuraatheid van die maan se middelpunt te bied. Die akuraatheid van die maan-middelpunt algoritme en moontlike foute is evalueer en bespreek in beide ideale sowel as werklike toets gevalle. Die sensor was op hardeware geimplenteer. Die gevolgtrekking van die lewensvatbaarheids analise is dat die sensor effektief sal funksioneer as 'n aanvullende sensor (d.w.s saam met 'n son sensor) eerder as 'n alternatiewe sensor. Die resultate verkry van die evaluasie van die maan-middelpunt algoritme is bevredegind en is voldoende vir oriëntasie bepaling. Die sensor kan dus ernstig oorweeg word vir gebruik op 'n sateliet in die toekoms.