SIMULTANEOUS MULTI-SITE PHOTOMETRY OF LEO SATELLITES TO CHARACTERISE THEIR ROTATION STATES

Abstract

The photometry of space objects (SO)makes it possible to determine their state of rotation aroundthe center of mass, orientation of the rotation axis androtation speed in the most cost-effective manner. However,the methods for determining the attitude parameters fromphotometric data from a single observation site (OS) requirelong series of high-quality and high-frequencymeasurements. We propose a method for determining theorientation parameters of slowly rotating SO based onsimultaneous multi-site photometry with a high temporalresolution. Preconditions for planning and building a localphotometric network that can accomplish such a task havebeen tested via computer simulation. Synchronousobservations of the unoperated spacecraft TOPEX/Poseidonwere carried out. They were attended by the observatories ofOdessa, Lvov and Uzhgorod universities, as well as theobservation station of the State Space Agency of Ukraine inZalistsi, Khmelnytsky region, took part. Synchronousnetwork-based photometric observations from three OSsenable us to calculate time lags between correlated light-curve segments and promptly determine the direction ofrotation, as well as the spatial orientation of a SO’s spin axisand its angular spin rate. A local network of severaldistributed observation sites for synchronous monitoring ofthe rotation of various SO in LEO will make it possible todetermine the rotation parameters of also slowly rotatingobjects that do not exhibit glints within their light curves.