Orbit Determination for the Canx-2 Nanosatellite Using Intermittent GPS Data

The CanX-2 nanosatellite has been in orbit since April 2008. Among other payloads, it is carrying a NovAtel OEM4-G2L GPS receiver. The receiver is operated intermittently, and is warm started using scripts which are generated ahead of time on the ground. The scripts are based on published ephemerides for both the nanosatellite and the GPS constellation; however, this paper investigates the possibility of using GPS data in conjunction with the VEC2TLE and NORAD’s SGP4 to generate the required information for warm starting the receiver. Four different experiments are carried out to assess the suitability of the model. The output is compared to the published NORAD ephemerides, the impact of operating the receiver for different lengths of time is investigated, the sensitivity of the model to weighting the GPS epochs is investigated, and finally the sensitivity of the model to the value of the drag parameter is investigated.