Pioneer 10 data analysis: Investigation on periodic anomalies

International audienceThe Pioneer Anomaly refers to the difference between the expected theoretical tra jectory of the Pioneer 10 and 11 spacecrafts and the observed tra jectory through Doppler measurements. It has been interpreted by the Jet Propulsion Laboratory (JPL) as a constant anomalous acceleration (Anderson et al. 2002). For this analysis, the Groupe Anomalie Pioneer (GAP) composed of several french laboratories has developped a specific tra jectography software, ODYSSEY, which enables to test different anomaly models. The paper will present, after a brief description of the software and the implemented models, the last results obtained: in addition to the constant anomaly, time dependent signatures of the anomaly have been noticed which can be described geometrically. The fit of the Pioneer 10 data with these new models yields a reduction of the standard deviation of the residual by a factor 2 with respect to the simple constant anomaly