The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data has consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of ~6 x 10^{-9} Hz/s and can be interpreted as a constant sunward acceleration of each particular spacecraft of a_P =(8.74 +/- 1.33) x 10^{-10} m/s^2. The nature of this anomaly remains unexplained. Here we summarize our current knowledge of the discovered effect and review some of the mechanisms proposed for its explanation. Currently we are preparing for the analysis of the entire set of the available Pioneer 10/11 Doppler data which may shed a new light on the origin of the anomaly. We present a preliminary assessment of such an intriguing possibility. (Refer to PDF file for exact formulas.)

Date of creation, presentation, or exhibit



"The Pioneer Anomaly and Its Implications," Proceedings of the 21st IAP Colloquium on "Mass Profiles and Shapes of Cosmological Structures". Held in Paris, France: July 4-9, 2005. AND also archived at arXiv:gr-qc/0510081 v1 17 Oct 2005 The work of SGT and JDA was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. MMN acknowledges support by the U.S. Department of Energy.Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Proceeding

Department, Program, or Center

School of Physics and Astronomy (COS)


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