On the anomalous acceleration of Pioneer spacecraft
  The anomalous acceleration of Pioneer 10 and 11 spacecraft of (8.74 \pm 1.33) \times 10^{-8} cm. s^{-2} fits with a theoretical prediction of a minimal acceleration in nature of about 7.61 \times 10^{-8} cm. s^{-2} 
Moshe Carmeli, John G. Hartnett, Firmin J. Oliveira