Figure 28

Figure 5.1: Early unmodeled sunward accelerations of Pioneer 10 (from about 1981 to 1989) and Pioneer 11 (from 1977 to 1989). Adapted from [27], which contained this important footnote: “Since both the gravitational and radiation pressure forces become so large close to the Sun, the anomalous contribution close to the Sun in [this figure] is meant to represent only what anomaly can be gleaned from the data, not a measurement.”