Garth

Note also:

1. The acceleration is a_P = (8.74 ± 1.33) × 10⁻¹⁰ m/s².

2. What is actually measured is a time acceleration of a_t = (2.92 ± 0.44) × 10⁻¹⁸ s/s²).

3. The effect has been constant and equal for both spacecraft from 10AU - 90AU. (Pioneer 10 - Feb 2003) (Other effects swamped it when they were closer than than 10AU from the Sun.)

4. That 'normal physics' from On-Board Systematics can so far explain a maximum of:

i Radio Beam Reaction Force a = (1.10 ± 0.10) × 10⁻¹⁰ m/s². .
ii Anisotropic Heat Reflection a = (−0.55 ± 0.55) × 10⁻¹⁰ m/s². .
iii Differential Change of the RTG’s Radiant Emissivity a = 0.85 × 10⁻¹⁰ m/s². .
iv Constant Electrical Heat Radiation as the Source: not viable.
v Helium Expulsion from the RTGs a = (0.15 ± 0.16) × 10⁻¹⁰ m/s². .
vi Propulsive Mass Expulsion a = ±0.56 × 10⁻¹⁰ m/s².
(source The Study of the Pioneer Anomaly: New Data and Objectives for New Investigation Turyshev et al.)

This makes a maximum total of a_n = (2.1 ± 0.8) × 10⁻¹⁰ m/s² that can be caused by normal physics leaving at least a minimum anomalous acceleration of a_x = (6.6 ± 2.1) × 10⁻¹⁰ m/s² to be explained.

5. Furthermore note the Hubble acceleration cH = 7.2 × 10⁻¹⁰ m/s², which is consistent with this unexplained residual.

The PA may therefore be cosmological and not local in nature, which would also explain why it does not show up in the closed orbits of the Outer Planets.

Garth