PDF《Support for the thermal origin of》

3 TABLE II: Error budget for the Pioneer

10 thermal model;

the contributions shown in percentages, relative to aP . Description Error Other sources <

0.1% Quantization error in telemetry data 2.2%

11 1-W radioisotope heater units 2.2% Discrepancy in TWT telemetry 2.5% Inaccuracy of geometric modela 5.0% Modeling of instrument openingsb 5.0% Subtotal: 8.1% RTG surface degradation 25.0% TOTAL: 26.3% aAssuming a fore-aft positional uncertainty of 2.5 cm. bHeat escaping through instrument openings is ill-documented. sorbed energy increased the HGA temperature and was then emitted as IR radiation. The model was evaluated for Pioneer

10 at eleven dif- ferent heliocentric distances ranging from

3 AU to

80 AU (see Fig. 2). Four temperature telemetry locations on the equipment compartment and two on the instrument compartment were examined. The deviation between the predicted values from the model and the ?ight telemetry was tracked in each of the eleven cases. The di?erences between telemetered temperature values at the six plat- form temperature sensors on board vs. values computed from the model reveal a root-mean-square (RMS) error of 5.1%. This discrepancy is consistent with, and is likely a consequence of, the known sources of error listed in Table II. Of these, the most signi?cant is the e?ect of possible surface d........