There has never been a satisfactory answer to this effect. Finally, due to lack of good explanation, it has been considered as an 'experimental' error or material problem (but observed at least on two probes i think, may be three)
I wonder if this effect was observed on recent 'far space' probes.
Thank you for any information.
Unfortunately no, New Horizons was not tracked during its journey towards Pluto like Pioneer 10 and 11 were during their respective journeys. The original New Horizons mission plan called for the spacecraft to remain in a kind of hibernation during much of the cruise phase, with only occasional communication with the Earth. To change this to the kind of continuous two-way radio tracking that would have been required to obtain Doppler data of sufficient quality would have represented a significant additional cost to the mission. We did propose this, but there was never any funding, so it never happened.
I would like to express disagreement though that the "experimental error" explanation of the Pioneer effect is "due to lack of good explanation". On the contrary, there were many explanations offered. However, we performed a very careful re-analysis of the mission, including a newly built thermal engineering software model of the spacecraft (actually, more than one such model, but one built using the exact same tools and by the same engineers who do thermal analysis for current spacecraft). This re-analysis demonstrated that the thermal recoil force was previously significantly underestimated, and that once it is accounted for, the remaining discrepancy between modeled and observed Doppler data is less than the noise threshold.
Still, we would have loved to see more data. New Horizons was an obvious candidate: like the Pioneers, it is spin-stabilized, and it performed very few trajectory or attitude correction maneuvers during its cruise phase. Contrast this with the Voyagers, which are three-axis stabilized, utilizing their thrusters several times a day to maintain an Earth-pointing attitude, resulting in acceleration noise that overwhelms something as small as the presumed Pioneer effect. Simply put, New Horizons was the only spacecraft (and will remain the only one for quite some time) that could have offered a verification of the Pioneer effect (even if it is just verifying a null result.) Oh well.
Unfortunately no, New Horizons was not tracked during its journey towards Pluto like Pioneer 10 and 11 were during their respective journeys. The original New Horizons mission plan called for the spacecraft to remain in a kind of hibernation during much of the cruise phase, with only occasional communication with the Earth. To change this to the kind of continuous two-way radio tracking that would have been required to obtain Doppler data of sufficient quality would have represented a significant additional cost to the mission. We did propose this, but there was never any funding, so it never happened.
I would like to express disagreement though that the "experimental error" explanation of the Pioneer effect is "due to lack of good explanation". On the contrary, there were many explanations offered. However, we performed a very careful re-analysis of the mission, including a newly built thermal engineering software model of the spacecraft (actually, more than one such model, but one built using the exact same tools and by the same engineers who do thermal analysis for current spacecraft). This re-analysis demonstrated that the thermal recoil force was previously significantly underestimated, and that once it is accounted for, the remaining discrepancy between modeled and observed Doppler data is less than the noise threshold.
Still, we would have loved to see more data. New Horizons was an obvious candidate: like the Pioneers, it is spin-stabilized, and it performed very few trajectory or attitude correction maneuvers during its cruise phase. Contrast this with the Voyagers, which are three-axis stabilized, utilizing their thrusters several times a day to maintain an Earth-pointing attitude, resulting in acceleration noise that overwhelms something as small as the presumed Pioneer effect. Simply put, New Horizons was the only spacecraft (and will remain the only one for quite some time) that could have offered a verification of the Pioneer effect (even if it is just verifying a null result.) Oh well.
Thank you for your very precise answer. What's a pity to miss this occasion because if (one now distant day) it appears that this effect is real, it will be a gold nugget for physics (in my opinion).
Thanks to Toth for this precise answer to the question of my co-worker Gilles d'Agostini. Occasion missed. Too bad !
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