Pioneer Anomaly Un-Solved.
Pioneer Anomaly Un-Solved.
A number of correspondents have asked about these papers as the ‘Anderson deceleration’ forms a cornerstone of my Vorticitating Hypersphere Cosmology.
Physical Review Letters, here: "Support for the thermal origin of the Pioneer anomaly" by Slava G. Turyshev, Viktor T. Toth, Gary Kinsella, Siu-Chun Lee, Shing M. Lok, and Jordan Ellis.
Turyshev et al have created a very complicated theoretical model which appears to explain the Pioneer 10 anomaly in terms of asymmetric thermal photon emissions from the spacecraft. They assert that the observed 8 x 10^-10 m/s^2 ‘Anderson deceleration’ can result from this.
Theoretical debate rages about just how much thrust photon emission might actually provide in practise, but K.Iwami et al have actually performed an experiment:-
Nanonewton thrust measurement of photon pressure propulsion using semiconductor laser.
K. Iwami ; Taku Akazawa ; Tomohiro Ohtsuka ; Hiroyuki Nishida ; Norihiro Umeda
‘To evaluate the thrust produced by photon pressure emitted from a 100 W class continuous-wave semiconductor laser, a torsion-balance precise thrust stand is designed and tested. Photon emission propulsion using semiconductor light sources attract interests as a possible candidate for deep-space propellant-less propulsion and attitude control system. However, the thrust produced by photon emission as large as several ten nanonewtons requires precise thrust stand. A resonant method is adopted to enhance the sensitivity of the biflier torsional-spring thrust stand. The torsional spring constant and the resonant of the stand is 1.245 × 10-3 Nm/rad and 0.118 Hz, respectively. The experimental results showed good agreement with the theoretical estimation. The thrust efficiency for photon propulsion was also defined. A maximum thrust of 499 nN was produced by the laser with 208 W input power (75 W of optical output) corresponding to a thrust efficiency of 36.7%. The minimum detectable thrust of the stand was estimated to be 2.62 nN under oscillation at a frequency close to resonance.’
So, if 75 W of laser optical output only yields a meager 499nN of thrust, and Pioneer 10 weighs about 250kg, then clearly the number of watts of optical laser output required to impart an acceleration of 8 x 10^-10 m/s^2 to it comes out at 30 watts!
So Pioneer 10 would have to have emitted an excess of 30 watts of photons continually in its direction of travel to account for its deceleration by this mechanism. Considering that the maximum power output from its nuclear batteries declined from a peak of 141 watts to 65 watts over the period of study it seems incredible that the mere asymmetric geometry of the craft could lead to such an effect.
Thus the Pioneer anomaly still seems to point towards some new physics, and its mysterious spin down during its voyage also deserves investigating as well.