The Pioneer anomaly or Pioneer effect is the observed deviation from predicted trajectories and velocities of various unmanned spacecraft visiting the outer solar system, most notably Pioneer 10 and Pioneer 11.
Some possible explanations
* observational errors, including measurement and computational errors, in deriving the acceleration.
o Approximation/statistical errors
o Significant errors in computation are not likely since (at current count) 7 independent analyses have shown the effect.
a real deceleration not accounted for in the current model, such as:
o gravitational forces from unidentified sources such as the Kuiper belt or dark matter. However, an acceleration does not show up in the orbits of the outer planets, so any generic gravitational answer would need to violate the equivalence principle  (see modified inertia below).
o drag from the interplanetary medium, including dust, solar wind and cosmic rays. However, the measured densities are too small to cause the effect.
o gas leaks, including helium from the spacecrafts' radioisotope thermoelectric generators (RTGs)
o radiation pressure of sunlight, the spacecraft's radio transmissions, or thermal radiation pressure from the RTGs (See Radioisotope rocket), or asymmetrical radiation of the heat from the spacecraft electronics, reflecting from the back of the spacecraft’s dish-like main antenna, causing a recoil like sunlight striking a solar sail.
+ The pressure of sunlight is too small at this distance, and points into the wrong direction. The same applies to the spacecraft's radio emissions.
+ The others are prime suspects, as presented at the second ISSI meeting in Berne, Feb 2007.
+ A recent presentation at the APS April 2008 meeting suggests that differential heating may account for as much of 1/3 rd of the observed acceleration.
o electromagnetic forces due to an electric charge on the spacecraft
* New physics
o clock acceleration between coordinate or Ephemeris time and International Atomic Time.
o A modification of the law of gravity. The theory MOND (Modified Newtonian Dynamics) proposes that the force of gravity deviates to a very different force law at very low accelerations of order: 1.0−11 m/s2 from the traditional Newtonian value.
o Modified inertia. MOND can also be interpreted as a modification of inertia, perhaps due to an interaction with vacuum energy and such a trajectory-dependent theory could account for the different accelerations apparently acting on the orbiting planets and the Pioneer craft on their escape trajectories.
 More recently, a model for modified inertia using Unruh radiation and a Hubble-scale Casimir effect has been proposed to explain the Pioneer anomaly, and a possible test for evidence of modified inertia on Earth has been proposed. It has also been suggested that a modification of inertia can explain the flyby anomaly.
o Down-scaling of photon frequency as a consequence of integrable Weyl geometry. This connects the Pioneer anomaly with the Hubble parameter via conformal geometry, and in a sense obviates the need for an assumed expansion of space in favor of a local “down-scaling” of photon frequency – an effect similar to “tired light” but originating in the geometry of spacetime rather than as a higher-order gravitational effect.
o Extending the Hubble law (which relates the increase (redshift) of the wavelength of a photon from another galaxy to the expansion of the universe) to the realm of unbounded massive particles, the particle's associated de Broglie wavelength will be redshifted due to the expansion. This redshift corresponds to a decrease in the particle's momentum over time. Thus, the Pioneer spacecrafts' anomalous accelerations may be a counter example to the hypothesis of dark matter in the Milkyway galaxy.
Altri ricercatori, come Robert Sanders dell'Università di Groningen e Mordehai Milgrom del Weizmann Institute of Science a Rehovot, si spingono però più in là: se confermate, le conclusioni di Tangen sarebbero estremamente importanti, ha osservato Sanders: “O l'anomalia del Pioneer non è reale, ossia esiste un altro effetto fisico di cui in qualche modo non si è tenuto conto, o esiste qualche alterazione della gravità che non ubbidisce al principio di equivalenza della relatività generale”.
Zret , proprio il fatto che siamo arrivati agl inizi della comprensione per il controllo di queste forze, porta alla necessità a mio parere di un “esame” che faccia da filtro
Il Sole è un “Occhio” dell'Uno O-O
Il Centro della Galassia è un “Cuore” dell'Uno :cor: