For more than 20 years, a problem has intrigued the planetary scientists and the physicists "a tiny, unexplained sunward acceleration in the motions of the Pioneer 10, Pioneer 11 and Ulysses spacecraft " which move away from the sun (www.geocities. com/solarstormmonitor/Pioneer.html).

Many other sites on the Web bring information on this subject.

The anomalous acceleration of the spacecrafts has several characteristics:

1) Its value, according to authors, would be of :

7,59 x 10^-8 cm/sec^2 (http://renshaw.teleinc.com/papers/prl-pi/prl-pi.stm),

8,74(+-1,33)x10^-8cm/sec^2(http://csep10.phys.utk.edu/newsgroups/mond/messages/22.html) , (J.D. Anderson and all. NASA JPL - 1980, 1998, 2002)

"about 10 billion times smaller than the acceleration we feel from Earth's gravitational pull"

(www.geocities.com/solarstormmonitor/Pioneer.html, http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNStat.html).

3) This anomalous acceleration, independent of the distance, is constant for a spacecraft velocity.

4) This anomalous acceleration is radial.

This unexplained effect results, in a necessary and accurate way, from the universal isotropic temporalist field of acceleration G' of the temporalist model.

1) The order of magnitude of this anomalous acceleration c x Ho corresponds to the temporalist model with c / To (Ho = 1 / To) = G ' with To temporalist constant and G' temporalist constant of gravitation.

3) The universal temporalist field of acceleration does not disturb the circular or elliptic orbits planets of the solar system but only the radial trajectories.

4) An experimental measurement validates the temporalist model. In September 1998, the slowing of the speed of Pioneer 10 had led to a delay on its predicted trajectory of approximately 400.000 km. The radial trajectory of Pioneer 10, started between 1973 and 1974 had thus lasted approximately 24,5 years is 7,73 x 10^8 sec. The deceleration for this duration, with an universal temporalist constant of acceleration of 6,582 x 10^-8 cm/sec^2 is equal to 6,582 x 10^-8 cm/sec^2 x 7,73 x 10^8 sec x 7,73 X 10^8 sec = 3,93293 x 10^10 cm = 393.293 km.

http://nedwww.ipac.caltech.edu.level5/Sept01/Milgrom/Milgrom_contents.html

The MOND theory is proposed like an alternative to the dark mass. The temporalist model does not deny the existence of the dark mass. When the acceleration due to a mass is lower than Gn, the Newtonian model does not apply any more in The MOND theory. In the temporalist model, the Newtonian theory does not apply any more for one acceleration lower than G', like in The MOND theory, but that is due to the finished range of the ray of gravitation of the masses and to the universal temporalist field of acceleration G'.