Thursday, June 14, 2007

Pioneer 10/11 Anomaly

The astrophysics community has been baffled by the apparent anomalous behavior of Pioneer 10/11, as they have been observed to be attracted toward the sun slightly more than predicted by the force given by Newtonian gravity.

The anomalous Pioneer 10/11 acceleration (8.74 +/- 1.33) * 10^-8 cm/s^2 has been reported. For more info, visit .

The acceleration of the Earth in its orbit is 0.593 cm/s^2 on average (1 AU)*(2*pi/yr)^2 making this anomalous acceleration 1.5*10^-7 of that.

However, Pioneer 10 was 67 AU from the Sun in 1997, when its mission was downgraded to a sort of background status, and Pioneer 11 was 40 AU from the Sun when contact with it was lost in 1995. This means that the anomalous acceleration is ~10^-4 of the Sun's acceleration of them at that distance.

Finally, it is noted that calculated nongravitational effects, such as radiation reaction from the spacecraft's radio transmissions and the glow of the RTG's, are not much smaller than the anomalous acceleration itself, suggesting that one may have to model such effects more carefully.

Also, there are no similar effects reported for the Voyager spacecraft, so these may be due to some quirk of the Pioneers.

The following is a quote from the report from NASA at JPL and LANL.
Dispassionately, the most likely cause of the anomalous acceleration of the Pioneer spacecraft is on-board systematics, but the smoking gun has not yet been found. The only other possibility is the existence of new physics. This dichotomy represents a healthy win-win situation because either one of these two explanations for the Pioneer anomaly would constitute an extremely important discovery. (Author Slava Turyshev and John Anderson are at the NASA Jet Propulsion Laboratory, Pasadena and Michael Martin Nieto at the Los Alamos National Laboratory, US)

One possible explanation of this anomaly may be found within the theory of dipole gravity. Since the rotating parabolic antenna of Pioneer represents a dipole gravity rotor, the observed additional acceleration toward the sun can be explained if the antenna is focused toward the sun which means the wider (open) side of the parabola faces the sun. And Pioneer is reported to be spinning at 14.1 sec per revolution which makes it spinning at 4.25 rpm. However, since the effect was not observed from Voyager as prominently(if at all) as it was observed from Pioneer, this may still be an open question.

If Voyager has different mechanical parameter (it also has parabolic antenna) compared to that of Pioneer in such a way that the dipole gravity effect is minimal (for example, the spinning rate is lower and it has more longitudinal axially symmetric configuration), then the mystery could be resolved. For this purpose, the detailed mechanical configuration including the rate of the spin rotation for both Pioneer and Voyager may be needed. This data may be found in the detailed original engineering design in terms of the mass distributions inside the craft.

In the mean time, the following information has been available which can be very significant.
Is the same effect seen with the Voyager spacecraft?
The Pioneers are spin-stabilized spacecraft. The Voyagers are three-axis stabilized craft that fire thrusters to maintain their orientation in space or to slew around and point their instruments. Those thruster firings would introduce uncertainties in the tracking data that would overwhelm any effect as small as that occurring with Pioneer.

This difference in the way the spacecraft are stabilized actually is one of the reasons the Pioneer data are so important and unique. Most current spacecraft are three-axis stabilized, not spin stabilized.
If the above information is true, in the three-axis stabilized spacecraft case, the anomalous effect would have been automatically canceled or diluted, because of the continuous adjustment of the orientation of the craft. However, in the case of the spin-stabilized craft, the dipole gravity effect will not be corrected which will make the effect prominently visible.

The following information is exactly what can be expected from a dipole gravity rotor placed in the empty space.
What really puzzles scientists, Turyshev said, is that the anomaly is constant with respect to time and distance from about 1 1/2 billion miles away from the sun to about 6 1/2 billion miles out. The anomalous behavior has been observed in other deep space vehicles such as Voyager and Ullyses.

The magnitude of anomaly seems larger than one would expect from a spin rotation of 4.25 rpm regardless of the size of the rotor. But the exact mechanical configuration of the craft is not yet available at the moment. And there is an uncertainty on the average distance and the amount of the mass of the universe which are not well defined relative to the location of the dipole gravity rotor. So, in case a terrestrial experiment is planned for the second confirmation, the Pioneer data will make a good starting point.

In a sense, the alternative experiment that has been proposed for the test of dipole gravity in the page may have already been done in the space without our knowledge.

Sunday, June 10, 2007

Dipole Gravity and The Big Bang Cosmology

Some people in the field may engage into immediate expansive thoughts on what will be the consequence of this result on the current understanding of the big bang cosmology. Since the inflationary theory of cosmology depends largely on the ideas of the elementary particle physics, one has to assume that the current understanding of the theoretical elementary particle physics is complete and infallible to put 100 percent faith on it.

However, as I mentioned in the digression page, it must be emphasized that the exact physical nature of the neutrinos, which are the most mysterious particles in elementary particle physics today, is still controversial, although there is a great chance that they are tachyons. And such assumption doesn't seem to contradict the nature of dipole gravity, instead it helps understanding the cause of the gravity in general. Furthermore, the number of such supporting empirical evidences seems to be growing.

If neutrinos are tachyons, the homogeneity and the isotropy of the universe will be guaranteed at any time in the past and in the future. One doesn't have to worry about if some globular clusters may be older than the age of the universe predicted by the big bang theory.

The reason for the continuous expansion of the universe may be answered if neutrinos are magnetic monopoles themselves as well. It also explains the missing dark energy problem. Will there be final crunch after all these expansions? No one will be able to tell for sure at the moment. We are not certainly in the stage of science being able to contemplate any possibility after the complete expansion of the universe, if there is such a thing as complete expansion.

One thing that can be stated for sure is that there are stages of development of science where certain conjectures can be made on certain questions of the nature. Since no one survived to tell what happened at the time of big bang, most of the features of the theory must be categorized as speculations.

Our visible part of the universe may be expanding but no one knows what is happening to the other invisible part of the universe. So, our ability to foretell the mechanism of the universe is severely limited by our own limitations. As our science progresses to the higher level to be able to physically reach far out side of our own galaxy, our ability to predict the future of the universe will grow as well and become more reliable.