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sâmbătă, 28 iulie 2012

Pioneer anomaly explanation

Many people know that the Pioneer spacecraft launched by NASA in 1972 and 1973 are subject to additional forces to the Sun, force that can not be explained only by gravity, and this effect is called "Pioneer effect" or "Pioneer anomaly".

Recently, Russian Turyshev proposed an explanation that seems to me at least strange: they say that, by the construction, the ships emit more heat on one side. And it seems that ships sit quietly just with the necessary position to give more heat in the direction opposite the Sun. I am not satisfied with this explanation and I will try here to show that the Pioneer effect has a simple mechanical explanation.

We know that an isolated system have constant energy, constant momentum and constant angular momentum. Therefore, the center of mass of an isolated system moves undisturbed, on a straight line (in an sufficient approximation equivalent to the degree of isolation to the system). Thus, an isolated system tends to maintain constant energy. Any loss, how small, the energy of a system must necessarily put on the presence of another system, able to absorb the energy they lose this system, so that the new system formed by the two systems have constant energy, he is isolated system.

Now, let to concretize deepen this interesting energy conservation law. We established that an isolated system can not lose energy. How so? The isolated system does not lose energy even if it is hot? Well, even if it is hot! For thus saith the law of conservation of energy of an isolated system. The only way that a system can lose energy is that around it to be mandatory another system that can absorb energy transferred! If the energy has nowhere to go, then it is not going anywhere! Let us be clear that! That's the law of conservation of energy! More specifically, if around the Sun there would be nothing, then Sun would not lose energy! Because it would be an isolated system and the isolated systems do not lose energy.

Let's see now what happens if the energy still have where to go. Suppose that in the Universe there are only two systems A and B; the system A has given up more energy and the system B, beside him, is hungry for energy, just waiting to suck some from the system A. Both system A and system B are both moving in the Universe, and their total momentum must be conserved, which means that their center of mass moves rectilinearly and uniformly, regardless of what happens in the isolation system consists of two subsystems A and B. So, the common center of mass moves freely, even if the system A yield energy to the system B.

Ok, but any energy transport means also a mass transport, because energy is equivalent to mass. This means that with the energy transfer from system A to system B, there is also a mass transfer. More specifically, the mass of the system A decreases while the mass of the system B increases. But common center of mass of the two systems still moving freely, even if the mass of the system A decreases and the mass of the system B increases. This means that, while the continuing the transfer of energy (and mass), the system A departs from the common center of mass, while the system B approaches to the common center of mass. Of course, if the mass of the system A is huge compared to the system B (like in the case the Sun and the probe Pioneer), the movement of A from the center of mass will be imperceptible, leaving only noticeable movement of B about the center of mass common, center located very close to A in this case.

These reasons can be easily implemented of the system consists of Sun and Pioneer probes, knowing that we can admit that the solar system is an isolated system, in a sufficient approximation, over tens of years since moving probes, because the path of the Sun in the Galaxy has a very large radius of curvature, so that decades are negligible compared to the period of revolution of the Sun around the Galaxy. Therefore, the Pioneer anomaly explanation is just the mass transfer that occurs from the Sun to probe by heating them. This effect is not related to the flyby anomaly, I'll talk about on another occasion.

Note: this is an approximate translation obtained with the great help of the Google Translate of the previous material from Romanian.

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