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cury’s orbit as an open free-fall path, isolated from other

planets gravitational interference. It is certainly a difficult

and complex duty but clearly available with the current

development of our technology and also not expensive.

Messenger spacecraft, now orbiting the planet, should

provide an excellent opportunity to perform it, giving

precise radiometric data on the day to day real position of

Mercury. A detailed study and related tests on relativistic

and gravitational effects that could be achieved with a

Mercury orbiter mission, is summarized in [14]. Another

alternative is to wait till the Bepi Colombo be launched

in 2015, an European mission to Mercury where, testing

relativistic gravity is recognized as a crucial scientific

objective.

To assess the influence of each planet in the orbit of

Mercury, is not enough to replace it by the approxima-

tion due to a uniform ring of matter. We need to perform

a software calculation based on elliptical and inclined

orbits, positioning each planet in every moment.

5. Conclusions and Open Comments

1) A first solution is a constant angular precession and

a lineal accumulation along the orbit.

2) Angular precession may oscillate about a mean

value. The magnitude depends on the alternative theo-

retical method we use. There are significant differences

and coincidences between them. In all of them, angular

precession has a non-zero effect in the perihelion neither

the aphelion, nodes where radial velocity is null.

3) The orbital precession produced by the perturbing

potential, involves oscillations with a negative advance

and turns back, opposite to Mercury’s own progress in its

orbit. Any elliptic orbit with eccentricity e < 0.22, would

have the same behaviour with a lead/lag related to the

final/initial precession. However, the final one orbit pre-

cession does not change in any case and is always ex-

actly the expected relativistic one.

4) Eccentricity should have great influence in the

magnitude of oscillations of the angular precession.

5) The astronomical determination of the angular and

orbital precession at each single point of the orbit, has

not been yet achieved, so it is considered that Messenger

spacecraft, now orbiting the planet or the future mission

BepiColombo, should provide an opportunity to perform

it.

6) Close to reach the centenary of the formulation and

first success of General Relativity, there are still some

open issues: Is it right to accept a constant precession?

How large is the magnitude of oscillations if there are

any? Has the orbital precession any turn back? Which of

these theoretic proposals fits on the real trajectory of

Mercury?

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