The Pioneer Anomaly Options

[remcook]

http://www.planetary.org/news/2005/pioneer_anomaly_faq.html

The planetary society may be checking it out...

The Planetary Society has committed to raise the funds to preserve the priceless Pioneer data from destruction.


After years of analysis, but without a final conclusion, NASA, astonishingly, gave up trying to solve the "Pioneer Anomaly" and provided no funds to analyze the data. The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers. The agency is going to scrap, literally demolish, the only computers able to access and process that data in the next few months!

[Guest_Richard Trigaux_*]

Thanks to recent posters this thread took an interesting turn, that we could summarize that a mission specifically dedicated to the Pionneer anomaly would be potentially very interesting, but that it is not likely to fly one day.

It could become more likely if it is send with other equipments, for instance for the study of solar wind effect, interplanetary magnetic fields, etc. The overal design of such a probe could allow to measure the "Pioneer effect" with much more accuracy, or at least to prove/disprove its existence.

How could such a probe work?
Basically a test mass, a raw piece of metal, should freely navigate into the solar system, on a trajectory fleeing the sun, while being protected of any spurious accelerations: solar wind, electric/magnetic effecs, outgassing, position control, etc.

To achieve this, it would be completelly enclosed into a metal casing, while having no physical contact/interaction with it. The casing would use thrusters to lock itself on a fixed position relative to the test mass.

So the overall thing navigates as if it was in really complete vacuum, without solar wind, outgassing, etc. and it can provide accurate informations of pure gravitationnal nature, eventually different of the 1/r2 law, or accounting for unknown bodies. The info on the trajectory corrections achieved by the casing would on its side provide very accurate data on solar wind. This makes this probe more interesting and more likely to fly than just a Pioneer anomaly test probe.

The only spurious gravitationnal effect on the test mass would be... the gravitationnal field of the probe itself. Thus the test mass should be placed right at the center of mass of the probe. An error on this would produce a permanent offset that we could not distinguish from true effects. If preleminary calculations show this is a problem, we can use a better overal design: the probe is formed of three parts, linked with cables: at the centre the protective casing, and at the extremities the radio transmitters, thrusters, and any other payload useful for science (and also useful to make this mission more likely). The whole thing rotates on an axis which is perpendicular to the sun direction, right around the test mass.
This design will allow to know preciselly the centre of mass and to adjust it. But above all, any permanent offset will be cancelled, as it will pull at times toward the Sun, at times opposite to the Sun. So we can really maintain the test mass free of spurious gravitationnal effects from the probe itself.

Such a probe would be relatively light wheight, so that it could be launched on an interstellar trajectory directly from the surface of the Earth, without using gravitationnal assistance. So it could bring results after only a few years. Otherwise we can use Jupiter' assistance.


Will this design lead one day to a real experiment?

[jamescanvin]

How could such a probe work?
Basically a test mass, a raw piece of metal, should freely navigate into the solar system, on a trajectory fleeing the sun, while being protected of any spurious accelerations: solar wind, electric/magnetic effecs, outgassing, position control, etc.

To achieve this, it would be completelly enclosed into a metal casing, while having no physical contact/interaction with it. The casing would use thrusters to lock itself on a fixed position relative to the test mass.

So the overall thing navigates as if it was in really complete vacuum, without solar wind, outgassing, etc. and it can provide accurate informations of pure gravitationnal nature, eventually different of the 1/r2 law, or accounting for unknown bodies. The info on the trajectory corrections achieved by the casing would on its side provide very accurate data on solar wind. This makes this probe more interesting and more likely to fly than just a Pioneer anomaly test probe.

The only spurious gravitationnal effect on the test mass would be... the gravitationnal field of the probe itself. Thus the test mass should be placed right at the center of mass of the probe. An error on this would produce a permanent offset that we could not distinguish from true effects. If preleminary calculations show this is a problem, we can use a better overal design: the probe is formed of three parts, linked with cables: at the centre the protective casing, and at the extremities the radio transmitters, thrusters, and any other payload useful for science (and also useful to make this mission more likely). The whole thing rotates on an axis which is perpendicular to the sun direction, right around the test mass.
This design will allow to know preciselly the centre of mass and to adjust it. But above all, any permanent offset will be cancelled, as it will pull at times toward the Sun, at times opposite to the Sun. So we can really maintain the test mass free of spurious gravitationnal effects from the probe itself.

Such a probe would be relatively light wheight, so that it could be launched on an interstellar trajectory directly from the surface of the Earth, without using gravitationnal assistance. So it could bring results after only a few years. Otherwise we can use Jupiter' assistance.
Will this design lead one day to a real experiment?

Interesting idea, and pretty much identical to the concept for the LISA gravitational wave mission, which would reduce the costs of such a mission considerably if the systems could be reused.

Of cource that would rely on LISA ever geiing off the ground, I wrote a undergraduate report about LISA and that was a long time ago! (~9 years) I can't remember what the planned launch date was back then but I don't think it was more than ten years, today, still ten years (2015)!

James