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 The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers.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_*]

Messenger,

my idea was intended to detect a gravitationnal effect (or gravitationnal-like). We could modify the shielding, for instance using a transparent shield to allow for electromagnetic effects. But in this case, we shall not know if the effect is gravitationnal or electromagnetic...
Or we can make several experiments, several test mass... but the probe has only one mass center. I do not come with more "clever" designs, unless to use several concentric shields around the test mass: one metallic, shielding the test mass from EM effects, and locked on the test mass without physical contact. And around, a second shielding, avoiding solar wind but transparent to electromagnetic effects, and locked on the first shield. This may allow for a separate measurement of both three effects, gravitationnal, EM and wind effect. But this fairly complicates the design, and does not make sure that the result would be better. Especially the intermediary shield will need some thrust, and thus it will "pollute" the results of the outer shield.

So I think it will be better to keep with my first simple design, perhaps adding it sensitive electromagnetic instruments. If gravitationnal effects are ruled out, we can still check for electromagnetic effects, but they offer much less potential for interesting discoveries. (but they cost much less to search)

Thank you also Messenger for your contribution on the Oort clouds and similar. We know litle things about the Kuyper belt and Oort cloud. We usually assume they have a syymmetrical structure (a disk for the Kuyper belt, a sphere for the Oort cloud). At least they would have gained such a symmetry after rotating around the Sun for 4 billion years. If they have such symmetrical structures, they cannot have gravitationnal effects in the inner solar sytem (a hollow spherical structure has no gravitationnal effect inside).

But many things may cause such clouds to have transcient or permanent "lumps" in it:
-part of the mass is in the form of massive bodies, such as the one recently detected which is larger than Pluto. (Many trajectory calculations should be remade accounting with it). It could even exist very dark and cold massive gaseous planets very far from the Sun.
-the solar wind shockwave with the interstellar wind concentrates mass
-a spherical cloud is in orbit around the Sun
-an interstellar cloud is currently at close vicinnity with the solar system (such clouds can have mass ranging from a giant star mass to Earth mass)
-a large wandering planet is currently at close vicinnity with the solar system


A last there is one difficulty with my probe: it will only tell us what there is in one direction. If we obtain enough precision, we could try to model the effect with an 1/R2 gravitationnal field, and find the culprit. But this will take ten years, and if the probe flight path is not in a proper direction, it will not work. So ideally we should send three probes in three perpendicular directions to definitively find (or rule out) any gravitationnal effects. In practice we could send one, wait two or three years to see the results, and take the decision to send another one in a proper direction.