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Astronomy/pioneer space craft

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Expert: - 10/2/2010


Question
what could cause the 2 pioneer space craft to be slowing down in a way not yet explained?

Answer
Hello,

I think you're probably referring to the so-called "Pioneer Anomaly".  Probably the simplest way to account for it is extraneous  gravitational forces from other celestial bodies that have not been taken into account.

We know that the outer solar system is likely teeming with large comets, for example, most of which would be beyond telescopic resolution or other detection. Any one of these could cause a perturbation, such as I examined in detail in an earlier question-answer:

http://en.allexperts.com/q/Astronomy-1360/2010/3/Celestial-mechanics-question.ht...

A less likely (but also somewhat plausible) explanation is that whoever was doing the computing simply made a mathematical error hitherto unrecognized (or the onboard computer was wrongly programmed). Ordinarily this might be dismissed but let's bear in mind that some years ago a Mars-bound vehicle missed its mark by several thousand km because a rocket jockey at NASA forgot to convert from metric units to British ft-lbs. (Or, maybe it was the other way around!)

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Philip Stahl

Expertise

I have forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics as applied to astronomical investigations.

Experience

Astronomy: more than forty years experience starting with construction of my own simple telescopes. Worked at university observatory in college, doing astrographic measurements. M.Phil. degree in Physics/Solar Physics and more than ten years as researcher.

Organizations
American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union

Publications
Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'.

Education/Credentials
B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research

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