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Bug NASA Space Science

Heat 'Most Likely Cause' of Pioneer Anomaly 133

Posted by timothy
from the that-dog's-not-so-shaggy-after-all dept.
astroengine writes "Everything from clouds of dark matter, weird gravitational effects, alien tampering and exotic new physics have all been blamed for the 'Pioneer Anomaly' — the tiny, inexplicable sun-ward acceleration acting on the veteran Pioneer deep space probes. However, evidence is mounting for a more mundane explanation. Yes, it's the emission of heat from the spacecrafts' onboard radioisotope thermoelectric generators (RTGs), slowly nudging the Pioneers off course, that looks like the most likely culprit. It's unlikely that this new finding will completely silence advocates of more exotic explanations, however."
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Heat 'Most Likely Cause' of Pioneer Anomaly

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  • by nido (102070) <> on Tuesday July 26, 2011 @03:16AM (#36880712) Homepage

    The Pioneers were spin-stablizied (like tops), whereas Voyager was 3-axis stabilized (with thrusters).

    The first probes fired at the moon were also spin-stabilized. Both the US probes and the Soviet probes missed, by large margins. The Russians were the first to hit the moon - I guess they loaded extra propellant to perform course corrections.

    The proper thing to do is launch another spin-stabilized probe on an extragalactic trajectory. I wonder how much that would cost.

    What is the "Pioneer Anomaly"... <snip>
    Is the same effect seen with the Voyager spacecraft?
    The Pioneers are spin-stabilized spacecraft. The Voyagers are three-axis stabilized craft that fire thrusters to maintain their orientation in space or to slew around and point their instruments. Those thruster firings would introduce uncertainties in the tracking data that would overwhelm any effect as small as that occurring with Pioneer.

    This difference in the way the spacecraft are stabilized actually is one of the reasons the Pioneer data are so important and unique. Most current spacecraft are three-axis stabilized, not spin stabilized.

    - []

An inclined plane is a slope up. -- Willard Espy, "An Almanac of Words at Play"