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→Discovery: Anomaly is much bigger than classical vs. GR
==Discovery==
==Discovery==
Every spacecraft sent to the outer solar system is intended to follow a specific course. The theory of [[General relativity|general relativity]] is used to predict these courses. The spacecraft are then tracked during flight. By using [[Doppler effect|Doppler radar]], scientists have found that the courses for both the Pioneer spacecraft show a constant acceleration towards the sun of <math>8.74 \times 10^{10} \frac{m}{s^2} \ </math> which was not part of the predicted course.
Every spacecraft sent to the outer solar system is intended to follow a specific course. The theory of [[General relativity|general relativity]] is used to predict these courses. The spacecraft are then tracked during flight. By using [[Doppler effect|Doppler radar]], scientists have found that the courses for both the Pioneer spacecraft show a constant acceleration towards the sun of <math>8.74 \times 10^{-10} \frac{m}{s^2} \ </math> which was not part of the predicted course.
Although the Galileo and Ulysses spacecraft showed some unexpected sunward acceleration, other unpredictable factors, such as the [[Yarkovsky effect]] and the thrust caused by radioactive material onboard, prohibit any accurate measurement of the effect on these two spacecraft.
Although the Galileo and Ulysses spacecraft showed some unexpected sunward acceleration, other unpredictable factors, such as the [[Yarkovsky effect]] and the thrust caused by radioactive material onboard, prohibit any accurate measurement of the effect on these two spacecraft.
Other craft suffer the same difficulties as the Galileo and Ulysses craft, although more significant, preventing even a discussion of whether these craft are affected at all.
Other craft suffer the same difficulties as the Galileo and Ulysses craft, although more significant, preventing even a discussion of whether these craft are affected at all.
The Pioneer anomaly is about 1000 times bigger than the two effects contributing to the difference between the acceleration predicted by general relativity and that predicted by classical (Newtonian) gravity. The effect of the increase in inertia due to the Lorentz transform is less than <math>10^{-12} \frac{m}{s^2} \ </math>, and the difference in acceleration due to the Schwarzschild metric is also less than <math>10^{-12} \frac{m}{s^2} \ </math>.
==Explanations==
==Explanations==