Difference between revisions of "Pioneer anomaly"
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==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 | + | 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 | + | 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 | + | 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. |
==Explanations== | ==Explanations== | ||
Revision as of 06:23, December 1, 2009
The Pioneer anomaly refers to deviations in projected courses for several spacecraft sent to the outer solar system. The effect is believed to have influenced the courses of both Pioneer spacecraft, Galileo, and Ulysses. The courses for the Voyager spacecraft and Cassini were not able to be predicted accurately due to known but unpredictable effects on these craft, and if the anomaly affects these spacecraft, it would not be distinguishable from other effects.
Critics of general relativity cite the Pioneer anomaly as an error in the theory.
Discovery
Every spacecraft sent to the outer solar system is intended to follow a specific course. The theory of general relativity is used to predict these courses. The spacecraft are then tracked during flight. By using Doppler radar, scientists have found that the courses for both the Pioneer spacecraft show a constant acceleration towards the sun of 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.
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.
Explanations
There are many possible explanations for the effect, including a failure of general relativity at these speeds or distances.
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