Changes

==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 spacecrafts are then tracked during flight.  By the use of [[Doppler effect|Doppler radar]], the courses for both the Pioneer spacecraft have showed 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 unpredicatble 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 crafts suffer the same difficulties as the Galileo and Ulysses crafts, although more significant, preventing even a discussion of whether these crafts are effected 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.

==Explanations==

==Explanations==