One less thing to worry about - Pioneer 10 Anomaly resolved

[doodab]

That is good news.

[OwlHoot]

Pioneer Anomaly Solved By 1970s Computer Graphics Technique

Previous calculations have only estimated the effect of reflections. So Francisco and co used a computer modeling technique called Phong shading to work out exactly how the the emitted heat is reflected and in which direction it ends up travelling.

Phong shading was dreamt up in the 1970s and is now widely used in many rendering packages to model reflections in three dimensions. It was originally developed to handle the reflections of visible light from 3D objects but it works just as well for infrared light, say Francisco and co.

In particular, Phong shading has allowed the Portuguese team to include for the first time the effect of heat emitted from a part of the spacecraft called the main equipment compartment. It turns out that heat from the back wall of this compartment is reflected from the back of the spacecraft's antenna (see diagram above).

Since the antenna points Sunward, towards Earth, reflections off its back would tend to decelerate the spacecraft. "The radiation from this wall will, in a first iteration, reflect off the antenna and add a contribution to the force in the direction of the sun," say Francisco and co.

Lo and behold, this extra component of force makes all the difference. As Francisco and co put it: "With the results presented here it becomes increasingly apparent that, unless new data arises, the puzzle of the anomalous acceleration of the Pioneer probes can finally be put to rest." In other words, the anomaly disappears.