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Pioneer Anomaly Solved By 1970s Computer Graphics
Frans Faase updated us on a Pioneer Mystery we've been following for many years: something is tugging Pioneer 10 & 11. A few years ago a theory surfaced but now "A new computer model of the way heat is emitted by various parts of the Pioneer spacecraft, and reflected off others, finally solves one of the biggest mysteries in astrophysics. Previous calculations have only estimated the effect of reflections. A computer modeling technique called Phong shading was used to work out exactly how the the emitted heat is reflected (PDF) and in which direction it ends up traveling. Taking into account the reflections on the antenna seem to make the anomaly disappear."
The technique for Phong Shading was introduced in 1973 as an improvement to Gouraud Shading, but was too computationally intensive to be used for graphics back then. This is no longer the case.
How does it feel to be a liar with pants constantly on fire?
... from Slava Turyshev which describes what they did to model the craft and show that heat could be the culprit.
http://www.planetary.org/programs/projects/pioneer_anomaly/update_20080519.html
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Yes, he said "at least it wasn't the Greeks", because of how often he finds out that something he thought was novel was discovered by them. Which would be 2000 years ago. Merely 300 years ago is better. Thus "at least it wasn't the Greeks".
Got it now?
The enemies of Democracy are
They did explain why. Thermal effects. The only thing that Phong shading did was to remove an obstacle to that hypothesis that was merely due to built-in inaccuracies in how they accounted for those effects initially.
In other words, the shading increased the accuracy of the calculations and it was found that when it was applied the most likely solution became even more likely.
While it is true that the Phong solution is still likely "wrong" due to being not perfectly accurate, it's still a lot less wrong than thermal effects uncorrected, and much, much less wrong than assuming aliens or an entirely new discovery in gravitation.
They don't have to worry about the radiation of the universe. Pioneer has a radioactive battery which serves not only to power the on board electronics, but to keep them from freezing. The heat from the Warm Electronics Box is soaking through the craft and being emitted as infrared photons. These photons are bouncing off the back of the radio dish antenna and are slowing down the craft.
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The WORST thing is light, because light has so very little momentum for so much energy.
Unless of course the light is free. The solar constant is about 1 kW/m**2, so solar sails get 1 N per 150,000 m**2, or a circle of about 250 m diameter.
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