New theory proposed to explain Pioneer probe gravitational anomaly

(PhysOrg.com) — Portuguese physicists might have finally solved the decades old mystery of why the Pioneer probes, launched in the early 70’s, haven’t been decelerating from the Sun’s gravitational pull at the rate expected; it seems it might be something as mundane as adding in the tiny forces that occur when minute traces of heat from the plutonium on board the probes bounce off their receiving dishes, creating a counterforce, which in turn, causes the craft to slow; if ever so slightly.

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New theory proposed to explain Pioneer probe gravitational anomaly