Pioneer; Looking Back. (Credit: Artists conception NASA/JPL).
Every advocate of alternative physics’ favorite spacecraft anomaly has been finally laid to rest recently. In 1972 & 1973 The Pioneer 10 and 11 spacecraft were sent on trajectories past Jupiter and Saturn that would take them out of the solar system. Now at a distance of 103 and 83 A.U. moving at 11.5 km per second, these spacecraft fell silent in 2003. Over the years, however, scientists mulling over their positional data had come up with an effect that just wouldn’t go away; dubbed the “Pioneer Anomaly” it seemed that the spacecraft were not quite where they should be. Was an unseen body or medium creating a drag on the Pioneer spacecraft? Some even whispered that Newtonian physics itself was to blame, and that these hallowed laws of gravity and motion were due for a tweaking, the likes of which hadn’t been seen since Einstein. In 2006, Slava Turyshev of the Jet Propulsion Laboratory announced that uneven radiational heating could explain some of the anomaly. Consider the Yarkovsky Effect, where heating and radiation can alter an asteroids course over time. Now, Portuguese physicists have used a method known as Phong shading to model how the diffuse patterns of light and shading work on the twin Pioneer spacecrafts’ paraboloidal antennae. These 2.7 meter dishes are pointed sunward, and slowly radiate propulsive waste heat outward and towards the shaded equipment compartments. These models accurately describe the motions of the Pioneer spacecraft seen before they went silent. No need to trash-talk Newton or Einstein. Physics works, both in our solar system and outside of it, but it probably won’t stop basement crackpots from trying to re-invent what’s already been observed… further platforms will put this model to the test, as the twin Voyager spacecraft are still transmitting, and New Horizons is on an outward journey as well. Pioneer 11 is off in the southern hemisphere constellation Scutum, and Pioneer 10 is headed in the direction of the bright star Aldebaran in the constellation Taurus.