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Bruce Murray Space Image Library

Anisotropic thermal emission from Pioneer 10

Anisotropic thermal emission from Pioneer 10
Anisotropic thermal emission from Pioneer 10 This graph represents the direction and power of thermal emission from Pioneer 10 at a distance of 25 AU from the Sun. The spacecraft's antenna points toward the top of the graph; the direction of spacecraft motion is toward the bottom of the graph. If Pioneer 10 radiated heat away in all directions equally, the plot would look like a circle (dark blue line). But Pioneer 10 does not radiate heat isotropically; the thermal model predicts that most of the power comes out the sides of the spacecraft, with almost none radiating directly along the spacecraft's direction of motion (magenta line). NASA / JPL / Slava Turyshev