Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly coat-tailing a planet orbiting the Sun, extracting some of the orbital energy to gain a big boost in speed. While the Sun has a strong gravity field, its hopeless as a slingshot, because as Galileo pointed out its the stationary heart of the Solar System. As such, it has no orbital energy to pass on to the spacecraft.
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