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Space missions

Another two-body trick before Dawn


You claim that NASA's Dawn probe is the first to have orbited two extraterrestrial bodies (Nature 519, 134; 2015), having arrived at the dwarf planet Ceres on 6 March after orbiting the asteroid Vesta in 2011–12 (see also Nature; 2015). But the Galileo mission to Jupiter had already accomplished the two-body trick.

Leaving aside a Copernican view that every space probe orbits the Sun even before launch, a gravity-assist trajectory passing Venus (once) and Earth (twice) put the Galileo craft in orbit around the Sun for more than three years. After heading to Jupiter, Galileo orbited it for almost eight years before plunging into the planet in 2003 to protect Jupiter's moon Europa from contamination.

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Correspondence to John D. Rummel.

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Rummel, J. Another two-body trick before Dawn. Nature 520, 157 (2015).

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