Interplanetary spaceflight

Interplanetary spaceflight or interplanetary travel is travel between planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System.

Remotely guided space probes have flown by all of the planets of the Solar System from Mercury to Neptune, with the New Horizons probe having flown by the dwarf planet Pluto and the Dawn spacecraft currently orbiting the dwarf planet Ceres. The most distant spacecraft, Voyager 1, has left the Solar System, while Pioneer 10, Pioneer 11, Voyager 2 and New Horizons are on course to leave it.

In general, planetary orbiters and landers return much more detailed and comprehensive information than fly-by missions. Space probes have been placed into orbit around all the five planets known to the ancients: first Mars (Mariner 9, 1971), then Venus (Venera 9, 1975; but landings on Venus and atmospheric probes were performed even earlier), Jupiter (Galileo, 1995), Saturn (Cassini/Huygens, 2004), and most recently Mercury (MESSENGER, March 2011), and have returned data about these bodies and their natural satellites.

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