Science Fair Project Encyclopedia By definition, interplanetary
travel is travel between bodies in a given star system. Current
achievements in interplanetary travel NASA's Apollo program
landed twelve people on the Moon and returned them to Earth:
Apollo 11-17, except 13, i.e. six missions, with each time three
astronauts of which two landed on the Moon; Robot probes have
been sent to fly past most of the major planets of the Solar
system. The most distant probe spacecrafts Pioneer 10, Pioneer
11, Voyager 1 and Voyager 2 are on course to leave the Solar
system, but will cease to function long before reaching the Oort
cloud. Robot landers such as Viking and Pathfinder have already
landed on the surface of Mars and several Venera and Vega
spacecraft have landed on the surface of Venus. The NEAR
Shoemaker orbiter successfully landed on the asteroid 433 Eros,
even though it was not designed with this maneuver in mind.
Orbital mechanics of interplanetary travel To date, the only
form of spacecraft propulsion used