Editing Interplanetary spaceflight (section)

{{short description|Crewed or uncrewed travel between stars or planets}}[[File:Solar System Missions.png|thumb|All [[List of active Solar System probes|active Solar System space probes]] in 2024 (and a list of upcoming ones)|310x310px]]

'''Interplanetary spaceflight''' or '''interplanetary travel''' is [[spaceflight]] ([[Human spaceflight|crewed]] or [[Uncrewed spacecraft|uncrewed]]) between bodies within a single [[planetary system]].<ref>Interplanetary Flight: an introduction to astronautics. London: Temple Press, [[Arthur C. Clarke]], 1950</ref> Spaceflights become interplanetary by accelerating [[spacecraft]]s beyond [[orbital speed]], reaching [[escape velocity]] relative to [[Earth]] at 11.2 km/s, entering [[heliocentric orbit]], possibly accelerating further, often by performing [[gravity assist]] [[Flyby (spaceflight)|flyby]]s at Earth and other planets. Most of today's spaceflight remains Earth bound, with much less being interplanetary, all of which performed by uncrewed spacecrafts, and only just a few spaceflights having accelerated beyond, to system escape velocity, eventually performing [[interstellar spaceflight]].

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Uncrewed space probes have flown to all the observed planets in the [[Solar System]] as well as to [[dwarf planet]]s [[Pluto]] and [[Ceres (dwarf planet)|Ceres]], and several [[asteroid]]s. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the [[Moon]] and have been planned, from time to time, for [[Mars]], [[Venus]] and [[Mercury (planet)|Mercury]]. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe.

A number of techniques have been developed to make interplanetary flights more economical. Advances in computing and theoretical science have already improved some techniques, while new proposals may lead to improvements in speed, fuel economy, and safety. Travel techniques must take into consideration the velocity changes necessary to travel from one body to another in the Solar System. For orbital flights, an additional adjustment must be made to match the orbital speed of the destination body. Other developments are designed to improve rocket launching and propulsion, as well as the use of non-traditional sources of energy. Using extraterrestrial resources for energy, oxygen, and water would reduce costs and improve life support systems.

Any crewed interplanetary flight must include certain design requirements. Life support systems must be capable of supporting human lives for extended periods of time.  Preventative measures are needed to reduce exposure to radiation and ensure optimum reliability.