Space vehicle

A space vehicle is a rocket-powered vehicle used to transport unmanned satellites or humans between the Earth's surface and outer space. The earliest space vehicles, starting in 1957, consisted of expendable launch systems carrying spacecraft payloads (satellites or human-bearing space capsules) which were relatively small portions of the total vehicle size and mass. The single or multistage rocket without the payload is referred to as a launch vehicle. Although reusable launch systems have been envisioned since the late 1960s, and are still under development today, as of 2013 most space vehicles in production use are expendable systems.

Visionary space ships

The "space ship" (or "rocket ship") was first envisioned in twentieth century science fiction, such as Flash Gordon, as a self-contained, presumably rocket-powered, unitized vehicle capable of reaching an extraterrestrial destination keeping its structure intact, and requiring only refueling, like an airplane. Real-world rocket technology did not make this possible; while the airplane requires an amount of fuel occupying a relatively small fraction of the total size and mass, the rocket requires an oxidizer in order to operate in the vacuum of space. It also cannot use atmospheric air as its propellant; this function is served by the high-volume and high-mass fuel and oxidizer. Also, the high amount of energy required to reach at least low Earth orbital speed requires an extremely high proportion of propellant to dry vehicle mass. Also, mid-twentieth century structural technologies made it impossible to construct a single set of propellant tanks capable of holding enough mass to reach the required velocity. Thus, expendable multi-stage launch vehicles were the necessary design choice when spaceflight began in the late 1950s.

Expendable space vehicles

Main article: Expendable launch system

Reusable space vehicles

Main article: Reusable launch system