Space vehicle

[4] The concept of a "space ship" (or "rocket ship") was further developed 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.

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.

However, starting in the 1990s, developmental work began on such unitary single-stage-to-orbit (SSTO) space vehicles with projects like X-33, Roton, McDonnell Douglas DC-X, and Skylon.

They typically consist of several stages which detach in sequence as the vehicle gains speed and altitude and propellant is exhausted.