A space gun, sometimes called a Verne gun because of its appearance in From the Earth to the Moon by Jules Verne, is a method of launching an object into space using a large gun- or cannon-like structure. Space guns could thus potentially provide a method of non-rocket spacelaunch. It has been conjectured that space guns could place satellites into Earth's orbit, and could also launch spacecraft beyond Earth's gravitational pull and into other parts of the Solar System by exceeding Earth's escape velocity of about 11.20 km/s. However, these speeds are too far into the hypersonic range for most practical propulsion systems and also would cause most objects to burn up due to aerodynamic heating or be torn apart by aerodynamic drag.
Therefore, a more likely future use of space guns would be to launch objects into Low Earth orbit, at which point attached rockets could be fired or the objects could be "collected" by maneuverable orbiting satellites.
The Quicklauncher spacegun
Two sections of the Project Babylon gun
Project HARP, a prototype of a space gun.
The firing of a space gun in Jules Verne's From the Earth to the Moon
From the Earth to the Moon
From the Earth to the Moon: A Direct Route in 97 Hours, 20 Minutes is an 1865 novel by Jules Verne. It tells the story of the Baltimore Gun Club, a post-American Civil War society of weapons enthusiasts, and their attempts to build an enormous Columbiad space gun and launch three people — the Gun Club's president, his Philadelphian armor-making rival, and a French poet — in a projectile with the goal of a Moon landing. Five years later, Verne wrote a sequel called Around the Moon.
Cover of an early English translation
The projectile, as pictured in an engraving from the 1872 Illustrated Edition
The firing of the Columbiad