What is a Space Fountain?
A space fountain is a hypothetical active structure that would use the momentum of a stream of projectiles to hold a structure aloft. Because a space fountain would need to be hundreds or thousands of kilometers in height, it is referred to as a megastructure, and the cost of its construction would be prohibitive for the next couple of decades at least. In contrast to a space elevator, which uses tensile strength to stay aloft, a space fountain’s means of suspension would be the same means that a hypothetical Frisbee being barraged by a stream of water from a hose would use. For a space fountain, the projectile stream would need to be encased in a vacuum to prevent massive power loss. The vacuum would be contained by a tube that uses magnetic levitation to remain disengaged from the projectile stream. For this reason, one of the only serious studies of a space fountain uses a continuous, segmented iron ribbon just 2 inches (5 cm) across as the projectile stream. Despite the initial ene
