Non-rocket spacelaunch  Non-rocket spacelaunch refers to concepts for launch into space where some or all of the needed speed and altitude are provided by something more powerful or other than rockets, or by other than expendable rockets. A number of alternatives to expendable rockets have been proposed. In some systems such as a combination launch system, skyhook, rocket sled launch, rockoon, or air launch, a rocket would be part, but only part of the system used to reach orbit. Present-day launch costs are very high – $2,500 to $25,000 per kilogram from Earth to low Earth orbit (LEO). As a result, launch costs are a large percentage of the cost of all space endeavors. If launch can be made cheaper, the total cost of space missions will be reduced. Due to the exponential nature of the rocket equation, providing even a small amount of the velocity to LEO by other means has the potential of greatly reducing the cost of getting to orbit. Launch costs in the hundreds of dollars per kilogram would make possible many proposed large-scale space projects such as space colonization, space-based solar power and terraforming Mars. In this usage, the term "static" is intended to convey the understanding that the structural portion of the system has no internal moving parts. A space tower is a tower that would reach outer space. To avoid an immediate need for a vehicle launched at orbital velocity to raise its perigee, a tower would have to extend above the edge of space (above the 100 km Kármán line), but a far lower tower height could reduce atmospheric drag losses during ascent. If the tower went all the way to geosynchronous orbit at approximately 36,000 km, or 22,369 miles, objects released at such height could then drift away with minimal power and would be in a circular orbit. The concept of a structure reaching to geosynchronous orbit was first conceived by Konstantin Tsiolkovsky. The original concept envisioned by Tsiolkovsky was a compression structure. Building a compression structure from the ground up proved an unrealistic task as there was no material in existence with enough compressive strength to support its own weight under such conditions. Other ideas use very tall compressive towers to reduce the demands on launch vehicles. The vehicle is "elevated" up the tower, which may extend above the atmosphere and is launched from the top. Such a tall tower to access near-space altitudes of has been proposed by various researchers.