The high cost of reaching orbit is the major factor preventing the large-scale exploration and exploitation of space. Since Sputnik inaugurated the space age in 1957, chemical rockets have propelled every payload into orbit and beyond. Rockets work well, but they are expensive. Their high costs have restricted access to space to the governments, corporations, and organizations that can afford tens or hundreds of millions of dollars to launch a satellite. Magnetic levitation and magnetic propulsion systems would give a high initial velocity to a spaceplane, which would then use a scramjet or rocket to propel itself into orbit. These are not true GBSs, but ways to replace the lower stages of a rocket with a more efficient, less costly way of reaching the upper atmosphere. The concept of GBS encompasses a range of technologies with payloads ranging from a kilogram to hundreds or thousands of kilograms. All assume a high frequency of launches, so that a GBS system could launch thousands of tons per year, an order of magnitude more than current launchers.
