Innovative Breakthroughs to a Reusable STS

Markets for fully-expendable/partially-expendable rockets including Two-Stage-To-Orbit (TSTO) and for a fully reusable human-rated Space Transportation System (STS) are discussed. Internet-related space business and in-orbit maintenance, the resupply of consumables, and the replacement of sub-systems are considered as the most important future markets for launchers. The corresponding state-of-the-art technologies of STS are reviewed, pointing out the problems. A new propulsion system, which could lead to a breakthrough for a reusable STS, is proposed.