In our eternal strive for progress the most important technologies are those of paradigm shift that suddenly emerges as a wholly new reap from a field of technology in saturation. Such was the emergence of the jet engine technology that superseded the reciprocal engine technology at its almost saturated stage. The tether technology is one technology of a similar, important kind. It will support our space activity in conjunction with conventional rocket technology much more efficiently, from a variety of fields and aspects. The specific features tether technology embodies as its most important aspects are 1) simplicity and low mass, 2) strength in tension 3) compact in (wound) volume, 4) autonomous construction, since deployment is possible without relying much on the limited human resource in orbit, and 5) a broad range of potential applications, particularly for the electrodynamic tether. This special issue is to summarize present status and expectations of the tether technology, namely to provide inherently sustainable space technology without a need for either propellant or carbon dioxide gas discharge.
