Today there is no common vision on sustainable space transportation. Rockets expel gasses and solid rockets often small particles. These have negative effect on the environment, but it is not understood to what extent. With ever growing demand for access to space, sustainable technology developments are to be made. In this respect a truly sustainable means of transportation seems to be the space elevator. However state of the art tether technology can already contribute today to sustainability and further tether developments are stepping stones for sustainable space transportation. This paper provides firstly an outlook into sustainable space transportation, from a mainly European perspective. Here we address that tethers are a building block for sustainable space transportation and hence technological advancements are of key interest. Potential next steps for Europe are discussed. We then zoom in further towards the state of the art for tethers in Europe, mainly based on the results of the 2nd Young Engineers' Satellite (YES2) project, that completed a 32 km tether deployment in September 2007, and of which the technology and design is publicly available. Discussed are the YES2 tether deployer system, its scalability and supporting rigs/tools as well as the hurdles encountered on the road from concept to space demonstration such as critics' concerns about safety and simulation validity. We address tether controllability, based on mission results, showing good agreement between tests, simulations and YES2's flight measurements of the various deployment parameters. Observations of tether stiffness, damping, sound waves and lateral waves are analyzed including conclusions on scope of validity of simulation and test. We conclude that Europe can take a prominent role in sustainable space transportation development.