Book excerpt: Michel van Pelt explains for the first time the principle of space tethers: what they are and how they can be used in space. He introduces non-technical space enthusiasts to the various possibilities and feasibility of space tethers including the technological challenges and potential benefits. He illustrates how, because of their inherent simplicity, space tethers have the potential to make space travel much cheaper, while ongoing advances in tether material technology may make even seemingly far-fetched ideas a reality in the not too distant future.