Now that serious industrialization of space in the name of data centers is within the Overton window, it feels like time to bring up Rotovators again. Even if Starship completely meets all design goals with low overhead orbital reusability, it isn’t the end-all of cost effective access to space. Momentum exchange tethers could substantially reduce propellant consumption and operational challenges. The idea is that you have a tapered cable a few hundred km long attached to a substantial dead weight, and you set it spinning like one spoke of a wheel as it orbits earth. A rocket could fly up to space at much less than orbital velocity and grab onto the end of the rotating tether, then get pulled up to a faster speed and fling the payload off into a stable orbit. Falcon precision landings (with suicide burns!), and now SuperHeavy catches demonstrate that big rockets can precisely dock with infrastructure, and doing it in space is generally easier than doing it on the ground. The big win is in electrodynamic tethers, where you can theoretically use (lots and lots of) solar panels to raise the tether orbit after it has pulled itself lower while picking up a payload. That would be a game changer, but it hasn’t been unequivocally demonstrated to be practical. Even without that, just using chemical propulsion, it could still give significant efficiencies. Only the mass of the payload that is actually flung off the top of the tether needs to have the velocity made up by engine burns. The rest of the mass of the rocket “gives it back” when it drops back off at the bottom several rotations later over the launch site. Because the pickup and dropoff happen at much less than orbital velocity, there is no terrible reentry heating challenge. The vehicle gets simpler and more robust. So, you could rebalance a two stage rocket to be more propellant efficient, or you could make a reusable single stage to tether rocket. A SSTT might still use more propellant per kg of payload than Starship, but the operational advantages would be large. You lose lots of flexibility with tether systems compared to conventional rockets, but it would be like putting deep water harbors in key places.