Spinning Tethers for Space Propulsion

I love rocket launches. They are loud, carry cool things into space, and last a surprisingly long time considering how fast the rocket is already traveling when it clears the tower. But I think we’re going to look back on this era of space travel and marvel that launches & rockets were our only means of getting things into and around space (planetary gravity assists notwithstanding). We’re already moving in that direction; the initial tests of a space sail inspired by Carl Sagan have been promising. Another space propulsion idea is to use spinning space tethers to whip smaller, slower space vehicles from relatively low altitudes to higher orbits or even to the Moon, Mars, or beyond. This video from Kurzgesagt explains how these tethers work and what we could do with them.