Back in 2012, before seeing Kerbal Space Program, I thought of it too. Well, if we build a tower 1 km tall (or find a suitable mountain), have two bobines with

Back in 2012, before seeing Kerbal Space Program, I thought of it too. Well, if we build a tower 1 km tall (or find a suitable mountain), have two bobines with 5-10 km cable rotating and gradually increasing the radius while keeping the weight above the ground, then it could launch the vehicle at reasonable g's and within reasonable radius. But still the centrifugal force formula is cruel, and the size of the device is huge. Actually, I wonder if cold gas thruster can do the same job. (https://en.wikipedia.org/wiki/Cold_gas_thruster https://en.wikipedia.org/wiki/Cold_gas_thruster) At least some gases are extractable on the Moon surface.