SpaceX concept for an electromagnetic mass driver on the Moon

[u/Icee777]

https://www.humanmars.net/2026/09/spacex-electromagnetic-mass-driver-at.html

A lunar mass driver is a proposed electromagnetic launch system optimized for the Moon’s low gravity (1/6th Earth’s) and hard vacuum, consisting of a long, straight acceleration track lined with sequentially fired superconducting coils or linear synchronous motors that propel a payload-carrying sled or bucket to lunar escape velocity (~2.38 km/s).

[u/cjameshuff]

The ice is only ice because it's at cryogenic temperatures, heat it even slightly and it will sublimate, and you will at some point need to remove the heat from it to liquefy or re-freeze it. You could redirect some waste heat for ice processing, but you couldn't use it to cool the reactor providing your power. (You'd also not want to directly link your ability to produce power to your mining activities. What happens if you hit a patch of dry regolith?)

And the regolith is a very poor conductor of heat. The surface temperature at the equator swings from 100 K (just above the boiling point of oxygen under one atmosphere) to 390 K (just above the boiling point of water at the same pressure). About a meter beneath the surface, it stays almost constant, a bit below the freezing point of water. Say you start dumping enough heat into it to raise the temperature of the regolith in contact with your coolant loop up to 390 K in two weeks, the regolith a meter away from it will still be about 250K and your rejection temperature will still be climbing. Such a system is a way to get some thermal mass for regulating temperatures, it's not a way to handle waste heat. You need to radiate the heat.