Mass Drivers or: What to Do With the Leftovers of Mining

[CaptRobau]

While suggesting resource mining itself is off the table, this suggestion pertains to an engine type that can be a result of resource mining. With the recent announcement of resources being a future feature of KSP, I think it's a relevant suggestion to make. Mods, if you consider this a violation of the suggestions rules, by all means lock it down.

One interesting engine type that (asteroid) mining could provide would be the space-based mass driver. The ground-based linear mass driver (where more people will be familiar with) uses a linear motor to accelerate and launch spacecraft from the surface of (low-gravity) bodies. This would however be a massive colony-like building, which goes beyond the current scope of KSP. A space-based mass driver however would fit KSP quite well. In the simplest form it works sort of like an ion engine: accelerating matter away from the spacecraft creates thrust. While it can technically use any type of matter as propellant, the most cited is rock dust. One because it would not leave dangerous matter in its wake (imagine a rocket that leaves space debris in its wake) and two because rock could be easily mined from asteroids and almost every celestial body. As such I think it'd be an interesting addition to the future resources system, which has been hinted at revolves a lot around asteroids. The drill would create rock as a natural byproduct and that could either be dumped automatically or converted into dust to power a mass driver. This could then be used as fuel to move the asteroid.

The space-based mass driver is also quite balanced right out of the box. It has high Isp, but low thrust. In reality it has a TWR under 1, meaning you can't lift off with it. If the TWR was made relative to KSP's ion drive it'd be 4.2, but like the ion engine it requires a lot of electricity so it's not an engine that would replace all other engines with the current state of stock electrical power production.