The point is obviously more probes. I think a sufficient gravity field and planetary mass is going to let you work a lot faster. Robotic probes with basically n

The point is obviously more probes. I think a sufficient gravity field and planetary mass is going to let you work a lot faster. Robotic probes with basically no atmosphere to get through means you can use kinetic cannons to get off-world. Your initial "factory line" would be a mostly underground equatorial band on Mercury.