It is true that it is a lot of unknowns while drilling in Europa. But, the biggest problem with drilling on earth is the heat from the core itself, which we don't have on Europa (or Mars for the matte). Other problems like structural resistance and heavy equipment management can also be a lot easier in low gravity, although much of drilling on earth benefits from gravity "pulling" the drill.
I know this because I was always interested in the possibility
of deep mining operations in other planets, and did some research on it. There are a few interesting things we can achieve with deep mines in other planets:
- Preserving resources and nature on earth. Mining is quite disruptive to the ecosystem and other planets are abundant with common minerals, like iron, cobalt, gold and silicates.
- Underground bases might be easiest and simpler way of building any settlements on other planets, removing material can be done in-situ without need send as much construction materials. It gives great protection against radiation, good insulation agains temperature changes, and can be pressurized to Earth's atmosphere.
- It gives access to materials only found deeper in the crust. And different planets might have different mineral deposits
- This is not practical, but also interesting, you could technically dig deep enough to have enough air pressure in a open cave to not need a pressurized suit. In Mars that would be around 20 km, a much more comfortable atmospheric pressure would be found around 40km though.