Bagging the Asteroid
In the microgravity of space, thermal spalling creates a massive problem: exploding rock and high-pressure steam will simply fly off into the void and be lost forever.
The Enclosure
To solve this, the mining spacecraft completely envelopes the target asteroid (or a large section of it) in a flexible, high-strength containment bag made from advanced textiles like Kevlar or Nextel.
This bag serves a dual purpose. First, it prevents dangerous rocky debris from damaging the spacecraft's solar arrays. Second, and most importantly, it acts as a pressure vessel. It traps the outgassing steam and channels it through dedicated exhaust vents into the ship's processing systems.