If, as is sometimes necessary, MIR has to be deployed or recovered at night in blustery conditions, what is already a tricky process becomes extremely dangerous. The MIR 1 filmed by MIR 2 . . . . . . . . . . . . . . . . . . . . . . MIR is propelled by a large main propeller at the stern. Since it moves through the water very slowly, and is often required to maintain its position with great precision, a rudder would be pointless. Steerage is achieved through two smaller propellers located mid-laterally and mounted on swivels so that they can provide thrust in any direction.
Illumination is provided by a battery of extremely powerful headlights.
At the point where hydrothermal fluids meet with cold sea water many of the minerals precipitate out of solution. This results in the formation of chimneys and black 'smoke'. The geochemists participating in the cruise were particularly interested in the composition of the hydrothermal fluids. Sampling hydrothermal fluids . To sample the fluids they designed and built a syringe-like piece of equipment with a long, bent tube which could be inserted into the mouth of a chimney.