NASA is designing a mission to explore titan, the largest moon of Saturn. Titan has numerous hydrocarbon lakes containing a mix of methane and ethane in unknown proportions. A small submersible vehicle will exlpore Kraken Mare, the largest lake. Assuming maximum depth od the lake is less than 400 meters how much pressure in atmospheres must the submersible be designed to withstand? Assume surface tension is 147 kilopascals, surface temp is 94 Kelvin and gravity is 1.35 m/s^2 .
The specific gravity of liquid methane is 0.415 and specific gravity of liquid ethane is 0.546