Here is my design for a wet workshop concept for a Mars base. Some of the designs out there are very impressive but overlook one big problem: Getting lots of material to Mars and landing it there safely is very difficult and expensive. The "wet workshop" concept has been thought of before, but never carried out. It has been talked about using the external tank on the shuttles, and the second stage of the Saturn V, and here is my idea for a Mars base. There are several stages for the mission to be carried out. The first part of the mission can be added as an upper stage for a rocket. The fuel tank is used for the Mars transfer burn. Once the tank is empty, the crew has about seven months to convert the empty fuel tank into useful space. The transfer engine is taken off of the ship and is left to collide into the Martian surface or burn up in the atmosphere. Finally, the crew adds solar panels, parachutes and radial engines for landing. The ship then lands and the crew can use the tank as storage space. Region one on the cross section model has living space, life support systems and experiments. Regions 2 and 4 are from the empty kerosene tank; and 3 and 5 are from the liquid oxygen tank. Regions 4 and 5 can be used as laboratory space or living space, and regions 2 and 3 can be used for storage of experiments, or other things. This type of design can be used to save lots of rocket fuel and dramatically reduce mission costs.