The WISP is one self contained structure. Its torpedo like appearance is to aid in smooth travel through the ice crust of Europa until the water interface is reached. The shape will also help in conducting the maximum amount of heat throughout the surface of the probe to ensure the surrounding melted water film does not refreeze around the probe during descent. The probe will be constructed using a double hull design. The inner hull will house all needed material and experimental equipment that the probe will utilize during its mission. The outer hull will house the inner hull, obviously and also contain a highly conductive thermal fluid which will circulate around the RTG unit in order to provide a dynamic thermal circulation system, used to distribute the intense heat from the RTG to all portions of the probe's exterior. As mentioned previously, this is very important and ensures that the probe will not get hung up due to the refreezing water medium. The double hull will be sealed from the environment so as to not leak the conductive fluid to the surroundings due to its radioactive properties. The hulls will have accesses for the floatation device to fit through when inflated, but will be sealed until the device is activated.
The inside of the probe's cavity will also be lightly shielded to halt the attenuation of alpha and beta particle transmission to the interior instruments. The interior of the probe is also insulated to shield from the heat generation in the probe's tip and skin covering and will be regulated by using the surrounded melted water for cooling if need be. The outer hull will also have to accommodate sections of transparent material in order to allow the microscopic camera to take pictures of the surrounding ice. The outer casing will also accommodate insulated metal electrodes used to measure water properties. The exterior or the outer hull is designed with channeled grooves that will aid in removing the melted medium from the probe's path, allowing proper movement of the probe through the ice crust.
The probe's outer hull is made of a highly thermally conductive metal like tempered aluminum or another metal if aluminum is found to be deficient in melting properties. The inner hull is an advanced ceramic/graphite/epoxy composite structure that resists thermal changes and will not act as a heat sink and yet will be lightweight and very strong. The apperatures are to be made from advanced plastics or advanced tempered glasses whose crystalline structure will not be altered by the radioactive environment and thus turn opaque with time. The RTG itself will also be supported by ceramics in order to keep it in contact with the outer hull's tip and in the center of the circulating fluid and yet kept away from the inner hull. The internal support structures that support the equipment can be constructed from composites and nonthermally conductive materials as well.