A Soyuz spacecraft consists of three parts. From front to back, a roughly spherical orbital module, a small smooth reentry module, and a cylindrical service module with solar panels attached. The first two portions are habitable living space. By moving as much as possible into the orbital module, which does not have to be shielded or decelerated during atmospheric reentry, the Soyuz is both larger and lighter than the Apollo spacecraft's command module. The Apollo command module had 6 cubic meters of living space and a mass of 5000 kg; the 3-part Soyuz provided the same crew with 9 cubic meters of living space, an airlock, and the service module for the mass of the Apollo capsule alone.