The ISS began taking shape in earnest in 1998. On November 20, the Zarya Control Module launched on a Russian Proton rocket. It was the first piece of the station, the battery power and fuel storage unit onto which later modules were added. The Unity node followed in December, and in May of 1999 the shuttle orbiter Discovery fitted the station with logistics and stocked it full of supplies. Four assembly missions in May, July, September, and October of 2000 saw addition of the Zvezda Service Module as well as installation of the Z1-Truss, a third pressurized mating adapter, and a Ku-band antenna. These missions also delivered supplies and performed maintenance on the Station. It was finally ready for a human crew.