This "exploded diagram" tracks progress on the assembly of the International Space Station (ISS), a crewed laboratory being built in low-Earth orbit. Orbital construction of the ISS commenced in 1998, and is slated for completion in late 2011. This image, generated from public-domain NASA data by multiple users of the popular website Wikipedia, shows the configuration of the ISS as of May 2010. That date was when the space shuttle Atlantis delivered a Russian-built module to the ISS, bringing the total number of pressurized compartments to 14. Orange denotes elements currently on orbit; blue denotes elements awaiting a US space shuttle launch; pink denotes elements awaiting a launch on a Russian Proton rocket. In its current state and upon completion, the ISS is the most massive structure humanity has ever assembled in space. And, with an estimated cost of more than $150 billion, it is also quite possibly the most expensive object ever constructed.