Outside, the main new feature of Mir is a spherical docking module at the front end, with five docking ports. There is also a single docking port at the other end, making six in all. This design has allowed Mir to be expanded.
The first add-on unit docked automatically with the rear port in April 1987. It is called Kvant, after the physics term "quantum". In fact it is now called Kvant 1, because in December 1989 a large unit called the Reequipment Module, or Kvant 2, docked at the other end. It was later repositioned to a sideport of the docking module.
Kvant 2 is, at 13.7 m, a metre longer than the base unit itself. It houses an experimental compartment, an airlock and a shower, the first on board Mir. It also carried up to Mir the first model of the Russian version of the American MMU, or manned manoeuvring unit. This jet-propelled backpack, named Icarus, runs on compressed air. It will be used for inspecting and repairing the Mir complex.
A third module, the Kristall materialsprocessing module, docked with
the complex at the port opposite Kvant 2, in 1990. It is described as a
mini-factory that is intended to produce flawless semiconductor crystals
for use in electronics and ultra-pure drugs for use in medicine. The manufactured
materials would probably be returned to Earth from time to time by unmanned
Soyuz-type craft.
The Mir space station in July 1987, as photographed by the crew of the departing Soyuz TM-2. By now the base unit has been expanded by the addition of the Kvont 7 module, in place since April. Docked with Kvant 7 in the picture is the newly arrived Soyuz TM-3,
