It served as a docking port for visiting Soyuz crew ships and Progress freighters for nearly 20 years and as an airlock for Russian spacewalks.
The much larger 44,000-pound Nauka module features an airlock and docking port, expanded crew quarters, research space, an additional toilet, oxygen generator, solar arrays and a European Space Agency-built robot arm.Assuming no problems are found, the lab module will complete its rendezvous with the space station Thursday, moving in for docking at Zvezda's Earth-facing port at 9:24 a.m.Nauka's docking will come the day before a United Launch Alliance Atlas 5 rocket launches a Boeing CST-100 Starliner crew capsule to the station for an unpiloted test flight.and partner-agency astronauts to and from the space station on a commercial basis, helping end NASA's post-shuttle reliance on Russian Soyuz spacecraft for crew transportation.
An initial Starliner test flight in December 2019 had major software problems, prompting Boeing to launch a second unpiloted test flight before the ship's first planned launch with a crew on board late this year or early next year.