The Orbital Piloted Assembly and Experiment Complex is a Russian proposed third-generation modular space station in Low Earth orbit.
A space station, also known as an orbital station or an orbital space station, is a spacecraft capable of supporting a crew, which is designed to remain in space for an extended period of time and for other spacecraft to dock.
Earth is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.
A low Earth orbit is an orbit around Earth with an altitude between 160 kilometers, and 2,000 kilometers.
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OPSEK would initially consist of modules from the Russian Orbital Segment of the International Space Station.
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency.
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The proposal would use OPSEK to assemble components of manned interplanetary spacecraft destined for Mars, the Moon, and possibly Saturn.
The Moon is an astronomical body that orbits planet Earth, being Earth's only permanent natural satellite.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury.
A spacecraft is a vehicle, or machine designed to fly in outer space.
The returning crew would also recover on the station before landing on Earth.
This OPSEK could form part of a future network of stations supporting manned exploration of the Solar System.