page_title: Orbital Piloted Assembly and Experiment Complex
section_title: Modules
hierarchical_section_title: Orbital Piloted Assembly and Experiment Complex / Modules
caption_attribution_description: English: Screencap from NASA 3D model. I removed the USOS radiators in order to get a better view of ROS. No visiting vehicles are shown in this image.
context_page_description: The Orbital Piloted Assembly and Experiment Complex was a 2009–2017 Russian proposed third-generation modular space station for Low Earth orbit.
  The concept was to use OPSEK to assemble components of crewed interplanetary spacecraft destined for Mars, the Moon, and possibly Saturn. The returning crew could also recover on the station before landing on Earth. Thus, in the concept, OPSEK could form part of a future network of stations supporting crewed exploration of the Solar System.
  In early plans, the station was to consist initially of several modules from the Russian Orbital Segment of the International Space Station. However, in September 2017, the head of Roscosmos Igor Komarov said that the technical feasibility of separating the station to form OPSEK had been studied and there were now "no plans to separate the Russian segment from the ISS ... We keep the same position, that we should work on the ISS together with our partners."
context_section_description: Expected Russian Orbital Segment modules around the time of OPSEK separation (2020 or later) arranged by launch dates:
  2000, Zvezda (DOS-8) - potential part of OPSEK
  2009, Poisk (MRM-2) - potential part of OPSEK
  Poisk (Russian: По́иск; lit. Search), also known as the Mini-Research Module 2 (MRM 2), Малый исследовательский модуль 2, or МИМ 2. Poisk is a Russian airlock module with two identical hatches. Its predecessor, Pirs, is used to store, service, and refurbish Russian Orlan suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the station. 
  2020, Nauka (FGB-2) - to form part of OPSEK
  Nauka (Russian: Нау́ка; lit. Science), also known as the Multipurpose Laboratory Module (MLM) or FGB-2, (Russian: Многофункциональный лабораторный модуль, or МЛМ), is the major Russian laboratory module. This module will be separated from the ISS before de-orbit with support modules to become the OPSEK space station. It contains an additional set of life support systems and orientation control. Nauka's mission has changed over time; during the mid-1990s it was intended as a backup for the first FGB, and later as a universal docking module (UDM). Its docking ports will be able to support automatic docking of both spacecraft, additional modules and fuel transfer. Prior to the arrival of the MLM, a Progress robotic spacecraft will dock with the ISS PIRS module, depart with that module, and both will be discarded. Nauka will then use its own engines to attach itself to the ROS after 2014. The European Robotic Arm, which will service the Russian Orbital Segment, will be launched alongside the MLM. 
  2020, Uzlovoy Module - to form part of OPSEK
  Node Module (UM)/(NM) This 4-ton ball shaped module will support the docking of two scientific and power modules during the final stage of the station assembly and provide the Russian segment additional docking ports to receive Soyuz TMA (transportation modified anthropometric) and Progress M spacecraft. NM is to be incorporated into the ISS in 2016. It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion and flight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of the Nauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. More importantly, the node module was conceived to serve as the only permanent element of OPSEK. Equipped with six docking ports, the Node Module would serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. Uzlovoy will be launched after Nauka MLM; launch dates will be 2017 or later  
  2022, Science and Power Module 1 (NEM-1) - to form part of OPSEK.
caption: Computer generated image of the ROS after Nauka docking.
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