Artist rendering depicting separation of the newest Russian modules from the ISS as approved by Russian space agency in February 2015. Image credit: Anatoly Zak

Feb 26, 2015 What Russia's next space station might look like

Sen—On Feb. 24, the Russian space agency, Roscosmos, endorsed a plan to undock its three yet-to-be-launched modules of the International Space Station, ISS, to form the new all-Russian outpost in Earth's orbit. To the relief of Russia's ISS partners, the split will take place nine years from now and not in 2020, as some Kremlin officials threatened in the wake of Russian annexation of Crimea and subsequent Western sanctions.

The official press-release announcing the ISS "divorce plan" named the three new components of the ISS as the foundation of the future Russian station.

The first 20-ton piece of the orbital puzzle would be the Multi-purpose Laboratory Module (MLM) currently scheduled for launch to the ISS in 2017. The module, which derived from the Soviet-era heavy transport ship, features docking ports on both ends and a pressurized laboratory. It will dock to the nadir (Earth-facing) docking port on the Zvezda Service Module (SM), the current backbone of the Russian ISS segment.

Within a year after the MLM launch, it should be followed by the eight-ton Node Module, which is currently under construction at RKK Energia in Korolev. With its six docking ports on all sides of the globular structure, the UM module will serve as a three-dimensional interesection for future permanent modules and transport ships visiting the ISS. Given the incredible lifespan warranty of 30 years, the UM can stay as the only permanent core of the future station, while other "plug-and-play" pieces of the station come and go. This will be the most drastic difference of the new Russian station from the ISS, whose in-line architecture essentially locks most of its components in place, making replacement nearly impossible.

Last but not least, the Science and Power Module, NEM, will fly to the ISS as early as 2018 to dock at the UM. The 20-ton spacecraft will represent a new-generation of Russian modules designed with deep-space missions in mind. In addition to a bigger, roomier lab and sleeping compartments than those in the previous-generation Russian modules, the NEM will carry expansive solar panels, making the Russian segment fully independent in terms of power supply. This latest feature will lay the ground for the independent existence of the Russian segment. 

It is important to point out that, according to the current plan, the two earliest Russian-built ISS components—the Zarya Control Module (FGB) and the Zvezda Service Module (SM)—will remain in place and not separate from the ISS. As a result, the Russian Progress cargo ships will still be able to deliver cargo and refuel the outpost, while Soyuz spacecraft could carry crews. The propulsion system onboard Zvezda is also critical for maintaining the orientation of the entire complex in orbit and during controlled reentry of the station into the atmosphere at the end of its lifespan. As result, even after the separation of the three newest Russian modules, the ISS could continue its mission as late as 2028, according to some estimates and money provided.

In the meantime, once the three newest Russian modules are in free flight, the MLM and the NEM will jointly provide flight control, life support and power supply onboard the nascent station. Given the importance of human presence to correct unforseen glitches during the early stages of the new outpost's life, Roscosmos will likely keep a crewed Soyuz spacecraft docked at the segment during its separation from the ISS. However even with Soyuz parked at the new station, its UM module would still have three docking ports available for future add-on components. On that end, Russian engineers have two more modules on the drawing board: an inflatable habitat, which will test innovative flexible structures and serve as an additional room in the process, and an airlock module, which will be used by spacewalking cosmonauts.

Since both of these modules are unlikely to be ready before 2024, they will head directly to the new station, bypassing the ISS.