arrival of Prichal because, although it is the second module after Rassvet to use a port initially used by Soyuz or Progress spacecraft, it is not able to dock to SSVP-G ports like the Rassvet module. As a result, the Prichal module with its active hybrid docking port was only able to dock to the reconfigured port. With its docking, the number of docking ports on the ISS Russian Orbital Segment increased to eight. Full guidance and navigation control, enabled by an attitude control system using MDDK thrusters, provide roll control to the station using its advantageous position far from the station's fore-aft axis, which provides the greatest mechanical advantage for roll corrections of all the station's thruster-equipped modules. Nauka is also able to collect and store propellant delivered by Progress spacecraft and transfer it to Zvezda. The European Space Agency's (ESA) European Robotic Arm located on Naukas exterior enables the installation, removal or replacement of external experiment payloads; the transfer of payloads through the science airlock; and visual inspections of the station. It can support spacewalks by providing foot restraints, tether points, and control panels both on the inside and outside of the station. Nauka contains life support equipment including an oxygen production system capable of supporting six crew, a galley, a toilet with a urine recycling system, and one of the three sleep stations aboard the Russian Orbital Segment. There is a large observation window similar to Destiny nadir window for the crew on the aft side of the docking sphere, towards the nadir port, while one 9-inch-wide window hatch is on the forward port for the airlock module, similar to the two windows on the Kibo Pressurized Module. Science (or Experiment) Airlock The airlock, Shk, is designed for a payload with dimensions up to , has a volume of 2.1 m³, weight of 1050 kg and consumes 1.5 kW of energy at the peak. Prior to docking the MLM to the ISS, the airlock is stored as part of MRM1. In the summer of 2022, the chamber is planned to be moved by the ERA manipulator and docked to the forward docking station of the pressurized docking hub of the Nauka module. It is intended to be used: for extracting payloads from the MLM docking adapter and placing them on the outer surface of the station; for receiving payloads from the ERA manipulator and moving them into