SSVP was initially conceived in 1967 by the TsKBEM design bureau for use on the then-planned OIS military space station.
[1] The Russian segment of the International Space Station features eight available passive SSVP-G4000 ports, located on Zvezda-aft, Rassvet, Poisk, and Prichal.
In addition to Russian spacecraft, the SSVP was also used on the European Automated Transfer Vehicle, which docked to the aft port of Zvezda.
[4][5] An upgraded version, designed for reusability and to provide a wider tunnel, is planned for use on the next-generation Orel spacecraft.
The probe enters the drogue, and its tip is grasped by soft-capture latches which are then retracted using electrically driven motors to provide close alignment.
The ring surrounding this tunnel also includes a number of connectors, providing for transfer of power, data, and fuel between two docked vehicles.