ISS Docking Ports: How Spacecraft Connect to the International Space Station
When a spacecraft like Crew Dragon or Soyuz approaches the ISS docking ports, physical interfaces on the International Space Station that allow safe, airtight connections for crew and cargo transfer. Also known as docking mechanisms, these ports are the literal gateways between Earth and orbiting life. Without them, astronauts couldn’t get to the station, supplies couldn’t arrive, and science couldn’t keep running. The ISS has six active docking and berthing ports, each designed for specific spacecraft and purposes. Some are built for automated arrivals, others for manual control. They’re not just holes in a wall—they’re high-stakes engineering systems that handle extreme pressure differences, thermal swings, and precise alignment in zero gravity.
Two main types of ports exist on the ISS: Pressurized Mating Adapters, conical connectors that link U.S. modules to Russian segments and accommodate older Space Shuttle and current Crew Dragon vehicles, and Harmony module docking ports, the primary locations for visiting spacecraft like SpaceX’s Dragon and Northrop Grumman’s Cygnus. The Russian segment uses the Androgynous Peripheral Attach System, a universal docking interface developed during the Apollo-Soyuz era that allows any compatible spacecraft to connect regardless of origin. These systems don’t just snap together—they use sensors, latches, and seals that activate in sequence to create a perfect seal. One misfire, and the entire station’s air pressure could drop. That’s why every docking is rehearsed, monitored, and verified by ground teams and astronauts alike.
These ports aren’t just for crew. They’re the lifeline for food, water, oxygen, spare parts, and science experiments. When a cargo ship docks, it doesn’t just drop off supplies—it becomes part of the station’s temporary structure. Astronauts walk through it like a hallway. And when it’s time to leave, the port must release cleanly, without leaking or damaging the station’s outer shell. The design has evolved since the 1990s, but the core idea hasn’t changed: reliability above all. Even as new spacecraft like Boeing’s Starliner and future lunar landers come online, they all need to talk to these same ports. That’s why NASA and its partners keep upgrading the hardware—adding redundancy, improving sensors, and testing new materials that won’t outgas or degrade in the harsh environment of space.
What you see in videos—ships gliding in smoothly—is the result of decades of trial, error, and global cooperation. No single country owns these ports. They’re shared infrastructure, maintained by teams from the U.S., Russia, Europe, Japan, and Canada. That’s why a Russian Soyuz can dock next to a Japanese cargo craft, and why astronauts from Brazil or Saudi Arabia can fly in on American rockets. The ISS docking ports are more than hardware. They’re symbols of what’s possible when nations work together in space. And as we prepare for Artemis missions to the Moon and beyond, the lessons learned from these ports will shape how future stations connect, refuel, and survive.
Below, you’ll find detailed breakdowns of how these systems work, what happens during a docking, and which missions depend on them most. Whether you’re curious about the tech behind the scenes or how astronauts live inside a connected spacecraft, these articles cover it all—no jargon, no fluff, just clear answers.
