Arriving, docking and berthing

A visiting cargo vehicle must approach the station under controlled conditions. In a capture-and-berthing sequence, a robotic arm captures the vehicle and moves it to a suitable attachment interface. In docking, the vehicle joins through its docking system. Both create a connection, but they require different hardware and operations.

Cygnus provides an example of robotic capture and berthing. The newer Cargo Dragon used on CRS-21 automatically docked to the station in 2020 and later returned in January 2021. Earlier Dragon cargo missions used robotic capture, so the family name alone does not identify the arrival method.

Approach and attachment require a compatible location, an approved sequence and available station support. Robotics and crew time can be needed for a berthing operation; docking still requires monitoring and integrated planning. Automatic does not mean disconnected from the station’s operating rules.

For a teaching schedule, a robotic operation requires 40 minutes of setup, 50 minutes of work and 30 minutes of closeout. It occupies 120 minutes of the team’s plan. A planner who books only the central 50 minutes creates a conflict with the next task.

A photograph of a vehicle in an arm’s grasp can support a claim about capture, but it need not show completed installation or an opened hatch. A docked exterior view likewise does not prove that every internal transfer check has finished. The sequence matters when interpreting images and captions.

This attention to stages is useful beyond cargo vehicles. It explains why arrival, attachment, commissioning and useful work should have separate entries in an engineering timeline. Each completed step creates the conditions for another; none should silently stand in for the rest.