The mission becomes real when people and machines act inside the environment.

Human missions and robotic missions share much of the same Tube. The operator branch changes: an astronaut may perceive and act directly, while a robot combines onboard autonomy with commands from Earth.

• What can the vehicle do autonomously?
• What requires a human decision?
• What can the crew or robot observe locally?
• What happens when communication is delayed or unavailable?

Alan Shepard represents the human-in-the-loop case: the person receives the world, makes decisions and acts from inside the mission.