In Star Trek, what dish-shaped system deflects dangerous particles and debris from a starship's path?

In Star Trek, a navigational deflector deflects dangerous particles and debris from a starship's path.

The navigational deflector is usually the large dish or emitter mounted at the front of a Federation starship. It projects energy and force fields ahead of the vessel, helping clear dust, atoms, radiation, and other hazards that could damage the ship during high-speed travel.

It is often confused with deflector shields. Shields protect the vessel from directed attacks and hostile energy, while the navigational deflector is primarily a forward-facing navigation and engineering system. The same equipment can also be modified for unusual tasks, including focused energy emissions or long-range manipulation.

The prominent dish became a visual hallmark of Constitution-, Galaxy-, and Sovereign-class starships. Because it is exposed and essential, the deflector is also a frequent target in stories involving sabotage or emergency repairs.