What are the different types of sensors used in nuclear missile defense systems?

The detection and tracking of ballistic missiles are crucial for any nuclear missile defense system. To achieve this, different types of sensors are utilized. There are primarily two types of sensors that are used in these systems: ground-based and space-based sensors. Ground-based sensors are used to detect the launch of a missile. These sensors include radar systems and electro-optical/infrared (EO/IR) sensors. Radar systems can detect missile launches by using radio waves to locate the missile's position and traject....