Active

The term "active" can have various meanings depending on the specific application. Generally, it refers to a system or component that is actively controlled or adjusted in real-time to achieve a desired outcome.

Here are some examples and applications of "active" in aerospace:

1. Active Control Systems: These are systems that actively control the behavior of an aircraft, spacecraft, or other vehicle. One example is an active control surface, which is a surface that can be actively adjusted in real-time to control the vehicle's attitude or trajectory. Another example is an active vibration control system, which uses sensors and actuators to actively dampen unwanted vibrations in the vehicle.

2. Active Aerodynamics: This refers to the use of active control systems to improve the aerodynamic performance of a vehicle. For example, active flow control systems use small jets of air to manipulate the flow of air over a wing or other surface, improving lift and reducing drag.

3. Active Thermal Control: This refers to systems that actively manage the temperature of a spacecraft or other vehicle. Examples include active thermal coatings, which use materials that can actively adjust their thermal properties in response to changing conditions, and active cooling systems, which use pumps and heat exchangers to actively transfer heat away from critical components.

4. Active Materials: These are materials that can change their properties in response to external stimuli, such as electric or magnetic fields. One example is an active shape memory alloy, which can be trained to remember a specific shape and then return to that shape when heated or cooled. Another example is an active damping material, which can actively dampen vibrations in a structure.

5. Active Noise Control: This refers to systems that actively cancel out unwanted noise in a vehicle or other environment. For example, active noise cancellation headphones use microphones to detect unwanted noise and then produce a sound wave that cancels out the unwanted noise.

Similar terms to "active" in aerospace include "adaptive," "intelligent," and "smart." These terms also refer to systems that can adjust or adapt in response to changing conditions or inputs. For example, adaptive optics is a technique that uses actively controlled mirrors to compensate for atmospheric distortion in telescopes, while smart materials are materials that can sense and respond to changes in their environment.