> ## Documentation Index > Fetch the complete documentation index at: https://docs.celestra.space/llms.txt > Use this file to discover all available pages before exploring further. # Glossary ## A * **API (Application Programming Interface)**: A set of protocols and tools that allows different software applications to communicate and interact with each other. ## C * **Constellation**: A network of interconnected satellites working together to provide specific services, such as global communication coverage or Earth observation. ## E * **Earth Observation**: The collection and analysis of data from satellites and other sources to monitor and study Earth's surface, atmosphere, and oceans. ## L * **Launch Services**: Services that provide the transportation of satellites and payloads into space using rockets. ## M * **Mission Planning**: The process of defining the goals, objectives, and requirements of a space mission, including trajectory calculations, resource allocation, and risk assessment. ## O * **Orbital Mechanics**: The branch of aerospace engineering that deals with the motion of objects in space, including the calculation of orbits, trajectories, and orbital transfers. ## P * **Payload**: The equipment, instruments, or devices carried by a satellite or spacecraft to perform specific tasks or experiments. ## S * **Satellite Deployment**: The act of releasing a satellite into its intended orbit from a launch vehicle. * **Space Situational Awareness (SSA)**: The ability to monitor and predict the movement of objects in Earth's orbit to avoid collisions and ensure the safety of space assets. * **Spacecraft Telemetry**: Real-time data transmitted from a spacecraft to the ground, providing information about its health, status, and performance.