Spacecraft assembly is the process of constructing a spacecraft from various components and systems. This involves integrating parts such as the structure, propulsion system, avionics, and payload into a single unit. Engineers and technicians work together to ensure that all systems function correctly and meet safety standards. Once the assembly is complete, the spacecraft undergoes rigorous testing to verify its performance and reliability. This includes simulations and environmental tests to mimic the conditions of space. Successful assembly and testing are crucial steps before a spacecraft is launched into orbit or on a mission to other celestial bodies.