There are many steps before you launch a spacecraft, and many kinds of spacecraft are important to the technology we use today. Multiple types of satellites watch the world around us. Meteorological satellites give meteorologists information about what the weather will look like. Communication satellites make television possible to watch; navigation satellites help people guide their ships in water; geodetic satellites help record unknown places on Earth. Satellites that are used by militaries help perform observations to find enemies in specific places. Many more types of innovations are used to go to space.
It takes many months to launch a spacecraft. Before a launch, the instruments will perform the experiments and functions for the assigned mission to ensure everything works properly. This takes place in phases, where technicians put together components and make sure they work together. While the spacecraft's instrumentation is being powered up, the components for the launching vehicle also go through the same process.
The last step for integration is connecting the spacecraft and launcher and having them be part of a countdown practice. The spacecraft and the launcher are set next to each other on a launching pad, the support base that holds the spacecraft in place. This support structure, called the gantry, holds the spacecraft from falling over on its side.
Before the spacecraft is launched, a countdown is performed.
It is similar to an airline pilot's checklist, except it is a lot more complicated and needs more staff members. This checklist is made to ensure the safety of the ground crew and astronauts. If astronauts are on board, they must wear specialized clothing. The launch has to take place at the precise time it is scheduled to make sure that the tracking and recovery systems are coordinated properly and know what to do.
The time before liftoff is known as minus time or t-minus. Depending on the difficulty of the spacecraft and its mission, the total amount of the t-minus countdown takes anywhere from several hours to a few days. When it is done, the launch is counted as MET, also known as mission elapsed time.
Space travel and the steps to launch a spacecraft are incredibly complicated but essential to understand about space.
[Source: Britannica Space]