The main purpose of a space shuttle orbiting the Earth is to conduct scientific experiments and observations in space that cannot be done on Earth. It also serves as a means of transportation for astronauts and supplies to and from the International Space Station.
The space shuttle maintains its orbit around the Earth through the use of thrusters and its orbital speed. The thrusters are used to adjust the shuttle's speed and direction, while its orbital speed allows it to continuously fall towards the Earth while also moving forward enough to maintain a circular orbit.
The space shuttle experiences a continuous state of free-fall due to the Earth's gravity. This means that the shuttle is constantly falling towards the Earth, but its forward motion keeps it in a circular orbit instead of crashing into the planet.
The Earth's magnetic field has a minimal effect on the space shuttle's orbit. However, it does help protect the shuttle and its occupants from harmful cosmic radiation by deflecting charged particles away from the shuttle's path.
The time it takes for the space shuttle to complete one orbit around the Earth, known as its orbital period, is approximately 90 minutes. This can vary slightly depending on the shuttle's altitude and speed.