What primary balance maintains a satellite in orbit without constant thrust?

The balance between Earth’s gravity and the satellite’s tangential speed

The continued presence of a satellite in orbit relies entirely on a critical interplay between two forces: the constant downward pull exerted by Earth’s gravity, and the satellite’s massive forward velocity, known as tangential speed. This immense speed ensures that as gravity pulls the satellite toward the planet, the satellite moves so far horizontally that it continuously curves around the Earth without ever striking the surface. If this speed were to decrease significantly, gravity would dominate, leading to a lower orbit and eventual atmospheric reentry. Conversely, if the speed were too high for that specific altitude, the satellite would move into a higher, elliptical, or entirely different orbit, possibly escaping Earth's influence altogether.