申論題

1. As shown in Figure (1), space shuttle travels in a circular orbit 2R above the surface of the Earth with a period of T, where R is the radius of the Earth. The shuttle is now returning to the ground from point A of the orbit, it must reduce the speed at point A and enters a new elliptical orbit with the center of the Earth at one focus, and the orbit is tangent to the Earth's surface at point B. AB is the major axis of the ellipse. How long does it take for the shuttle to land from point A to the ground (point B)? In terms of T.