Answer to Question #61549 in Field Theory for Sakura

Question

1.A space vehicle is in orbit around a planet and moving in a clock wise fashion. If the vehicle wants to move to a lower orbit, should the first rocket that fires aim to decelerate or accelerate the vehicle, and similarly, what should the second firing of the rockets aim to do?
2. If a space vehicle re-enter Earth's atmosphere at too shallow an angle, what will happen to the vehicle and why?
3.In using the gravitational field of a planet to propel a vehicle farther into space, what two important quantities are conserved?
4.What is it about the position of the three antennae in NASA's Deep Space Network (DSN) that allows Earth-based observers to keep in contact with vehicles deep in space?