1. The problem statement, all variables and given/known data As its coming back to earth from orbit, the space shuttle enters the atmosphere travelling at a speed of roughly 8000 m/s. Just before it lands, its speed has already decreased to about 100 m/s. The gravitational potential energy of the earth-shuttle system has also decreased. Where does all of the shuttle's momentum go? 2. Relevant equations There is no equations but knowledge of the spring theory 3. The attempt at a solution The spring theory is responsible for the loss of momentum. The surface molecules act like spring and turn the kinetic energy into thermal energy through friction causing the shuttle to slow down.