Moon crash: Discarded rocket part to hit Moon in hours, say scientists

The three-tonne rocket part, which is hurtling through space at 5,800mph, is expected to hit at 12:25 on Friday. The rocket part is what's known as space junk - hardware discarded from missions or satellites without enough fuel or energy to return to Earth. The European Space Agency estimates there are now 36,500 pieces of space junk larger than 10cm. No space programme or university formally tracks deep space junk. Tracking space junk is often "Detective work," Mr Gray explains. The rocket insignia cannot be seen - astronomers have to piece together its identity by tracking its route backwards through space. Some space missions, including China's, don't publicise their routes. Prof of Astronautics Hugh Lewis at Southampton University says the scientific value of tracking deep space junk is limited.