Nowadays modern science and technology has brought Man into outer space.People have realized the dream to walk on the moon.They even sent home devices to Mars.And，our China-made “Shen Zhou” spaceships have also entered space.It is said in not far future，Chinese astronauts will set their steps on the moon，too.Man-made satellites launched in space has become an important part of our ordinary life.They are used to provide weather forecasts，take photos of the earth，connect international calls and help people worldwide to find their exact location.