①Every now and then you may see news of satellites（卫星）sent into space. On Feb 21, for example, US company Space X took 46 satellites into orbit. On Feb 27, China sent 22 satellites into space. Why do we need so many satellites? What do they do out there?

②At present, there are more than 3,000 satellites moving around the Earth, according to Germany. Satellites are very helpful to humans. They do all kinds of work, from transmitting (传送) TV signals to giving you directions on the road to helping scientists do research. 

③For example, the 22 satellites China just sent up are part of the Beidou Navigation Satellite System. Shared bikes that use BeiDou chips can be easier to find. Drones (无人机) can also use BeiDou to fly. 

④Before satellites, TV signals didn't go very far. Mountains or tall buildings would stop them. Phone calls to faraway places were also a problem. With satellites, TV signals and phone calls can be sent directly to a satellite and back down to different places on Earth.

⑤Satellites can also provide information about clouds, oceans, land and ice. They help scientists predict changes in weather. By monitoring ( 监测) wildfires and volcanoes, satellites help people deal with natural disasters. Farmers can use satellite pictures to decide the best time to water their fields. 

⑥Some satellites fly near other planets. They may look for water on Mars or take close-up pictures of Saturn's rings (土星环). In 2020, Bilibili sent a satellite into space. Its job is to look at other planets and share the pictures and videos with Bilibili's users.