On February 21, 2022, US company Space X sent 46 satellites (卫星) into space. Then six days later, China sent 22 satellites into space. Why do we need so many satellites? What do they do for us?
At present, there are more than 3, 000 active satellites moving around Earth. Satellites have all kinds of roles, from sending TV signals, giving you directions on the road, to helping scientists with their research. For example, the 22 satellites China sent up are part of the BeiDou Navigation (导航) Satellite System. Shared bikes that use BeiDou chips can provide more correct positions, making them easier to find.
Before satellites, TV signals didn't reach very far. Mountains or tall buildings would block the signals. Phone calls to faraway places were also a problem. Setting up telephone wires over long distances is difficult. With satellites, TV signals and phone calls can be sent directly to a satellite and back down to different places on Earth. Space X's Starlink project plans to use satellites to provide people with the Internet all over the world.
Satellites can also provide information about clouds, oceans and land. They help scientists to predict changes in weather. By watching and checking wildfires and volcanoes (火山) , satellites help emergency workers deal with natural disasters. Farmers can use satellite pictures to decide the best time to water their fields.
Some satellites fly near other planets. They may look for water on Mars or take close-up pictures of Saturn's (土星) rings. Video website Bilibili even sent a satellite into space to look at other planets and share pictures and videos with Bilibili's users.
