① Man has known more and more about space today. Space is not only wonderful but also dangerous. While working in space, astronauts are facing danger.
② Scientists have found out that radiation (辐射) is the greatest danger to astronauts in space. When astronauts are working in space, they are in danger of radiation from the sun and other stars, which is bad for their health. The damage of radiation is difficult to discover until their children or even grandchildren are born. Some special medicine may work a little, but there isn't really helpful medicine.
③ Space rubbish is also a great danger to astronauts. There are 9000 man-made (人造) things flying in space. About 30% of these are man-made satellites (卫星), 10% are spaceships, and others are space rubbish. Even a small piece of these knocked against a spaceship window and did some damage. Scientists are watching and telling any possible danger all the time. They are working on helpful ways to do with space rubbish.
④ Although space is really dangerous, everyone on the earth is interested in it. In the near future, it may become usual for people to spend a few days in a space hotel. We may even choose to leave the earth and live in space for a few years. So we should care for space and do something to help improve the space environment.