太空競賽白熱化，美國NASA拒絕中國公民參與

Nasa, the United States' space agency, has recently decided to block Chinese nationals from working at its facilities, even if they have valid US visas. This means that Chinese students and contractors who were helping with research at Nasa can no longer access the agency's systems or buildings. Many of them found out about this new rule on September 5, when they suddenly lost access to Nasa's data and were not allowed to join meetings, whether in person or online. Nasa confirmed the restriction, saying it was necessary to protect the security of their work and information.

The relationship between the US and China in space exploration has become more competitive in recent years. China has been rapidly developing its space program, which has made the US more cautious. For example, Chinese astronauts are not allowed to participate in the International Space Station because the US government has banned Nasa from sharing data with China. This latest move by Nasa makes it even harder for scientists from both countries to work together, and it reflects growing concerns about national security. Chinese students who want to study science and technology in the US are finding it more difficult to get visas or even enter the country, even after they have received permission.

There have also been several cases in the US where Chinese nationals, especially scientists, have been accused of spying. This has led to more suspicion and tighter rules. It is not clear how much notice Nasa gave to the Chinese workers before cutting off their access, but reports say it happened suddenly. Nasa's press secretary said the agency took steps to restrict both physical and cybersecurity access for Chinese nationals. China has made it clear that it wants to achieve big things in space, and both countries are competing to send astronauts to the moon. Nasa's acting administrator said that the US will reach the moon before China, and US lawmakers have stressed the importance of winning the space race. The competition is not just about landing on the moon, but also about controlling its valuable resources, such as rare minerals and metals. Both countries are determined to be leaders in space exploration.