太空旅行即将成为可能，人类探索宇宙秘密的同时又将受到哪些正面和负面影响?
相关题目：Some people think space tourism can help to develop countries' economy. What's your opinion? What are the effects?
提纲：Positive：Economic Broaden horizon Private experiments
Negative：Body+psychology environment
范文：
American, Russia and my country China have successfully sent their astronauts to the outer space. Inspired by space technology, some wealthy ambitious explorers have extended their sight beyond the earth. While the idea of commercial space flight is being conceived by some pioneer organizations, some concerns are raised in terms of the adverse effects on human body and the environment. (非谓语，平行句型)
Surely orbit flight is an exciting and worthwhile experience. The breath taking view of our blue Earth from the space, the non-twinkling starts hanging on the dark endless outer space background and walking in the space of microgravity definitely would expand their horizon and impress the participants for life. The most important drive behind this enthusiasm for space tourism should be the potential billion dollar business. Such a trip can cost 20 million dollars for each person now, but the price is expected to decline gradually with the advance of aviation technology, hoping to attract wider spectrum of class groups. Therefore prosperity in space tourism is being predicted in future decades by some optimists. (转折句，非谓语，现在进行时的被动句)
However, cautious optimism is another attitude towards this prospect. Scientists are concerned about the impact on the environment of launching a rocket, which emits much larger amount of carbon than any other transportation on the earth, accelerating global warming. In addition, safety and health issues have to be considered. It has obviously been noticed that astronauts living long term in weightlessness are confronted with physical deterioration including loss of bone and muscle mass. Constrained in a small cabin tends to suffer from psychological changes such as depression, anxiety and insomnia. However, space tour tends to be as short as a couple of hours and these effects can be minor and temporary. (定语从句，比较句型，非谓语，形式主语)
To sum up my idea, space tourism can be expected to flourish like the international tourism on the earth in the last decades. Meanwhile it is also true that there will be some negative impacts on the environment and tourists’ physical and psychological condition. As humans always do, they gain some progress at the cost of something else. (形式主语，形式状语从句)
