Thirty-one years ago today, on September 17, 1994 (August 12, 1994 lunar calendar), American scientists walked out of the "Biosphere 2". On September 17, 1994, the second batch of seven experimenters in the once sensational "Biosphere 2" in the United States left the man-made small earth that had lived in it for more than 6 months ahead of schedule. "Biosphere 2" is located in the desert area 55 kilometers northeast of Tucson, Arizona. On the 17th, when the second batch of people left this man-made small earth, they all showed a state of good nutrition and good health, in sharp contrast to the thin and haggard faces of the first batch of people who lost an average of more than 11 kilograms in two years. Today, the overarching goal of Biosphere 2 has also been translated into studying the human living environment on Earth, where the unfavorable conditions of high carbon dioxide levels have just turned into the most favorable factor to help determine the potential human impact of the rising trend of carbon dioxide levels in the earth's atmosphere. The completely failed Biosphere 2 proved that with the current level of human technology, it is impossible to recreate the cradle of life in the universe.