Human beings always have a long-term vision before doing anything. According to the current development of human space industry, we will certainly establish a long-term habitable living base on the moon within hundreds of years. < p > < p > the same is true on Mars, where human beings are irresistible on the way to conquer other planets. In addition to the technical factors, we will also have to face a special problem, that is, can we really reproduce in outer space? < / P > < p > no matter what human beings do on earth, they are all under the acceleration of 1 g of gravity. We have been born and evolved for millions of years in such an environment. If we leave gravity, many seemingly ordinary things will become extremely difficult. < / P > < p > can even break the inherent rhythm of the organism and cause us to lose some functions. Since NASA’s Gemini mission in the 1960s, we have realized the harm of microgravity to human beings. < p > < p > for example, in less than two weeks in space, bone mineral density will decrease by 6%, cardiopulmonary function will begin to weaken, muscle atrophy will accelerate, mental stress will increase, and the whole person will become extremely irritable in space. Therefore, astronauts should be trained professionally and have strong psychological quality. Even if they stay in outer space for no more than half a year, they have to return to the earth to recover their physical strength. < / P > < p > in addition to gravity, there are also radiation hazards higher than the earth’s surface in outer space. These charged particles will directly penetrate the human body, impact DNA and cause ionization. If the ionization of DNA is slight, the body will repair itself. However, if the radiation dose is too high, the damage is irreversible, which will directly lead to cancer or reproductive problems. As a result, human beings have to consider whether we can reproduce ourselves even if we set up an alien base one day? If not, then humans are ultimately trapped in the earth by their own problems. However, scientists have not directly asked people to have sex in space to verify whether it is feasible, because there are great unknown risks. < p > < p > as mentioned above, if a person is allowed to conceive directly in space, there will be gene mutation. This result is beyond our endurance, at least not in line with ethics. < / P > < p > and the microgravity in outer space makes it impossible for two people to communicate normally. After all, the force is mutual, and we don’t know how sperm changes in microgravity environment, whether its vitality is the same as that on earth, and whether it can reach the exact position to find the egg cells. These are unknown and uncertain factors, so it is impossible to conduct human experiments directly. All of the experiments we’re doing are in animals. < / P > < p > after the space race ended in the last century, scientists began to study this kind of problem. In reality, the Drosophila, fish, Ascaris lumbricoides, frogs and lizards were put into orbit. < / P > < p > but in an experiment in Russia in 1979, researchers brought male and female mice to the space station. During the 18.5-day experiment, some mice either failed to conceive normally or chose not to reproduce. This shows that the low gravity environment has an impact on the reproduction of mice, and they show insensitivity to the opposite sex. Because the relationship between previous organisms and human beings is relatively far away, and mice belong to mammals, which are similar to humans in anatomy and physiology. Therefore, the performance of mice has put a question mark on whether humans can conceive normally in space. For decades to come, we have been carrying out mammalian experiments in outer space. < / P > < p > in 2009, a team of Japanese researchers extracted sperm and eggs from mice and simulated the microgravity environment in space on the ground. After several days of weightlessness, these germ cells were allowed to combine under normal gravity. The results were also mixed. Some mice had normal offspring, but some did not survive. < / P > < p > the researchers believe that this can also happen in microgravity outside the earth. But there are also high radiation hazards. For further study. < / P > < p > in 2013, the team sent three groups of frozen mouse sperm to the space station. The three samples were respectively in space for different times to study the effect of radiation on male germ cells. < p > < p > when these sperm returned to earth after 288 days, the researchers compared them with normal sperm, and found that these sperm had been damaged to varying degrees, and more DNA fragments were found, that is, breakage; < / P > < p > but this small damage in subsequent experiments produced offspring. Moreover, the offspring of these mice developed healthily and had reproductive ability, and no abnormality was found. < / P > < p > the researchers believe that eggs can repair sperm that has been slightly damaged to a certain extent. It is concluded that the germ cells exposed in outer space still have reproductive capacity, and the gene expression in the brain of mice after adult is normal. Moreover, judging from the reproductive capacity of astronauts returning from space, short-term space travel will not affect the quality of germ cells. This is worthy of our celebration. < p > < p > but the question is, what happens when we send eggs and sperm into space? Can eggs repair damaged sperm? Studies have shown that in such an environment, the egg’s ability to repair sperm will decline, and with the growth of age, this repair ability will also decline. < p > < p > therefore, although the short-term space life can allow us to have normal babies, there are still problems in the long-term living in such an environment. This is also the problem we will study in the future. Moreover, pregnancy is only the first step in giving birth to a baby. There is also embryonic development behind it. Whether the baby can adapt to the environment of outer space is also an unknown question. < / P > < p > at present, it seems that we human beings should not only develop the ability to carry out long-term space travel and establish bases on other planets, but also find ways to solve the problem of their own reproduction. We can never return to earth as soon as we have children. However, it can be predicted that if we want to reproduce in space in the future, we must have in vitro fertilization, let the embryo grow in the incubator, simulate the gravity environment of the earth, and block the radiation invasion. Such scenes are often seen in science fiction movies. Continue Readinggather and watch! Huawei P40 Pro evaluation: excellent mobile phone photography elegant design, do you like it?