The ultimate goal of human exploration of space is to get out of the earth and live permanently in outer space. The future we can foresee is that humans will establish a temporary transit base on the moon to provide a "refueling base" for further penetration into space. stand". Even establishing permanent human settlements in the sky above Mars or Venus. As long as the technology is in place, all of this can be achieved, but if we want to succeed permanently, we need to solve a bigger problem: How do we reproduce in outer space?
Not only do we have to breed offspring within the colony, but we also have to solve this problem during long-term space journeys. You may think that this should be simple, but everything is different after humans leave the earth. Scientific research shows that microgravity environments can have an impact on the development of fetuses in mice, geckos, and even birds. The survival rate is usually lower, and sometimes unusual developmental abnormalities and functional deficits occur. In addition, scientists are concerned that space pregnancy may also cause physical burden on pregnant women.
The first major issue to consider when breeding outside of Earth is the lack of gravity. Life on Earth, as well as the reproductive and ontogenetic processes of all living species and their ancestors, evolved under the continuous influence of the Earth's 1g gravity field. The weightless environment of space will definitely affect various stages of mammalian reproductive development, including fertilization, embryogenesis, pregnancy, childbirth, postnatal growth, etc. Because gravity regulates gene expression in mammals, gravity also affects vertebrate cell structure and function, organ system development, and even behavior.
Secondly, during space flight, the microgravity environment will also cause many physiological changes in the human body. The amount of radiation on the International Space Station is a hundred times that on the earth, which will first affect sex and reproduction. Other influencing factors include: noise, vibration, claustrophobia, disrupted circadian rhythm, stress, etc.
Mammalian reproduction in microgravity, including experiments on rats and mice. Experiments have found that mice raised in a microgravity environment lack the ability to self-regulate. Another experiment in fertilizing mouse embryos in microgravity found that the fertilization rate of mice in microgravity was lower than that of mice in normal gravity.
In 2001, NASA invited an astronaut couple to conduct a pregnancy experiment in a microgravity environment. It was found that those who moved with each other in a microgravity environment It is relatively difficult. Due to the existence of Newton's third law, it is difficult for two individuals to contact each other without relying on other objects. Therefore, it is difficult to complete this movement unless the two individuals are fixed together. Furthermore, the microgravity environment can only rely on radiation to dissipate heat. There is no air convection. After a short period of exercise, you will sweat a lot and accumulate heat. Therefore, after going through many difficulties and trying for more than ten days, she still failed to conceive. So trying to get pregnant by traditional means in an off-Earth environment can be a problem.
So if traditional methods don’t work, what about in vitro fertilization?
Montserrat Boada, an embryologist in Barcelona, ??Spain, led an experiment in which they froze 10 human sperm samples in microgravity conditions to observe conditions similar to those in space. environment, will have a negative impact on the viability of these samples. The research team conducted 20 flight tests simulating microgravity using an aerobatic aircraft. Each time, the samples were exposed to a space-like environment for about eight seconds.
The study found that sperm concentration, motility and DNA fragmentation rate in a microgravity environment are not significantly different from those under earth conditions. A subsequent series of tests using unfrozen sperm samples yielded similar results. This suggests that microgravity, unlike radiation, does not have a negative impact on male fertility in the short term.
But in addition to the influence of gravity, the radiation on the International Space Station is more than 100 times higher than on Earth. An average daily cosmic ray dose of 0.5 millisieverts is enough to damage the DNA code in living cells, including sperm. Another space test showed that fish eggs could be fertilized and develop normally during a 15-day orbit, suggesting that brief space travel doesn't do much harm to reproduction.
According to a report in the Proceedings of the National Academy of Sciences, freeze-dried mouse sperm samples were stored on the space station for 9 months before being returned to Earth and thawed at room temperature. Although the sperm DNA was slightly damaged by radiation during the trip, it was still able to fertilize mouse eggs and create healthy "space mice." Researchers believe that after sperm's DNA is slightly damaged by radiation, the egg can repair the damage. If sperm samples are stored in space for longer periods of time, the DNA damage can be increased to the point of being irreparable, exceeding the limits of the egg cell's ability to repair it.
So, space radiation is the biggest obstacle to reproduction in outer space. It is worth noting that there is also a Van Allen belt on the outer periphery of the earth. This magnetic field belt can protect the earth from too many high-energy particle impacts. Therefore, if we go to the moon, Mars or even other planets, the radiation will be greater than near the earth's orbit. Much more. This still leaves us with a huge question: whether mammals, including us humans, can survive and thrive permanently in space. So far, all the research suggests, maybe not.
If mammals want to reproduce in space outside the Van Allen Belts, we must build "radiation-resistant" facilities to protect sperm, eggs and embryos from harm.
"Birth, aging, sickness and death" are the inevitable laws of all things in the universe. For life, it can be as short as a day or as long as hundreds of years. Life and death are the most normal things in this universe. The earth has a history of almost 4.6 billion years, and life on earth can be traced back to about 3 billion years ago. Although humans have developed intelligent civilization, it is undeniable that our existence on earth is indeed short. The forest apes that lived 15 million years ago parted ways with the ancestors of chimpanzees 6 million years ago, and developed into Africa for the first time 2 to 3 million years ago. Homo sapiens walked out of Africa hundreds of thousands of years ago (this is "human"). (the second time), came to all parts of the world and has developed to this day.
It can be said that our evolutionary development path is completely suitable for the earth's environment. This is easy to understand, because it was the earth's environment that chose us.
With the development of human civilization, we will no longer be limited to the small environment of the earth. Since the 1950s and 1960s, humans have been exploring space, and this The road can only go further and further. With the advancement of science and technology, we gradually understand the vastness of the universe. The diameter of the solar system alone can reach 2-3 light years (the Oort cloud is the boundary). Taking Voyager 1 as an example, if it wants to fly out of the solar system It will take at least 17,600 years.
The Milky Way we are in is even larger. The latest data currently shows that the diameter of the Milky Way is 200,000 light-years. We are located on one of the spiral arms of the Milky Way, 26,000 light-years away from the center of the Milky Way. One day we will fly out of the earth to find a new home, or even fly out of the solar system to find a new star system. In 1964, former Soviet astronomer Nikolay Kardashev classified biological civilization into levels. Human civilization is currently ranked at level 0.7 (planetary civilization). Flying out of the earth seems to be the only option if we want to continue developing in the future.
This faces a problem. The process of human reproduction must adapt to the living environment of outer space. This is currently the biggest challenge. When it comes to outer space, our most intuitive feeling is that astronauts are floating, which is weightlessness. In a state of weightlessness, it seems too difficult to complete shy movements, because weightless people may be pushed far away if they touch each other. At the same time, it is a very big challenge for reproductive cells (sperm and eggs). .
In the environment of outer space, the blood in the human body will be distributed differently. It is mostly concentrated near the heart, just like edema, and the limbs will become thinner and thinner. An even more embarrassing problem is that with low blood pressure in outer space, your little penis may face startup problems and its size will also become smaller. The third point is very important, that is, there is no obvious convection process in space, and the heat released by the body cannot be dissipated immediately. If you do shameful things, it will be abnormally wet and hot, and the body will not be able to bear it for a long time. .
The most important point is space radiation. We must know that before this, seeds of some plants were often sent into space. It is hoped that these radiations can cause beneficial genetic mutations in the seeds, making the fruits bigger and redder. Sweeter, of course this needs to be filtered.
Human beings must also face such threats in outer space. Radiation is everywhere and has a fatal impact on reproductive cells. What if the space baby born is a superman?
Space babies are currently difficult to achieve, but some small animals have accomplished these feats, such as the simple cockroach. Russian scientists once took a cockroach into space and gave birth to a baby in 12 days of orbiting the earth. More than 30 "space babies" have been produced.
As humankind’s future space development enters the interstellar age, these are inevitable problems, because our life span is too short and we may spend most of our time sailing.
Human beings should be able to give birth to children in space, but normal growth and development of babies cannot be guaranteed. Human beings have not conducted enough biological experiments in space, and human reproduction and fetal care in space will not be carried out for the time being. Work.
Space biological research has been proceeding slowly, including raising small animals in space. This is because of the current limitations of human aerospace capabilities and insufficient space and equipment in spacecraft, making it difficult to conduct many studies. Scientists Observations on the development process of mammalian embryos have been carried out. Due to the special environment of space, no experiments on mammal birth in space have been carried out. In the past, many astronauts' physical conditions have undergone some changes after entering space. In a short period of time, the impact of the microgravity environment in space on the human body will be relatively low. It is possible for human beings to give birth normally due to the microgravity environment of the human body. However, I have never conducted a similar experiment, so how could I try it rashly? Therefore, the Dutch plan mentioned in the question will be difficult to realize in the short term.
This kind of experiment also faces a serious problem. When humans are currently launching spacecraft, due to the tearing of the earth's gravity, there will be more frequent vibrations during the rocket launch. Rapid acceleration after takeoff will also cause the spacecraft to People bear a "weight" that far exceeds the surface of the earth. 3 or 5 G is very common. How to ensure the safety of pregnant women and fetuses? Besides, the microgravity environment of space and the physical strength of a pregnant woman and other factors make it difficult for her to give birth naturally. In space, Insufficient medical equipment will also put some risks in the delivery process, and a large amount of amniotic fluid and other things will flow out during human delivery, which is not conducive to maintaining the internal environment of the spacecraft.
The space environment has various effects on the human body, affecting the absorption and distribution of calcium in the body, affecting the human immune function, and the existence of cosmic rays may also induce some tumor diseases in the body of newborn babies. Weak, with low immunity, God knows what it would be like in space. Judging from the space launch technology and the current space biological experiments conducted by humans, the implementation of the Dutch plan may take a long time. The source said that this is a plan proposed by a Dutch start-up company. The idea seems to be very far-reaching, but the gimmick is greater than the possibility of actual implementation. It is probably just a self-marketing activity of the start-up company.
However, for humans, such experiments may have to be carried out. Human beings cannot always stay on the earth. One day they will need to embark on an interstellar journey, and giving birth in space may be necessary.