Which planet is suitable for immigrants?

Emigration to another planet is a way out and a long-cherished dream of mankind. Stephen Hawking, a famous physicist, recently accepted the Copley Medal awarded by the Royal Society, saying that human beings must emigrate to other planets in order to get rid of the fate of extinction. Hawking believes that as long as human beings are trapped on a unique planet, their long-term survival is in danger. Threats such as asteroid impact on the earth and nuclear war will destroy us sooner or later. However, if we expand into space and build self-sufficient settlements, our future should be secure. There is no place like the earth in the solar system, so we must look for another planet and use more advanced space rockets to help people move to a planet suitable for survival. This is the second time in six months that he has made such amazing remarks. Griffin, director of NASA, also said that historically, species on a single planet cannot survive forever. "We have conclusive evidence that, on average, every 30 million years, species on earth will suffer massive destruction; One day we will definitely immigrate to another planet, but I don't know when that day will be. " There are four criteria for immigration destinations. What difficulties need to be overcome and when can it be realized? The first level of immigration: where to migrate. At the beginning of the 20th century, some people thought that Mars and Venus might be good choices, but NASA soon found that other planets around the sun were not suitable for our survival. People on the surface of Venus must live at a temperature high enough to melt lead. As for Mars, living on it is like living twice as high as Mount Everest. Dr. Margaret Tenbar, an astronomer at the Carnegie Institute in Washington, DC, summed up four criteria of "the most suitable galaxy for life": 1, at least 3 billion years, enough to form planets and show complex life; 2. The volume of the central star should not exceed 1.5 times that of the sun, otherwise it is difficult to produce planets suitable for life; 3. There should be enough iron to form Earth-like planets; The central star should be neither a red giant nor a white dwarf, so that the complex life on the surrounding planets can exist for a long time. According to this standard, he concluded that there are five galaxies in the universe that meet the standard: one is CVn, the dog constellation 26 light years away from the earth; The second is HD10307; , 42 light years away from the earth; 3. HD 2 1 14 15, and its metal content is about half that of the sun; The fourth is Scorpio SCO18; ; Fifth, Pegasus 5 1. Level 2: How do humans get to these planets? According to calculation, Alpha Centauri, the closest star to the Earth, is about 42.3 light years. According to the current speed of the space shuttle, it will take 1.58 million years to arrive. This requires the vehicle to reach the speed of light. The American sci-fi movie Star Trek has such a background: in the mid-265,438+century, engineer Cochrane invented a "warp drive" that can surpass the speed of light. Because "warping technology" is the threshold to enter the galactic civilization family, human beings have been brought into the interstellar Federation, and the degree of civilization has reached a new level. In fact, scientists are moving towards this goal. According to New Scientist magazine, the US Air Force and NASA are currently secretly studying a "hyperspace engine". It is said that scientists are expected to make a prototype of the "hyperspace engine" and test it within five years. Once the "hyperspace engine" is proved to be feasible, it only takes three hours from the earth to Mars, and it only takes 80 days from the earth to the planet with a distance of 1 1 light-year. Some scientists predict that the time when a suitable spaceship can really be built and set off for the destination planet is in the 26th century, and the estimated arrival time is 12500. The third level: how to solve the problem of life security after human beings arrive at the planet. The United States, Russia and other countries have cultivated peas, wheat, corn, rice, onions, orchids and other plants 100 in the space station. Animals such as fruit flies, spiders and fish can also grow and reproduce in weightlessness. If this technology can be applied to the future planet, the problem of human survival will be solved. But living in weightlessness for a long time, it is also a question whether human beings can reproduce. A French scientist found that the important structure of living cells could not be formed normally under weightlessness. This means that human beings cannot survive and reproduce for a long time in near weightlessness. However, some scientists say that after human beings settle on another planet, their race and body structure will also change with the environment, and perhaps the problem of reproduction can be completed in another way. Returning to the earth and moving to other planets seems hopeless, but can we change our minds? Dr. O 'Neill of Princeton University believes that the best way is to build a space city in space and gradually move all human beings to the space city. After hundreds or even thousands of years of recovery, the earth will become a flock of animals without human intervention, and the weather will be good, and human beings can return to the earth. O 'Neill's Space City consists of a pair of cylinders. The inner wall of the space city has a natural environment suitable for plant growth. There are roads, residential areas, commercial areas and work areas in the space city. At one end of the space city is a solar power station, and at the other end is a hatch for parking the space shuttle or spacecraft.