Why have countries been calling for manned space flight for so many years, but the reality has not been realized? What are the reasons? What stage have countries reached at present?

Why can't humans engage in manned space flight? Because humans can only fly in space with rockets! It is no longer a question of "what stage". It's just that if you humans can't find a power system that doesn't breathe fire or jet, you humans can only stay on the earth, launch at most two detectors, look for aliens, and deceive people out of curiosity. For example, Musk said that he would immigrate to Mars for one million, which would be completed within twenty or thirty years. This is purely a lie, not negotiable! He can transport several people and live on Mars for a few days. Think he really has some skills. Musk should be the pioneer of interstellar immigration, move himself up first!

At present, humans can only use rockets for space activities; Experts say how good the rocket he built is and what specific impulse he used. In fact, people only care about the fuel-to-load ratio of the rocket, that is, how many tons of fuel matter you need to lose in space to transport one ton of payload; For example, the Saturn V rocket in the United States has a total weight of 3,400 tons, a low-earth orbit load of 120 tons, and a load delivered to the moon of only 48 tons. Then, its fuel load ratio is roughly 3000:48≈62: 1, that is, every ton of goods transported to the moon needs a net loss of 62 tons of earth organic matter.

If every ton of soil on the moon contains100g of helium 3, and millions of tons of helium 3 need to be transported back to the moon, then if rockets are used to do this work, the earth will lose 6.2 trillion tons of organic matter. The earth has lost so much organic matter that the ecological environment of the earth will be completely and irreversibly destroyed! The carbon emission of human industrial activities increases the carbon dioxide content in the earth's atmosphere, which is a reversible cycle process, and the earth automatically adjusts within a certain threshold range. Therefore, human beings rely on rockets for space exploration, which is purely a disaster for the earth and the extinction of mankind!

It is said that in the future, human beings will invent plasma rockets, nuclear fusion rockets, interstellar migration, interstellar mining and interstellar colonization, all of which are nonsense in "Three-body".

What is a plasma rocket? In fact, it is an EFI rocket, which turns the substance to be sprayed into plasma and then ejects it through electromagnetic field. First of all, turning neutral matter into plasma is extremely energy-consuming; Secondly, to generate a powerful electromagnetic field requires heavy electromagnetic equipment, and the rocket carries a set of heavy electromagnetic equipment. Do you think it can be efficient? Thirdly, the energy flow density of plasma rockets can't be very high, and humans can't make rockets with high energy flow density for thousands of years; Fourth, when a plasma rocket ejects a substance, the ratio of the lost substance to its load is at least dozens to one. Therefore, the plasma rocket is not the "savior" of human spaceflight!

What is a nuclear fusion rocket, that is, a nuclear fusion reactor is installed on the rocket to heat the substance to be ejected to form power; Not to mention when your nuclear fusion reactor will be realized, even if it is realized, its miniaturization will take thousands of years to realize. Or will it take hundreds of thousands of years to achieve it? This miniaturized nuclear fusion reactor is not generally miniaturized, but it is much smaller than the miniaturized fission reactor. You can't imagine how difficult this technology is! Even if you install a nuclear fusion reactor on the rocket, it is just a heating furnace to heat the substances to be ejected! Its ratio of loss material to load is not much lower than that of chemical rocket; In other words, its efficiency is not higher than that of chemical rockets, or even lower than that of chemical rockets!

Later, various magic wands in the headlines said that after human beings invented antimatter rockets, dark matter rockets, curvature of space-time engines and wormholes, they could travel around the universe. These are mindless ideas that are hard to refute.

In short, no matter what fancy rockets human beings have invented, as long as they are used for space flight, it is best not to eat them! Otherwise, the extinction of mankind will be faster!

Fifty years ago, the United States and the Soviet Union engaged in a space race purely to bring down each other economically. In fact, the United States did achieve its goal. Of course, this competition has also brought great development to human science and technology, which is a positive aspect of its progress and a dividend of aerospace science and technology. But now, the dividend of aerospace science and technology has basically disappeared, and more importantly, the negative impact is huge.

Americans haven't mentioned landing on the moon for more than 50 years. Why? Do they have no money? No one? No technical strength? None of these! Americans don't even want to build a space laboratory; Going to the space lab is to rent the Russian Soyuz spacecraft!

Americans' attitude towards space flight can only explain one thing: space flight can not bring great benefits to Americans. On the contrary, it is a bottomless black hole with great losses! If space flight can bring huge profits to Americans, do you think Americans can let a liar Musk brag and force others to cheat without being keen on it?

To put it bluntly, Musk is a buffoon, a deceitful pawn used by the United States to fan China into space!

It's not that you are not allowed to engage in space flight, but that you can't invest in space flight on a large scale at the current level of science and technology; Even if you invest on a large scale, it will be a huge loss, and it will completely bring down the earth's ecological environment, without any substantial benefits! No harm is good!

Even if the United States, 20 billion kilometers away, has awesome telemetry and remote control technology, the spacecraft 45 years ago can still communicate and send back pictures. This is mostly because the liar is cheating! In other words, humans can't communicate when they send detectors 20 billion kilometers away, and the life of electronic equipment can't be reached.

Human space science and technology have entered the bottleneck. No matter electronic technology, material technology or biotechnology, especially power technology, it will not be able to advance for a long time. Basically, we can only rely on deceiving national leaders, taking projects and taking funds.