The construction of the tower has extremely high requirements for building structure, materials and construction methods. In addition, with the facilities to prevent typhoon and lightning hazards, Du Xingyu spent nearly one million energy points to preliminarily complete the simulation.

    "The most important thing of the ground station is the artificial island and tower. When these two points are completed, it is almost the same." Du Xingyu pushed forward the simulation progress of the space elevator again, and then the most difficult point in the whole space elevator - cable!

    Just imagine, what kind of material can ensure that the cable is more than 36000 kilometers long, can maintain no deformation, no collapse, maintain its own physical properties, and will not be damaged by wind, rain and lightning?

    At present, such materials can not be found all over the world!

    So the seemingly simple thing, the cable, is the most difficult link in the space elevator!

    Fortunately, Du Xingyu is not fighting alone. The expert team has given the most appropriate alternative, that is carbon nanotubes!

    Carbon nanotube is a tubular nano graphite crystal. It has extremely high strength, which is 100 times higher than that of steel by theoretical calculation! It is also very soft and can be regarded as a "super fiber".

    Its electromagnetic properties, adsorption capacity and other properties are excellent. If there is a material that can be used as the cable of space elevator, it must be carbon nanotubes!

    The headache for material scientists in various countries is that human beings are still unable to manufacture and synthesize high-purity carbon nanotubes. At the same time, the excellent mechanical, electrical and thermal properties of carbon nanotubes in the micro field can not be shown in the macro when making tools and appliances.

    As a result of these factors, so far, scientists in various countries have not been able to find a suitable carbon nanotube as the material of space elevator.

    The first mock exam is made in Du Xingyu''s database, which includes dozens of alternative carbon nanotubes, single-walled carbon nanotubes, multi walled carbon nanotubes, different lengths of metal and non-metallic carbon nanotubes.

    "Invest 100000 energy points to carry out C1 carbon nanotube test." Du Xingyu uses C1 carbon nanotube to synthesize cable material in the simulator, extending 36000 kilometers. Its lower section is fixed with ground station and tower, and its upper end is connected with counterweight and Tiangong space station.

    Science and technology simulator: "carbon nanotube cracks, irreversible damage of materials, test failure!"

    Du Xingyu began to check the damage condition, save the material data and start the next test.

    "C2 carbon nanotubes have appropriate strength and poor macroscopic conductivity, so they are not suitable for transportation lift cars."

    "F92 carbon nanotube has barely appropriate performance and high manufacturing difficulty. It is an alternative."

    ……

    Du Xingyu simulated the carbon nanotubes of experts from various countries on the science and technology simulator, and basically failed to meet the demand.

    However, he also obtained a lot of data to enable him to carry out the next test.

    "Invest 100000 energy points to develop A1 carbon nanotube materials." Du Xingyu began to try with his own ideas based on the data.

    A few days later, the science and technology simulator finally reported to him: "the A21 carbon nanotube test was successful."

    "Very good!" Du Xingyu failed the simulation 20 times and finally got a carbon nanotube material with excellent mechanical, electrical and thermal properties.

    Most importantly, its synthesis technology is also relatively simple and can be used for large-scale manufacturing.

    During this period, countries debated over the location of the space elevator.

    The reason behind this is that all parties want to control this ground to space transportation hub - even if the super project may not be completed smoothly.

    "Everybody!" a European member of the core Committee of the human Guardian Alliance said, "we have no time to drag on. This meeting must decide on the location of the space elevator. I think it is a good choice to build a space elevator near the equator in the Indian Ocean and south of Maldives."

    "Building artificial islands and space elevators in the equatorial waters of the South Pacific is the best place!" the members of the Americas and Australia spoke.

    "The South China Sea area is the most suitable place," Du Xingyu said. "Regardless of other factors, this place is the place where the construction task can be realized as soon as possible."

    "But we have to build not only artificial islands, but also lift cars and the most critical cables!" said the European Commission.

    Yoshisuke Akiyama, a member of the island state committee, said: "the cable is the most important thing. If the cable can not be manufactured, everything is empty talk! Commander Du, I don''t know how you demonstrated the carbon nanotube scheme we sent?"

    "We have demonstrated that you have made great achievements in carbon nanotube manufacturing technology, but the material strength is still not enough," Du said

    Akiyama nodded and said, "it''s true, so we must find a suitable carbon nanotube material as soon as possible."

    "We have found it!" said Du Xingyu, taking out a small piece of A21 carbon nanotube material. This is the sample he synthesized in the materials laboratory.

    "This A21 carbon nanotube material perfectly meets our needs, which is its performance parameter."

    Du Xingyu showed the laboratory test results that the toughness, strength, conductivity and heat resistance fully met the expectations.

    Akiyama looked, his eyes lit up and said, "that''s it! This is the effect we imagine. How difficult is it to make?"

    "At present, laboratory synthesis is fairly smooth," Du Xingyu said truthfully, "but if you want large-scale manufacturing, you must cooperate with chemical enterprises in various countries."

    "Everybody," said Du Xingyu, "the main body of the space elevator, ground station, cable, car, synchronous track station and counterweight, China has the conditions for construction and manufacturing. It is the only place most suitable for the construction of space elevator in all places. Now there should be no objection to the choice of address?"

    Everyone on the core committee looked at each other. Although they were reluctant to bear it, this was a fact. Therefore, the site of mankind''s first space elevator is located in the southern waters of China!

    The space elevator project is called the "ladder project". The ground station will build a large artificial island called "Penglai Island". At that time, the island will have large facilities such as towers, seaports and airports with an overall height of more than 15 kilometers.

    For higher efficiency and resource utilization, the ladder project still needs to assign tasks to all parties.

    Huaxia is mainly responsible for the construction of the artificial island. On the day when the plan is passed, the offshore exploration team has set out, the Design Institute began to issue drawings overnight, and the construction party is also mobilizing seabed dredgers and island building artifacts to the target sea area.

    At the seminar of the TIANTI project, Du Xingyu said: "the ground station part and the Huaxia construction team will be completed within the deadline, and the space station part will be served by our Tiangong space station."

    "The other three main parts still need the cooperation of Member States, lift car, cable and counterweight."

    "Our European team will be responsible for designing and manufacturing lift cars!" said a senior engineer in Germany. In fact, their design work has begun.

    "Our chemical enterprises in island countries and South Korea will be responsible for manufacturing A21 carbon nanotube cables and completing them on time!" Akiyama said.