Through Wang Qing, Du Xingyu contacted the Haleakala Observatory in Hawaii.

    This Observatory is one of the main implementation points of the "Pan Star Program" of the United States, which is an astronomical program for optical measurement of all sky objects with panoramic Sky Survey Telescope and rapid response system.

    "We have four ultra wide-angle telescopes with a caliber of 1.8 meters. We inspect the stars every four to seven days. Compared with the previous inspection results, we can find out the asteroids or comets that threaten the earth." Beth, a female professor of the school of astronomy of the University of Hawaii at the Haleakala Observatory, told Du Xingyu in a video call.

    "In fact, through this program, we have found some new asteroids or celestial bodies in the Kuiper belt."

    Du Xingyu said in English: "Professor Beth, have you found any asteroids with abnormal trajectories recently? That is, they are threatening the earth."

    Professor Beth shook her head and said, "no, our observation of the Kuiper belt is also very limited. The original intention of our pan Star program is to observe asteroids or comets that may pose a threat to the earth in the Kuiper belt."

    "If there is an asteroid thrown out of the Kuiper belt and flying to the earth with a diameter of tens of kilometers, it is difficult for us to observe it directly. We can only observe it in advance unless its distance from us has reached the distance from Uranus or Neptune to the earth."

    "It will take about twenty years for the celestial body at that distance to fly to the earth. At that time, we can only pray to God, can''t we?"

    "I hope not," said Du Xingyu.

    He felt a little relieved. In that case, at least he had some time before he observed the asteroid hitting the earth.

    "Professor Beth, I enjoyed communicating with you. If there are important observations in the future, if conditions permit, I hope we can continue to communicate," Du Xingyu said.

    "I''d love to." the other party didn''t refuse.

    ……

    "Will what I foresee happen?" Du Xingyu wondered. If we follow the original development track, China will land on the moon in ten years and asteroids will destroy mankind.

    But now it seems that this should not happen in ten years.

    He asked the technology simulator for the answer.

    The science and technology simulator replied: "the space-time annihilation bomb is a weapon of cosmic rules and has no entity. My ability can only collect the information in the universe for preliminary speculation. You have made this space-time development track deviate from the original track of the world, which will also have an impact on the space-time annihilation bomb."

    "The disaster that will destroy mankind will come. It''s just a matter of time and way."

    "Can''t you foresee more?" asked Du Xingyu.

    "I need to collect more information in this space-time," said the science and technology simulator. "The universe is composed of matter and energy. The trigger of space-time annihilation bomb will certainly affect the matter or energy in space-time. These are information."

    "If enough information is collected, it is possible to make a more detailed prediction."

    "How to collect information?" Du Xingyu continued.

    "Go to space," said the technology simulator. "Particles and energy in space and time will carry information. If I travel long enough, I can collect more information."

    The open space is not empty. All kinds of radiation is that celestial bodies in the universe are constantly transmitting energy and information. Sunlight is the electromagnetic radiation visible to human eyes. In addition, there are all kinds of invisible particles and dark matter.

    Du Xingyu thought that he had been to the moon, and the science and technology simulator still failed to collect enough information. For a longer space trip, according to the current situation, then we have to go to Mars!

    Go to Mars! Du Xingyu made a quick decision. He resigned his position in the lunar base to the Bureau. Now the construction of the lunar base has been on track, and he doesn''t need to worry about it anymore.

    Du Xingyu will devote all his energy to the Mars mission. In more than half a year, Mars and the earth will move to similar orbits again. At that time, there will be a window period for exploring Mars.

    Last time, the tianwen-1 Mars probe and Rover launched by Huaxia space agency have landed on the Martian surface and obtained some Martian information.

    This time, NASA plans to continue to launch unmanned probes and rovers to prepare for landing on Mars.

    But Du Xingyu suggested that this time we should directly launch a manned spacecraft and land on Mars for scientific research!

    "Flying to Mars, exploration satellites and Mars rovers are mature." Du Xingyu thought, "there must be no problem landing. With experience on the moon, it is not a problem to establish a simple Mars base."

    "Then the biggest problem is to build a Mars spacecraft!"

    The spacecraft to Mars is different from the lunar spacecraft. The lunar spacecraft only needs to conduct short-distance space navigation, and has low requirements for speed and material carrying.

    When Mars is closest to the earth, it will be more than 50 million kilometers, more than 150 times the distance between earth and moon!

    This requires higher requirements for spacecraft, which needs to have faster speed, stronger load capacity and navigation distance!

    "The overall design of the spacecraft should not be difficult. The most difficult thing is the propeller." Du Xingyu quickly found the problem.

    According to the current experience of human exploration of Mars, it takes nearly 200 days for unmanned spacecraft to fly to Mars.

    This is because the journey is long. In order to reduce fuel consumption, the spacecraft has to fly along the "Horman transfer orbit" of earth and Mars, that is, the elliptical transition orbit tangent to two concentric circular orbits in the same plane.

    In this orbit, the spacecraft needs to accelerate or decelerate twice in an elliptical orbit, which increases a lot of additional sailing distance.

    In this way, a lot of time will be wasted. In Du Xingyu''s vision, the speed and time of space flight from earth to Mars are more important than fuel consumption.

    If you take a straight distance and use more advanced thrusters, the time from earth to Mars will be shortened to one sixth of the original!

    Du Xingyu has opened the technology simulator. He calls up the original nuclear thermal rocket thruster.

    The nuclear thermal rocket thruster absolutely meets the speed demand. It can accelerate the spacecraft to the speed of the third universe in a short time, that is, enough speed of more than 16.7 kilometers per second.

    Nowadays, the speed of chemical energy rockets is generally about 10 kilometers per second, and they also need to carry a large amount of chemical fuel.

    However, in space navigation, the spacecraft mainly relies on inertia. If it continues to accelerate, the nuclear thermal rocket will also consume liquid hydrogen and liquid oxygen. If the distance is long, the fuel will not be enough. This is why so far, the speed of spacecraft is not fast, and it depends on the gravitational acceleration of the planet. It is impossible for existing spacecraft to carry so much fuel!

    "In contrast, nuclear thermal rocket thrusters are more suitable for flying in the atmosphere and near earth space. Mars spacecraft need to fly in the earth''s atmosphere, space and Mars atmosphere. Nuclear thermal thrusters can be used in the atmosphere to escape from planetary gravity."

    "Flying in space requires a propulsion system with higher energy conversion efficiency." Du Xingyu soon thought of the nuclear power rocket in the rocket science and technology branch!

    Nuclear power rocket, as the name suggests, is to use nuclear power to generate electricity. These electricity are used to create electromagnetic fields, control electric ion jet and start ion thrusters!

    In other words, this will be an ion propeller of nuclear power energy!

    The ion thruster can ionize the working medium, accelerate the ejection of ions under the action of strong electric field, and push the satellite for attitude adjustment or orbit transfer through reaction force.

    Ion thruster has the characteristics of high specific impulse, high efficiency and low thrust. Its energy conversion efficiency is very high. It only needs to consume a small part of the mass to give the spacecraft higher acceleration. It is more suitable for long-distance space navigation than traditional thrusters.

    Conventional solar panels simply cannot meet the acceleration requirements of Mars spacecraft, while nuclear power can supply stable power for a long time.