Descending Orbit: Return Plan

In the year when the dark celestial body "black wedge" passed through the solar system, the Earth's orbit was dragged by its gravity from a near-circular orbit to a far-solar ellipse. The average distance between the earth and the sun has expanded to 1.37 Times its original value, and the solar constant has dropped to about half. In the first year, sea ice crossed 30 degrees north latitude; in the third year, the equatorial granary was lost; in the seventh year, humans retreated into the underground thermal well city, leaving only wind, ice, and a night so cold that it could chew steel. The United Earth Government announced to the public the "Growth and Return Plan": sending planetary collection teams to collect materials from the inner asteroids and the near-solar debris belt, transporting them back to the earth, increasing the mass of the earth, thereby reducing the radius of the earth and the sun, and returning the earth to a habitable orbit. Orbital dynamics engineer Shen Yan knows that this is only half the truth that people can understand. Adding weight to the Earth alone would hardly bring it closer to the Sun on its own. What can really change the orbit is angular momentum: If enough low-angular-momentum matter can be transported back from the inner orbit and incorporated into the Earth in a controlled manner, the Earth's overall orbital angular momentum will be diluted; at the same time, through solar sail traction, mass driver ejection, and multiple gravitational slingshots, the Earth's perihelion will be gradually pushed back. This was not a heroic charge, but a ruthless project spanning centuries.