1994, Mexican physicist Miguel Alku Bailey put forward the concept of curvature drive for the first time in real life.
His curvature-driven concept includes a football-shaped spacecraft surrounded by a large ring structure. The scientific explanation is that the universe is not flat but has curvature. Liu mentioned this concept in his Three-body Death and Immortality, which plays an important guiding role in the launch of spacecraft.
The space of the universe is not flat, but has curvature (curvature is the reciprocal of the radius of curvature, and the greater the curvature, the greater the degree of curvature). If you imagine the whole universe as a big film, the surface of this film is curved, and the whole film may even be a closed soap bubble. Although the part of the film looks like a plane, the spatial curvature is still everywhere.
If the spacecraft in space can flatten the back part of the space and reduce its curvature in some way, then the spacecraft will be pulled by the space with greater curvature in front, which is curvature drive.
An experiment with similar physical principles can make curvature drive easy to understand. First, fold a boat with paper, then make a hole in the tail of the boat and put a piece of soap in the water. You will find that the boat is sailing forward automatically. This is because soap dissolves in water, which reduces the water tension behind, and the ship is pulled by the greater tension in front. Curvature drive is similar. If the curvature behind the spacecraft is reduced, the spacecraft will be pulled by more space in front.
Purpose and function
At the beginning of space propulsion, the upper stage blades of the launch vehicle fell off; ? Perform functions such as main propulsion, reaction control, space station maintenance, precise pointing and orbital maneuver. The main engine used in space provides the main propulsion for orbital transfer, planetary orbit and additional planetary landing and ascent. . ? Reaction control and orbit maneuver system provide propulsion for orbit maintenance, position control, space station maintenance and spacecraft attitude control.
In space, the purpose of the propulsion system is to change the speed or V of the spacecraft. Because it is difficult for a spacecraft with large mass, designers usually discuss the spacecraft performance with the momentum change of unit propellant consumption, which is also called specific impulse.
The higher the specific impulse, the better the efficiency. The ion propulsion engine has high specific impulse (~3000 seconds) and low thrust. Chemical rockets, such as single-component or two-component rocket engines, have low specific impulse (~300 seconds) but high thrust.
When launching a spacecraft from the earth, the propulsion method must overcome higher gravity to provide positive net acceleration. In orbit, any extra pulse, even very small, will lead to the change of orbit path.
1, forward/backward (tangential direction/acceleration in the opposite direction)-increase/decrease the track height.
2, perpendicular to the track plane-change the track inclination.
The rate of change of speed is called acceleration and the rate of change of momentum is called force. In order to achieve a given speed, a small acceleration can be applied for a long time or a large acceleration can be applied for a short time. Similarly, people can achieve a given pulse with a strong force in a short time or with a small force for a long time.
This means that for space maneuvering, the propulsion mode with small acceleration but long running time can produce the same impulse as the propulsion mode with large acceleration in a short time. When launched from a planet, the tiny acceleration cannot overcome the gravity of the planet, so it cannot be used.
The surface of the earth lies in the depth of gravity well. The escape speed needed to escape from it is11.2km/s. With the human being in 1g (9.8 m/s? ), the ideal propulsion system for human space flight should be a system that provides 1g continuous acceleration (although the human body can bear greater acceleration in a short time).
Passengers of rockets or spaceships equipped with this propulsion system will be free to fall down from all adverse effects, such as nausea, muscle weakness, loss of taste or leaching calcium from bones.
The law of conservation of momentum means that in order to change the momentum of a spacecraft by propulsion, it is better to change the momentum of something else. Some designs use factors such as magnetic field or light pressure to change the momentum of spacecraft, but in free space, the rocket must carry some mass to accelerate its departure and push itself forward. This mass is called reaction mass.
In order for a rocket to work, it needs two things: reaction mass and energy. The impulse provided by the reactive substance particles with mass m emitted at velocity v is mv.
But the kinetic energy of this particle is mv/2, and it must come from somewhere. In the traditional solid, liquid or hybrid rocket, the fuel burns to provide energy, and the reaction product flows out from the back to provide the reaction substance. In ion thrusters, electricity is used to accelerate ions from behind. There must be other sources to provide electricity (possibly solar panels or nuclear reactors), and ions provide the reaction quality.
Refer to the above? Baidu encyclopedia-curvature drive