APTnovel Chapter 12: Navigation Power
Chapter 12: Navigation Power
A month later, several research reports or briefings were presented to Zhou Yuan. These reports or briefings included: Interstellar Travel Dynamics (main author: Mark, spacecraft dynamicist, Academy of Sciences), The Law of the Speed of Light (main author: Wenming, physicist, Academy of Sciences), Methods for Galaxy Calibration (main authors: Lyle, astronomer, Academy of Sciences, and Wenming, physicist, Academy of Sciences), The Law of Life Replication and Consciousness Transplantation (main authors: Maria, anthropologist, Academy of Sciences, and Bonben, neuroscientist and life scientist, Academy of Sciences), Deterrence and Barrier-Breaking Execution Plan (main authors: Zhou Yuan, physicist, Academy of Sciences, Jiang Xiaoyan, astrophysicist, Academy of Sciences, and Eisen, commander-in-chief of the Earth Federation Fleet), and Planetary Resource Development Plan (main authors: Jess, materials physicist and chemist, Academy of Sciences, and Osai, researcher, Academy of Social Sciences).
Zhou Yuan was very interested in the first three reports, and since the next three reports were also very important, he focused on them. The last three briefings were what he could imagine.
The first report was a research report on interstellar travel propulsion.
The report is divided into four parts: a historical review (recounting airplanes, chemical rockets, etc. from decades ago); current propulsion systems (primarily analyzing the controlled nuclear fusion propulsion used in current warships and spacecraft); future propulsion and navigation methods (analyzing several possible propulsion engines or navigation methods in the future, such as interstellar ramjet engines, antimatter engines, ion engines, stellar light pressure sails, nuclear pulse engines, space curvature drive, and the use of artificial black holes); and a summary and recommendations.
A brief historical overview: Decades ago, the most familiar engine to humankind was the rocket engine, which Pioneer and Voyager probes used to fly out of the solar system. However, the drawbacks of this engine were obvious: the chemical fuel took up too much volume and weight while the thrust was too small, resulting in limited efficiency.
The controlled nuclear fusion engine currently in use is inertial confinement fusion, also known as pulsed fusion. It uses a particle beam to detonate small fuel spheres within the propulsion module at the rear of the spacecraft. These spheres generate extremely high temperatures, producing an ion slurry a trillion times denser than that of magnetic confinement fusion, thus initiating fusion. Because this reaction is extremely fast, a strong magnetic field is unnecessary to confine them; the inertia of the fuel spheres themselves can maintain the heat for a sufficiently long time for the reaction to occur. Using particle beams in the vacuum of space offers significant advantages over Earth with its atmosphere, as it is unaffected by atmospheric molecules. Nuclear fusion significantly reduces the radiation pollution of nuclear fission, producing no gamma rays or neutrons, only alpha particles, making it a remarkably clean reaction.
Interstellar Ramjet Engine: A typical interstellar ramjet engine is actually a type of nuclear fusion engine. Spacecraft using interstellar ramjet engines can solve the fuel-carrying problem without sacrificing flexibility. Because hydrogen, the fuel needed for nuclear fusion, is abundant in interstellar space, it can simply be collected during flight and sent to the reactor. Of course, the density of interstellar matter is extremely low, so such a spacecraft would need to install a huge funnel-shaped hydrogen collector. Calculations show that if a 1-ton spacecraft accelerates at 1g, it would need to collect fuel from an area of 1 square kilometers in a high-density nebula, and 1 square kilometers in low-density interstellar space. Such a funnel is enormous; even a 1-millimeter-thick polyester film covering 1 square kilometers would weigh 25 tons, let alone a funnel shape. Of course, we could fire lasers or electron beams forward to break up the outer electrons of interstellar matter, forming ions, which could then be collected using a magnetic field. However, the extension range of this magnetic field funnel would be even larger than the originally designed funnel; its diameter would need to reach 5 kilometers to obtain sufficient fuel. However, when flying at high speeds, this magnetic field will produce a huge drag effect, just like when we are swimming while pushing a large wooden tub. Calculations show that such a spaceship cannot actually reach speeds close to the speed of light, and can only reach up to 21% of the speed of light.
Antimatter engine: When antimatter and matter meet, they annihilate each other, converting all their mass into energy. According to Einstein's mass-energy equivalence formula, this releases enormous amounts of energy. In terms of all known physical reactions, this is the most efficient fuel. We can compare the energy released per kilogram of fuel in an interstellar spacecraft engine: an ideal chemical fuel reaction produces 1 x 10^7 joules of energy, nuclear fission produces 8 x 10^13 joules, nuclear fusion produces 3 x 10^14 joules, while the annihilation of antimatter produces 9 x 10^16 joules—10 billion times that of a hydrogen-hydrogen chemical reaction and 300 times that of the thermonuclear reaction in the core of the sun. Such a spacecraft would have the highest specific impulse and possibly the highest thrust-to-weight ratio. The energy released from the annihilation of a piece of antimatter the size of an aspirin tablet with matter would be enough to propel a spacecraft for hundreds of light-years. The design of an antimatter engine, with its highest specific impulse, involves a particle beam core that directly annihilates particles one-to-one. Charged mesons are then controlled by a magnetic field and ejected directly from the nozzle. Since these mesons travel at near-light speed, the engine's specific impulse could exceed 10 million seconds. Because the charged mesons produced by annihilation decay into charged m-mesons with longer half-lives, this method is entirely feasible. Furthermore, this method only requires antimatter fuel, eliminating the need for propellant and significantly reducing the spacecraft's payload. However, since the annihilation products travel at near-light speed, the spacecraft must be very long. But antimatter production and storage present significant challenges. Firstly, production is extremely energy-intensive. Since we currently lack alternative methods for producing antimatter, we must reverse the annihilation process, using particle accelerators to create antimatter (in the form of elementary particles) from energy according to Einstein's mass-energy equivalence formula. For this reason, the world can currently only produce one hundred-millionth of a gram of antimatter annually. If a particle beam core antimatter engine were used, a few milligrams of antimatter would be needed to travel within the solar system, and several kilograms would be needed to reach the nearest star, Proxima Centauri—far exceeding our manufacturing capabilities. Another obstacle is storage. Because antimatter annihilates and explodes upon encountering matter, we cannot use any matter-made containers to store it. Currently, we use ultracold vacuum Penning ion traps, utilizing superimposed electromagnetic fields to store antimatter elementary particles. This is a portable antiproton storage device, and progress has been made to store 1^15 antiprotons. However, to meet the requirements for antimatter propulsion, 1^21 antiprotons would be needed.
Ion Engine: An ion engine (electrostatic accelerator engine) works by mimicking the method of accelerating ions using an accelerator. Its biggest advantage is that it can accelerate ions to near the speed of light. This means it's possible to achieve extremely high jet speeds. Since there are no high-temperature issues within the engine, the exhaust speed can be increased indefinitely, even approaching the speed of light. The ion engine employs a dual-source system, combining a dual-plasma ion source and a permanent magnet PIG ion source. A high-power dual-source is a single-charge, high-current ion source capable of producing ion currents exceeding ampere levels. Structurally, the dual-source system simply adds a counter-cathode outside the anode of the dual-plasma ion source. The first three electrodes form a system similar to the dual-plasma ion source, which can be considered an electron source. Because the counter-cathode is charged with the same or slightly more negative voltage as the intermediate electrode, electrons oscillate and reflect between the intermediate electrode and the counter-cathode, improving ionization.
Stellar light pressure light sails: The theoretical basis of light sails is that when light is reflected, photons are transferred to the sail, generating acceleration. The more energy reflected, the more propulsion is gained. In other words, the better the reflectivity of the sail's surface, the better its effect. The focus of light sail development is on finding materials that can be very large, very thin, very light, highly reflective, and not torn by meteorite impacts. The biggest advantage of light sails is that they have a free propulsion system, requiring neither an engine nor fuel, saving significant weight, and can accelerate over long periods. This combination means they can ultimately achieve very high speeds. However, the drawbacks of using starlight for light sails are quite obvious. First, the thrust-to-weight ratio of light sails is extremely small. Second, as the spacecraft using light sails moves away from the sun, the density of sunlight decreases, and the pressure decreases until it becomes negligible and no longer exerts pressure on the light sail or produces acceleration. Third, in order to sail and carry a certain payload, the area of the light sail must be very large to obtain sufficient thrust. Finally, light sail spacecraft lack maneuverability. They are fine for transporting probes, but few people would have the patience to transport people. If lasers are used instead of starlight, the spacecraft's speed increases, but the spacecraft still lacks maneuverability.
Nuclear pulse engine: Instead of using controlled nuclear reactions, this propels the spacecraft using nuclear explosions. It's no longer an engine, but rather a nuclear pulse rocket. This type of spacecraft carries a large number of nuclear warheads, which are jettisoned one by one behind it and then detonated. A propulsion disk is installed at the rear of the spacecraft to absorb the shockwaves of the explosions and propel it forward. The nuclear warheads do not directly impact the propulsion disk. After releasing the warheads, solid disks made of high-polymer materials or nanofibers are released. When the spacecraft has traveled a certain distance, the warheads explode behind it, vaporizing the disks and converting them into high-heat plasma. Since the disks are located between the warheads and the spacecraft, a significant portion of the plasma catches up with the spacecraft and impacts the massive metal propulsion disk at the rear, propelling the spacecraft at high speed. The instantaneous thrust on the propulsion disk is so immense that it exceeds human tolerance. Therefore, the spacecraft design also includes a vibration absorption system between the propulsion disk and the forward hull. The pulse energy is temporarily stored in the absorption system and then gradually released, preventing violent oscillations caused by the explosion's impact and allowing the spacecraft to fly relatively smoothly.
Space Curvature Travel: One theory posits that the universe is not flat but possesses curvature. If we imagine the universe as a large membrane with an arc-shaped surface, the entire membrane might even be a closed soap bubble. Although parts of the membrane appear flat, spatial curvature is ubiquitous. Many ambitious interstellar travel concepts have emerged in the past, one of which is space folding. Space folding envisions infinitely increasing the curvature of a large area of space, folding it like a sheet of paper and bringing together two distant points on the "paper." Strictly speaking, this shouldn't be called space travel but rather "space towing," because it doesn't actually travel to the destination but rather drags it there by altering the curvature of space. This requires breaking through fundamental theoretical limitations, a mature understanding of spacetime, and perhaps extremely high energy, which is currently impractical. Meanwhile, some have proposed a contrasting idea: if a spacecraft could somehow "flatten" a portion of space behind it, reducing the curvature of that area, then the spacecraft would be pulled by the space with greater curvature in front, potentially achieving light-speed or faster-than-light travel.
Traveling using black holes: Given that we have already created artificial black holes, can we boldly imagine using them for faster-than-light travel? Of course, we need a complete understanding of the theories of natural and artificial black holes, but we can experiment. For example, we could send an AI-controlled spacecraft into an artificial black hole to see if any unusual phenomena or faster-than-light effects occur. Perhaps the powerful gravitational field generated by a black hole can locally alter the structure of space, creating changes in spatial curvature, allowing for warp drive. Utilizing this spatial tension propulsion, the spacecraft could safely travel at speeds several orders of magnitude faster than the speed of light, circumventing the speed of light limit through spatial propulsion while also avoiding the relativistic problems of time dilation.
The following are recommendations: Currently, the focus should be on the development and mass production of ion engines, while simultaneously conducting theoretical research on (artificial) black holes and feasibility tests for faster-than-light travel.
(PS: The main content of this chapter comes from online materials, which the author collected and organized.)