1973,65438+10, a team of scientists headed by Allen Bond was established by the British Interstellar Navigation Association. In the "Daedalus" research project, they designed the "Daedalus" automatic spacecraft to fly to Barnard, which is 6 light years away from the Earth. The spacecraft consists of two stages and is propelled by nuclear pulse. The spacecraft has a total length of 200 meters and an initial mass of 54,000 tons, including 46,000 tons and 4,000 tons of two-stage nuclear fuel respectively.
Using hydrogen isotope neon and helium isotope helium -3 as fuel, pellets with a diameter of 2 ~ 4 cm were made by mixing at a low temperature of -270℃. When the power plant works, fuel particles are injected into the combustion chamber of the engine. At the same time, dozens of electron beam generators emit high-energy electron beams, bombarding the nuclear fuel pellets together, raising the temperature to tens of millions of degrees, and the nuclear fusion reaction of neon and helium -3 generates huge energy, pushing the spacecraft forward. If 250 pellets are burned per second, that is, the nuclear pulse rate reaches 250 times per second, the thrust can be approximately continuous.
After 2.05 years of work, the first stage was separated from the second stage. The second stage continued to work 1.76 years, making the speed of the spacecraft reach 36,000 kilometers per second. Because of the speed effect, it can fly to Barnard for about 50 years. A few years before approaching Barnard, a probe was released to detect Barnard, its planets and moons. It took about 60 years after the launch of the spacecraft to receive the detection information of the "Daedalus" spacecraft.
In the early 1980s, Freeman Dixon proposed using microwave sails to propel spacecraft. 1984, Robert Falat designed the "star beam" spacecraft. It has a circular net sail with a diameter of 14 meter, which is made of extremely thin aluminum wire and weighs only 20 grams. There are 10 trillion aluminum wire intersections on the net sail, and each intersection is a microelectronic circuit. They are all computer components, and they are light-sensitive and have the function of a miniature pinhole camera.
Solar satellite power stations orbiting the earth convert electric energy into microwaves. A Fresnel lens is arranged between the satellite and the "Starbeam" spacecraft, focusing the microwave emitted by the satellite on the sail of the spacecraft, opening 10 trillion microelectronic circuits, and adjusting the conductivity of the mesh sail to maximize the reflected energy of the sail. The photon pressure of the microwave beam acting on the mesh sail accelerates the spacecraft. According to scientific calculation, a microwave beam of 20 GW can make the spacecraft get an acceleration of1.55g, and reach the speed of light of 1/5 in six or seven days, that is, 60,000 kilometers per second. Due to the speed effect, it takes about 20 years to reach proxima centauri. If the acceleration time of microwave beam is prolonged, the arrival time can be shortened.
During the flight, the VLSI module on the spacecraft will automatically use the wire in the net sail as a microwave antenna to collect the energy of the microwave beam, and then automatically analyze the spectral information of the target star like the photosensitive cells on the retina of the human eye, and take pictures at a speed of 25 pictures per second, and then use the net sail as a directional antenna to send the detected information back to Earth.
Laser-driven spacecraft can be turned into microwave beam or laser beam because of the electric energy of solar satellite power station, and laser beam is less divergent than microwave beam. For this reason, in the late 1980s, Robert Fawart used laser beams instead of microwave beams to design the "Star Set" spacecraft. It consists of three coaxial rings, the outer layer is an acceleration stage with a diameter of 1000 km, the middle is an intersection stage with a diameter of 320 km, and the inner layer is a return stage with a diameter of 100 km. The sail on the spacecraft is made of aluminum film, with a thickness of 16 nm, a diameter of 3.6 km and a weight of about 5 tons. Fresnel lens focuses the laser beam on the sail with a diameter of 1000 km, which is located in the orbit around the sun between Saturn and Uranus. Thin aluminum sail can reflect 82% light energy, let 4.5% light pass through and absorb 13.5%. The calculation shows that 65 GW laser beam can make the spacecraft get 4% acceleration of the earth's gravity. After three years of continuous acceleration, the spacecraft can reach the speed of light of 1 1%, and it will reach proxima centauri about 40 years later.
If the laser power is increased to 43,000×1.01.2 watts, the spacecraft can accelerate to1/3g, and 1.6 years will fly for 0.4 light years, with the speed reaching 50% of the speed of light. Due to the speed effect, we can reach the E.E. galaxy 10.8 light-years in 20 years. At a distance of 0.4 light years from the E.E. star, the outer layer moves and reflects the laser beam to the rendezvous stage. Because the direction is opposite, after slowing down 1.6 years, you can land on a planet at a low speed or fly at a low speed for investigation. The total sailing time is 23.2 years. If the spacecraft explores there for five years, and then separates from the return phase, the rendezvous phase faces the solar system, and the spacecraft accelerates to return to Earth, with a round-trip time of 5 1 year.
Photon rocket propels spacecraft propelled by photon rocket, which was conceived by Sangl in the early 1950s. It is divided into three parts. In front is the cockpit where astronauts work and live. The middle part is the fuel tank. Behind it is the power part. Its main component is a huge concave mirror with an area of several tens of square meters. The photon generator pushes the spacecraft forward at high speed at the focus of the mirror.
So, where do photons come from? Matter is composed of atoms, which are composed of nuclei composed of protons and neutrons and extranuclear electrons. Different substances only have different numbers of protons, neutrons and electrons. For example, the hydrogen nucleus is a proton and the electrons are outside the nucleus; Helium nucleus consists of two protons, two neutrons and two electrons outside the nucleus. Particles such as protons, neutrons and electrons are collectively called subatomic particles. In 1930s and 1940s, scientists found that each subatomic particle has its corresponding antiparticle, such as antiproton, antineutron and antielectron. Positive particles make up positive matter, that is, all kinds of substances we contact every day, and antiparticles make up antimatter. So far, however, no natural antimatter has been found in the universe, and only a few particles can be produced in the high-energy nuclear physics laboratory.
Scientists believe that in the early days of the Big Bang, when matter was created by energy, positive matter and antimatter appeared in pairs. Contrary to this process, when positive matter and antimatter meet, they both disappear (scientifically called annihilation) to release photons, and at the same time release energy locked in matter. Sanger's photon rocket is thought to generate photons through the annihilation of protons and antiprotons, that is, hydrogen and antiprotons.
Anti-matter propulsion Humans can not only use the photons generated by the annihilation of positive and negative matter as the power of spacecraft, but also use the huge energy released by them to propel spacecraft. According to the calculation, a spaceship weighing 1 ton can be sent to proxima centauri at the speed of 10% as long as it heats 4 tons of liquid hydrogen with the energy generated by the annihilation of 9 kilograms of positive and negative hydrogen. Because of the annihilation of positive and negative matter, matter can be converted into energy 100%, while nuclear fission is only 0. 1% and nuclear fusion is only 0.7%. The rocket fuel derived from antimatter under development has an impulse ratio of 50000 ~ 65438+ million seconds, which is 5 ~ 50 times higher than that of ordinary rocket fuel.
Robert Page, an American, conceived an intergalactic spaceship propelled by antimatter. It took five million years to fly to Andromeda, the nearest galaxy to the Milky Way. This requires the life extension of 654.38 million+generations. In order to ensure the population quality and cultural stability (the most important thing is to remember where you come from and where you are going), you need tens of millions of people from several races to go with you. This is the whole society. Therefore, this ship must be able to provide hundreds of billions of square meters of surface area for living, living and working. The mass of the spacecraft exceeds 50 billion tons, and with almost the same mass of antimatter (such as antimatter stored in magnetic levitation), the total mass is about 65.438+000 billion tons. Among them, personnel and hundreds of millions of tons of materials only account for 1%. It takes thousands of years to build spaceships and synthesize antimatter. In order to prevent the energy radiated by spacecraft from working (equivalent to the total energy of nuclear weapons in the world) from causing harm to human beings, spacecraft should be built and assembled in orbits other than Pluto.
The spacecraft set sail with the annihilation energy of antimatter and its own structural materials, and at the same time provided energy for social functional institutions such as life, transportation, industry and agriculture, commerce and schools. The speed of light reaches 0.2% after 500 years of acceleration, 8.8% after 20,000 years, 25% after 40,000 years, and 40% after 50,000 years. At this time, 90% of the spacecraft's mass has been converted into energy and consumed, while the population has increased to 1 100 million. The spaceship has flown out of the galaxy. The acceleration time of 50,000 years seems to be very long, but in fact it is only 1% of the whole sailing time, just like a car with a journey of 100 km, which accelerates to 60 km/min.
During the cruise, it will take thousands of years to transform the spacecraft into a cushion shape in order to keep enough heat and accommodate a sufficient number of towns and electronic, communication, transportation and other systems.
It began to slow down when it was 40 thousand years away from its destination. After reaching the destination, 9% of the original mass of the spacecraft was converted into energy, and the population increased to 5 billion.
What energy is used to generate electricity for the accelerated navigation of the interstellar ram spacecraft 1 g is always the main problem of space navigation, which is related to both the speed and the quality of the spacecraft. Of course, the most advantageous way is to obtain high-performance energy materials directly from space.
Hydrogen is a common substance in the universe. In the vast space, although there is a high vacuum, there are still hydrogen molecules and atoms. The space around the sun is scarce, with only 0. 1 hydrogen atom per cubic centimeter, and more in the interstellar molecular cloud, reaching about 40,000 atoms per cubic centimeter. Of course, this is very thin compared with the earth's atmosphere. Every cubic centimeter of the earth's atmosphere contains 40,000 trillion molecules of nitrogen and oxygen.
Scientists imagine installing a huge funnel-shaped hydrogen collector on a fairly fast spacecraft, so that it can collect hydrogen in space during its progress, and then make it undergo fusion reaction, and accelerate the spacecraft with the generated energy. The fusion of 1 g hydrogen atom can generate 630 billion joules of energy, which is 20 million times that of bituminous coal. Because this spacecraft is similar to a ramjet, it is called an interstellar ramjet. If the initial velocity of the interstellar ram spacecraft is 16.7 km/s, in order to collect 0.5 g of hydrogen per second, the diameter of the hydrogen collector must be more than several hundred km.
In terms of increasing speed and gaining time, the greater the acceleration, the better, of course, but excessive acceleration and overweight will affect people's physical and mental health. So, how much acceleration is appropriate?
Living on the surface of the earth for a long time, human beings are used to bearing the gravity of the earth, that is, the acceleration of gravity of 1 gram. If the interplanetary ram spacecraft flies at an acceleration of 1 g, people will live and work on the spacecraft, neither overweight nor weightless, just like on the surface of the earth.
Acceleration 1 g, the speed is very fast. In two years (3.8 years on earth), it can reach 97% of the speed of light and fly over the distance of 2.9 1 light-year. If you go to Tiancangwu (Goldfish) at 1 1.8 light years, after flying over the midpoint of the voyage, the spacecraft will turn around at 180 degrees, and you will slow down at 1 gram and finally arrive at a lower speed. After 1 year inspection, you will return by the same procedure, and go back and forth for about seven or eight years (on earth). If you travel around the universe, the spacecraft will continue to accelerate and fly out of the Milky Way in 12 year; 14 flies over the Andromeda galaxy; It has flown a distance of 654.38+000 billion light years in 20 years. If the universe is spherical with a circumference of 90 billion light years, the spacecraft has circled the universe 1/9 times. Because the speed of the spacecraft is very close to the speed of light, the speed effect is very significant. It only takes 1 ~ 2 years to fly over the remaining 8/9 laps and return to Earth. Of course, 90 billion years have passed on the earth.