To the stars
Astronomers recently announced strong evidence of an Earth-like alien planet near Proxima Centauri, the star closest to our sun. Although the star system is our cosmic neighbor, it is still 4.2 light-years or 25 billion miles from Earth. Could we ever visit the newly discovered planet at such distances? Even the next stars would take tens of thousands of years to travel with conventional spacecraft such as the robotic probes that are now being used to study the solar system. These spacecraft are powered by a combination of chemical rockets, low-thrust ion propulsions and gravity-assisted trajectories – including so-called “skid maneuvers” around the sun or large planets that give them a big boost in speed. But if we want to go beyond our solar system, we need something faster – maybe something like the gigantic Project Daedalus fusion rocket shown here in scale by NASA’s Saturn V rocket. The graphic artist and space artist Adrian Mann, whose work in thisCountdown of futuristic space technologies are presented. Here are seven ways in which robots or even human explorers can visit the Proxima Centauri system or other cosmic neighborhoods.
Project Daedalus is a concept design for an interstellar probe developed in the 1970s by a group of technical specialists for the British Interplanetary Society. The target was Barnard’s Star – a red dwarf about six light-years away, similar in many ways to Proxima Centauri.There astronomers report that they have found signs of a potentially habitable planet. When the Daedalus project was conceived, some astronomers thought a gas giant might be in orbit around Barnard’s star, but since then no planets have been found in the star system. The result of the five-year project was the design of the Daedalus spacecraft, a 54,000-ton two-stage nuclear missile capable of lifting a 400-ton robotic probe to around 12 percent of the speed of light. This would allow the probe to make the 6-light journey to Barnard’s Star in about 50 years. The missiles of the Daedalus spaceship would be propelled by nuclear fusion, using electron beams to detonate a stream of fuel pellets, such as helium-3, that could be broken down from the surface of the moon. Even so, the engines would use tens of thousands of tons of fuel to get the spacecraft up to its maximum speed in about four years – and with no fuel to slow down, the final result of the 50-minute flight is an annual journeyIt would only be a 70-hour flyby of the target system before the spaceship raced past the interstellar space. The Daedalus would be far too large to be lifted off the surface of the earth and therefore would need to be built in orbit, which means that a spaceship like this can not be built without the ability to stand in a roomspace scientist Ian Crawford, professor of planetology and astrobiology at Birkbeck College in the UK. While Crawford believes that the science behind the Daedalus concept is better understood today than in spacecraft development, the immense cost and enormous technical challenges would probably take more than 100 years for something like the Daedalus to take off Way to the stars.
The 1970s Project Daedalus concepts are the inspiration behind Project Icarus, an ongoing collaborative project between the British Interplanetary Society and the Icarus Interstellar Organization, an international network of scientists, engineers and enthusiasts seeking to develop the skills of interstellar spaceflight want to develop to the yearThe Icarus project aims to reach every star within 22 light years around the earth, which has a potentially habitable exoplanet.So if a planet is confirmed near Proxima Centauri, it could become a target. The Icarus project aims to update the Daedalus design with new technologies and ideas. The proposed improvements include fusion rocket engines using another nuclear fuel that is ignited by lasers rather than electron beams – a technology that could be derived from recent advances in laser ignition fusion at the National Ignition Facility of the Lawrence Livermore National LaboratoryCalifornia said Crawford. The Ikarussonde could also be smaller than the 400-tonne probe intended for the Daedalus project.This is due to advances in electronic miniaturization and robotics, as well as future nanotechnologies, where the spacecraft would need to use less fuel to reach full speed.
Our best bet for interstellar travel might be not using a rocket at all, Crawford said. Lightweight sails that use the pressure of light to propel a payload are already being considered for interplanetary spacecraft, and in 2010, Japan’s experimental spacecraft IKAROS successfully deployed its 20-meter wide light sail to during a six-meter flightManeuver. Month’s journey to Venus. Sunlight-driven light sails are already an effective way to explore the solar system, but they are not fast enough to travel interstellar distances in a timely manner. Crawford said the answer could be to use powerful lasers to flash the light sail at high speeds at the start of the journey until the spacecraft is too far away from the laser source to get more thrust from the light beam As the driving lasers were built on Earth or in orbit, the interstellar light sail spaceship would not need to carry fuel for the voyage, so the bulk of the spaceship could be kept small. Laser powered light-sailing spaceship is the basis of the Breakthrough Starshot project announced this year by investor Yuri Milner and physicist Stephen Hawking. The project aims to build a viable prototype by 2036 at a final contract value of approximately $ 10 billion. The project envisages a swarm of approximately 1,000 stamp-sized StarChip spacecraft, each weighing a few ounces, mounted on a 4-meter-diameter light sail set off from a “mother ship” in orbitbefore accelerating from ground-based lasers to speeds of about 15 to 20 percent of the speed of light. This would allow the spaceship to make the four-light-year journey to the Alpha Centauri system – a triple-star system that includes the star of Proxima Centauri and its possible planet – in 20 to 30 years. The concepts behind the Breakthrough Starshot project were studied by Philip Lubin, professor of cosmology at the University of California at Santa Barbara.The biggest remaining challenge is to develop enough powerful lasers to power the light sail spaceship.
The Bussard Ramjet concept, proposed by physicist Robert Bussard in 1960, combines the high thrust of fusion rockets with the low fuel requirements of light sails. Instead of carrying its own fuel, a Bussard Ramjet would capture the very thin traces of gas and dust found in interstellar space, the so-called interstellar medium, by using a huge funnel-shaped electromagnetic field that spanned thousands of mileslocated in front of the spacecraft. Hydrogen from the interstellar medium would then be compressed and used as fuel in a fusion rocket at the stern of the spacecraft propelling it forward. Theoretically, a spacecraft powered by a Bussard Ramjet could continue to accelerate as long as there was enough interstellar gas on its way to deliver enough thrust, and could reach a high fraction of the speed of light. As a result, the venerable Buzzard has served long and honorable service in many sci-fi genres, notably Larry Niven’s “Known Space” series of novels and short stories, including the “Ringworld” books. And the 1970s Poul Anderson novel “Tau”.Zero “(Doubleday, 1970), in which an interstellar crew brings its stranded buzzard spaceship to relativistic speed to avoid destruction. Unfortunately, the interstellar medium around our solar system and the nearby stars is particularly thin, and scientists have calculated that there is not enough hydrogen to run a buzzard ramjet. “It’s not the ideal part of the galaxy,” said Crawford. He explained, however, that various ideas have been proposed to circumvent this limitation, including a concept known as “Ram Augmented Stellar Rocket,” which uses the collected material as the reaction mass to power the spacecraft.which is blasted by a laser on it to propel forward. and an “interstellar runway” that would use fuel deposits positioned in advance on the way of an accelerating buzzard spacecraft.
In addition to light sails, giant lasers, and fusion rockets, some have proposed even more exotic options for interstellar travel, such as rockets propelled by the extremely violent (and extremely efficient) destruction of matter and antimatter. Antimatter would be an excellent rocket fuel because its energy density is so high, “said Crawford.But of course it does not exist in nature, we have to make it. And it’s very difficult and expensive to do and very dangerous once you’ve done it – so who knows if it could ever be used as a rocket fuel? Another suggestion for using the exotic physics to power a spacecraft is the “Schwarzschild Ball Light” drive, which uses a microscopic artificial black hole in the engines as an energy source. An idea for a ship equipped with the so-called “SK Drive” shown above would capture Hawking radiation from the fast and extremely violent decay of the tiny black hole and convert it into energy that can be used to power the spacecraft Each of the artificial black holes would only survive for a few years, so new black holes would have to be created as needed, possibly by compressing matter pellets with gamma-ray lasers. According to a 2009 study, an SK-powered spacecraft powered by a microscopic black hole with the mass of a modern supertanker could accelerate to 10 percent of the speed of light within 20 days. The black hole would take about 3.5 years before it completely disintegrated and would deliver more than 160 petabytes or 160 quadrillion watts of power in his lifetime.
Human “slow boats”
Even with super-fast rockets flying at a speed of 10 percent or more of the speed of light, it would take many lives to reach everyone except the next. And though Crawford is an advocate of human exploration of the solar system, he said interstellar distances are too large to make a human journey conceivable within the next few hundred years. I think that humans can explore the planets more effectively than robots, and I think there are cultural reasons for sending people into space to broaden our experience and enrich human culture, even on the interstellar scale -it’s just that the distances are so great and the technical difficulties so great that advocacy is almost unthinkable at the time. Nevertheless, there are different ideas for so-called “slow boat” concepts that could one day lead people to the stars, including: Sleepers, where human crew members are kept in a state of “deep sleep” or “floating animation” for the duration of the very long journey. This idea has been featured in several sci-fi films, including Stanley Kubrick’s “2001: A Space Odyssey” from 1969, Ridley Scott’s “Alien” from 1979, and James Cameron’s “Avatar” from 2009. Also known as generational ships or interstellar arks, World Ships are vast, self-contained space habitats that transport large populations of humans and other species from Earth on a relatively leisurely journey to colonize exoplanets – travelthat would take many centuries to complete. Whole generations would live and die during the journey, and only the offspring of the original population would arrive at their destination. Embryo ships sent cryogenically frozen embryonic humans instead of sleeping or living humans to a distant colonial planet where they were “hatched” and cleared by a crew of protection robots.
Faster than the light?
Wherever astronomers look into the universe, the theory of relativity applies. As Albert Einstein has shown, it is neither possible to accelerate a mass in space at the speed of light nor to get past it. But Einstein’s equations may also contain some tricks that could one day enable science to circumvent the known laws of physics and travel faster than light (FTL) – a holy grail for generations of science fiction The best-known scientific concept for FTL travel is the Alcubierre propulsion proposed by the theoretical physicist Miguel Alcubierre in 1994. The proposed propulsion system uses intense gravitational forces generated by two rotating rings of dense exotic matter to reduce the physical dimensions of the space in front of the spacecraft and at the same time increase the space behind it at a speed that appears to increase speedof exceeding light. In Alcubierre’s proposal, which requires a kind of exotic matter for the rings that is not known to exist, the spacecraft within the propelled “warp bubble” would never travel faster than the light in its local space, and thusnot violating the “warp bubble” laws of relativity. Other speculative ideas for FTL travel are the use of transdimensional wormholes – theoretically possible but not known – to travel between interlocked but distant regions of the space. Or boldly view the edges of a large,flying over a spinning black hole, as depicted in Christopher Nolan’s 2014 film Interstellar. Crawford notes, however, that the concept of traveling at speed above the light is fraught with unknowns and obvious contradictions;For example, the principle of causality is violated, where events are caused by other events that occurred earlier, not the other way around. So it’s likely that the proposals would prove impossible, even if they were technically feasible. I do not want to sound too pessimistic because I see great benefits in traveling to the stars, but the laws of physics are the laws of physics, and it’s going to be really difficult, “said Crawford.
Source Credit @LiveScience