字幕表 動画を再生する 英語字幕をプリント About 4.3 light-years from Earth lies our closest stellar neighborhood. The Alpha Centauri system consists of three known stars. Alpha Centauri A and Alpha Centauri B are a binary pair, which means they orbit a common center of mass. The third star, Proxima Centauri, is the closest to Earth at about 4.22 light-years away. In 2016, astronomers detected an Earth-sized planet orbiting Proxima Centauri within the star's habitable zone - the right distance to potentially support liquid water on its surface. Which is why eyes are on Alpha Centauri as our first destination once we master interstellar travel. So is this deep space journey possible in our lifetime? And if so, how will we get there? Outer space is bigger than we can comprehend and sending a spacecraft into its depths takes a lot of time. NASA's Voyager 1 is Earth's farthest spacecraft to date. It was launched in 1977, and in 2012, it was the first craft to enter interstellar space. If Voyager 1 was pointed in the direction of Alpha Centauri, it would still take tens of thousands of years to reach the system. And that's because its propulsion system is not ideal for deep space travel. So clearly we need a faster way to get to our stellar neighbors. Some scientists believe that our best attempt at interstellar travel are lightsails. These sails would be made of ultra-thin sheets that will be propelled using light instead of wind. One of the major initiatives researching their potential is Breakthrough Starshot. The program, initially backed by late cosmologist Stephen Hawking, aims to create a nanocraft comprised of a lightsail and a gram-scale wafer that hosts a number of instruments called a StarChip. The nanocraft has a mirror-like sail design and is measured at 10 square meters with a mass of less than 1 gram. By comparison a penny weighs 2.5 grams, so these spacecraft will be ultralight. The lightsail will purportedly be accelerated by laser radiation pressure from Earth at about 20 percent the speed of light. The planned laser array, called a Light Beamer, will fire beams as powerful as 100 gigawatts of specific wavelengths of near-infrared light. The nanocraft sail would need to reflect a huge majority of the laser light to avoid instantly burning up on contact. The idea is to launch thousands of nanocraft at once to increase the chances that at least a few will conquer the elements and reach Alpha Centauri. If they do make it, it's estimated, the journey will only take around 20 years. Though some critics are skeptical about the ability to execute Breakthrough Starshot, some of the world's greatest minds are actively working to make it a reality. The project is pushing the boundaries of science, challenging humans to create an entirely new material that meets all the extreme needs of the lightsails and to design the largest laser ever constructed. But, if engineers and scientists are able perfect these pint-sized spacecraft and we achieve interstellar travel, humanity will be rewarded with an entirely new understanding of the alien worlds beyond our own. If you're looking to learn more about space exploration and astronomical phenomena be sure to watch this episode of Space Crafts. And don't forget to subscribe to Seeker for all things science. Thanks for watching!