Our ambitions for space exploration have taken us to the Moon, spacecraft to Mars, and spacecraft to the far reaches of the solar system. But can humans or spacecraft ever reach Alpha Centauri, the closest star system to our own?
Alpha Centauri is about 4.4 km long. light years (about 25 trillion miles, or 40 trillion kilometers) from Earth and is home to three separate stars. The closest star, Proxima Centauri, also hosts an exoplanet that scientists believe may be conditions necessary for life.
But getting to this star system won’t be easy. NASA estimates that using a space shuttle like NASA’s now-retired 122-foot (38-meter) shuttle, DiscoveryIt will take About 150 thousand years To reach Alpha Centauri.
If humans were able to travel at the speed of light, we could reach Alpha Centauri in four years. However, the laws of physics dictate that only massless particles of light called photons can reach this cosmic speed limit. So while humans will never reach Alpha Centauri, it is possible that spacecraft designed to reach a much smaller fraction of the speed of light could reach these stars in a human lifetime. For scientists to hope to get a spacecraft to reach the top speed, they will need something much smaller than Discovery.
Marshall EubanksThe CEO of startup Space Initiatives Inc. and a fellow in NASA’s Innovative Advanced Concepts program is exploring ways to remotely visit the star Proxima Centauri using swarms of picometer-sized spacecraft. (A picometer is a trillionth of a meter.)
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“We are in the midst of a true revolution in spaceflight and space exploration, with very small systems,” Eubanks told Live Science in an email. “While individual small spacecraft will not be as capable as larger spacecraft like Voyager, their development times are much shorter and they are relatively inexpensive.”
Small spacecraft also require less energy to propel them, which could be a key advantage in increasing their speed.
Eubanks is not the only one pursuing this type of research. Breakthrough Initiatives has begun Starshot Project In 2016, nanoscale spacecraft were integrated with light sails, and In 2017NASA has begun funding its own project to launch a mission to Alpha Centauri by 2069100 years after Apollo 11.
While small spacecraft are easier to accelerate than larger probes, conventional fuel sources alone are not powerful or abundant enough to propel these vehicles to speeds approaching the speed of light. Instead, Philip LupinThese vehicles will likely rely on light instead, John Curry, a physics professor at the University of California, Santa Barbara, whose ideas about interstellar travel inspired the Starshot team, told Live Science.
Solar energy
Speed in space requires a vehicle to be small and low-mass, Lubin says. One of the main benefits of optical propulsion is that it is massless. By contrast, conventional rocket fuel creates thrust by converting heavy fuel into energy by burning it. With either a solar sail, powered by sunlight, or a photonic sail, powered by laser light, you get all the power without any weight.
Lubin said you can think of it like throwing a ball at a piece of paper. When the ball hits the paper, it applies a force, causing the paper to bounce or be pushed away. Similarly, The momentum carried by light is transferred. to the spacecraft, causing it to bounce and accelerate.
The system is a giant flashlight – it’s a giant laser array. [on Earth]“If spacecraft are sailboats, then laser light is the wind in their sails,” Lupin said.
The technology needed to build and test such vehicles, such as communications equipment small enough to fit inside them, is still being developed. But there’s no physical reason to believe such a spacecraft couldn’t do a flyby of Alpha Centauri, Lubin says.
This mission could behave very similarly to the Voyager 1 and 2 probes, transmitting high-resolution images of the star system back to Earth, some of which may include our first look at the potentially habitable planet Proxima Centauri.
While Lubin stressed that the journey to Alpha Centauri would be a long-term endeavor, Eubanks said he was confident that significant progress could be made this century.
“I think we will reach the Alpha Centauri system with small probes in the 2040s, and then we will reach the 2060s,” Eubanks said. “Much larger probes are possible by the end of the century, but in the absence of any unexpected breakthroughs in propulsion physics, I think human missions will be the mission of the next century.”
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