Our ambitions for space exploration have taken humans to the Moon, rovers to Mars, and spacecraft to the outer reaches of the Solar System. But could humans or spacecraft ever reach Alpha Centauri, the closest star system to our planet?
Alpha Centauri is about 4.4 Light years (about 25 trillion miles or 40 trillion kilometers) from Earth and is home to three different stars. The closest star, Proxima Centauri, also hosts an exoplanet that scientists believe may be the Conditions for life.
But reaching this star system would be no easy task. NASA estimates that with a space shuttle such as the now retired 38-meter-long discoveryit would need almost 150,000 years to reach Alpha Centauri.
If humans could travel at the speed of light, they could reach Alpha Centauri in just 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 probably never reach Alpha Centauri, it’s possible that spacecraft designed to travel at a much smaller fraction of the speed of light could reach these stars in a human lifetime. To even hope to get a spacecraft to top speed, scientists need something much smaller than Discovery.
Marshall Eubanks, CEO of startup Space Initiatives Inc and a fellow at NASA Innovative Advanced Concepts, is researching remote methods for visiting Proxima Centauri using swarms of picometer-sized spacecraft. (A picometer is one trillionth of a meter.)
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“We are in the midst of a real revolution in spaceflight and space exploration with extremely small systems,” Eubanks told Live Science in an email. “While a single small spacecraft will not be as capable as a larger spacecraft like Voyager, their development times are much shorter; they are relatively inexpensive.”
In addition, tiny spacecraft require less energy for propulsion, which could be a decisive advantage in increasing their speed.
Eubanks is not the only one conducting this type of research. Breakthrough Initiatives launched its Starshot Project in 2016 to combine nanometer-sized spacecraft with light sails and in 2017NASA began funding its own project aimed at launching a mission to Alpha Centauri until 2069100 years after Apollo 11.
Although small spacecraft can be accelerated more easily than larger probes, conventional fuel sources alone are not sufficient to bring these vehicles to near the speed of light. Philip Lubina physics professor at the University of California, Santa Barbara, whose ideas about interstellar space travel inspired the Starshot team, told Live Science that these spacecraft will likely rely on light instead.
solar power
To move quickly in space, it helps to be small and have a low mass. A big advantage of light-powered propulsion is that it is massless, Lubin said. Traditional rocket fuel, on the other hand, generates propulsion by converting heavy oil into energy by burning it. Using a solar sail, powered by sunlight, or a photon sail, powered by laser light, provides full power without the weight.
Lubin said that you can think of it like throwing a ball at a piece of paper. When a ball hits the paper, it exerts a force that causes the paper to rebound or be pushed away. Similarly, the The impulse carried by the light is transmitted to the spaceship, causing recoil and acceleration.
“The system is basically a giant flashlight – it’s a giant laser array [on Earth]said Lubin. If the spacecraft are sailboats, then the laser light is the wind in their sails.
The technology to build and test these spacecraft, such as communications equipment small enough to fit on them, is still under development. But there is no physical reason to believe that such a spacecraft could not perform a flyby of Alpha Centauri, Lubin said.
This mission could behave similarly to the Voyager 1 and 2 probes, transmitting high-resolution images of the star system to Earth, some of which may include our first glimpse of the potentially habitable planet Proxima Centauri.
While Lubin stressed that a trip to the star Alpha Centauri would be a long-term endeavor, Eubanks expressed confidence that great progress is still possible this century.
“I think we will reach the Alpha Centauri system with small probes being launched in the 2040s, arriving in the 2060s,” Eubanks said. “By the end of the century, much larger probes should be possible, but without unexpected breakthroughs in propulsion physics, I think manned missions will be a task for the next century.”