Will we ever reach Alpha Centauri, our closest neighboring star system?

Our space-exploration ambitions have boldly 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 (roughly 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 could have the conditions necessary for life.

But reaching this star system would be no small feat. NASA estimates that, using a space shuttle like NASA's now-retired 122-foot-long (38 meters) Discovery, it would take close to 150,000 years to reach Alpha Centauri. 

If humans could Travel at the speed of light, we could reach Alpha Centauri in four years flat. However, the laws of physics dictate that only massless light particles called photons can reach this cosmic speed limit. So, while humans will probably never reach Alpha Centauri, it's possible that spacecraft designed to go a much smaller fraction of the speed of light could reach these stars in a human lifetime. To even hope of getting a spacecraft up to top speed, scientists will need something much smaller than Discovery.

Marshall Eubanks, CEO of the 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 space flight and space exploration, with extremely small systems," Eubanks told Live Science in an email. "While an individual small spacecraft will not be as capable as a larger spacecraft, such as the Voyagers, their development times are much shorter; they are relatively inexpensive."