There's a star nearly 5 light-years from Earth. Stephen Hawking is sending a spacecraft to it

Stephen Hawking, Mark Zuckerberg and a group of tech and science giants want to send a tiny probe no bigger than an iPhone traveling at 100 million miles per hour to the Earth's nearest star system beyond the sun.

This $100 million "Breakthrough Starshot" project is a "proof of concept" program designed to assess the feasibility of sending a tiny spacecraft out to Alpha Centauri, 4.37 light years away, by surfing on a beam of light sent from a giant laser array. 

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Sails would be attached to the nanocraft that would catch the light from a ground-based light beam, thereby propelling it through the solar system and beyond.

"We commit to this next great leap into the cosmos because we are human and our nature is to fly," Hawking said during a press conference about the initiative in New York on Tuesday.

"Without new methods of propulsion, we simply can't get very far, not unless we are prepared to spend thousands of years in flight," he said.

On the way to Alpha Centauri, the probe would examine other objects in our solar system, project officials said. For example, traveling at great speed, it would take about 3 days for the spacecraft to reach Pluto, a destination that took the New Horizons spacecraft 9 years to reach.

If the project is a success, a nanocraft could make it to Alpha Centauri within about 20 years of launch, far faster than any spacecraft has traveled before. 

In an ideal world, some people still alive today will be able to see this spacecraft hurtle through the cosmos.

The project is funded through Breakthrough Initiatives. Yuri Milner, the CEO of Digital Sky Technologies, created the organization in 2015 to develop new ways of hunting for habitable worlds in the universe.

The Starshot project comes on the heels of the Breakthrough Listen initiative, announced last year, which aims to hunt for signs of alien life by surveying 1 million of Earth's closest stars.

Challenges ahead

The Starshot program is an audacious plan, however, and one that will take major advances in our understanding of science and engineering to make it happen.

Scientists will effectively need to invent a system that will allow even a tiny spacecraft to fly interstellar distances on a beam of light.

Figuring out how to communicate with a tiny spacecraft across such vast distances is also a huge problem, but the minds behind the project have some idea of how to get data back from the nanocraft at that great of a distance.

In theory, a small laser on the craft could send back a small number of photos from the Alpha Centauri system, said Pete Worden, Breakthrough Starshot's executive director, during the news conference.

Money could also be an issue for this plan.

While the $100 million investment may be a good start, it will take a lot more money and time to actually build and send a spacecraft to Alpha Centauri. The full-scale mission would “require a budget comparable to the largest current scientific experiments,” according to a statement from Breakthrough Starshot.

For reference, NASA’s James Webb Space Telescope currently has a budget of more than $8 billion.