Stephen Hawking's new ship could reach the "second Earth" in the next 20 years

Stephen Hawking says humanity must find a new home Max Alexander/Starmus

The renowned physicist Stephen Hawking is working on a spacecraft that can travel at a fifth of the speed of light – meaning it could reach the nearest star and send back images of a suspected ‘Second Earth’ within 25 years – in a bid to save humanity.

In a speech at the Starmus Festival, Professor Hawking warned humans must soon colonise another planet if we are to survive.

One explanation for why Earth has not been contacted by an advanced civilisations from another part of the Universe is that every time ‘intelligent’ life evolves it annihilates itself with “war, disease and weapons of mass destruction”, he said.

And in addition to the chance that we will meet this fate, Professor Hawking said the planet had become too small for our burgeoning population with its “physical resources … being drained at an alarming rate”. Climate change, an asteroid strike or some other kind of cataclysmic cosmic event also pose significant threats.

The proposed spacecraft, called a Star Chip, would be just a few centimetres in size with a lightsail weighing a few grams. It would be powered by an array of lasers based on Earth that would drive the tiny probe “on a beam of light” at about 100 million miles an hour, a fifth of light speed.

Credit: duluthnewstribune

“Such a system could reach Mars in less than an hour, reach Pluto in days, pass Voyager [the space probe launched in 1977] in under a week, and reachAlpha Centauri in just over 20 years,” Professor Hawking said.

“Once there, the nano craft could image any planets discovered in the system, test for magnetic fields and organic molecules, and send the data back to Earthin another laser beam. 

“This tiny signal would be received by the same array of dishes that were used to transit the launch beam, and return is estimated to take about four light years.

“Importantly, the Star Chips’ trajectories may include a fly-by of Proxima b, theEarth-sized planet that is in the habitable zone of … Alpha Centauri.”

And he admitted: “Of course, this would not be human interstellar travel, even if it could be scaled up to a crewed vessel. It would be unable to stop. 

“But it would be the moment when human culture goes interstellar, when we finally reach out into the galaxy. And if Breakthrough Star Shot should send back images of a habitable planet orbiting our closest neighbour, it could be of immense importance to the future of humanity.”

Because it is travelling so fast any pictures taken by a camera on the Space Chip would be “slightly distorted” due to the effects of special relativity, as first described by Albert Einstein. This would be the first time anything has travelled fast enough to see such effects.

And extolling the virtues of the human attribution – “out most powerful attribute” – he said: “With this, we can roam anywhere in space and time. And I do. 

“We can witness nature’s most exotic phenomena while in a car, snoozing in bed, or pretending to listen to someone boring at a party. And I do.”