Breakthrough Starshot Probes Could Be Damaged En Route to Alpha Centauri

Breakthrough Starshot is one of the most exciting scientific concepts of our time, promising to launch a tiny spacecraft to the stars.

But scientists at Harvard University are taking into account the effects of a potential collision with a speck of dust and gas, which could damage the spacecraft.

"We did a thorough analysis, taking all the relevant physics into consideration," Avi Loeb of Harvard University who leads the scientific team, said in a report by New Scientist. "We didn't see any showstoppers."

Breakthrough Starshot, a million-dollar research and engineering program led by billionaire Yuri Milner, renowned physicist Stephen Hawking and Facebook founder Mark Zuckerberg, aims to demonstrate the capabilities of light beams to propel a gram-scale spacecraft or "nanocraft" to 20 percent the speed of light. The fly-by mission will capture images of possible planets and other scientific data in the Alpha Centauri - the nearest star system to Earth - over 20 years after launch.

For a normal spacecraft, a speck of dust would just bounce harmlessly off the surface of the vehicle. But since Breakthrough Starshot wants to accelerate its nanocraft a fifth of the speed of light, a collision with a bit of dust could be catastrophic. Even individual atoms could damage the craft.

In a study published in arxiv, Loeb and his team carefully explores the effects of collisions with the interstellar medium of gas and dust - the first of 20 identified challenges that need to be addressed to make the mission successful.

According to the scientists, the probes, dubbed "wafersats," will be hit by interstellar dust collectively, consisting of heavy atoms instead of a single particle, which means they will simultaneously bombard the surface, heat the craft and form craters.

Gas consist of lighter elements, therefore it will have less impact, the scientists said. It is only likely to cause damage if the craft encounters a single grain slightly larger than a hundredth of a millimeter. But according to the authors, most grains are smaller than this based on astronomical observations.

To tackle the challenges, the scientists suggested adding a small layer of graphite at the front of the craft to diffuse the heat. Another is to fold and retract the wafersats' light sails, which are responsible for picking up powerful laser blasts from the Earth and accelerating the probes. But Loeb pointed that this could add weight to the spacecraft.

"It's very important to recognize the difficulties and try to find the solution," Loeb said.