A tiny piece of space debris chipped a window on the International Space Station

When hurtling in orbit around the Earth at 17,150 miles per hour (about 5 miles per second), the last thing you want to see is a chipped window, but that’s precisely what British astronaut Tim Peak saw while inside the Cupola module of the International Space Station (ISS).

“I am often asked if the International Space Station is hit by space debris,” Peake said. “Yes—this is the chip in one of our Cupola windows, glad it is quadruple glazed!”

What’s most astonishing is the size of the debris that hit Cupola. According to the European Space Agency (ESA), the small chip was likely caused by a paint flake or small metal fragment no bigger than a few thousandths of a millimeter across.

Despite the threat of space debris, the ISS, including the Cupola observation capsule, is protected by extensive shielding around all vital crew and technical areas, which means small impacts such as this pose no threat. However, say a larger piece of debris were to strike the ISS, the astronauts aboard the space station would be in serious trouble.

Here’s what the ESA said about a possible impact from a large object:

An object up to 1 cm in size could disable an instrument or a critical flight system on a satellite. Anything above 1 cm could penetrate the shield of the Station’s crew modules, and anything larger than 10 cm could shatter a satellite or spacecraft into pieces.

As you can see in the image above, all that stands between Peake and the vastness of space is a chipped piece of glass. Space sounds fun!