Space debris danger: Fast-moving paint flake dings window of space station

A small paint flake orbiting Earth chipped one of the windows on the International Space Station. Space debris could be a growing danger to future space missions.

Space travel brings with it a list of potential dangers, but astronaut Tim Peake added one more on Thursday: paint chips.

The International Space Station (ISS) was struck sometime last month by a flake of paint or small metal fragment that caused a chip in the windows of the Cupola, "the best room with a view anywhere," the European Space Agency (ESA) said in a press release. Besides its official duty as the control room for the ISS's robotic arms, the Cupola room also serves as an observation area for astronauts on board to get a good view of Earth and approaching spacecraft.

The ISS and the view from the Cupola are largely unharmed and safe. The ISS' most crucial areas for crew and technical equipment are built with shielding to withstand small strikes in orbit.

Space debris, however, remains a danger.

"While a chip like the one shown here may be minor, larger debris would pose a serious threat," the ESA said.

The debris left behind from previous space missions and created from collisions between orbiting bodies has been a growing concern in the space community for decades. In 1984, the ESA first sent a decommissioned satellite out of the geosynchronous orbit, home to most satellites, because of worries that the popular orbit was filling up with defunct equipment.

"Thus it seems that development of the space frontier has already reached a level where neighborhood trash removal has become a necessity," The Christian Science Monitor's Robert C. Cowen wrote at the time. 

Fourteen years later, the National Research Council (NRC) of the National Academy of Sciences released a study that rated the danger astronauts face from space debris is equal to that of launch and reentry in a spacecraft. Estimates at the time indicated there were more than 10,000 trackable space debris objects, with 70,000 to 150,000 untrackable fragments.

Since then, that number has grown to more than 150,000 tracked pieces of debris in orbit, all of which travel at roughly 17,500 miles per hour and could cripple a satellite or spacecraft, according to NASA. The amount of debris grows as debris collide with each other, creating even more fast-moving particles. In 2009, for example, a defunct Russian satellite collided with and destroyed an American commercial satellite, resulting in 2,000 more pieces of traceable debris orbiting the planet.

Even in the expanse of space, small untracked pieces of debris can pose an unintended threat.

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

How do you take out the trash in space? Scientists are still working on figuring that out.

There have been some ideas on how to clean up some of the debris. Researchers with Ecole Polytechnique Fédérale de Lausanne (EPFL), a Swiss school of technology, began work on a "Pac-Man" type net capable of capturing small pieces of debris and dragging them into the atmosphere to burn up in 2015. No official plan to address the debris has been set, however. 

In the meantime, the ISS and assets belonging to major space agencies are maneuvered to avoid large incoming space debris.

Beyond that, the goal appears to be to avoid contributing anymore to the trash collection orbiting Earth.

"The best way to avoid problems from orbital debris is not to cause them in the first place," Holger Krag, Head of ESA's Space Debris Office, said in the agency's statement.