International Space Station in orbit

Space debris sensor attached to ISS to monitor debris

Image credit: Dreamstime

Nasa has attached a space debris sensor (SDS) to the outside of the International Space Station (ISS) to allow researchers to track space debris impacts in real-time.

There are more than 1,000 working satellites in orbit around Earth which are relied on for long-distance communications, internet services, navigation and other services.

Over the past decades, many satellites have fallen into disuse and remain orbiting Earth amid other space debris, including pieces of broken-up launch rockets, flecks of paint, bags of rubbish, solidified droplets of coolants from Soviet-era nuclear satellites and human remains disposed of via space burial.

Nasa estimates that there are more than 100 million pieces of debris weighing 5,500 tonnes, mostly in low-Earth orbit. Although most are very small, collisions with these pieces when orbiting Earth at high speed inflict severe damage on spacecraft.

In 2009, for instance, a former Russian communications satellite collided with a US communications satellite, creating an enormous cloud of new debris. Some fear that major collisions such as these could result in an uncontrollable chain reaction of collisions in low-Earth orbit; this scenario is known as the ‘Kessler syndrome’.

“Debris this small has the potential to damage exposed thermal protection systems, spacesuits, windows and unshielded sensitive equipment,” said Dr Joseph Hamilton, who is leading the space debris sensor project at Nasa, in a statement.

“On the space station, it can create sharp edges on handholds along the path of spacewalkers, which can also cause damage to the suits.”

Although there is no international agreement on tackling space debris, many government agencies have introduced their own measures to prevent a further build-up of the junk. For instance, the Japan Aerospace Exploration Agency launched a “fishnet” space debris collector in a trial for the technology.

Due to the expense, habitability and size of the ISS, great importance is placed on protecting the satellite from catastrophic collsisions with space debris. It breaks up small pieces of debris with its ‘Whipple shields’ and changes its orbit to avoid contact with larger pieces of debris.

Now, Nasa scientists have delivered an SDS to the space station. The sensor was carried to the ISS on the last Dragon cargo mission, then unloaded and attached to the Columbus module using ISS robots.

Over the next two to three years, the SDS will monitor small space debris measuring 0.05mm-0.5mm.

Impacts will be detected in real-time using an acoustic system consisting of three layers of sensors. This data will allow Nasa researchers to determine the size, density and speed of the debris. The agency hopes that this project could help inform the design of sensors in the future, as well as map and learn about the properties of debris in orbit.

“The orbital debris environment is constantly changing and needs to be continually monitored,” said Hamilton. “While the upper atmosphere causes debris in low orbits to decay, new launches and new events in space will add to the population.”

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