spaceSpace and Physics

Space Junk As Small As A Grain Of Sand Will Be Tracked By A New Sensor Launching This Week


Jonathan O'Callaghan

Senior Staff Writer

Space debris can be a bit of a problem in Earth orbit. NASA's Goddard Space Flight Center/JSC

A new sensor being sent to the International Space Station (ISS) this week is going to help scientists track the amount of tiny space debris in orbit.

Currently, about 23,000 objects larger than a baseball are tracked by the US Air Force from the ground. Knowing their position, satellites can be moved if they’re in danger of a collision, and even the entire ISS can be moved to avoid hitting something.


However, it’s estimated that many thousands or millions of pieces of space debris the size of a grain of sand are also in orbit. Tracking these is a lot more difficult, so NASA is going to use a new device called the Space Debris Sensor (SDS) to try and work out how many bits are up there.

It will be launched to the ISS on Tuesday this week aboard a SpaceX Dragon capsule. Once it arrives at the station, it’s going to be mounted to the outside of the European Space Agency’s (ESA) Columbus module, which points “forwards” in the direction the station is traveling. Here, it will record the amount of incoming debris.

The sensor itself is a flat square measuring about 1 meter (3.3 feet) on each side, and its 20 centimeters (8 inches) thick. It’s made up of three layers, with two softer layers allowing incoming debris to penetrate the center. Incoming debris will break wires inside the layers, which will confirm the size of the debris.

A third more rigid layer will stop the incoming debris, and scientists will measure how fast it took the debris to pass through the first two layers to record its speed, reports The intensity of the impact will also reveal the density of the debris.

A tiny piece of space debris punched this hole in NASA's Solar Maximum Mission. NASA

"Even small debris less than a millimeter [in diameter] can impact, say, a handrail and create a crater with sharp edges on it," Joseph Hamilton, principal investigator for the SDS at NASA, said during a teleconference in November.

The sensor will be able to detect pieces of debris as small as 0.05 millimeters (0.0019 inches) across, about the width of a grain of sand. From the ground, we can’t detect anything smaller than 10 centimeters (4 inches) across.

According to Science Magazine, the data will also reveal what sort of orbit the debris is on and tell us about its origins. If it’s an elliptical orbit, then it's probably a natural micrometeoroid. A circular orbit suggests it is manmade.

It’s hoped that with this information, we’ll get a better handle on how much debris is in Earth orbit. And in the future, we could send similar missions to a higher altitude and track debris in different regions. All of this will be crucial in keeping satellites, including the ISS, safe in Earth orbit.


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