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A small satellite launching in early 2021 will test a novel method to track satellites in orbit 鈥� using light-emitting diodes (LEDs) that flash to relay its position to the ground.

LEDSAT, a cube-shaped satellite measuring around 10 centimetres on each side, will be equipped with 140 LEDs across its faces. These will flash every few seconds, enough to be noticeable to observers and to give the satellite鈥檚 location and even its orientation. The solar-powered satellite is designed to operate for at least a year.

The LEDs won鈥檛 be visible to the naked eye and will be dimmer than most stars in the night sky, so they aren鈥檛 expected to cause any problems for astronomers. But the light should still be bright enough to spot the satellite from Earth using a telescope, while different coloured LEDs on each side will reveal which face of the satellite is pointing towards our planet.

鈥淵ou recognise the stars that are behind the flashing pattern,鈥� says Paolo Marzioli at the Sapienza University of Rome, part of the team behind the project. 鈥淪o you know which position the satellite is [in].鈥�

Currently, satellites are tracked in a number of ways, including by radar. It is also possible to track larger satellites by spotting them in the sky, but this is generally only possible at twilight, when the satellites are illuminated by the sun. LEDs could allow for optical tracking throughout the night.

CubeSats聽like LEDSAT can also be difficult to track because of their small size, but LEDs could make them easier to spot. 鈥淏elow half a metre, it鈥檚 very difficult to see something,鈥� says Marzioli.

What鈥檚 more, LEDs could also help us聽keep on top of space debris, providing an easier way to track larger satellites that are no longer operational and so avoid collisions. 鈥淏igger satellites could have independent units that can still flash if the satellite has some problems,鈥� says Marzioli.