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First laser detection of space debris in daylight

on 31 March 2021

Lasers on Earth are used to measure the position of space debris high above, providing crucial information on how to avoid in-space collisions. Until now, this technique has suffered from a fatal flaw.

For some time, lasers could only be used to measure the distance to space debris during the few twilight hours in which the ‘laser ranging’ station on Earth is in darkness, but debris objects high above are still bathing in the last of the Sun’s rays.

In the same way that the Moon is brightest when it is glistening in sunlight while it is night on Earth, space debris is easier to spot when reflecting the Sun’s light as seen from a dark vantage point.

Because debris objects are so much closer to Earth, however, there is only a small window in which they are lit up but observers on Earth are not.

Now, a recent study has proved it is indeed possible, in full daylight, to use lasers to determine the distance to debris. This new laser ranging method will help improve orbit predictions for debris objects, drastically increasing the time available to make observations and keeping valuable spacecraft safe.

By using a special combination of telescopes, detectors and light filters at specific wavelengths, researchers have found that it is in fact possible to increase the contrast of objects with respect to the daylight sky, revealing objects previously hiding in plain sight.

More details here.

Image credit: ESA/Alan Baker, CC BY-SA 3.0 IGO