Physics: Tracking space debris in daylight

Space debris laser ranging can now be performed during daylight hours, reports a study in Nature Communications this week. The findings greatly increase the period over which this technique can be used to track space debris in order to avoid collisions, from a few hours to most of the day.

Defunct satellites and rocket bodies in Earth’s orbit constitute space debris and increasing numbers of these are a threat to active satellites. A technique called space debris laser ranging measures the distance to these objects, which can then be used to help avoid damage to satellites and spacecraft. However, this method is currently only possible for a few hours around twilight, when the satellite laser ranging station on Earth is in darkness and the debris is still illuminated by the Sun.

Michael Steindorfer and colleagues combine a telescope, detector and filter to increase the contrast of objects with respect to the daylight sky. They also developed real-time target detection software that calculates the target-prediction offset, which is then used to correct inaccurate predictions. The authors demonstrate that daylight space debris laser ranging is possible and would increase the potential observation times for all satellite laser ranging stations. They suggest that observation times at the space laser ranging station in Graz, Austria could increase from 6 to 22 hours a day, depending on the season. Significantly longer observation times would allow more precise orbital predictions of space debris that will aid safer satellite and space station operations in Earth’s orbit, they conclude.

doi: 10.1038/s41467-020-17332-z

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