Researchers in Austria say they may have found a way to better track space debris with the hope of eventually helping to warn of impacts, assist in avoidance manoeuvres, and even remove the orbiting junk.
Space debris consists of human-made objects orbiting the Earth that no longer serve any purpose. Estimates suggest there may be more than 128 million items of debris, whether that's defunct satellites or discarded rocket stages, some smaller than 1cm. While larger objects can cause serious damage to spacecraft in a single blow, tiny pieces cause harm with multiple impacts akin to sandblasting.
Pinpointing the location of space debris is a tough job. The standard approach is to target the junk from a satellite laser ranging (SLR) station while other SLR stations detect the diffuse reflection. The problem is that this technique has only been effective at twilight – just before dawn or just after sunset. This is when the target debris is sunlit while background sky – and the SLR station – is in relative darkness. The approach only offers a few hours each day when observations can take place, weather permitting.
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Michael Steindorfer and his team at the Austrian Academy of Sciences have proposed a new technique which they say increases the time junk hunters have to detect debris from six to 22 hours each day. They have combined a telescope, detector, and filter to increase the contrast of objects with respect to the daylight sky.
In a paper published in Nature Communications, they describe how they tracked the path of a four different upper-stage rocket bodies. Using their specially developed software, the team detected the illuminated object and calculated the offsets from the predicted path in real time. These calculations were then used to centre the target within the field of view of the SLR receiving telescope before the SLR search routine began.
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, the researchers said.
"The results are a starting point for all space debris laser ranging stations to drastically increase their output in the near future," the study concluded. "A network of a few stations worldwide will be able to improve orbital predictions significantly as necessary for removal missions, conjunction warnings, avoidance manoeuvres or attitude determination." ®