Earth-Orbiting Objects Leave the Equivalent of "Scratch Marks" on Space Photos
When the Hubble Space Telescope was launched in 1990, there were about 470 artificial satellites orbiting Earth. By 2000, that number doubled. But by 2023, the rising number has grown almost exponentially to nearly 8,000 satellites. For Hubble this means that satellites photobomb about 10% of its exposures on celestial targets. But a typical satellite trail is very thin and will affect less than 0.5% of a single Hubble exposure.
Nevertheless, these denizens leave annoying pencil-thin, white streaks across a Hubble image as they zoom overhead. And, they are not the only image artifacts Hubble astronomers have to contend with. Cosmic rays rain onto Hubble's camera detectors. These leave what looks like "scratch marks" too. In fact, they are a bigger nuisance than satellite trails.
Astronomers at the Space Telescope Science Institute in Baltimore, Maryland have developed tools for cleaning up this clutter. Hubble observations consist of more than just one exposure. And so, artifacts can be identified and subtracted between exposures because they are not in the same place on a detector.
It's estimated that by 2030 there could be ten times as many satellites circling Earth as there are now. But even as the number of satellites increases, the Space Telescope Science Institute's tools for cleaning the Hubble pictures will still be useful. To date not one Hubble science program has been affected by satellite trails.
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