Trails of light from satellites appeared on twice as many photos taken by the Hubble Space Telescope聽in 2021 compared to 2002. Although the unwanted light streaks haven鈥檛 yet interfered with Hubble鈥檚 scientific operations, they may do so in future 鈥� particularly as the number of communications satellites launched is rising.
Hubble orbits Earth at an altitude of around 535 kilometres, which is below many orbiting satellites. When taking long exposure shots, where its light-sensitive aperture is open for several minutes to gather more light, satellites that pass in front of it can leave a white streak on the resulting image.
and his colleagues at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, noticed these streaks while analysing Hubble images for a citizen science project looking for asteroids.
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They decided to analyse all images taken by Hubble that had an exposure time of approximately 11 minutes that had been taken between 2002 and 2021 鈥� a total of more than 100,000 exposures 鈥� using a machine learning algorithm to detect when a satellite had crossed an image. 鈥淭he fraction of images that were crossed by satellites has increased over the last 20 years, from about 2.5 per cent in 2002 to 5 per cent in 2021,鈥� says Kruk.
Given the large number of additional satellites put into orbit since 2021, the fraction of images affected is likely to be even higher now, he says.
While a significant number of images have been affected by satellite trails, we have yet to see an impact on Hubble鈥檚 scientific operations. Future satellite streaks could be mitigated using post-processing techniques, such as taking multiple images and then using comparison algorithms to filter out the satellite streaks, says Kruk.
However, this wouldn鈥檛 work for rare events that happen only once and very briefly, says of Dark Sky Consulting, a company based in Tucson, Arizona. If space companies launch as many satellites as they have publicly announced that they plan to, then the contamination rate of Hubble photos will increase by a factor of 10 over the next decade, adds Barentine.
鈥淭here is clear reason to conclude from their study that it鈥檚 only a matter of time before the scientific productivity of the Hubble Space Telescope begins to decline somewhat as a result of data lost to satellite trails,鈥� says Barentine.
Nature Astronomy
