Researchers have developed software they believe will be at least 10 times more effective than existing algorithms at detecting the pesky satellite trails that increasingly appear in Hubble Space Telescope images.
The team from Baltimore’s Space Telescope Science Institute (STScI) also claims that their software identified roughly twice as many trails as other studies.
“We have a set of tools that people use to clean the Hubble data and calibrate it. And our new application is another tool that will help us get the most out of every Hubble exposure,” said Dave Stark, STScI team scientist.
The proliferation of space hardware may be useful for telecommunications, defense and other industries, but it has astronomers terrified of the havoc it can wreak on the images produced by their high-budget telescopes.
For example, when the $10 billion Hubble Space Telescope was launched in 1990, there were about 470 artificial satellites orbiting Earth. Ten years later, this has doubled, and by 2023, the growing number has grown almost exponentially to nearly 8,000 satellites. Satellite photobombs now affect about one in 10 images from the first generation space telescope, although the trace is usually so thin that less than 0.5 percent of a single exposure can be affected. Hubble is in a low orbit, so many satellites orbit Earth at a higher altitude than the space telescope.
According to a study is presented this week on 242nd Meeting of the American Astronomical Societythe new Radon Transform software is “sensitive to traces with an average brightness as low as ~0.1 times the background noise, although sensitivity depends on the length of the trace and will decrease towards the corners of the images.”
“Our algorithm is about an order of magnitude more sensitive than the current algorithm proposed by the Advanced Camera Survey team for identifying satellite tracks,” the researchers said.
Meanwhile, by applying the instrument to historical Hubble data taken between 2002 and 2022, the team found that trail contamination has roughly doubled over the past two decades, although there is no evidence of a corresponding change in the brightness of the the trace.
The result confirms the results of a study published earlier this year. It found increasing interference with astronomical images caused by commercial satellites, adding to concerns about the effects of the private space industry on science.
Using deep learning algorithms to scan historical images taken by the Hubble Space Telescope between 2002 and 2021, the researchers found that 2.7 ± 0.2 percent of images with a typical exposure time of 11 minutes contained at least one satellite track.
But during this period the probability of a cosmic hardware photobomb has increased sharply. This means that the satellite fraction for the affected Advanced Camera Survey/Wide-Field Channel (ACS/WFC) increased from 2.8 ± 0.2 percent in 2002-2005 to 4.3 ± 0.4 percent in 2018 -2021, for example.
However, the team behind the Radon Transform tools is working to help clean up the satellite interference. Because images are usually composited from multiple exposures of the same celestial target, satellite photobombs may appear in only one frame. The software can be used to select the affected images and tag them.
“When we mark them, we should be able to reconstruct the full field of view without a problem after combining the data from all the exposures,” Stark said in statement.