SpaceX’s Starlink satellites leave trails in asteroid-hunting telescope images

A leading ground-based observatory that scans the skies for explosive stars and dangerous near-Earth asteroids is battling disruptive light trails from SpaceX’s Starlink internet satellite constellation, a new study has found.

The observatory, called the Zwicky Transitional Facility (ZTF), opened its telescope eye in California in 2017. Scanning the entire sky every two days, the observatory looks for the temporary brightening or sudden appearance of objects that remain visible only briefly. He hunts for supernova explosions to die stars and asteroids passing near the Earth.

A new record of its observations dating back to 2019, the year SpaceX began launching its ambitious Stellar Link megaconstellation, revealed that a considerable percentage of the telescope’s views contain trailing caused by the satellites as they pass overhead.

Images capturing the twilight sky around sunrise and sunset are most affected, the team behind the new study said. in a report. These observations are particularly important for spotting potentially dangerous asteroids coming from the direction of the Sun, the scientists added.

Related: Cosmic photos: first light from Zwicky’s transitional installation

The ratio of twilight images affected has increased sharply with the growth of the Starlink megaconstellation, rising from just 0.5% at the end of 2019 to 20% at the end of 2021. But only a fraction, around 15%, of the constellation that SpaceX envisions could go up to 12,000 satellites are currently in orbit, suggesting the ultimate impact will be far greater. Additionally, SpaceX hopes to eventually expand the size of its Internet broadcast fleet to 42,000 spacecraft. And there are other companies with similar projects, including OneWeb, Amazon or SatNet in China.

To date, SpaceX has 1,469 active Starlink satellites and just launched 49 new satellites late Tuesday (January 18), the company’s second Starlink launch of 2022.

“We don’t expect Starlink satellites to affect non-twilight images, but if other companies’ constellation of satellites go into higher orbits, it could cause problems for non-twilight observations,” Przemek said. Mróz, the study’s lead author and former postdoctoral researcher at the California Institute of Technology (Caltech), which runs ZTF, said in the statement.

In total, the scientists found 5,301 satellite sequences on the observations of the period studied.

However, all is not catastrophic. The study also found that since SpaceX began installing visors on its satellites, the brightness of the craft decreased by a factor of five, as well as that of the streaks.

Caltech physics professor Tom Prince, co-author of the study, added that only about 0.1% of pixels in an image are damaged by the footage.

“There is a small chance that we miss an asteroid or other event hidden behind a series of satellites, but compared to the impact of weather, such as cloudy skies, these are rather small effects for ZTF,” said he said in the statement.

Astronomers have worried about the potential impact of Starlink satellites on new discoveries since the first batch reached orbit in May 2019. At first, many skywatchers were in awe of the spectacular Pearl necklace crossing the sky after launch, but that fear was only short-lived.

Since then, the International Astronomical Union has called on the United Nations to protect the pristine night sky as human heritage and a recent workshop of the American Astronomical Society compared the potential damage that megaconstellations can cause to astronomy to that caused by light pollution.

The controversial technology also has many opponents among space security experts. According to Professor Hugh Lewis, European specialist in space debris, Starlink satellites are now responsible for more than 50% of collision risk situations between two orbiting satellites.

Scientists who study the Earth’s atmosphere are concerned about the possible effects that megaconstellation satellites could have on the planet’s climate. Megaconstellation operators such as SpaceX plan to regularly replace their technology with newer models and de-orbit old satellites used to burn them into Earth’s atmosphere. This combustion, however, will produce potentially dangerous particles which could have unforeseen effects on the planet.

The ZTF study was published in Astrophysical Journal Letters on Monday, January 17.

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