Space near the Earth is becoming crowded by thousands of orbiting satellites and astronomers now … [+]
Satellites and space junk are brightening the night sky and making it harder for astronomical observatories to make scientific discoveries, says a new report published today in the journal Nature Astronomy.
Since 2019, the number of functional satellites in orbit has more than doubled, according to the authors, who fear that an uptick in collisions between space junk and the extra debris they generate could mean that important astronomical discoveries are “lost in the noise” in the coming decade.
The paper calculates the effects of satellites and space debris in low Earth orbit (LEO) on major ground-based astronomy research facilities. It finds that reflected light from objects in LEO may add an extra $22 million to the cost of a flagship night sky survey.
The number of satellites in orbit is expected to increase from 9,000 today to over 60,000 by 2030 while estimates suggest there are already more than 100 trillion untracked pieces of old satellites circling the planet.
“The threat to the integrity of the night sky now posed by satellites and space debris is without precedent,” said lead author John Barentine at Dark Sky Consulting. “We find that it imperils access by professional astronomers and casual stargazers alike.”
Building on earlier research that predicted an increase in the brightness of the night sky of about 12% during the 2020s, the authors found that debris in orbit reflect far less sunlight to the ground than large satellites, but are much more abundant.
The collective effect is that reflections from small fragments of “space junk” is brightening the night sky from across the globe.
“The significance of this problem can’t be underestimated,” said Barentine. “It will change how we do astronomy under an increasingly industrialized night sky.”
The collisions that are causing more debris and thus more reflected light to interrupt scientific observations are becoming more likely as space fills with new satellites. SpaceX currently has over 3,500 satellites in its Starlink constellation—with an initial target of 12,000—while OneWeb has around 550. Meanwhile, Amazon’s proposed Project Kuiper is planning 3,236 satellites, with the first two test satellites due to launch this year. Other sources of debris include the intentional destruction of satellites in space warfare tests, according to the authors.
The research comes against a backdrop of an alarming rise in light pollution caused by Artificial Light at Night (ALAN) on Earth. In January a paper revealed that over the past 12 years the brightness of the night sky has increased by seven to 10% per year. The researchers said that if it continues to increase then a child born in a place where 250 stars are visible today will only be able to see 100 stars on his or her 18th birthday.
Research published in September 2021 showed that light pollution has increased by at least 49% over 25 years globally, a figure that accounts only for light visible by satellites. However, the researchers suggested that the actual increase in light pollution could be up to 270% globally—and as much as 400% in some regions.
That—combined with space junk reflections—is a huge problem for the upcoming Vera Rubin Observatory’s Legacy Survey of Space and Time. This cutting-edge observatory built on a mountaintop in Chile’s southern Atacama desert will, from 2025, conduct a hugely ambitious all-sky night sky survey.
The authors claim that the efficiency of the LSST program will be diminished by 7.5% and, over the 10-year lifetime of the survey, problems with reflected light from space junk will add $21.8 million to the total project cost. Although scientists can try to back-correcting data with computer algorithms by removing satellite streaks in images using software, the streaks essentially introduce gaps into the data collected by telescopes.
The potential loss of new scientific discoveries is impossible to put a number on, according to the authors.
Wishing you clear skies and wide eyes.
