The increasing number of artificial satellites and associated debris in low Earth orbit (LEO) increases the overall brightness of the night sky. This rising population threatens ground-based astronomy and the ecosystems that rely on dark skies.
Formation of Megaconstellations
Since the launch of the first artificial satellite in 1957, the orbital space near the Earth has been radically transformed. By early 2019, the number of functional satellites in low Earth orbit had more than doubled because of the advent of large groups of satellites called mega constellations as the low Earth orbit became an increasingly congested space. The dangers of collision between and among objects and the likelihood of an uncontrolled chain reaction of debris-generating events increase exponentially.
In just three years, satellite megaconstellations have seriously threatened astronomy. There has been a dramatic and partial transformation of the night sky without historical precedent and with limited oversight.
Direct illumination of failed and functional satellites, debris fragments, and leftover launch hardware by sunlight makes them visible as streaks or trails in optical and infrared images. Smaller objects also contribute to the increase in diffuse brightness of the night sky, compromising scientific data.
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Threats From Congested Space
Regarding astronomical observations, the Vera Rubin Observatory (VRO) is a unique lookout. Unlike other imaging tools, such as the Giant Magellan Telescope and the European Extremely Large Telescope, which focus on distant objects, VRO's mission is to survey the entirety of the night sky over a decade.
However, its particular purpose also makes it more vulnerable to space junk. All the space junk can look like transient events, impairing the observatory's vision and polluting its results.
In a new study conducted by Harvard physicist/astronomer Avi Loeb, it was suggested that the operations of Vera Rubin Observatory have been affected by the impact of space debris. The result of his study is discussed in the paper "Flares from Space Debris in LSST Images."
The problem stems from VRO's extreme sensitivity, which is critical to its success. Loeb predicts that the upcoming LSST images of the observatory will be contaminated by numerous flares from space debris that measures a few centimeters. Millisecond-duration flares from these objects are expected to form detectable image streaks of a few arcseconds with AB magnitudes brighter than 14.
As of December 6, 2023, 130 million objects are measuring 0.1-1 centimeters orbiting our planet, according to the Space Environment Statistics from the European Space Agency. There are also one million objects between 1 and 10 centimeters and 36,500 objects larger than 10 centimeters. The problem is even getting worse with so many launches in recent years. As space becomes a burgeoning economy, a certain amount of space junk goes with it.
Loeb noted that not all the debris is found in the critical low-Earth orbit region, but a large subset of them are. He also reported that this space junk population has implications for the Vera Rubin Observatory. In his study, he examines the impact of LEO debris for the upcoming Legacy Survey of Space & Time of the Vera Rubin Observatory in Chile.
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