While the space-based Hubble Telescope is often the first to come to peoples’ minds, the majority of telescopes are actually ground-based. This means that their ability to observe celestial objects is affected by light pollution (which can be somewhat mitigated by building them in high, remote locations), atmospheric distortion, and the absorption of certain portions of the electromagnetic spectrum by Earth’s atmosphere. And now, another obstruction has been added to the list: photobombing by Starlink.
How? Starlink’s 42,000 satellites constitute as a ‘megaconstellation’. Large networks such as these can completely dominate a telescope’s field of view, leading to them capture images such as the one below.
Each streak of white in this photo, captured by a telescope in Chile, is caused by light reflecting off a Starlink satellite. The reflectiveness of these satellites surprised many astronomists and given the lack of domestic or international regulations on satellite brightness, it was only a matter of time before this became a major issue. In 2019, there were around 200 objects orbiting Earth that could be seen by the naked eye; Starlink then singlehandedly added another 240 by February 2020.
Since many ground-based telescopes use long-exposure photography to create composite images, the passing of a single satellite can create a streak that stretches across the entire photo. Not only are they unsightly, they also block the view of the space behind them, which severely impacts the work of astronomers who compare images of the night sky to find minute differentiations in the light. Even worse, the positioning of these satellites so close to Earth result in them being most reflective during dusk and dawn— the best time period for viewing and photographing comets.
When SpaceX was informed of the situation, they attempted a variety of methods to reduce the satellites’ reflectiveness. These efforts included changing the orientation of the satellites in orbit, painting one black (which was eventually fried thanks to the heat absorbing qualities of black paint), and adding sunshades to cover the main source of reflection, the antennae. Fortunately, it seems that the sunshade-equipped satellites, known as ‘VisorSats’, are on average only 31% as bright as those without the feature, according to a 2021 study by Anthony Mallama. Yet despite this improvement, these satellites continue to be visible to telescopes and are likely to remain that way unless another solution is devised.
In addition to obstructing optical astronomy, Starlink also poses a risk to radio astronomy. As the name suggests, radio astronomy is the study of space using radio waves, which have longer wavelengths than both visible and infrared light. When combined with optical telescopes that capture visible light and other instruments specialising in the infrared region of the electromagnetic spectrum, astronomers are able to create more detailed and complete representations of celestial objects.
Even without Starlink’s interference, radio telescopes must contend with the radio frequency interference caused by everyday devices and services, ranging from mobile phones to radio broadcasts and wireless garage door systems. Still, the significance of these sources of interference pales in comparison to that of satellites. Last year, the Square Kilometre Array in South Africa, an international radio telescope project hoping to create the highest resolution images of space to date, announced that Starlink and other satellite constellations would interfere with one of the frequencies it uses to detect organic and water molecules as part of its work in cosmology.
Their analysis concluded that 6,400 satellites would increase the time needed to observe an object clearly, a marked decrease in efficiency. Should the megaconstellation grow to include 100,000 satellites, an entire frequency band would be rendered unusable. To gain a sense of how easily this could happen, Starlink currently has 1,434 satellites in orbit out of a planned 12,000 already approved by the US Federal Communications Commission (FCC).
It is no exaggeration to say that satellite internet is entering a new period of development. Starlink is just one project in an incoming wave of similar satellite constellations, involving both private companies like OneWeb and Amazon’s Project Kuiper as well as state-funded efforts like Russia’s Sfera and China’s Guowang. As more and more satellites are launched, the interferences they cause will only increase. These involve not only those discussed in the article, but also include other concerns such as increasing congestion in the orbits, which could lead to collisions that produce deadly space debris. Thus, while we rightfully celebrate our scientific advancements, we must not be blind to their faults and dangers. Space is a vast and yet largely untapped resource – it would a great tragedy for all of humanity if it is destroyed before we can unravel all its secrets.
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