The night sky is about to get a whole lot brighter, and it's not just because of the stars. With the planned launch of thousands of new satellites, the sky could become three times as bright as it currently is, posing a significant threat to astronomical observations. This is particularly concerning for projects like the Vera C. Rubin Observatory, which aims to create a 10-year time-lapse movie of the universe. The study, published on the preprint server arXiv, highlights the potential consequences of these satellite constellations and the need for strict regulations to mitigate their impact.
The issue isn't just about the number of satellites; it's also about their size and brightness. Some satellites, like AST SpaceMobile's BlueWalker and BlueBird, are massive, with dimensions comparable to a large studio apartment and a tennis court, respectively. Others, such as those from Reflect Orbital, are designed to be highly reflective, resembling false stars in surveys. These satellites could leave bright streaks in photographs, causing 'saturation cross-talk' and erasing entire images. The light from these satellites is also scattered by the atmosphere, contributing to light pollution and further obscuring the night sky.
To understand the extent of the problem, the study's author, Hernan Hainaut, created a computer model that simulates how incoming visible light scatters in Earth's atmosphere. By accounting for two types of scattering, the model can predict the sky's appearance from various Earth-based observatories. Focusing on instruments in Chile, Hainaut found that even a relatively small number of satellites could have a significant impact. A megaconstellation of 60,000 satellites, all dimmer than magnitude 7, would contribute only 0.1% of the sky's natural light but would still saturate 6-15% of the LSST Camera's field of view, erasing many observations.
The situation becomes even more dire with extra-large mobile broadband satellites and superbright Reflect Orbital-type satellites. The model predicts that a constellation of 50,000 Reflect Orbital satellites could make the night sky three times as bright as it is now, rendering the LSST Camera's images unusable. This is a cause for concern, as it could significantly impact astronomy, even with moderate numbers of satellites.
To address this issue, Hainaut recommends strict restrictions on satellite size and brightness. He suggests that most satellites should be fainter than magnitude 7, with fewer than 10 satellites brighter than 7 allowed in the sky at any given time. Additionally, the total number of satellites should be kept under 100,000 to minimize the impact on astronomical data. These recommendations are crucial to preserving the night sky and ensuring the success of projects like the Vera C. Rubin Observatory.
In conclusion, the planned satellite launches could have a profound effect on our view of the night sky. It is imperative that satellite operators and regulators take these findings seriously and implement measures to protect our ability to observe the universe. The future of astronomy may depend on it.
