Mon. Dec 4th, 2023
Satellite Swarms in Low-Earth Orbit: A Growing Problem

The problem of satellite swarms in low-Earth orbit is becoming increasingly concerning. Recently, a satellite named BlueWalker3, launched by US-based AST SpaceMobile, has become one of the brightest objects in the night sky. This satellite is just a prototype, and the company plans to launch a whole constellation of similar satellites.

A team of researchers led by astronomer Sangeetha Nandakumar from the University of Atacama in Chile emphasizes the urgent need to take effective measures to mitigate the impacts of these satellite swarms. Despite efforts by various stakeholders to mitigate these impacts, the trend of launching larger and brighter satellites continues to grow.

Currently, there are approximately 8,693 artificial satellites orbiting the Earth, most of which are in low Earth orbit. Since 2019, thousands of new satellites have been launched, including nearly 5,000 from Starlink alone. It is estimated that by 2030, around 100,000 satellites will be in Earth orbit, significantly altering the night sky.

BlueWalker3, a communications satellite, highlights the need for regulation. It is designed to provide cellular broadband directly to mobile phones. The satellite’s antenna measures 64.3 square meters (693 square feet), and it was launched into space packaged in a cylinder called the Launch Vehicle Adapter (LVA).

Observations of BlueWalker3 reveal fluctuations in brightness. It initially started off very bright, dropping to a dimmer magnitude of 6. However, by April 4, 2023, the satellite had brightened again to a magnitude of 0.4, similar to the brightness of Betelgeuse. The researchers note that the satellite’s apparent brightness is influenced by its elevation above the horizon, and it shows a correlation with solar phase angle.

The researchers also found that the jettisoned LVA reached a magnitude four times higher than recommended, posing risks to ground operators trying to prevent collisions. In addition to collision risks, satellite swarms cause light pollution, which hinders ground-based astronomical observations and interferes with radio telescopes.

To address these issues, Nandakumar and her team suggest that satellite companies should conduct impact assessments prior to launch to evaluate the potential harm caused by their satellites. Implementing such studies as part of the launching authorization process could help minimize the negative impacts on space and Earth environments.

This research has been published in Nature.