Sun. Dec 3rd, 2023
BlueWalker 3 Satellite: A Bright Object in the Sky

Back in 2022, AST Space Mobile introduced BlueWalker 3, a prototype telecommunication satellite capable of providing satellite internet directly to regular mobile phones without any hardware modification. The satellite features a massive antenna, measuring 64 square meters (693 square feet), making it the largest commercial antenna deployed in low Earth orbit. Recently, a study revealed that BlueWalker 3 is among the brightest objects in the sky.

Astronomers use a measurement called magnitude to determine the brightness of an object. The lower the magnitude, the brighter the object, and some objects even have negative magnitudes. While stars with a magnitude around two are typically visible in cities, in darker sky regions, objects with magnitudes as low as six can be seen.

BlueWalker 3 itself is not inherently bright; what we perceive as brightness is actually sunlight reflecting off the satellite. At the right angle, it reaches a magnitude of 0.4, placing it among the top 15 brightest objects in the sky. This makes it brighter than Betelgeuse or Saturn.

The impact of satellites like BlueWalker 3 extends beyond visibility. Radio signals transmitted from space interfere with radio astronomy, hindering studies of distant galaxies and potentially endangering the study of hazardous asteroids. The increase in the number of satellites also contributes to light pollution, which has led to the term “noctalgia” to describe the loss of access to a pristine night sky.

Furthermore, transmitting phone signals from space poses a challenge to facilities like the Square Kilometer Array Observatory (SKAO), which require radio quiet zones. Frequencies allocated to cell phones are already difficult to observe and new satellites like BlueWalker 3 could further worsen the situation if not properly managed.

The International Astronomical Union’s Center for the Protection of the Sky (IAU CPS) emphasizes the need for satellite companies to consider the impact of their crafts on the night sky and astronomy. Authors of a recent study suggest that impact assessments should be conducted prior to satellite launches to evaluate the effects on both the space and Earth environments. By implementing such studies as part of the launching authorization processes, the negative impact can be mitigated.

AST Space Mobile plans to launch 90 more satellites like BlueWalker 3. The findings of the study on the brightness of BlueWalker 3 were published in the journal Nature.