|BlueWalker 3 is a groundbreaking satellite that can turn smartphones into satellite phones, providing global mobile broadband access to billions of people who currently lack reliable connectivity.|
|It creates significant light pollution that interferes with astronomy and the night sky, posing a challenge to the existing regulations and norms of space activities.|
|More collaboration and mitigation strategies among satellite companies, policymakers, astronomers, and consumers to balance the benefits of satellite communication with the preservation of the night sky is needed.|
BlueWalker 3 is a next-generation communications satellite that has become one of the brightest objects visible in the night sky, according to a new study published in Nature. The satellite, launched by AST SpaceMobile in 2022, is the first of its kind to enable direct connectivity between unmodified smartphones and a low Earth orbit (LEO) satellite network.
This means that anyone with a smartphone can access global mobile broadband services, even in remote and underserved areas. However, the satellite also poses a serious threat to astronomy, as its large size and high reflectivity create significant light pollution that interferes with ground-based and space-based telescopes.
Essentially, BlueWalker 3 is bad for stargazing.
We will explore how this satellite works, what benefits and challenges it brings, and what solutions are being proposed to reduce its impact on the night sky.
How BlueWalker 3 Works
BlueWalker 3 is a revolutionary satellite that can connect directly with ordinary smartphones, providing global mobile broadband access to billions of people. It is a prototype for a constellation of 158 satellites that will cover most of the Earth’s surface by 2024. Unlike other satellite constellations, such as Starlink or Project Kuiper, BlueWalker 3 does not require any special equipment or devices to use its service.
The satellite has a massive phased array antenna that can track and serve thousands of smartphones at once, and its antenna is the largest of its kind in low Earth orbit. Measuring 64 square meters (693 square feet) it transmits and receives signals with low power and high speed. Operating in the S-band frequency range, it is less prone to interference and has the ability to route voice and data calls between two unmodified smartphones where cellular coverage is scarce or nonexistent.
That sounds amazing, but with every technological advance, there’s always a drawback.
Comparison of BlueWalker 3 with Other Satellites
|Satellite||Dimensions (m)||Mass (kg)||Orbit (km)||Magnitude||Frequency (GHz)||Service|
|BlueWalker 3||8 x 8 x 0.5||900||700||-1.9||2.0 – 2.3||Mobile broadband|
|Starlink||2.8 x 1.4 x 0.3||260||550||4.7 – 6.2||10.7 – 12.7, 37.5 – 42.5||Internet|
|Project Kuiper||N/A||N/A||590, 610, or 630||N/A||N/A||Internet|
|Iridium||3.1 x 2.4 x 0.9||860||780||6 – 8||1.6 – 1.7, 19.4 – 19.6, 29 – 29.3||Voice and data|
|Globalstar||1.3 x 1.1 x 0.2||650||1414||N/A||1.6 – 2.5, 19 -20, or 29 -30||Voice and data|
What Benefits and Challenges BlueWalker 3 Brings
BlueWalker 3 has the potential to revolutionize mobile communication by providing global coverage, high speed, low latency, and low cost services to billions of people in many parts of the world that struggle with poor or no connectivity. However, BlueWalker 3 also has a major drawback: it is extremely bright. The satellite reflects so much sunlight that it outshines most stars and planets in the night sky.
According to the study by Tregloan-Reed et al., BlueWalker 3 has an apparent magnitude of -1.9, which means it is in the same category as some of the brightest stars in the night sky and only slightly dimmer than Jupiter and Venus. The study also found that BlueWalker 3 is visible for about six hours per night at most locations on Earth.
Estimated Impact of BlueWalker 3 on Different Types of Telescopes
|Telescope||Location||Wavelength (nm)||Resolution (arcsec)||Sensitivity (mag)||Streaks (% over 1 night)||Sky glow (% over 1 night)||Interference (% radio telescopes)||Impact on astronomical observations||Recommendations|
|Hubble||LEO (547 km)||115 – 2500||0.05 – 0.1||28 – 31||10 – 20||N/A||N/A||Minimal impact on most observations.||Use filters to reduce the brightness of BlueWalker 3.|
|Vera C. Rubin Observatory||Chile (2200 m)||320 – 1060||0.2 – 0.4||24 – 27||30 – 40||10 – 15||N/A||Moderate impact on some observations, such as astrometry.||Schedule observations during times when BlueWalker 3 is not visible.|
|Square Kilometre Array||South Africa and Australia (100 m – 3000 km)||70 – 25000||0.001 – 10||-10 to -30||N/A||N/A||10 – 20||Significant impact on radio telescope observations.||Use filters to reduce the interference from BlueWalker 3.|
|Very Large Telescope||Chile (2635 m)||300 – 20000||0.02 – 0.5||25 – 30||20 – 30||5 – 10||N/A||Moderate impact on some observations, such as spectroscopy.||Use filters to reduce the brightness of BlueWalker 3.|
The brightness of BlueWalker 3 poses a serious problem for astronomy, as it creates light pollution that affects both ground-based and space-based telescopes.
What does this mean and who cares?
Light pollution from satellites can cause several issues, such as:
|Streaks: Satellites can leave bright trails across images taken by telescopes, obscuring or contaminating the objects of interest. Starlink satellites have caused streaks in images taken by the Hubble Space Telescope and the Vera C. Rubin Observatory in Chile.|
|Interference: They can emit radio waves that interfere with radio telescopes, which are used to study phenomena such as pulsars, black holes, and cosmic microwave background. They can cause interference for radio telescopes such as the Square Kilometre Array in South Africa and Australia.|
|Sky glow: The overall brightness of the sky background is increasing partially due to satellites, making it harder to detect faint or distant objects. Some estimate satellites have already increased the sky glow by about 10% at some observatories.|
These issues can hamper scientific discovery and exploration, as well as cultural and spiritual values associated with the night sky. And if there are eventually enough of them zooming across the sky at night, light pollution from satellites might affect wildlife, such as birds and insects, that rely on natural light cues for navigation and behavior.
What Solutions are Being Proposed to Reduce BlueWalker 3’s Impact
The impact of BlueWalker 3 on the night sky has raised concerns and criticisms from the astronomical community and the public. The International Astronomical Union (IAU) issued a statement in 2020, calling for more regulation and coordination among satellite operators, policymakers, and astronomers to protect the night sky.
The IAU also recommended some possible solutions, such as:
|Adjusting satellite designs||Satellites can be modified to reduce their size, reflectivity, or emission. SpaceX, as an example, has tried different coatings and orientations for its Starlink satellites to make them less bright.|
|Regulating satellite launches||More stringent rules and standards could be applied to satellites before they are authorized to launch. In the US, the Federal Communications Commission (FCC) has recently proposed new regulations that would require satellite operators to demonstrate how they will mitigate light pollution and orbital debris.|
|Developing anti-reflective coatings||Satellites can be coated with materials that absorb or scatter sunlight, making them less visible. A team of researchers from the University of Arizona, for instance, has developed a thin film that can reduce the reflectivity of satellites by up to 10 times.|
AST SpaceMobile has stated that it is aware of the issue and is working with NASA and other astronomy working groups to find solutions. The company has also claimed that its future satellites will be less bright than BlueWalker 3, as they will have smaller antennas and lower orbits. However, some astronomers remain skeptical and urge more action and transparency from the company.
BlueWalker 3 poses a challenge to the existing regulations and norms of space activities, and calls for more collaboration and mitigation strategies among satellite companies, policymakers, astronomers, and consumers.
The question is: can we balance the benefits of satellite communication with the preservation of the night sky?
We sure hope so!
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About the Authors
We are avid stargazers Jason and Alison Takacs also known as “Roadtrippin’ with Takacs”. With our two boys Preston and Grayson, we seek out some of the darkest skies in the country while also going on many incredible hiking and other outdoor adventures. As part-time RVers, we try to see as much of this amazing world as possible in our spare time and hope you will join us through this blog and other forms of social media as we explore the night sky and other natural wonders as hardcore astrotourists.