Too Bright and Not a Star: How Huge Satellite Spoils Space Observations

The International Astronomical Union (IAU) is concerned about the level of light pollution emanating from Texas-based AST SpaceMobile's new BlueWalker 3 artificial satellite, which was recently launched into orbit.

Scientists have issued a collective statement noting that the 64m² phased array orbiter has turned out to be one of the brightest objects in the night sky and could hinder scientific research.

The space researchers in their appeal point to the "unprecedented brightness" of the artificial object in orbit and note their concern over the fact that AST SpaceMobile plans to launch dozens of additional BlueWalker-like satellites in the future.

"New measurements reveal that this low Earth orbiting satellite is now one of the brightest objects in the night sky, outshining all but the brightest stars," said a collective letter from scientists at the IUA, which includes about 12,000 specialists.

The researchers published a photo of BlueWalker 3 moving along the night sky to prove their point.

CC BY 4.0 / CLEOsat/Ckoirama Observatory/IAU CPS. E. Unda-Sanzana / The image shows Bluewalker 3 with a measured apparent magnitude of V=6.6 for Bluewalker 3 at a range of 865 km.

CC BY 4.0 / KPNO/NOIRLab/IAU/SKAO/NSF/AURA/R. Sparks / Trail left by BlueWalker 3 over McMath-Pierce Solar Telescope at Kitt Peak National Observatory, a Program of NSF's NOIRLab.

CC BY 4.0 / A. Block/IAU CPS / Trail of BlueWalker 3 crossing the night sky, taken from a backyard in Tucson, Arizona, on 20 November 2022.

Another problem, according to the scientists, is that BlueWalker 3 is essentially a very powerful space cell tower. The device is designed to transmit radio signals and provide satellite communications to conventional smartphone owners. The bottom line is that these radio signals could interfere with the use of radio telescopes on Earth, the IAU believes.

“Astronomers build radio telescopes as far away as possible from human activity, looking for places on the planet where there is limited or no cell phone coverage. Frequencies allocated to cell phones are already challenging to observe even in radio quiet zones we have created for our facilities. New satellites such as BlueWalker 3 have the potential to worsen this situation and compromise our ability to do science if not properly mitigated."

Philip Diamond

SKAO Director-General

In response to the scientists' statement, AST SpaceMobile said:

“We are eager to use the newest technologies and strategies to mitigate possible impacts to astronomy. We are actively working with industry experts on the latest innovations, including next-generation anti-reflective materials... We are also engaged with NASA and certain working groups within the astronomy community to participate in advanced industry solutions, including potential operational interventions.”