Astronomers ‘Troubled’ as New Satellite Outshines Most Stars in the Sky

Trails in the night sky left by BlueWalker 3 are juxtaposed against the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona, a Program of NSF's NOIRLab. The breaks in the trail are caused by breaks between four twenty second exposures that were stacked to create this image.

Cell phone towers in space may be the next frontier of mobile communication, but astronomers are starting to get worried. AST SpaceMobile successfully deployed its new BlueWalker 3 communication satellite, and the International Astronomical Union (IAU) says this enormous satellite is now one of the brightest objects in the sky. The IAU warns that the proliferation of objects like BlueWalker 3 could have disastrous effects on astronomy.

AST SpaceMobile launched BlueWalker 3 in September aboard a SpaceX Falcon 9 rocket, deploying its expansive communication array earlier this month. The satellite has a total surface area of 693 square feet (64 square meters), and it’s in a low-Earth orbit. Even before launch, many in the astronomical community feared this object would outshine nearly all the stars in the sky, and that’s exactly what happened.

BlueWalker 3 needs that gigantic antenna because of the way it intends to deliver connectivity directly to existing cell phones. The antenna in your phone is designed to talk to nearby towers on the ground — getting connected to a satellite is much harder. Satellite phones usually have bulky adjustable antennas, but no one wants to carry one of those around. Thus, BlueWalker 3 has its giant antenna array to deliver 4G and 5G service. The company plans to use BW3 to test services that could eventually come to partners like AT&T and Vodafone.

Officially, the IAU is “troubled” by the “unprecedented brightness” of BlueWalker 3, but it does not necessarily oppose the launch of such satellites. Increasing connectivity in underserved areas is a noble goal, but the group is asking companies to adopt technologies and designs that minimize the impact these satellites have on astronomy. To make the point, the IAU has provided some sample images of BlueWalker 3 photobombing telescopes. There is also concern that blasting cellular signals from space will increase interference at radio observatories, which are often built as far away from cell phone towers as possible.

Observation using the 0.6-meter Chakana telescope at the Ckoirama Observatory in Chile. This 10-second image shows BlueWalker 3 with a measured apparent magnitude of V=6.6 at a range of 865 km. Observers: Eduardo Unda-Sanzana, Christian Adam, and Juan Pablo Colque.

AST SpaceMobile is not alone in this quest to bring cellular service to space. Apple recently enabled Emergency SOS satellite communication via Globalstar, but it only supports text messaging with significant delays. Meanwhile, SpaceX and T-Mobile want to provide text and voice calls with next-gen Starlink v2 satellites. Astronomers are already up in arms about the existing Starlink constellation ruining images, and the larger Starlink v2 could be almost as bad for astronomy as BlueWalker 3. The skies are getting a lot more crowded, which makes space-based instruments like the James Webb Space Telescope all the more vital.

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