AST SpaceMobile Satellite Brightness and the Limits of Orbital Regulation

Abstract

Satellite mega-constellations have overtaken the population of spacecraft since the first Starlink launch in 2019, but the regulation on mega-constellations has lagged. The brightness and quantity of mega-constellation satellites can interfere with astronomical surveys, add naked-eye visible objects to the sky, congest low-Earth orbit, and their launches add pollutants to the atmosphere. Quantitative measurements of the brightness of these mega-constellations are lacking since their high relative motion makes them challenging to track with scientific instruments. We present measurements of AST SpaceMobile’s five Block 1 BlueBird satellites: an average V magnitude of 3.9 ± 1.1, with the brightest observation reaching V magnitude 1.2 ± 0.3 and the faintest V magnitude 6.4 ± 0.3. Our measurements reveal an average brightness seven times brighter than mitigation targets cited in FCC filings and peak values over 200 times brighter than the International Astronomical Union’s recommended threshold (V magnitude 7). Now, AST SpaceMobile is expected to deploy over 200 Block 2 satellites that are each three times larger (199 m2) which would be three times brighter than Block 1 (all else being equal), and regulations have not changed. The brightness of the current mega-constellations highlights the lack of enforceable photometric standards and environmental reporting, marking a critical regulatory gap that impacts both space and ground-based astronomy.