Letter to the Editor

Space debris contributions to night sky brightness

Comparing model predictions and implications for astronomical signal-to-noise ratios

¹ ICA, Slovak Academy of Sciences, 845 03 Bratislava, Slovakia
² Department of Astrophysics, University of Vienna, 1180 Wien, Austria
³ Department of Experimental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University, 842 48 Bratislava, Slovakia
⁴ Department of Astronomy, Physics of the Earth, and Meteorology, Comenius University, 842 48 Bratislava, Slovakia

^★ Corresponding authors: This email address is being protected from spambots. You need JavaScript enabled to view it. ; This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 30 September 2025
Accepted: 22 March 2026

Abstract

Aims. We quantify the uncertainty in space debris contributions to night sky brightness by comparing predictions from two major debris environment models and assessing the resulting signal-to-noise degradation for ground-based astronomical observations.

Methods. We compared debris population predictions from ESA’s MASTER and NASA’s ORDEM models, which differ in terms of their sub-millimeter particles by several orders of magnitude, due to divergent fragmentation assumptions. We calculated the debris-induced sky brightness contributions for six observatories worldwide and performed a detailed signal-to-noise analysis for VLT/FORS2 observations of extended sources ranging from 22 to 27 mag/arcsec².

Results. MASTER predicts debris contributions of 29.7–30.3 mag/arcsec² for zenith observations in 2024, while ORDEM-scaled estimates yield 26.2–26.8 mag/arcsec². By 2035, these values will end up reaching 28.7–29.5 and 25.2–25.8 mag/arcsec² respectively, representing 3–20% of natural sky brightness depending on model assumptions. For faint extended sources (27 mag/arcsec²), the S/N degradation ranges from 7% (MASTER) to 20% (ORDEM-scaled) over the next decade, potentially requiring 8–34% longer exposures to maintain sensitivity. The debris-induced brightness follows an 11-year solar cycle modulation, with 20–30% variations between solar maximum and minimum.

Conclusions. Model uncertainties, spanning an order of magnitude, prevent definitive predictions to be made on the impact of debris on astronomy. While large telescopes observing faint sources could face challenges under worst-case scenarios, smaller facilities with brighter sky-limited magnitudes remain relatively unaffected. Improved debris characterization through in-situ measurements or enhanced tracking is essential for reliable planning of future astronomical facilities. Signal-to-noise calculations isolate debris-specific degradation using debris brightness alone, providing observatories with debris-isolated planning metrics that are independent of local sky conditions.