Mega-Constellation Satellites Pose Grave Threat to Night‑Sky Observations

A new European Southern Observatory study warns that the rapid expansion of low‑Earth‑orbit satellite constellations could drastically increase night‑sky brightness, hampering astronomical research and disrupting ecosystems. Current satellites number over 14,000, but proposals aim to launch up to 1.7 million, with additional plans from companies such as E‑Space and China’s CTC‑1/2 potentially adding hundreds of thousands more. The study recommends limiting faint satellites to 100,000 to preserve the ability of modern telescopes to observe galaxies, exoplanets and near‑Earth objects, noting that brighter constellations could brighten the sky three to four times and affect biological clocks.

Researchers in the UK have demonstrated that coating satellites with an ultra‑black material, Vantablack 310, reduces reflected light to about 2 percent, keeping satellite brightness below the International Astronomical Union’s recommended magnitude‑7 threshold. Laboratory tests show the coating outperforms SpaceX’s DarkSat and VisorSat concepts, offering a practical mitigation path while satellite deployment for communications and data‑center services continues to grow.