The 1.7 million figure is not one company's plan — it is the aggregate of every major constellation now seeking approval or already announced. SpaceX accounts for the largest share by far, with plans on the order of a million satellites, the bulk of them intended not for connectivity but for space-based data centers to power AI workloads. Reflect Orbital, a U.S. startup, wants up to 50,000 large mirror satellites to sell sunlight after dark. E-Space's Cinnamon and China's CTC-1 and CTC-2 add hundreds of thousands more between them.

Context matters: the number of satellites in orbit has roughly doubled in under three years, from a few thousand before 2019 to about 14,500 today, already dominated by SpaceX's Starlink. The proposals now in front of regulators would multiply that figure more than a hundredfold.

The ESO study, led by astronomer Olivier Hainaut and accepted for publication in Astronomy & Astrophysics, is the first to quantify how large, bright constellations would raise background sky brightness. Two problems compound.

First, satellites catch sunlight and streak across long-exposure images — the researchers found that at 1.7 million objects, nearly every image from the new Vera C. Rubin Observatory's camera would be compromised. Second, the brightest proposals are in a different class: Reflect Orbital's full mirror constellation could make the whole night sky several times brighter, and each mirror, even when not aimed at an observer, would scatter light as brightly as Venus.

Beyond the optical problem sit two concerns operators know well: radio-frequency emissions that interfere with radio astronomy, and the collision-and-debris risk that rises with orbital density — the "Kessler syndrome" chain reaction. The study's recommendation is a hard ceiling of 100,000 satellites, all faint enough to stay below naked-eye visibility.

The study became the basis for a formal filing. The ESO, with the U.K.'s Royal Astronomical Society and the International Astronomical Union, submitted it to the FCC in response to the two most extreme applications pending — SpaceX's and Reflect Orbital's. The docket is busy: roughly 1,500 comments on the SpaceX application and about 1,800 on Reflect Orbital's.

This lands at a pointed moment. The same FCC is moving, at its July 22 meeting, to accelerate satellite licensing — replacing the decades-old Part 25 framework with a streamlined "Part 100" process built for the mega-constellation era — and has separately floated excluding satellite operations from environmental (NEPA) review. The Commission is trying to license faster at the exact moment a coordinated scientific coalition is asking it to license more carefully. Those two impulses are now on a collision course, and the astronomers have put brightness, interference, and debris into the formal record rather than the background.

The takeaway is not "astronomy versus industry." It is that sustainability conditions are becoming part of the licensing calculus. For any operator with filings in the queue, "how fast can I get approved" now travels with "under what brightness, coordination, and disposal conditions" — and a faster pipeline that later attracts brightness or debris litigation is not actually faster.