In almost 60 years of space activities, more than 5200 launches have placed some 7500 satellites into orbit, of which about 4300 remain in space. This number is set to skyrocket.
For the first time, a European Southern Observatory (ESO) study has quantified the threat to astronomy posed by a large number of highly reflective satellites planned to launch in the coming years.
In the paper, published in Astronomy & Astrophysics, ESO astronomer Olivier Hainaut argues that no more than 100,000 faint satellites – invisible to the naked eye – should orbit Earth.
Enforcing that guideline would preserve the darkness of the night sky and allow astronomers to continue cutting-edge science using modern telescopes.
Instead, there are existing proposals for more than 1.7 million satellites. These would have “devastating consequences for astronomy,” Hainaut claims.
The most disruptive of these, he argues, will be Reflect Orbital’s mirror-like satellites, which are designed to beam concentrated sunlight down to Earth at nighttime.






