Every 24 hours, the Sun disappears behind the western horizon and darkness envelopes the world. The Moon’s pale smudge in the sky polishes into a luminescent jewel. Stars and planets pierce through the velvety blanket. Under ideal conditions, the naked eye can observe some 4,500 pinpricks of light in the night sky. Modern telescopes make an uncountable number of additional marvels more accessible. Depending on the time of year, the dusty band of the Milky Way might stretch across heavens.
As astrobiologists, both of us obsess over the mysteries hiding between each tiny pinprick. But this fascination transcends science. The night sky provides us with a personal connection to the cosmos.
These days, light pollution threatens such celestial sights. The artificial luminance that pours out of buildings and streetlamps scatters off molecules in our atmosphere, raising its sheen such that only the brightest of astronomical objects can compete. Because a large fraction of humanity now clusters in urban settings, 30% of the world’s population, including 80% of Americans, can no longer see our galaxy’s band where they live. Those who live in dense cities may only be able to see a handful of constellations.
Now, a brand-new threat of anthropogenic light pollution looms. The Federal Communications Commission (FCC) is currently entertaining three proposals for satellite projects of unprecedented scale. If approved, these endeavors would fundamentally change the nature of the night sky.
Reflect Orbital, an aerospace startup based in California, plans to provide “sunlight on demand” by launching thousands of enormous mirror-wielding satellites. Their goal is to provide the nightside of Earth with enough light to extend solar farm activity, increase crop yield, and illuminate streets. To accomplish this task, their long-term goal is to launch 250,000 satellites, each hosting a 180-foot mirror, roughly the height of a 15-story building.
Even modest-sized satellite megaconstellations (far smaller than the SpaceX proposal) are estimated to affect some 30–80% of the dusk and dawn images taken by the Vera C. Rubin Observatory
In February, Elon Musk’s SpaceX acquired Elon Musk’s AI venture, xAI, and proposed launching up to one million satellites to serve as orbital data centers. Artificial intelligence relies on energy-intensive and heat-generating data centers, so the company hopes to circumvent Earthbound power and cooling limitations by launching its data-crunching infrastructure into space. Then, in March, a third venture landed on the FCC’s desk: Starcloud’s proposal to launch 88,000 satellites as orbital data centers.
Given that there are roughly 12,000 active satellites, these three corporations’ moves would multiply humanity’s orbital footprint by roughly a hundred. The skyglow from humanity’s present fleet of satellites already contributes a 10% bump to light pollution. Imagine how a million new satellites would transform our experience of the night sky.
Much has already been said about why polluting near-Earth orbit is a problem: it heightens the risk of satellite collisions; space debris endangers future rocket launches and Earth’s surface; and satellite megaconstellations disrupt human astronomy research and non-human ecologies.
We believe that unchecked expansion of an Earth-orbiting satellite fleet is also an ethical issue.
The Moral Value of Dark Skies
Last year, in collaboration with two experts in the ethics of space exploration, Chelsea Haramia and Julia De Marines, we introduced an expansive concept of moral value in the universe. Although we crafted this framework with the search for life outside of Earth in mind, we believe that learning to recognize the value of a Martian landscape or a hypothetical alien ecosystem can help us become more sensitive to the moral value of systems with which we interact every day—or every night—here on Earth.
All of nature’s projects—not just those that are alive and sentient, as we are—deserve moral consideration. The night sky may not be a creature capable of feeling pain or experiencing happiness, but its waning presence should still invite ethical concern.