Reflect Orbital and astronomers clash over space mirror plan
A -based startup, Reflect Orbital, is moving forward with plans to launch a demonstration satellite equipped with a large mirror to reflect sunlight to specific locations on Earth. The company says the technology could extend the operating hours of solar farms and provide light for disaster zones, but astronomers warn that the mirrors would create severe light pollution, potentially wiping out stars in the areas they illuminate.
The satellite and its purpose
Reflect Orbital has received a license from the S. Federal Communications Commission (FCC) to launch a demonstration satellite called EARENDIL-1 into an orbit 373 miles (600 kilometers) above Earth. The spacecraft will be fitted with a mirror measuring 60 by 60 feet (18 by 18 meters), according to the company. Reflect Orbital says the satellite is intended to test the technology and the safeguards that would control where, when, and how reflected light is delivered.
The company says it has no plans to illuminate Saskatchewan communities in the middle of the night, as some have speculated. It intends to provide light primarily to large solar projects, search-and-rescue operations, and construction sites, which are typically located away from populated areas. Reflect Orbital says every service would require permits, local authority approval, and customer verification before light is delivered. Consultation with Indigenous nations, municipalities, farmers, conservation groups, and residents would be a precondition for providing the service.
According to the company, the illumination inside the targeted area would be equivalent to a full moon. It says the physics of a flat reflector means the reflected light cannot exceed the brightness of the sun itself, and exposure would remain within International Commission on Non-Ionizing Radiation Protection safety limits when viewed through binoculars or a telescope.
Reflect Orbital says it is commissioning research by independent researchers and federal partners to study the effects of artificial nighttime light on wildlife and ecosystems. It is also working on a coordination agreement with the National Science Foundation and conducting environmental studies. The company says its service would be targeted and time-limited, with brightness thresholds calibrated to levels that humans and animals already tolerate. It says it can establish exclusion zones around protected habitats and areas containing endangered species and does not plan to operate over at-risk migration corridors. Its satellites would be turned off when idle and designed to remain below +7 stellar magnitude when not providing service. The company says feedback from astronomers has influenced its spacecraft design and operating plans.
The company says the technology could extend the operating hours of existing solar farms by providing reflected sunlight after the sun has set, producing additional clean energy without requiring new land or transmission infrastructure. Reflect Orbital expects the greenhouse-gas emissions associated with its energy service, including the launch of its satellites on a Falcon 9 rocket, to be comparable to terrestrial solar, though it did not provide a specific carbon-footprint figure. The company says it is taking an incremental approach and expects EARENDIL-1 to be the first of several test missions.
Astronomers' warnings
A study by astronomers, including Gaspar Bakos, a professor of astrophysics at Princeton University, found that each of the sun-reflecting mirrors proposed by Reflect Orbital would appear 40 times brighter than the full moon to observers standing within its beam on Earth. The study found that the light pollution produced by each mirror would completely wipe out stars from the sky for those underneath, turning the starry night into an eerie twilight zone.
"It will be worse than big cities like London. You would not see any stars if you were in the beam," Bakos told com.
The researchers calculated the impact of Reflect Orbital's operational mirrors, which would be 174 by 174 feet (54 by 54 meters) in size, larger than the demonstration satellite's mirror. They found that even at a distance of nearly 9 miles (14 kilometers) from the beam, the sky would be brighter than when the moon is full. At 21 miles (34 kilometers), the light-polluted area above the horizon in the direction of the beam would still appear brighter than the night sky during a full moon.
Bakos said the data suggests that to trigger energy generation even in the most efficient solar panels of today would require the combined reflected light from at least 400 such mirrors at the same time. The combined beam from 400 mirrors would be 10,000 times brighter than the full moon, according to the study. The sky glow resulting from the combined beams would be visible from 50 miles (80 kilometers) away and extend the twilight zone up to 9 miles (14 kilometers) from the beam.
"It would be almost daytime brightness. It would be just like before sunrise. But in fact, that's too low for solar panels to actually operate," Bakos said.
Bakos noted that the overall effect would depend on the reflectiveness of the illuminated surface and the cloudiness of the sky. He also said the light pollution from a town illuminated by the beam would be 10 to 20 times brighter than the artificial lighting in that same town.
The researchers criticized the company for failing to provide technical data to back up its claims. They point to the FCC's decision to license EARENDIL-1, which stirred an outcry among astronomers, environmental campaigners, commercial pilot associations, and other stakeholders. The FCC received around 1,900 objections against the Reflect Orbital application. In its Order and Justification of the mission license, the FCC stated that "impacts on optical astronomy fall outside [the FCC's] review and authorization." Satellite projects are exempt from the National Environmental Policy Act (NEPA), an exemption in place since the 1980s, meaning the FCC did not assess the environmental impact of the reflected light.
Bakos was among the astronomers who filed objections to the FCC against the plan. He said the new study provides hard numbers on Reflect Orbital's impact where previously there were only rough estimates. The study used data on light scattering in Earth's atmosphere based on papers going back decades, which have been extensively tested in real-life situations, he said.
Company response
In response to the study, a Reflect Orbital spokesperson said the findings were based on "inaccurate assumptions" and that "the vast majority of people will never see the light in their lifetime as the vast majority of service locations will be very remote." The spokesperson added that only the satellites required to serve approved locations would be active; inactive satellites would remain below naked-eye visibility.
Reflect Orbital insists that it engaged substantively with legitimate concerns raised by astronomers, environmental researchers, and scientists, and that such feedback informed its technology and operational plans. The company says it is working with NASA and the National Science Foundation and is an industry member of the International Astronomical Union's Centre for the Protection of the Dark and Quiet Sky.
Comparison with Starlink
For context, SpaceX's Starlink constellation currently consists of around 11,000 satellites, and around 30 Starlink satellites are visible in the sky from a single spot on Earth at any point in time. However, Starlink satellites are much smaller and dimmer than the Reflect Orbital mirrors, making the potential light pollution from the latter significantly more severe, according to the astronomers.