GoKawiilSolar energy, at any time of day or night — that’s the dream of space mirror projects. Futurists have been imagining satellite mirrors that could reflect the sun’s light onto the Earth’s surface for over a century. Russian scientists experimented with the concept in the ’90s with the Znamya project. The idea is to put a large mirror in orbit and angle it such that sunlight can be reflected onto a specific geographical area for illumination or the generation of solar power.
Now, the California-based company Reflect Orbital wants to try this idea again, launching a test satellite named Eärendil-1 as a precursor to a fleet of up to 50,000 space mirrors that would provide sunlight on demand as a service. The 18-square-meter mirror satellite has recently been approved for launch by the Federal Communications Commission (FCC) and will create what the company has said will be a 5-kilometer-wide beam of light that could be used for capturing solar energy in so-called solar farms, for boosting agricultural yields, or assisting in search and rescue operations during nighttime emergencies.
The consequences range from disrupting scientific observations to concerns over the safety of the public.
The goal is to benefit companies and municipalities as well, with Reflect Orbital aiming to provide a service to cities to illuminate streets at night, or to provide construction and industrial projects with lighting so that work can be completed faster and more safely.
More clean, renewable energy and help during a crisis — what’s not to like?
If you ask astronomers, there are plenty of concerns. The satellite will be strikingly bright, with estimates placing the illumination as being as bright as Venus from outside the beam and four times as bright as the Moon within the beam. The consequences range from disrupting scientific observations to concerns over the safety of the public, including the potential for permanent eye damage for anyone unlucky enough to be using a telescope in the wrong place at the wrong time.
Experts like Roohi Dalal, deputy director for public policy of the American Astronomical Society (AAS), and Robert Massey, deputy executive director of the Royal Astronomical Society (RAS), have warned that the plan could have disastrous effects on astronomy as a whole, as well as directly harming humans and wildlife in affected areas.
Light pollution has been proven to be a genuine threat to human well-being by disrupting circadian rhythms, and can be devastating to local ecosystems and migratory species in particular. But in the case of Reflect Orbital, the concern is not just the increasing brightness of our skies, but the particular dangers to both people and astronomy that space mirrors can cause.
If you’ve seen reports of streaks of white light trails ruining images from the Hubble Space Telescope, then you already know the kind of damage that can be done to astronomical observations from bright satellites. Reflect Orbital says it will work to avoid shining light on astronomical facilities, but hasn’t stated which facilities will be part of its exclusion zones.
Even with the best intentions to avoid individual facilities, the overall brightness of the sky from the planned tens of thousands of reflective objects in orbit would be an existential threat to astronomy. Not only would the many reflective objects create light trails that could disrupt astronomical images, but the background illumination of the night sky would also rise due to atmospheric scattering. The resultant glow from this scattering would “make the night sky three to four times brighter” in affected areas, according to the RAS.
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