The Scouring of the Earth – Eärendil-1, Space Mirrors and International Environmental Law

·       Dr Laurence Atkin-Teillet, Lecturer in Law, Nottingham Law School (https://www.ntu.ac.uk/staff-profiles/law/laurence-teillet)

·       Dr Ian Whittaker, Senior Lecturer in Physics, School of Science & Technology (https://www.ntu.ac.uk/staff-profiles/science-technology/ian-whittaker)

Image Credits: Nasa/Dave Ryan

Few names in literature evoke environmental stewardship quite like Eärendil. In J.R.R. Tolkien’s legendarium, Eärendil becomes the Evening Star, a symbol of hope and harmony between humanity and the natural world. More broadly, Tolkien consistently associates environmental destruction with domination and industrialisation. Morgoth scars Arda itself through exploitation, while Saruman’s industrialisation of Isengard and the subsequent Scouring of the Shire illustrate technological progress pursued without restraint or respect for nature.

It is therefore difficult to imagine a more ironic name for Reflect Orbital’s newly authorised satellite. On 9 July 2026, the United States Federal Communications Commission (FCC) authorised the launch of Eärendil-1, an experimental satellite equipped with an eighteen-metre reflector designed to redirect sunlight from low Earth orbit onto the Earth’s surface after sunset. According to Reflect Orbital, the technology could eventually extend the productive hours of utility-scale solar farms, reduce reliance on fossil fuels during periods of peak electricity demand and provide emergency illumination during natural disasters. The company presents the project as an exercise in responsible innovation, stating that it seeks to demonstrate that “sunlight from space can be an important part of humanity’s clean-energy future” while remaining “good stewards of space”.

This article does not argue that Eärendil-1 violates international environmental law as the customary prevention principle does not prohibit States from authorising environmentally risky activities. Rather, it requires States to exercise due diligence before authorising activities capable of creating significant transboundary environmental risks. The more interesting legal question is therefore procedural rather than substantive. Did the United States exercise the degree of due diligence required by customary international law before authorising a technology intended to modify the nocturnal environment from outer space?

Darkness is an environmental resource

That question only makes sense if darkness itself is recognised as an environmental resource worthy of protection. Increasingly, scientific research suggests that it is.

Life on Earth evolved under predictable cycles of daylight, darkness and lunar illumination. These natural rhythms regulate circadian clocks, migration, reproduction, pollination and predator-prey interactions across terrestrial and marine ecosystems. Darkness is an ecological condition upon which countless species depend. Artificial light at night has now been linked to declining insect populations, disrupted nocturnal pollination, altered migration routes, changes in feeding behaviour and broader ecosystem disturbance. It also limits the ability of humans to observe the night sky, breaking a cultural habit that has endured since humans have existed. To combat the growth of light pollution, sites around the world have been designated ‘dark sky’ areas, it has even affected streetlight design to reduce the glow produced away from the pavements and roads.

Unlike conventional forms of pollution, however, orbital sunlight reflection presents a new challenge. Most artificial lighting originates within the territory of a State, allowing that State to regulate both the activity and its environmental consequences. With Eärendil-1, the activity itself occurs in outer space, an area beyond national jurisdiction, while its environmental effects may be experienced on Earth. Reflect Orbital proposes to manipulate natural sunlight in orbit before redirecting it towards selected locations on the planet. Even if those reflections are geographically targeted and limited in duration, the environmental intervention originates within the global commons and has the potential to affect interests extending beyond the territory of the launching State.

Light does not respect political boundaries, nor do many of the ecological systems potentially affected by artificial illumination. Migratory species, astronomical observations, atmospheric heating, and the integrity of the night sky are fundamentally international concerns. Consequently, the legal framework governing the project cannot be confined exclusively to domestic licensing procedures. It also engages the broader principles of international environmental law, particularly the customary duty to prevent significant transboundary environmental harm.

The FCC’s decision and a regulatory gap

The FCC was clearly aware that Eärendil-1 raised environmental concerns. During the licensing process, it received almost 2,000 public comments from astronomers, environmental organisations and members of the public. Organisations such as the American Astronomical Society, the Royal Astronomical Society and DarkSky International warned that orbital sunlight reflection could interfere with astronomical observations, disrupt nocturnal wildlife, affect biodiversity and contribute to the degradation of the natural night sky.

What is interesting, however, is not that the FCC rejected these concerns, but why. The Commission did not conclude that reflected sunlight posed no environmental risks. Instead, it repeatedly mentioned that those risks largely fell outside its statutory competence. As the FCC’s decision explains, the FCC’s authority “pertains to the licensing and operation of a radio station using radiofrequency spectrum” and it “does not have regulatory authority over the licensing and operation of a solar reflector”. Consequently, it declined to require any further environmental review under the National Environmental Policy Act (NEPA), concluding that the environmental consequences of the reflector were too attenuated from its spectrum licensing decision.

The Commission nevertheless considered the environmental objections arguendo. Even assuming that environmental review was appropriate, it concluded that opponents had not demonstrated that authorising a single demonstration satellite, rather than Reflect Orbital’s proposed future constellation, was likely to produce significant environmental effects requiring an Environmental Assessment.

However, this viewpoint is not shared by the scientific community as even small scale geoengineering is capable of upsetting the environmental balance. Similar techniques have previously been tested from the ground in the Arctic using high-powered radio transmitters to heat layers of the upper atmosphere in order to study their effects on radio signal transmission. Although these experiments operated at only a fraction of the power proposed for Eärendil, they nevertheless accelerated atmospheric chemical reactions and caused signal instabilities, illustrating how seemingly modest interventions can produce unintended consequences.

As a commercial service, Eärendil also proposes to provide a 5 km circle of artificial illumination to customers on request. This raises a number of practical and legal questions. Will there be safeguards to ensure that customers have the legal authority to illuminate all of the land within the affected area? What protections will exist for neighbouring landowners whose properties may be subjected to unwanted artificial light throughout the night? Likewise, how will aviation safety be protected, particularly where bright illumination could interfere with pilots’ vision or require changes to established flight paths during night-time operations?

From the perspective of United States administrative law, the reasoning provided by the FCC is relatively coherent. Federal agencies possess only those powers delegated to them by Congress. International environmental law, however, asks a different question. International obligations attach not to domestic agencies but to States. Whether the FCC possessed statutory authority to undertake a transboundary environmental assessment is therefore not determinative of the United States’ international responsibilities. The more difficult question is whether the United States, as the launching State, exercised the degree of due diligence required before authorising an activity capable of affecting the global commons.

The Prevention Principle

International environmental law has never imposed an absolute obligation to prevent all environmental harm – States remain free to pursue technological innovation and exploit natural resources within their jurisdiction. What customary international law requires, however, is that they exercise due diligence before authorising activities capable of causing transboundary environmental harm.

This duty finds its origins in the Trail Smelter Arbitration (1941), in which an arbitral tribunal held that no State has the right to permit activities within its territory that cause serious injury in another State. Although frequently described as the “no-harm principle”, the rule is better understood as a duty of prevention. States are not required to guarantee that environmental harm will never occur; rather, they must regulate activities within their jurisdiction or control with reasonable care. The principle was subsequently broadened through Principle 21 of the Stockholm Declaration and Principle 2 of the Rio Declaration, both of which extend the duty beyond harm to other States to include damage to areas beyond the limits of national jurisdiction and outer space is itself part of the global commons.

In Pulp Mills, the International Court of Justice recognised that where there is a risk of transboundary harm, States are expected to undertake an environmental impact assessment before authorising the activity. Subsequent decisions, including MOX Plant and Gabčíkovo-Nagymaros, added that due diligence also includes notification, consultation and, where appropriate, negotiation in good faith with potentially affected States. These obligations do not require States to reach agreement or prohibit environmentally risky activities – their purpose is to ensure that decisions are informed, transparent and cooperative before irreversible consequences materialise.

The FCC did not conclude that reflected sunlight posed no environmental concerns, instead, it concluded that assessing those concerns fell outside its statutory authority. Consequently, no transboundary environmental assessment appears to have been undertaken before authorisation, nor does the Order suggest that potentially affected States were notified or consulted. The FCC engaged with scientists, astronomers and civil society organisations, but consultation with expert stakeholders is not equivalent to consultation between States.

The FCC repeatedly stressed that Eärendil-1 is a single demonstration satellite and distinguished it from Reflect Orbital’s longer-term ambition of deploying a constellation capable of extending daylight for utility-scale solar farms. Whether one prototype with the equivalent brightness of the moon is sufficient to trigger the full range of procedural obligations under customary international law is therefore open to debate.

Scientific uncertainty, however, cannot simply be dismissed as evidence that no legal obligations arise – quite the opposite. The precautionary principle developed precisely because waiting for conclusive scientific evidence often means waiting until environmental damage has already occurred. Principle 15 of the Rio Declaration therefore provides that the absence of full scientific certainty should not be used as a reason for postponing measures to prevent serious or irreversible environmental degradation. Although the legal status of the precautionary principle remains contested, it increasingly informs the interpretation of due diligence. Where a technology is unprecedented, its environmental effects uncertain, and its long-term deployment potentially global, the case for careful procedural scrutiny becomes stronger.

That, perhaps, is the greatest irony of Eärendil-1. In Tolkien’s world, Eärendil became a symbol of stewardship because he preserved the light of the heavens. Reflect Orbital’s satellite may yet contribute to a cleaner energy future, but it also reveals how technological innovation is beginning to outpace the legal frameworks designed to govern humanity’s relationship with the global commons. The challenge posed by Eärendil-1 is therefore not just whether orbital mirrors are environmentally desirable – it is whether international environmental law is prepared for an era in which States can deliberately engineer one of the Earth’s oldest environmental conditions from outer space, before the law itself has fully caught up.

Further reading:

FCC, In the Matter of Reflect Orbital Inc. Application for Authority to Construct, Launch, and Operate a Non-Geostationary Orbit Satellite in the Space Operation and Space Research Services (09 July 2026) <https://docs.fcc.gov/public/attachments/DA-26-706A1.pdf>

Ryan Mancini, ‘FCC approves startup’s space mirror to reflect sunlight to dark parts of Earth’ (The Hill, 2026) <https://thehill.com/policy/technology/5968228-fcc-approves-reflect-orbital/>

Hector Linares Arroyo et al., ‘Monitoring, trends and impacts of light pollution’ (2024) 5 Nature Reviews Earth and Environment 417.

Borisova, T.D., Blagoveshchenskaya, N.F., S.Kalishin, A. et al. Effects of modification of the polar ionosphere with high-power short-wave extraordinary-mode HF waves produced by the spear heating facility. Radiophys Quantum El 55, 126–141 (2012). https://doi.org/10.1007/s11141-012-9353-5