Dimming the Shared Sky

A Cost-Effectiveness Framework for Brightness Compliance in Mega-Constellations

Authors: Polkrit Panluek, Andrew Iwanoczko, Ciara McGrath & Ian Muirhead

Reviewers: Priyanka Dhopade, John Mackintosh & Marieta Valdivia Lefort

Executive Summary

The number of active satellites in orbit has more than quintupled in six years. As of May 2026, over 15,400 are circling the Earth, with roughly two-thirds of them being Starlinks and almost all in low Earth orbit (McDowell, 2026). The night sky is changing faster than the rules designed to protect it.

The clearest cost is to astronomy. Wide-field surveys now find that a fraction of their twilight images are streaked with reflected sunlight, and projections for the next generation of telescopes suggest the problem will worsen considerably before it improves. But the impacts extend further, and they are easy to underestimate because they are still modest. A single city outshines the entire active satellite fleet many times over, and satellites are not currently the dominant source of artificial light at night. What matters is the direction of travel. The coastlines satellites now reach were never touched by urban glow. The dark-sky reserves that offered refuge from ground-based light pollution have no equivalent shelter from a brightness that comes from orbit. And the constellations approved but not yet launched may dwarf everything currently in the sky.

The engineering dimension of this problem is illustrated most noticeably by BlueWalker 3. Its 64.3 m² phased-array antenna reaches an apparent magnitude of 0.4, making it 437 times brighter than the IAU's recommended invisibility threshold of magnitude 7. Applying every mitigation technique demonstrated to date, dark coatings, visors, and operational scheduling, still leaves it 25 times too bright. This is not a problem that can be patched after launch. Once a fleet of this scale is in orbit, the design is locked in for decades. There is no recall, no mid-season redesign, no pit stops.

Governance has struggled to keep pace. The EU Space Act represents the most ambitious attempt to address this, built on a safety-by-design principle that requires environmental considerations to be embedded in spacecraft from the earliest engineering phase. The Commission's June 2025 proposal included a binding magnitude 7 brightness threshold. By December 2025, the Council's negotiating text had removed that numerical limit entirely in response to industry pressure (Council of the European Union, 2025). The legislation remains under negotiation, but voluntary measures tend to deliver inconsistency rather than compliance. Disclosure rates of 78% for public companies compared to 6% for private ones (Callala Support Team, 2025) are not evidence that 94% of private operators are doing nothing, they are evidence that nobody can tell. Without disclosure, self-regulation becomes unverifiable, and unverifiable claims are indistinguishable from empty ones.

This report proposes two practical tools to bridge the gap between regulatory ambition and operational reality. The Cost of Compliance Taxonomy (CCT) organises the full financial burden of meeting a brightness threshold into three categories: the upfront capital cost of hardware and design changes, the ongoing operational cost of monitoring, reporting, and scheduling, and the regulatory risk cost of non-compliance. The Best-Effect-to-Cost (BEC) Framework then ranks mitigation options by the brightness reduction they deliver per pound spent, enabling operators, investors, and regulators to compare strategies on a common ground.

Under optimistic engineering assumptions, zero material degradation and sustained operator commitment, a layered strategy combining visors, dark coatings, and operational scheduling can achieve the magnitude 7 target for a reference 100-satellite, 250 kg-class fleet at an annualised cost of approximately £0.92–1.33 million per year, representing roughly 1–2% of total programme expenditure. That is a significant but not an unreasonably high burden. Neither assumption is guaranteed. In the LEO environment, atomic oxygen, ultraviolet radiation, and thermal cycling degrade coatings continuously, and commercial priorities have historically overridden brightness commitments when no binding standard prevents it. The framework is designed to make this fragility visible, not to hide it. A working tool that can be refined as data improves is more useful than a theoretically complete model that never leaves the page.

Satellite Brightness Mitigation - Polkrit Panluek et al - May 2026 - Web.pdf

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1. Introduction: Problem and Opportunity

1.1 The Growth of Megaconstellations and Its Consequences for the Night Sky

Thousands of new Low Earth Orbit Satellites (LEO) are turning a dark sky into something closer to a glowing, hazy screen. Their reflective surfaces add brightness that did not exist before the space age. What was once the occasional glint of a passing satellite has become a persistent problem. Astronomers now find their images streaked with trails of reflected sunlight, ruining data that took hours or even nights to collect.

These satellites serve a genuine purpose. They deliver global telecommunications, internet connectivity, and the positioning services we rely on daily. But their numbers have exploded. For six decades, the number of active satellites in orbit remained relatively stable, hovering below 2,000. Then, around 2019, the curve went vertical. As of May 2026, there are 15,400 active satellites in orbit around Earth, with 10,260 of them, roughly 66%, being satellites in LEO (McDowell, 2026). This rapid expansion creates a new night-time skyglow, one that compounds the urban light pollution already spilling upward from our towns and cities. Rural areas that once offered refuge for stargazers are losing that sanctuary.

On the surface, this might seem like a minor trade-off compared to the benefits of global connectivity and climate services delivered through Global Navigation Satellite Systems, commonly known as GNSS. These systems, which include GPS, Galileo, and BeiDou, underpin everything from smartphone navigation to precision agriculture and aviation safety. But the consequences run deeper than inconvenienced astronomers. For researchers, the pristine night has become a memory. Bright, variable backgrounds now demand constant data cleaning before observations become scientifically useful.

For life on Earth, satellites are not the dominant source of Artificial Light at Night (ALAN). A single city still outshines the entire active satellite fleet many times over. But satellites may add a distinct and growing layer to the problem, one that reaches places ground-based light pollution cannot. Remote deserts, oceans, and protected dark-sky reserves that have always been shielded from urban glow are now exposed to a diffuse, sky-wide brightening that did not exist twenty years ago (Kocifaj et al., 2021). That matters because the biological systems most vulnerable to ALAN are precisely those that evolved in naturally dark environments.

The broader evidence on ALAN is well established. In humans, chronic exposure suppresses melatonin production and disrupts circadian rhythms, with documented links to sleep disorders, metabolic dysfunction, and increased cancer risk (Touitou, Reinberg and Touitou, 2017). These effects are driven overwhelmingly by terrestrial sources, and it would be a stretch to claim satellites are currently contributing meaningfully to human health burdens. The concern is directional rather than immediate: satellites are steadily adding to a problem that already has measurable consequences, and the trajectory matters more than the current level.

For wildlife, the picture is more direct. ALAN interferes with navigation, foraging, reproduction, and predator-prey dynamics across species (Weber et al., 2025). Sea turtle hatchlings provide the clearest illustration. For millions of years, they have navigated from beaches to the ocean using moonlight and starlight reflected on the water. When artificial light overpowers these cues, hatchlings crawl toward land instead of the sea, where they face exhaustion and predation. In Florida alone, tens of thousands of hatchlings become disoriented each year (Access Fixtures, 2025). Here, the satellite contribution is more plausible than in the human health case. The cues these animals rely on are faint by design, and even a modest increase in background sky brightness can wash them out. Migratory songbirds travelling at night face similar risks, as they depend on stellar patterns for orientation.

There is also a cultural dimension. The 2007 La Palma Declaration, endorsed by UNESCO and the International Astronomical Union (IAU), recognised the night sky as part of humanity's common heritage (UNESCO et al., 2007). The progressive loss of dark skies represents not just a scientific inconvenience but a form of cultural erosion, affecting communities who had no say in the decision to fill LEO with reflective objects.

The scientific community has responded with urgent calls for mandated mitigation. The solutions exist, non-reflective coatings and sun-shields, and design changes can reduce satellite reflectivity before launch (Lalbakhsh et al., 2022, SpaceX, 2022). Simultaneously, researchers are also pushing for better measurement through specialised missions and ground based campaigns to quantify exactly how much sky brightness we are losing and whether mitigation efforts actually work (Walker et al., 2020).

Addressing this problem is complicated by the fact that satellites are already being tracked, but for entirely different reasons. Space Situational Awareness, known as SSA, monitors satellites to prevent collisions by predicting where objects will be and when. To the untrained eye, SSA observation appears visually similar to astronomical observation, yet serves a different purpose. Astronomers require access to this same positional data not for tracking purposes, but to actively mitigate light pollution (Walker et al., 2020), either through software that closes the shutter during a satellite pass or by cleaning contaminated observational data. Positional safety and environmental contamination are related problems, but they require different data and different solutions.

Regulatory frameworks are beginning to address this brightness crisis, though the path forward remains contested. The European Commission's original proposal for the EU Space Act, published in June 2025, was built on a core principle of “safety-by-design”. The idea is that environmental and safety considerations must be embedded into spacecraft from the earliest engineering phase, not bolted on afterward. The proposal established that the costs of commercial space must not outweigh the benefits, and it included a requirement that defined visual magnitude threshold throughout their operational lifetime (European Commission 2025). However, following industry feedback submitted in November 2025, the Council’s December 2025 negotiating text deleted this numerical threshold entirely (Council of the European Union, 2025). The current draft may require operators to submit a plan with adequate measures, but it sets no binding brightness limit. Section 1.2 examines this regulatory debate in detail, including the specific concerns raised by major operators.

This raises a fundamental question. Can regulatory frameworks that mandate processes without specifying performance deliver consistent brightness reductions across satellite fleets, especially as constellations scale in size and complexity? History suggests that without clear benchmarks, well-intentioned requirements often go unmet. The evidence from corporate responsibility research is telling that, while 78% of public companies disclose environmental impacts due to regulatory requirements, only 6% of private companies disclose voluntarily (Callala Support Team, 2025). It would be unfair to read this as proof that 94% of private companies are doing nothing. Some are almost certainly acting responsibly behind closed doors. The problem is that no one can tell which ones. Without disclosure, self-regulation becomes unverifiable, and unverifiable claims are indistinguishable from empty ones. A regulator cannot enforce what it cannot see. An investor cannot reward what it cannot measure. A competitor cannot be held to a standard that no one is required to meet publicly. In markets where mitigation costs money and performance is hidden, the rational operator has every incentive to cut corners and hope no one notices. This is why the 78% versus 6% gap matters, not because disclosure equals action, but because disclosure is the precondition that makes action measurable, comparable, and accountable. Consequently, the shift toward formal, performance-based standards is a recurring theme in policy analyses and governance discussions, including International Institute of Space Law (IISL) discourse and broader cross-border governance debates (Walker et al., 2020; Hainaut and Moehler, 2024; Halferty et al., 2022). Such standards are necessary not only to force action but also to enable consistent, meaningful reporting of mitigation efforts. Unless regulatory frameworks such as the EU Space Act are adopted globally, the future promises a sky obscured by ever-expanding constellations and steadily increasing diffuse sky brightness.

1.2 The Regulatory Framework

The Proposal for a Regulation of the European Parliament and of the Council on the Safety, Resilience and Sustainability of Space Activities in the Union (COM(2025) 335), widely known as the EU Space Act, represents Europe’s most ambitious attempt to govern commercial space activities (European Commission 2025, Hitchens 2025). At its core is a principle of safety by design. This means safety and sustainability features must be built into the satellite and launch vehicle from the initial engineering phase, not added as afterthoughts (European Commission, 2025).

Crucially, the proposal is designed to take the form of a Regulation, and not a Directive (Technology's Legal Edge 2025, EJIL: Talk! 2025), aiming to ensure a consistent regulatory landscape across Europe. This decision may be the single most important factor for its effectiveness.

• Uniform Standards: A Regulation means that once adopted, the rules will be directly applicable and binding in all EU member countries simultaneously, ensuring uniform standards without requiring each country to write its own national law. This is a strategic move, as the Commission justified choosing this path by arguing that the current fragmented rules (13 different national systems) are an obstacle to the EU’s internal space market (EJIL: Talk!, 2025).

• Target Dates: Given the ambitious target application date of the 1st of January 2030 (Technology's Legal Edge, 2025), the Act introduces a predictable timeline. A critical part of the plan involves using budgeting tools tied to measurable results to make sure performance-based standards, such as mandatory brightness goals, are actually met.

Anticipating the EU’s global influence is also understood to have helped shape the drive toward consistency across the internal market. The Act lifts the bar and given the global interconnectedness of space companies and supply chains, the EU intends the standard to be one that space companies outside of Europe may also adopt in order to supply into and work with EU companies (European Commission 2025, Hitchens 2025, Taylor Wessing 2025).

However, the Act’s provisions on satellite brightness have proven contentious. The Commission’s original June 2025 proposal included a requirement that satellites remain at or above magnitude 7 throughout their operational lifetime (European Commission, 2025). On the astronomical magnitude scale, higher numbers indicate fainter objects, meaning a magnitude of 7 would render satellites barely visible or invisible to the naked eye. This threshold was considered essential for preserving the darkness of the night sky, but it also represented a significant technical challenge for operators.

The industry response, submitted in November 2025, was revealing. Eutelsat supported graduated requirements but wanted the language softened from satellites “maintaining” a threshold to being “designed with the aim of achieving” it (Eutelsat, 2025). SpaceX described any fixed magnitude requirements as “technically infeasible” (SpaceX, 2025b). Amazon’s Kuiper project was bluntest of all, stating that “neither Kuiper, nor the satellite industry more broadly, have so far been able to develop technology that consistently mitigates brightness” to the threshold originally specified (Amazon, 2025). All three companies support working with astronomers and have invested in mitigation efforts. But they share a concern that setting an unachievable standard as a hard requirement could backfire, potentially ending the collaborative environment where solutions are freely shared.

The Council’s December 2025 negotiating text responded to this feedback by deleting the numerical brightness threshold entirely (Council of the European Union, 2025). The current draft requires operators to submit a plan with adequate measures and reference standards are still being developed, but it sets no binding brightness limit. It is important to note that nothing is final. The EU Space Act remains under negotiation between the European Parliament, Council, and Commission. The brightness threshold could be reinstated, modified, or replaced with an alternative approach. What we are seeing now is a snapshot of a moving target, and the final legislation may look quite different from the current draft.

This uncertainty creates a gap between regulatory ambition and operational reality. Even if a brightness threshold is eventually adopted, operators will face challenges translating that limit into actionable engineering and business decisions. Satellite companies must balance cost, timelines, performance, and compliance. Regulators need methods to verify mitigation claims. Scientists require standardised comparison frameworks.

What is missing is a conceptual bridge between regulatory compliance and practical spacecraft engineering (Bassa, Hainaut and Galadí-Enríquez, 2022, Hall, 2021). There is a need for a methodological tool: one that could translate performance requirements into design choices, budgets, and schedules. This report proposes such a framework, the Cost of Compliance Taxonomy (CCT) and Best-Effect-to-Cost (BEC) Framework, which is detailed in Section 1.6, below. This framework requires validation with industry data, but it offers a starting point for the conversations that need to happen.

1.3 Standardised Brightness Measurement and Reporting Protocols

Even if regulators agree on a brightness threshold, achieving consistent, verifiable compliance requires addressing a fundamental technical challenge. The apparent brightness of a satellite shifts constantly depending on several interacting factors, but three are especially significant. These are the angle of the sun, the position of the observer, and the attitude of the satellite itself, meaning its orientation in space (Mallama, 2021). Unlike an ideal surface that scatters light evenly in all directions, satellite surfaces reflect light unevenly depending on viewing geometry, a property known as non-Lambertian reflectance (Lu, 2024). To put this in practice, a satellite that appears faint from one location might be blindingly bright from another just minutes later. Without a standardised method for measuring and reporting brightness across these varying conditions, comparing satellites or verifying compliance becomes effectively impossible.

To understand why this matters, consider how astronomers measure brightness. They use a scale called apparent visual magnitude, written as MV. The magnitude scale is inverted, so lower numbers mean brighter objects. Under ideal conditions, with dark skies and a star near zenith, the naked-eye can detect dark objects as faint as approximately MV = 6 (Cinzano, Falchi and Elvidge, 2001). But conditions are rarely ideal. Stars near the horizon appear significantly dimmer than those overhead because their light must pass through more atmosphere. Astronomers call this overhead position the zenith. A star sitting just 10 degrees above the horizon loses nearly a full magnitude of brightness compared to one at zenith (Flanders, T and Creed, P.J. 2008). For regulatory purposes, the practical implication is clear. Any satellite routinely brighter than magnitude 6 or 7 becomes more visible to the naked eye under dark skies, directly contributing to the degradation of the night sky.

This can create confusion. For example, a statement suggesting a satellite of magnitude MV= 4 cannot be seen over the dark skies of the Peak District or the UK countryside is incorrect. Since MV= 4 is numerically lower than MV = 6 limit, the satellite is, in fact, more easily visible and brighter than the threshold of invisibility. That same satellite might be entirely invisible over a light polluted urban centre like Manchester, where the night sky itself is much brighter. The International Astronomical Union (IAU) recommends the standard of MV = 7 or fainter, a threshold derived from studies on the Vera C.Rubin Observatory, where it represents the limits at which detector artifacts can still be corrected, effectively invisible without a telescope (Tyson et al. 2020).

For governance, the IAU Centre for Protection of the Dark and Quiet Sky suggests clear brightness bands to guide regulatory policy, shown in Table 1 (IAU CPS, 2025).

Table 1:   Satellite Brightness Categories and Policy Thresholds

Brightness Band	Magnitude (MV)	Visibility Description	Policy Relevance
Invisible Goal	MV ≥ 7	7 Generally invisible to the naked eye, dimmer than faintest stars	Mandated Policy Standard
Marginal Visibility	6< MV ≤ 7	Barely visible, may be seen only under very dark, rural skies	Close to the human visual limit (MV = 6)
Readily Visible	MV < 6	Easily visible, clear light pollution, even in mildly polluted skies	Should be avoided to protect dark sky environments

The last category highlights the problem of extreme reflectivity. For example, the BlueWalker 3 satellite peak brightness reached an apparent V-band magnitude of about MV = 0.4. Because the magnitude scale is logarithmic, that seemingly small numerical gap translates to 437 times brighter than the IAU recommendation, as shown in Section 1.4.1 (Nandakumar et al., 2023).

Because raw measurements vary so widely, any regulatory standard needs a protocol that makes them comparable. To enable meaningful comparison and verification, each brightness report should clearly state what instrument and filter was used, the airmass, the phase angle.

Airmass refers to how much atmosphere the light passes through before reaching the observer. A satellite at zenith has an airmass of 1. One near the horizon might have an airmass of 5 or more, meaning its light travels through five times as much atmosphere, which dims and reddens it (Green, 1992). Reporting airmass allows observers to correct for these atmospheric effects.

Phase angle, in this context, is the angle between the sunlight hitting a satellite and the light reflected back toward the observer. In practice, this means the sun to satellite to observer angle. A phase angle near zero degrees means you are essentially looking at the satellite with the sun behind you, so the satellite appears fully illuminated, much like a full moon. As that angle increases, the observer starts seeing more of the satellite’s shadow side (Astronomy Staff, 2023). The brightness of any object is a function of this geometry. Since satellite brightness depends heavily on phase angle, recording it is essential for meaningful comparison.

The solution to standardising these variable measurements is to report the apparent V-band magnitude at zenith, with Bidirectional Reflectance Distribution Function (BRDF) corrections applied. The BRDF is essentially a mathematical tool that accounts for how a satellite’s surface reflects light differently depending on viewing angle. It converts the variable light measurements into a single, standardised number, providing everyone with a shared measurement system, which may be essential for international cooperation (Lu 2024, Hainaut and Moehler 2024, Hall 2021). Modern BRDF-based models are now reliable and commonly used to turn observed brightness into a consistent V-band reference across different viewing angles and surface types. This makes comparisons across constellations possible for both astronomy and ecology monitoring (Lu 2024, Hall 2021).

1.4 The Market-Driven Approach: Strengths, Weaknesses, and Transformative Needs

1.4.1 The Magnitude Challenge and the Failure of Incrementalism

The satellite industry has traditionally favoured a "learning by doing" approach, deploying fleets quickly, testing mitigation measures in orbit, and making incremental improvements over time. This strategy prioritises speed to market and allows operators to refine their designs based on real-world performance. It works well for commercial agility. But when applied to environmental concerns like brightness mitigation, it runs into a fundamental problem (Walker et al. 2020, International Institute of Space Law 2023).

To understand why, consider what incremental improvement actually delivers. Current mitigation efforts have been tested primarily on smaller Starlink satellites (Nandakumar et al. 2023, Lalbakhsh et al., 2022). Dark coatings reduce brightness by a factor of 7.6. Visors reduce it by a factor of 2.3 (Halferty et al., 2022). Combined, these measures achieve a reduction of roughly 17.5. For a typical Starlink satellite, that represents meaningful progress.

But to properly stress-test these mitigation strategies, it helps to examine a worst-case scenario. BlueWalker 3 is that scenario. Launched in 2022 by AST SpaceMobile, it carries a 64.3 m2 phased array antenna, one of the largest commercial structures ever deployed in LEO. At peak brightness, it reaches magnitude 0.4, making it one of the brightest objects in the night sky and briefly outshining all but a handful of stars (Nandakumar et al., 2023). If incremental mitigation can work anywhere, it needs to work here. If it cannot, that tells us something important about the limits of the current approach.

To meet the IAU recommended goal of MV = 7.0, BlueWalker 3 would need to become 437 times dimmer. This reduction factor is calculated using the standard Pogson Equation (Pogson, N. 1856), which describes the logarithmic relationship of the magnitude scale. Assuming the same mitigation strategies tested on Starlink satellites could be applied to the BlueWalker 3, the results would look something like Table 2.

Table 2: Estimated Mitigation Outcomes for BlueWalker 3

Mitigation Strategy	Starlink Trail Flux Reduction Factor	BlueWalker 3 Estimated	Outcome Still Short of MV of 7.0 Goal by…
Dark Coatings	7.6 (Halferty et al., 2022)	MV = 2.6	57 x
Visor	2.3 (Halferty et al., 2022)	MV = 1.3	190 x
Combined	17.5	MV = 3.5	25 x

Even combining the most effective incremental mitigation steps demonstrated to date only achieves MV = 3.5, leaving the satellite easily visible and 25 times short of the policy threshold. This estimate is deliberately generous. The Starlink-derived reduction factors assume mitigation measures scale directly from one spacecraft design to another. Still, BlueWalker 3's brightness is driven primarily by its 64.3 m² phased-array antenna rather than its bus (Nandakumar et al., 2023). Dark coatings and visors developed for a compact Starlink platform cannot simply be ported across to a 10-metre deployable antenna, and currently there is no published evidence that they would achieve the same reduction factors on such a different structure. Attitude control, tilting the antenna so that it does not reflect sunlight directly toward Earth, may in practice do more than coatings for satellites of this class, and AST SpaceMobile's own observations suggest reorientation can produce meaningful temporary dimming (Nandakumar et al., 2023). But attitude-based mitigation trades brightness against service availability, since the antenna must point at users to function. The broader point survives the uncertainty. If the most optimistic application of proven Starlink mitigations still leaves BlueWalker 3 twenty-five times too bright, then the realistic figure, accounting for differences in geometry and the operational cost of attitude manoeuvres, is almost certainly worse. Incremental fixes cannot close this gap.

This challenge runs deeper than simple arithmetic. Dark coatings, the most effective optical measure, create a significant engineering trade-off. By reducing reflectance, they increase absorbed solar heating, potentially leading to severe thermal control challenges for the spacecraft (Nandakumar et al., 2023). The DarkSat trial deployment faced these thermal and mission constraints, demonstrating that mitigation is not a simple add-on but requires integrated thermal and radio frequency co-design from the start, potentially involving advanced materials like Sandwich-Structured Fluorinated Polyimide Aerogel before fleet deployment (Shi et al., 2024).

This is where the learning by doing approach becomes problematic. Consider Formula 1 racing. Teams can bolt on new front wings or change tyre compounds within races and refine performance incrementally throughout the season. Satellites do not have that luxury. Once a fleet design is deployed at scale and locked into orbit, changes become prohibitively expensive, there is no pit stop, no midseason development, no chance to tear down the design and start fresh. The analogy extends further. In Formula 1, regulations exist not only to ensure safety but to create a level playing field. All teams must design within the same constraints, preventing a race to the bottom where the cheapest or most reckless approach wins. The same logic applies to satellite brightness. Without mandatory standards, operators who invest in mitigation bear costs that their less risk-tolerant competitors avoid. This punishes the responsible operators and rewards the ones cutting corners. Mandatory thresholds flip that dynamic. They ensure that all operators compete on the same terms, rewarding innovation in mitigation rather than penalising it. The incremental approach assumes problems can be fixed after launch. But the magnitude of reduction required for larger platforms like BlueWalker 3, which remains 25 times short even after combined mitigation, demands fundamental design changes from the outset (Nandakumar et al. 2023, Lalbakhsh et al. 2022, Halferty et al. 2022). By the time operators discover their mitigation is insufficient, billions of pounds may already be committed to a flawed design that will remain in orbit for decades.

1.4.2 Field of View Impacts

The problem of bright satellites becomes more serious for telescopes with a wide field of view (FOV), particularly wide-field surveys and imaging instruments. The technical hazard likelihood for these systems increases for two main reasons (Bassa, Hainaut and Galadí-Enríquez 2022, Tyson et al., 2020):

1. Increased Contamination probability: A wider FOV means the telescope is looking at a larger patch of sky at once. The larger the patch, the greater the chance that one or more satellites may pass through it during an exposure, simply because a greater proportion of sky is monitored simultaneously.

2. Increased Area Lost: LEO satellites at around 550 km altitude travel at roughly 7.6 km/s, which translates to an apparent motion across the sky of about 0.1 degrees per second near the horizon and up to 0.8 degrees per second at zenith (Osborn et al., 2022). That is far slower than a meteor, which flashes past in a second or two, but much faster than any star, which appears essentially fixed. A telescope taking a long exposure, therefore, sees the satellite sweep steadily across its field of view, carving a long streak rather than contaminating a single point. The length of that streak scales with the satellite's angular velocity and the exposure duration. Counter-intuitively, the slower the satellite moves and the longer the exposure, the more of the image is ruined.

   
   

Empirical and modelled evidence strongly support this. The Zwicky Transient Facility reported satellite streaks in 18% of twilight images (Nature, 2022). Projections for the Rubin Observatory point the same way. Tyson et al. (2020) modelled a scenario in which 48,000 unmitigated LEO satellites, at an apparent magnitude of 4.5, were in orbit simultaneously in a modelled future scenario, and found that roughly 1% of pixels in LSST images taken during nautical twilight would need to be masked to remove satellite trails. Heavier impacts follow for brighter satellites, and twilight windows are precisely when fast-moving satellites are most visible against a still-dark sky. These numbers become more sobering when set against broader industry projections of approximately 100,000 active satellites in orbit by 2030.

Consequently, wide-field, high-cadence surveys suffer more frequent and larger-area streaks than narrow-field instruments. This loss is critical because certain science cases, such as deep faint object photometry or rapid transient follow-up, are often irrecoverable after streak contamination. This FOV-driven exposure loss provides a strong technical argument for upstream brightness limits and fleet-level mitigation, rather than relying on inadequate post-processing techniques (Tyson et al., 2020).

1.4.3 The Limits of Voluntary Mitigation and the Need for Regulation

Voluntary mitigation is not worthless. A satellite dimmed by a factor of five still represents an improvement over an unmitigated baseline. The cumulative benefit is real (Weber et al. 2025, Eutelsat 2025, Amazon 2025, SpaceX 2025b). But voluntary measures depend on each operator choosing to act, choosing how much to invest, and choosing which mitigation methods to apply. Without coordination, different operators may achieve different levels of reduction, some meaningful, some marginal, some none at all. The result may be inconsistency across fleets and constellations, falling well short of the thresholds that regulators and astronomers have called for.

The pattern is familiar from other sectors. In the UK, voluntary agreements between the government and supermarkets ran from 2006 to 2009, with a target to reduce plastic bag use by 50%. It achieved a 48% reduction. But once the agreement ended, plastic bag consumption in England increased by 21.4% between 2010 and 2014. The voluntary commitment did not stick. By contrast, when Wales introduced a mandatory 5p charge on single-use carrier bags in 2011, usage fell by 78% over the same period (House of Commons, 2024). The lesson is straightforward. Voluntary measures may deliver short-term gains, but without binding requirements, those gains may evaporate once attention moves elsewhere.

The core issue is that incremental, uncoordinated improvements carry two major hazards that undermine whatever cumulative benefit they might otherwise provide:

1. Systemic Defeat by Scale: As demonstrated in Section 1.4.1, a 17.5 times reduction is dramatically insufficient for large, bright platforms like BlueWalker 3. For large constellations, the cumulative light from tens of thousands of slightly dimmed satellites still results in a massive, systemic increase in diffuse sky brightness. You cannot fix that by addressing individual glints one at a time. The problem is the fleet, not the satellite.

2. The "Good Enough" Trap: Relying on voluntary fixes risks operators deeming their efforts good enough after achieving only marginal reductions. They may point to the improvements they have made, declare the problem addressed, and move on. This may delay investment in the fundamental design changes necessary to achieve meaningful brightness thresholds. Worse, it could lock in billions of pounds across entire fleets into designs that remain inadequate for decades (Hall, 2021).

   
   

The conclusion is difficult to avoid. Small, voluntary fixes may not create the necessary consistent brightness reductions across all constellations worldwide. Without a stronger system of mandatory measurement and enforceable regulation, operators may have little incentive to go beyond good enough (Weber et al. 2025, Hall, 2021). The market alone may not solve this problem. It needs a frame that makes compliance measurable, verifiable, and unavoidable.

1.5 The Urgency of Action: A pragmatic Five-Year Operational Programme

The night sky is changing faster than regulators can write rules. Modern telescopes can detect the faintest increase in background brightness. A single satellite glint can ruin hours of data collection. These scientific realities justify starting technical work and early mitigation trials now, rather than waiting for final legislation to emerge from Brussels.

EU lawmaking takes time by design. The five-year timeframe proposed here should be understood as the window available for agreed-on measurement standards, running pilot projects, and sending clear market signals, all before mandatory rules take effect. This window can be aligned with the Commission's legislative schedule once the final text of the EU Space Act is confirmed (European Commission, 2025).

Voluntary measures matter, but history tells us they rarely deliver consistent results on their own. Section 1.4.3 made this case in detail. For this reason, the programme below begins with voluntary action but converts to mandatory requirements if targets are not met. This incentivises good behaviour earlier in the timeframe, potentially leading to compliance in the long run.

The evidence from sustainability reporting supports this approach. Research shows that voluntary disclosure alone rarely produces consistent and detailed participation across an industry. Jackson and his colleagues found that voluntary schemes can even create perverse incentives, firms may delay genuine improvements until after mandatory rules take effect, exploiting the gap rather than leading the change (Jackson et al., 2020). Christensen and his colleagues reached a similar conclusion, voluntary corporate social responsibility reporting tends to be selective, inconsistent, and difficult to compare across companies, limiting its effectiveness for stakeholders who need reliable data (Christensen, Hail and Leuz, 2021). These patterns suggest that relying on goodwill alone will not protect the night sky.

The five-year operational programme in Table 3 proposes three sequential phases, each with explicit triggers that determine when voluntary pilot actions should transition into binding standards.

Table 3: Five-Year Operational Programme Phases

Timeframe (month)	Deliverable	Policy Objective
0-12	Measurement and Validation	The goal is to agree on a common photometric and observational metric, conduct inter-laboratory validation, and secure baseline datasets for representative observatories and protected areas. These baselines allow incremental orbital contributions to be measured and verified.
12-36	Pilot and Market incentives	This stage could include field testing certification pilots for lower brightness satellite designs and aligning targeted public procurement and concessional finance with certified designs to stimulate early market demand and reduce first mover risk.
36-60	Scale and Regulation	Performance is evaluated against pre-announced conversion thresholds. If the benchmarks are not met, the system transitions to binding, performance-based reporting and licensing requirements, coordinated with the Regulation’s implementation timelines (European Commission, 2025).

Shifting operators’ risk-return incentives requires strategic tools. These measures are sequenced so that early commercial success leads to the required sector-wide standards when voluntary adoption rates prove too slow. Table 4 below outlines the key policy instruments, their strategic benefits, associated risks, and implementation considerations (Christensen, Hail and Leuz, 2021), (Jackson et al., 2020).

Table 4: Policy Instruments for Brightness Compliance

Policy Instrument	Instrument Strategic Benefit	Risk/Challenge	Cost
Government Contracts for Compliant Satellites	Satellites Government agencies commit to purchasing only compliant satellites, creating guaranteed revenue streams for early adopters and reducing market entry risk.	Established companies might have an easier time meeting requirements than start-ups, potentially blocking new competitors.	Medium – Requires coordination across government departments and contract restructuring.
Finance and Insurance Conditionality	Banks link favourable lending rates to operators that meet brightness standards, adding a cost-of-capital signal to compliance. On the insurance side, the realistic ask is narrower. An industry-wide agreement that underwriters will not penalise operators for adopting approved brightness mitigations, even where those measures involve novel materials or deployable hardware. Without this, operators face a perverse incentive where compliance raises their premiums.	Brightness compliance is not itself a loss-risk factor that insurers can easily price, and some mitigation measures (dark coatings, deployable visors) may genuinely increase engineering risk. Insurance neutrality therefore requires explicit agreement rather than market forces alone. Banking-side conditionality is more straightforward but risks disadvantaging smaller operators if applied too quickly.	Low to Medium – Uses existing banking systems; insurance neutrality requires sector-level negotiation rather than new capital.
Targeted R&D Support	Public funding accelerates development of advanced mitigation technologies (dark coatings, thermal management), sharing the upfront costs of innovation.	Some funded tech might never work commercially. Established companies might capture most of the funding, leaving small-scale innovators behind.	High – Requires sustained public investment for research programmes.
Third-Party Certification with Mandatory Reporting	Independent bodies verify brightness claims and publish results publicly, ensuring accountability and enabling cross-operator comparison.	Certification costs may disadvantage smaller operators; establishing credible, accredited certification bodies requires time and money.	Medium – Ongoing costs for certification audits and verification.

1.6 The Practical Aim and Policy Pathway

The principal objective of this report is to close the gap between what regulators demand and what engineers can deliver. The gap is non-trivial. Regulators speak to thresholds and compliance deadlines. Operators speak in mass budgets, thermal margins, and unit economics. Without a shared language, the conversation stalls. This report proposes a conceptual methodology, the Cost of Compliance Taxonomy (CCT) and Best-Effect-to-Cost (BEC) Framework, designed to bridge that divide and move the industry toward auditable, policy-grade financial metrics.

1.6.1  The Intent of the Framework

The CCT and BEC Framework are designed to work together, translating abstract regulatory requirements into concrete business decisions that operators, regulators, and investors can all understand.

The CCT provides a structured way to calculate the total financial burden of meeting the targeted brightness threshold. It breaks compliance costs into three categories. First, CAPEX, the upfront money needed for hardware, testing, and design changes. Second, OPEX, the ongoing running costs for software, monitoring, reporting, and staff; and Third, Regulatory Risk Cost, the financial exposure from potential fines, licensing delays, or enforcement actions if compliance fails. By making these costs explicit and comparable, CCT enables operators to budget for compliance while allowing investors to assess regulatory risk exposure.

The BEC Framework goes further. It ranks mitigation options based on their Cost per Unit of Effectiveness (CUE), essentially how much brightness reduction you get for every pound spent. Each mitigation measure is evaluated across four dimensions:

1. Technical Effectiveness, measuring how much brightness is actually reduced.

2. Implementation Cost, capturing the true total cost including both CAPEX and OPEX.

3. Operational Impact, assessing effects on satellite performance and mission constraints.

4. Regulatory Alignment, determining how well the measure satisfies policy requirements and reporting standards.

   
   

This multi-dimensional scoring system prevents operators from falling into the Good Enough trap, where cheap, partial fixes are chosen over fundamental design changes that would achieve compliance.

1.6.2  The Fragility of the Framework

The greatest weakness of this study is its optimism. The space sector has historically guarded its data closely, citing corporate confidentiality as essential to competitive advantage. Some of this restraint traces back to the industry’s deep links with defence. Some reflect a belief that environmental accountability simply does not apply to operations beyond the atmosphere. Whatever the cause, the result is the same, verified, firm-level cost data remains scarce.

This study proceeds by defining a methodology grounded in established cost-effectiveness principles, with the full recognition that its true value is only realised when comprehensive, verified industry data becomes available. The CCT framework adapts standard CUE analysis to the novel domain of satellite brightness mitigation. While the underlying methodology is well-established in fields such as health economics and environmental policy, its specific application to satellite constellation design is original to this study and has not yet been empirically validated. This is analogous to Probabilistic Life Cycle Assessment (LCA), where the methodological approach is widely accepted. Still, its practical utility in any specific application depends entirely on the quality and completeness of data input. Like Probabilistic LCA, the CCT can function with incomplete data by using ranges, sensitivity analysis, and conservative assumptions. Still, its credibility and regulatory acceptance will improve dramatically as verified industry data replaces hypothetical estimates.

1.6.3  Conceptual Methodology 

The methodology-driven strategy is designed to achieve three strategic outputs:

• Framework Design: Design and validate the CCT and BEC methodologies, linking technical choices like dark coatings or visors to their financial costs and regulatory risk.

• Regulatory Pathway Validation: Demonstrate that the phased pathway outlined in Section 1.5, above, can successfully move from voluntary measures to mandatory standards. The CCT and BEC methodologies provide the standardised measurement tools and auditable data that regulators need to verify compliance and enforce brightness thresholds.

• Global Scalability: Establish a toolkit whose methodology can be adopted by any country, regardless of their existing regulatory system, to assess compliance costs and rank mitigation options using standardised metrics.

1.7 Structure of the Report

The remainder of this report builds the case for the CCT and BEC Framework, tests its assumptions, and confronts its limitations honestly.

Chapter 2: The Strategic Mandate

This chapter frames the governance problem at the heart of satellite brightness regulation. Regulators need comparable, verifiable performance data. Operators need commercial flexibility and cost control. These demands often pull in opposite directions. The chapter explains why voluntary models tend to fail in practice and why a phased regulatory pathway, starting with incentives and converting to a mandate if targets are missed, offers a more credible route forward.

Chapter 3: The BEC and CCT Framework

This chapter formally defines the BEC and CCT methodologies, walks through the computational procedures, and provides worked examples using a hypothetical 100-satellite constellation. It also identifies where the framework breaks down, where industry data is withheld, selectively disclosed, or manipulated to present a favourable picture. A methodology is only as reliable as the inputs it receives, and this chapter makes that dependency explicit.

Chapter 4: Limitations of the Frameworks

This chapter addresses the limitations of the report as a whole, the assumptions that remain untested, the data gaps that persist, and the conditions under which the framework’s conclusions would need to be revised.

Chapter 5: Conclusions

This chapter draws conclusion and sets out what comes next, for operators weighing compliance investments, for regulators drafting enforceable standards, and the broader effort to protect a night sky that belongs to everyone.

https://video.wixstatic.com/video/e8d4ff_00c32adc83474ea0990edf45c10ecdba/1080p/mp4/file.mp4

2.  The Integrated Synthesis: View A versus View B, and the Strategic Resolution

2.1 View A: The Push for Strict Rules (The Regulator’s View)

The case for mandatory brightness rules rests on two foundations:

1. Environmental: Protecting orbital sustainability and terrestrial environments alike, from astronomical research to public health, from ecosystems that depend on natural darkness to the cultural value of a sky that humans have navigated by for millennia.

2. Accountability: The demand from policy experts that companies must prove their results, not merely promise them.

Section 1 documented the scale of the problem. Here, the question shifts, what do regulators actually need to address it?

The IISL and the IAU Centre for the Protection of the Dark and Quiet Sky have been explicit. Safety by design may only work if two conditions are met.

1. Standardised Measurement: Everyone must agree on how to measure brightness using consistent protocols, so that a magnitude reported in Edinburgh means the same thing as one reported in Chile.

2. Verified Compliance: Operators provide full technical data, including BRDF measurements, thermal models, and operational parameters, to an accredited third-party certifier. The certifier verifies compliance with brightness thresholds and may issue a certificate. Regulators and the public may receive the certificate of compliance rather than the underlying proprietary data. This protects commercial confidentiality while ensuring accountability.

   
   

This certification-based model enables compliance verification without forcing public disclosure of sensitive commercial information. It also facilitates international cooperation. Certificates issued in one jurisdiction can be recognised in another, reducing duplication and friction.

Recent observations show just how far the industry has drifted from acceptable limits. A December 2025 study published in Nature modelled the impact of up to 560,000 satellites projected or proposed for deployment by 2030- 2040. The findings are that if these constellations are completed, one third of Hubble Space Telescope images will contain satellite trails, and 96% of exposures from newer space telescopes like SPHEREx, ARRAKIHS, and Xuntian will be affected. Xuntian alone would average 92 satellite trails per exposure (Borlaff et al., 2025). The current 15,000 satellites represent less than 3% of what is coming. By late 2025, research published in the Monthly Notices of the Royal Astronomical Society confirmed what astronomers had feared, nearly all satellites from major constellations, including Starlink, BlueBird, Qianfan, Guowang, and OneWeb, exceed the magnitude 7 brightness limit established by the IAU for protecting professional astronomy. Most also exceed the magnitude 6 threshold where they become visible to the naked eye (Mallama and Cole, 2025).

In the United States, the Federal Communications Commission now requires satellite operators to coordinate with the National Science Foundation on mitigating impacts to optical astronomy, a condition (FCC, 2023). However, these are coordination requirements, no brightness limits. The FCC still does not set optical brightness thresholds, and in August 2025 proposed excluding satellite operations from environmental review entirely on the grounds that they are “extraterritorial activities" (AAS, 2025). This proposal drew sharp criticism, as the American Astronomical Society argued that light pollution and radio frequency interference clearly impact US territory, while 17 state attorneys general warned the FCC cannot ignore environmental consequences of launch emissions, re-entry debris and orbital congestion. Reply comments closed in October 2025, and the FCC is now drafting a final rule, such the outcome remains contested (AAS, 2025). At the international level, the UN Committee on the Peaceful Uses of Outer Space (COPUOS) adopted a five-year agenda item on dark and quiet skies in 2024, a significant step led by the delegations of Chile and Spain with IAU support (IAU CPS, 2024). But COPUOS operates by consensus among 102 member states, and its recommendations remain non-binding.

The EU has an opportunity to establish leadership in this area. By defining maximum brightness thresholds, standardising reporting requirements, and ensuring operator accountability, the EU Space Act could set a precedent that shapes future international standards (Bastida Virgili et al. 2016, Hall 2021). This regulatory leadership aligns with the Act's safety by design principle.

Critical Limitation of View A

While setting mandatory standards is politically and ethically essential, pursuing regulation alone carries a timing risk. The EU Space Act's target implementation date is January 2030, with a two-year transitional period for assets already in the critical design phases, (Technology's Legal Edge, 2025). By then, major constellations from SpaceX, Amazon, and Chinese operators may already be fully deployed. Tens of thousands of satellites locked into orbits with designs that cannot be recalled. The regulator's imperative is sound, but the question is whether legislation can move fast enough to matter.

2.2 View B: The Case for Flexibility (The Operator’s View)

When the first Starlink satellites launched in 2019, their brightness alarmed some astronomers immediately. SpaceX responded. By 2020, the company had introduced visors on its VisorSat models, reducing brightness to approximately 6.2, an improvement, though still above the magnitude 7 threshold astronomers had requested (Mallama et al., 2025). The company also developed proprietary dielectric mirror film to reflect sunlight away from Earth rather than scattering it diffusely, and began adjusting satellite attitudes to minimise reflectivity during critical observation periods. Together, these techniques reduced Starlink brightness by a factor of three compared to the original design (Mallama et al., 2025).

The DarkSat experiment offered another approach. Anti-reflective coatings reduced brightness by 0.77 magnitudes in Sloan d’ band compared to standard satellites (Tregloan Reed et al., 2020). But black surfaces in space absorb more heat, and SpaceX acknowledged that thermal balance issues forced them to abandon the coating approach in favour of visors (SpaceX, 2022). The dark coating also created an unintended consequence, while optical brightness dropped, the increased surface temperature negatively affected infrared observations. One form of interference was reduced while another was increased.

Then came the setbacks. In 2022, SpaceX removed the visors from its V1.5 satellites because they blocked the laser inter satellite links needed for the new generation of spacecraft. Brightness crept back up by about half a magnitude, to approximately 5.5 Mallama et al., 2023). The Direct to Cell satellites in 2024, designed to connect directly to smartphones, presented a bigger challenge still. These orbit lower, at 350 km rather than 550 km, and their mean apparent magnitude of 5.16 makes them nearly five times brighter than standard Starlinks (Mallama et al., 2025). SpaceX has since adjusted spacecraft attitudes to dim them, but the pattern is clear, each new capability introduces new brightness challenges, and mitigation must constantly catch up.

Amazon’s Project Kuiper, rebranded as Amazon Leo in November 2025, tells a similar story. The company launched its first 27 production satellites in April 2025 and signed a coordination agreement with the National Science Foundation in June 2025, committing to test dark coatings and attitude adjustments to reduce brightness (NSF, 2025). Early observations published in January 2026 found that 92% of Amazon Leo satellites exceed the IAU’s research brightness limit, while 25% were bright enough to affect naked eye appreciation of the night sky. Amazon has stated it is working with astronomers to address the problem, including applying custom dielectric film and non-reflective coatings (Mallama et al., 2026). The company faces a tight deadline, under its FCC licence, half of its 3,236 satellites must be operational by July 2026.

The Chinese constellation presents a different challenge. Qianfan and Guowang satellites are already in orbit, with apparent magnitudes of 5.76 and 5.07, respectively, well above the visibility threshold (Mallama, A., and Cole, R.E. 2025). Unlike SpaceX and Amazon, these operators have not published detailed mitigation plans or signed coordination agreements with international astronomical bodies. Communication has proven difficult as the IAU CPS has reported that engagement with Chinese operators remains restricted (Kom­pas, 2024). As these constellations scale toward their planned sizes of approximately 15,000 satellites for Qianfan and 13,000 for Guowang (China Satellite Network Group, 2024), the cumulative brightness impact will grow.

Critical Limitations of View B

These hardware fixes share a critical weakness. They are:

Geometry-Dependence and Verification Burden.

Photometric studies have found that while mitigation measures reduced effective reflectivity in certain geometries, they did not work uniformly across all viewing angles. Counterintuitively, satellites did not appear brightest at zenith. Instead, they were typically brightest at mid elevations opposite the sun, where visor equipped satellites still reflected significant light. This variability means that single geometry brightness claims are scientifically incomplete (Zhi Jiang and Wang 2024 , Lu 2024). A mitigation measure that works under one geometry can fail under others, forcing operators either to invest in extensive in orbit monitoring and modelling or to risk non compliance. In practice, the verification costs often exceed the nominal cost of the simple mitigation itself.

Operational Trade-Offs

Operational scheduling offers an alternative. Tools like Astrosat enable observatories to predict satellite passes and adjust observation schedules accordingly (Osborn et al., 2022). SpaceX's terminator tracking manoeuvre, which points the solar array edge toward Earth during twilight crossings, reduces brightness but comes at a cost. A 25% reduction in available power for the satellite. SpaceX designed their second-generation satellites to accommodate this power reduction (SpaceX, 2022), but this represents a substantial engineering concession that increases development costs and constrains operational flexibility.

Business Priorities Can Override Mitigation

The operators’ core argument remains consistent, hardware fixes work, collaboration with astronomers is productive,and mandatory thresholds risk locking in requirements that technology cannot yet meet. SpaceX has published its brightness mitigation best practices and offered to share its dielectric mirror film with other operators at cost (SpaceX, 2022). Amazon has emphasised that brightness mitigation is a “core level zero requirement” for Kuiper (Foust, 2025). These are not empty gestures.

But evidence also reveals the limits of voluntary action. Research cautions that “relying on self-imposed standards is unrealistic because there are no consequences for deviating from them, and voluntary adherence relies on good behaviour transparency, which are lacking from competitive commercial markets” (Spencer et al., 2025). The pattern across operators is consistent, with mitigation improving when regulators and astronomers apply pressure, and regresses when new commercial priorities emerge. SpaceX’s removal of visors for laser links, and the brightness increase from Direct to Cell satellites, illustrate the dynamic. Business requirements can override mitigation commitments when no binding standard prevents it.

By delaying fundamental co-design, operators risk locking billions of pounds into technically insufficient designs across entire fleets for decades. Once a constellation is deployed at scale, mid-mission redesigns become prohibitively expensive. The incremental approach assumes problems can be fixed after launch, but the magnitude of reduction required (often 25 times or more for large platforms like BlueWalker 3), demands fundamental design changes from the outset. (Nandakumar et al. 2023, Hall, 2021). The operators’ position is not without merit. Flexibility has produced real results. But the question regulators must answer is whether voluntary progress, however genuine, can keep pace with deployment schedules measured in tens of thousands of satellites per year.

2.3 Integrated Syntheses: The BEC Framework as the Bridge

Sections 2.1 and 2.2 reveal a familiar governance impasse. Regulators demand measurable, verifiable performance standards. Operators demand flexibility, cost control, and protection for commercially sensitive data. Neither side speaks the other’s language, and without a common framework, the gap between regulatory ambition and operational reality will only widen.

The BEC Framework is designed to resolve this tension. It does so by translating the regulator’s demand for measurable effectiveness into the operator’s language of cost efficiency. At the centre of every decision sits the CCT, ensuring that mitigation choices are evaluated not only on technical performance but on their true end-to-end economic impact. The BEC uses a four-part methodology to objectively rank every brightness reduction option, ensuring that the true, total cost of each fix is captured.

The Four Dimensional Resolution

The integrity of this four-part system is essential to avoid the Good Enough trap described in Section 1.4.3, as each dimension forces the internalisation of previously hidden costs, Table 5 below.

Table 5: BEC Framework Rating Categories

Rating Category	What It Measures
Technical Effectiveness	Addresses the lack of consistent, measurable brightness reductions (View A). Measures how much brightness is actually reduced, based on verified scientific modelling and real-world observations (Zhi, Jiang and Wang, 2024), (Lu, 2024), (Halferty et al., 2022).
Implementation Cost	Measures the total cost required to deploy and sustain the mitigation across the fleet. This is broken down into two components: CAPEX (Upfront investment for hardware, testing, and new asset acquisition/integration as the fleet grows) and OPEX (Ongoing, day-to-day costs like software licensing, maintenance fees, and staff required to manage the mitigation system) (Sohn, 2016). However, the CAPEX/OPEX distinction is not financially neutral. Experience from UK utility regulation demonstrates that companies may exhibit a "capex bias", preferring capital solutions over operating solutions even when the latter offer lower whole-life costs (Earwaker, 2025). This bias arises because OPEX is treated as an in-year cost funded from matched revenues, whereas CAPEX can be capitalised as a balance sheet asset, paid back over flexible multi-year periods via depreciation, and may even earn a return while held on the balance sheet. CAPEX can therefore increase company valuation and attract investor interest in ways that OPEX cannot. These dynamics mean that a satellite operator's choice between, for example, a hardware redesign (CAPEX) and scheduling software (OPEX) may be influenced by investor time horizons and balance sheet considerations rather than true cost-effectiveness. An investor seeking a short-term exit may prefer CAPEX-heavy solutions that inflate asset values, while an operator focused on long-term profitability may favour OPEX-efficient approaches that reduce recurring costs.
Operational Impact	Assesses how the fix affects the satellite's core mission: the negative effects on service delivery (extra mass, power consumption, thermal management challenges) and the OPEX of complex scheduling and data-sharing software (Lalbakhsh et al., 2022).
Regulatory Alignment	Assesses how likely the fix is to satisfy the EU Space Act and other future rules. Transparent data sharing and good reporting practices increase this score and help accelerate the development of formal standards (Bastida Virgili et al., 2016), (International Institute of Space Law, 2023) and reporting integrity.

This system then calculates the Cost per Unit of Effectiveness (CUE), which is the most powerful number in the framework. It translates all four scores into a monetary value, like finding the ‘best deal’ , enabling companies to compare any two mitigation solutions directly for portfolio planning.

The BEC Framework should not be positioned as a standalone optimisation tool. It is an instrument designed to be embedded within a broader policy mix that includes measurement standards, independent verification, and procurement-based incentives.

This framing is essential. Without these methodological safeguards, the BEC may risk enabling strategic misreporting and entrenching suboptimal mitigation choices (Christensen, Hail and Leuz, 2021). A score is only as credible as the data behind it.

Because the framework is methodology-driven rather than technology-prescriptive, it can be adopted by regulatory authorities outside the EU. This makes it a practical tool for building cross-border consensus on brightness standards.

3.  The Best-Effect-Cost (BEC) Framework and Cost of Compliance Taxonomy (CCT)

3.1 BEC in Practice

The BEC framework is built on four core dimensions described in Section 2.3. Each dimension introduces methodological vulnerabilities and opportunities for strategic misreporting. These risks can only be controlled through strict verification protocols and transparent, standardised data inputs.

1. Technical Effectiveness: The central question is straightforward. How much sky brightness can a specific mitigation package actually reduce? The literature demonstrates substantial brightness reductions with visor-equipped satellites in favourable geometries, but residual brightness remains a critical constraint. This underscores the need for layered mitigations and adaptive planning across multiple geometry classes (Zhi, Jiang and Wang, 2024), (Lu, 2024), (Halferty et al., 2022). Importantly, any final effectiveness score must incorporate material degradation, such as the fading of dark coatings over the mission lifetime. Effectiveness should be treated as a probabilistic distribution rather than a single point estimate, supported by documented inter-laboratory calibration and verified through in-orbit observations.

   
   

2. Implementation Cost: This dimension measures the total expenditure required to deploy and sustain a mitigation across the fleet. Hardware mitigations such as visors and dark coatings involve documented engineering trade-offs. SpaceX trialled anti-reflective coatings on its DarkSat prototype in early 2020, but the increased solar absorption created thermal control issues that made the approach unsustainable for fleet wide deployment (Tregloan-Reed et al., 2020). The company then turned to sun visors, which proved effective at reducing brightness but were discontinued in 2022 because they blocked laser inter satellite links needed for global coverage and generated excessive atmospheric drag at Starlink’s low operating altitudes (SpaceX, 2022). These are not isolated engineering setbacks. They illustrate a recurring pattern, each mitigation creates downstream costs that are difficult to predict at the design stage. The actual financial cost of these mitigations has not been publicly disclosed by any operator, making independent verification impossible. Separately, the ongoing costs for scheduling software and data sharing infrastructure scale with fleet size (Bassa, Hainaut and Galadí-Enríquez 2022, Halferty et al. 2022). This dimension must precisely capture the cost of complexity, explicitly broken down into CAPEX (for hardware, testing, and perhaps the full cost of thermal redesign necessitated by coating changes), and OPEX (such as software licensing and staff), ensuring the systematic underestimation of mitigation expense is avoided.

   
   

3. Operational Impact: This dimension asks a practical question. What does the mitigation cost the satellite’s primary mission? Adding visors or coatings affects mass, power, and thermal budgets, potentially shifting brightness harm from one part of the electromagnetic spectrum to another. The DarkSat experiment demonstrated this directly. While optical brightness dropped by 0.77 magnitudes in the Sloan g’ band, the increased surface temperature from the dark coating negatively affected infrared observations (Tregloan-Reed et al., 2020). One form of interference was reduced while another was increased. Some operators argue that sharing precise satellite location data helps observatories plan around satellite passes, framing this as a cooperative solution. SpaceX publishes detailed orbital predictions for its Starlink satellites, updated multiple times daily (SpaceX. 2025). In contrast, many other constellation operators including emerging Chinese megaconstellations such as Guowang and Qianfan, do not share such data directly, forcing astronomers to rely on less accurate third-party tracking (Nandakumar et al., 2023). Even where operators do share data, this argument overlooks who actually bears the burden. The cost of avoiding satellites falls on observatories, not on the operators causing the problem. Research shows that satellite avoidance strategies impose "significant and complicated overheads" on observatories, including lost observing time, increased data-processing burdens, and "opportunity costs in the form of sensor read-out noise" from splitting exposures (Bassa, Hainaut and Galadí-Enríquez, 2022). One study found that sacrificing 10% of observation time reduces streak incidence by only a factor of two (Hu et al., 2022). Furthermore, no single mitigation measure can solve the problem of satellite trails for all instruments and science cases (Bassa, Hainaut and Galadí-Enríquez, 2022). The burden of adaptation and its associated costs falls primarily on astronomical facilities, not on the operators responsible for causing the brightness harm. For this reason, the CCT calculation must quantify reduced service availability and constrained duty cycles as OPEX, ensuring that operational penalties borne by third parties are not obscured by anticipated improvements in operator scheduling predictability.

   
   

4. Regulatory Alignment: This dimension assesses how well a mitigation measure meets policy requirements, acting as the key link between technology and governance. Strong alignment with the EU Space Act’s safety by design principle is crucial, as it provides the auditable evidence that regulators, public procurers, and investors need to approve future operations (Bastida Virgili et al., 2016), (International Institute of Space Law, 2023). At present, many operators limit what they disclose to protect commercially sensitive information, but this approach increasingly risks market barriers, delays, and future penalties.The report notes that voluntary and unaudited claims are not reliable for comparing performance across firms, especially in an industry where data is often withheld for competitive reasons (Christensen, Hail and Leuz, 2021). For this reason, high regulatory-alignment scores are only granted when operators provide verifiable technical evidence, either as openly published data or as sealed, independently verified proofs. This ensures fair comparison across operators and reduces the scope for strategic misreporting. Being able to audit this minimum evidence set, without exposing proprietary pricing, creates a practical enforcement mechanism. It ensures that compliance is measurable and limits the industry’s ability to avoid accountability.

   
   

3.2 Cost per Unit of Effectiveness and Final BEC Score in Practice

3.2.1 Establishing the Reference Case and Technical Assumptions

To test whether the BEC Framework actually works, it needs a concrete scenario, Table 6 below. All cost and effectiveness metrics in this section are calculated against a simplified reference constellation designed for LEO. The specifications are deliberately modest, and this is not a model of any existing constellation, but a testbed for the methodology.

Table 6: Reference Constellation Specifications

Fleet Size	100 operational satellites (representing one batch or early deployment phase).
Satellite Mass/Power	Approximately 250kg class.
Mission Lifetime	7 years
Unmitigated Baseline Brightness	MV= 5.0 (consistent with early, unmitigated LEO satellites (Mallama and Cole, 2025))
Policy Compliance Target	MV=7.0 (the IAU CPS recommended threshold for naked eye invisibility, as originally proposed in the EU Space Act (European Commission 2025, IAU CPS 2025))

The compliance target of MV= 7.0 deserves a note on its origin. This threshold was not chosen arbitrarily. It derives from the IAU Centre for the Protection of the Dark and Quiet Sky, which established it based on studies of the Vera C. Rubin Observatory's detector artifact limits, the point at which satellite trails can still be corrected in imaging data without permanent scientific loss (Tyson et al. 2020, IAU CPS 2025). The European Commission adopted this threshold in its original June 2025 proposal for the EU Space Act (European Commission, 2025). Though discussed in Section 1.2, the Council’s December 2025 negotiating text subsequently removed the numerical limit (Council of the European Union, 2025).

3.2.2 Engineering Assumptions

The effectiveness (Δm) values are based on optimistic engineering judgement. They assume near-perfect performance and zero degradation across the full mission lifetime, Table 7 below. This is intentional. The purpose is to establish a best-case feasibility test. If compliance cannot be achieved even under ideal conditions, then it certainly cannot be achieved in practice.

Table 7: Brightness Reduction Engineering Assumptions

Mitigation Strategy	Model Δ	Justification	Supporting Evidence
Hardware Visor	MV =0.90	Assumes a near-optimal visor shape and orientation that achieves maximum predicted dimming without significant thermal penalty.	Measured VisorSat dimming averages approximately 1.29 magnitudes fainter than the original Starlink design at specific viewing angles (Mallama, 2021). This 0.9 value represents the visor's reliable contribution under optimal assumptions, accounting for the fact that visor performance varies with viewing geometry.
Dark Coatings	MV =0.60	Assumes high-quality, low-reflectivity materials (BRDF <0.05) are applied across 75% of the exposed surface and do not degrade over the 7-year lifetime.	Measured DarkSat dimming was 0.77 magnitudes in the Sloan g' band (Tregloan-Reed et al., 2020). This slightly lower value used here accounts for realistic integration challenges, including the thermal management penalties identified during the DarkSat trial, while still remaining optimistic about long-term durability.
Operational Scheduling	MV =0.50	Assumes perfect, near-real-time data sharing and orbital manoeuvring to avoid high-incidence sun angles during all prime observing hours.	Orbital adjustments can produce instantaneous brightness reduction exceeding 2 magnitudes under favourable conditions (Johnson, Scott and Thorsteinson, 2021). However, 0.50 magnitudes represents the maximum effective dimming achievable from scheduling alone as a sustained average, since operators cannot maintain optimal orientations at all times without compromising service delivery.

3.2.3 Engineering Financial Assumptions for Annualised Implementation Cost (AIC)

The AIC figures presented are hypothetical and annualised over a 7-year mission lifetime. They are not intended to represent actual market prices. Rather, they preserve the realistic cost proportions typically observed in space systems, distinguishing between high CAPEX hardware solutions and more scalable OPEX driven approaches. This distinction matters because public cost data for satellite brightness mitigation hardware remains scarce. SpaceX has stated it will offer its proprietary dielectric mirror film "at cost" to other operators, but has not published a price (SpaceX, 2022). Surrey NanoSystems' Vantablack coatings, now being flight-tested for satellite brightness reduction on the Jovian 1 CubeSat (The Engineer, 2025), are not commercially available without direct negotiation, and no public pricing exists. Starlink V1 satellites (260 kg) are manufactured for approximately $200,000, while V2 Mini satellites (730 kg) cost roughly $800,000 (Henry, 2024), but no operator has disclosed what fraction of this cost is attributable to brightness mitigation hardware specifically. Despite outreach to coating suppliers including Surrey NanoSystems and Keronite, verified mitigation specific costs remain unavailable. The figures below should therefore be interpreted as reasonable scenario based estimates, not confirmed market prices.

To ground these estimates as carefully as possible given these constraints, the cost rationale draws on three additional sources beyond operator disclosures. First, parametric cost estimation models from the standard space systems engineering literature. The Unmanned Space Vehicle Cost Model and Small Satellite Cost Model establish that Non-Recurring Engineering (NRE) typically represents 30-50% of total development cost for a new satellite subsystem, with Assembly, Integration and Test running 10-15% of hardware cost for small to medium LEO platforms (Wertz, Everett and Puschell, 2011, Ch. 11). These proportions anchor every NRE and AIT figure in Table 8. Second, publicly documented coating programmes for space missions provide reference points for material costs. Keronite’s plasma electrolytic oxidation coatings have flown on ESA’s BepiColombo, the James Webb Space Telescope NIRSpec instrument, Sentinel 2 and 5, and Euclid, and offer a reported 30% or greater cost advantage over traditional space paints (Keronite, 2023). VBx2, Surrey NanoSystems’ sprayable variant, is commercially available at approximately £200/m2 for non-space applications, but the space-qualified S-VIS variant requires direct negotiation (Surrey NanoSystems, 2024). At the upper end, traditional optical solar reflectors cost several tens of thousands of pounds per square metre to assemble and launch (Muskens et al., 2018). These data points define the lower and upper bounds of the coating cost range in Table 8, though none directly prices a brightness reduction coating at production scale. Third, standard thermal vacuum qualification protocols confirm that every satellite must undergo TVAC testing under ESA ECSS-E-ST-10-03C and NASA GEVS: GSFC-STD-7000A regardless of brightness mitigation (EnduroSat 2025, NASA SSRI 2021). This matters because the qualification costs in Table 8 are not standalone test programmes. Every satellite already goes through thermal vacuum testing as part of its standard qualification process. Adding a brightness-reduction coating to that existing campaign costs relatively little, typically a few extra test samples and longer soak times. The cost only becomes significant if the coating material has never been space-qualified before, in which case it requires its own dedicated testing programme.

Table 8 presents what it costs to add brightness mitigation to an existing satellite design, specifically a platform that has already passed its Critical Design Review (CDR). A typical LEO constellation takes approximately 7 years from programme initiation to first launch (IDA, 2024). NASA's Systems Engineering Handbook is explicit that from PDR onward, changes should represent refinements, not fundamental redesign (NASA, 2023). After CDR, any modification triggers a formal engineering change process that ripples through structural, thermal, power, and integration subsystems. The cost grows not because the visor or coating is inherently expensive, but because changing a frozen design is expensive.

If mitigation is instead embedded from the earliest concept phase, as the EU Space Act's safety-by-design principle requires, the picture changes fundamentally. The visor is in the structural baseline before PDR. The dark coating is in the thermal model from day one, the thermal engineer designs around its absorptive properties, so there is no redesign (NASA, 2025b). Under safety-by-design, the NRE costs in Table 8 either shrink dramatically or disappear entirely, absorbed into the satellite's baseline development. This report does not assign separate figures to that scenario because those costs are not separately identifiable, they are simply part of what the satellite costs to build. The operator's ongoing, separable compliance cost reduces to essentially the operational scheduling OPEX. The figures in Table 8 therefore represent a conservative upper bound. They show what operators pay when they act late.

Table 8: Annualised Implementation Cost Components

Cost	Type	Estimated Cost (one batch)	Cost Nature	Cost Rationale and Derivation
Hardware Visor	High CAPEX	£3.5 - 4.0M	0M One-time Paid during design and production.	NRE: estimated £2.5M for design, tooling, structural re-analysis, and qualification of a deployable RF-transparent sunshade on an existing platform. Derived from the standard NRE proportion of 30–50% of subsystem development cost (Wertz, Everett and Puschell, 2011, Ch. 11). Engineering scope informed by SpaceX's VisorSat programme: RF-transparent foam panels with hinge-actuated deployment, discontinued on V1.5 because visors blocked laser inter-satellite links and increased drag (SpaceX 2022, SpaceX 2020, Mallama, 2022). Includes re-analysis of structural loads, harness rerouting, and requalification, costs that would not arise if the visor were part of the original design. Recurring: estimated £10,000/unit hardware + £5,000/unit AIT, from standard recurring and AIT proportions for sub-300 kg deployable structures (Wertz, Everett and Puschell, 2011, Ch. 11). No operator has published per-unit visor costs.
Dark Coatings	Mid-range CAPEX	CAPEX £2.0 - 2.5M	One-time, Paid during design and production.	Coating materials: estimated £2,000- £6,000/unit across an estimated 5 m² treatable surface. The lower bound (~£2,000) reflects a pre-qualified, commercially mature coating such as Keronite PEO, informed by its reported 30%+ cost advantage over traditional space paints (Keronite 2023) The upper bound (~£6,000) reflects bespoke or less mature coatings. These bounds are triangulated from: VBx2 at ~£200/m² for non-space applications (Surrey NanoSystems, 2024); SpaceX's proprietary paint offered "at cost" with no published price (SpaceX, 2022); traditional optical solar reflectors at tens of thousands of GBP/m² (Muskens et al., 2018). No single source prices a brightness-reduction coating at LEO production scale. Application and inspection: estimated £2,000/unit for cleanroom application, quality control, and rework, based on standard surface treatment procedures for the 250 kg class. Thermal redesign NRE: estimated £500,000–£1,000,000. Near-zero if designed in (NASA, 2025b), but significant when retrofitting a frozen design. DarkSat confirmed dark coatings create thermal challenges (Tregloan-Reed et al. 2020, SpaceX, 2022). Impacts are design-specific: increased radiator area (100–350 W/m², up to 12 kg/m²), active cooling, or reduced duty cycles (NASA, 2025b). Integrated solutions like fluorinated polyimide aerogel composites are feasible but require early incorporation (Shi et al., 2024).
Operational Scheduling	Low CAPEX	£0.3-0.4M	Ongoing annual. Paid every year for 7 years.	Paid every year for 7 years. Estimated £100,000–£300,000/year for coordination with existing astronomical facilities, data-sharing agreements, and incremental staffing to manage brightness-aware attitude adjustments. This assumes the operator uses existing infrastructure. Observatories such as the Vera C. Rubin Observatory already conduct satellite tracking, and tools like Astrosat already forecast satellite transits for optical observations (Osborn et al., 2022). SpaceX publishes detailed orbital predictions updated multiple times daily (SpaceX, 2025). The operator's cost is therefore incremental: sharing positional data with existing tracking networks and allocating staff time to coordinate attitude manoeuvres during critical observation windows. The primary cost of scheduling is not financial but operational. SpaceX's terminator tracking manoeuvre reduces brightness at a cost of approximately 25% power reduction per satellite (SpaceX, 2022). This service penalty is captured in the Operational Impact dimension of the BEC Framework rather than in the AIC. For context, total LEO constellation management costs are reported at $500,000–$1,000,000 per satellite per year across all operational functions (Rusch, 2021). Brightness scheduling represents a small fraction of these broader costs. This figure captures operator-side expenditure only, observatory-side overheads are borne by the astronomical community (Bassa, Hainaut and Galadí-Enríquez, 2022; Hu et al., 2022).
Total		£3.5-5.0M one-time + £0.3-0.4M/ year on going	Mixed	One-time hardware: £6.5M (£65,000/unit). Ongoing OPEX: £0.1-0.3M/year (£15,000/unit/year). Baseline manufacturing cost is estimated at £100,000–$250,000 (approximately £160,000–£200,000) for a 250 kg class LEO satellite, based on publicly reported Starlink V1 unit costs (Henry, 2024). This figure reflects extreme mass-production volumes and is likely to understate the cost for operators manufacturing at smaller scales. Against this baseline, the one-time hardware uplift of £65,000/unit represents approximately 33–41% of manufacturing cost. However, manufacturing is only one component of total mission expenditure. Including launch at approximately £1.1M/unit ($5,500/kg Falcon 9 rideshare for a 250 kg satellite (SpaceX, 2025)), total per-unit mission cost rises to approximately £1.26–£1.3M. Against this more complete baseline, the hardware uplift falls to approximately 5%. No other operator has published verified manufacturing costs for non-Starlink platforms in this mass class, so both baselines should be treated as indicative. This demonstrates that operators who follow safety-by-design principles face materially lower compliance costs than those who bolt on mitigation after the design is established, consistent with the EU Space Act's core regulatory philosophy (European Commission, 2025).

As a cross-check on the per-unit recurring costs, the thermal control subsystem typically accounts for approximately 2–5% of total satellite cost and mass (IIT Bombay Satellite, 2018). The per-unit coating materials and application cost of £4,000–£8,000 falls within this range against the reference baseline, suggesting the recurring estimates are proportionally consistent. The higher fleet-level totals are driven by the one-time NRE components, which represent the cost of modifying a frozen design rather than the cost of the coatings themselves. The NRE estimates carry the greatest uncertainty in this analysis. They are derived from parametric cost proportions (Wertz, Everett and Puschell, 2011, Ch. 11) rather than verified programme costs, and could be significantly lower for operators with existing deployable mechanism heritage or pre-qualified coating materials.

The NRE components, design, tooling, qualification, are a one-off bill. It costs the same whether you are building 10 satellites or 100. A large operator can absorb that bill easily because it gets shared across hundreds of satellites. A small operator building just 10 satellites has to carry the same bill across far fewer units, which makes each satellite significantly more expensive to produce. This matters for policy. Every satellite causes the same brightness harm regardless of who built it, so all operators need to meet the same standard. But regulators need to recognise that the cost of meeting that standard falls harder on smaller companies. Practical solutions exist, small operators could pool qualification costs with others, draw on shared databases of pre-tested materials, or access suppliers who have already completed the expensive testing. The standard stays the same. The cost of reaching it is shared more fairly (Christensen, Hail and Leuz 2021, Jackson et al. 2020)

This report recommends direct engagement with spacecraft manufacturers to validate these cost assumptions as a priority for future work.

3.2.4 Cost-Effectiveness and the Fragility of Compliance

The Cost per Unit of Effectiveness (CUE) forms the economic foundation of the BEC Framework. It translates the mandatory brightness reduction target, expressed as Δm in magnitudes, into a verifiable financial metric, enabling direct comparison between mitigation strategies. Following established cost effectiveness methodology adapted from health economics (Sohn, 2016), the CUE is calculated as:

CUE = AIC/ Δm

Where AIC is the Annualised Implementation Cost (£/year) and Δm is the brightness reduction achieved (magnitudes). A lower CUE indicates a more cost-effective mitigation, more dimming per pound spent. To illustrate, a mitigation costing £500,000/year that achieves Δm = 1.0 magnitude has a CUE of £500,000/mag, whereas a £1,000,000/year mitigation achieving only Δm = 0.5 mag has a CUE of £2,000,000/mag, four times less cost-effective despite costing only twice as much. The CUE makes this kind of comparison immediate and auditable.

The CUE serves as the primary input for the Final BEC Score, which serves as a single, easy-to-use metric designed for decision-making. This report suggests a regulatory focused weighting: Technical Effectiveness at 40%, with Implementation Cost, Operational Impact, and Regulatory Alignment at 20% each. This prioritises achieving the magnitude 7 threshold as the primary policy objective. However, commercial operators may reasonably apply a different weighting: Implementation Cost and Operational Impact each at 40%, Technical Effectiveness and Regulatory Alignment each at 10%, reflecting the reality that satellite companies must balance compliance against capital preservation and service continuity.

This divergence is non-trivial. Mitigations that rank highly under both weighting scenarios represent robust choices, they satisfy both the regulator and the business case. Those ranking well only under regulator-focused weightings may require policy intervention, such as procurement incentives or concessional finance, to achieve market adoption. The BEC Framework thus serves not merely as a ranking tool, but as a diagnostic instrument for identifying where regulatory and commercial incentives are misaligned.

3.2.5 The Illustrative Scenario: Compliance Achieved Under Optimism

The scenario below, Table 9, tests whether the MV=7.0 target can actually be met using the assumptions detailed in Sections 3.2.1 and 3.2.3. To enable meaningful comparison, all costs are expressed as AIC, annualised over a 7-year mission lifetime and incorporating recurring expenditure. This ensures the CUE metric reflects true cost-effectiveness rather than conflating one-time capital investment with ongoing operational expense.

Table 9: Cost Effectiveness Analysis of Brightness Mitigation Strategies

Mitigation Strategy	Δm	Annual Cost	CUE (£ per mag)	Final MV	Policy Outcome
A. Hardware Visor	0.90 mag	£0.5 - 0.57M	0.55- 0.63	4.10	Fails
B. Dark Coatings	0.6 mag	£0.29-0.36M	0.48- 0.60	4.40	Fails
C. Operational Scheduling	0.5 mag	£0.30-0.40M	0.60-0.80	4.50	Fails
D. Combined Total	2.04 mag	£0.92-1.33M	0.45 -0.65	7.04	Passes

The first thing make clear is that no single mitigation measure achieves compliance on its own. Hardware visors, the most expensive option, deliver the target individual brightness reduction but still leave the satellite at MV = 4.0, easily visible to the naked eye. Dark coatings are the most cost effective on a per magnitude basis (CUE of £0.48/mag) but achieve less total dimming. Operational scheduling is the cheapest but also the least effective, and as discussed in Section 3.4, it carries ethical concerns when it merely shifts reflected light to other regions rather than reducing it at the source.

Only the combined, layered approach narrowly passes the MV = 7.0 target, reaching MV = 7.04. The combined effectiveness of 2.04 magnitudes is calculated using the established principles of astronomical photometry, accounting for the logarithmic nature of the apparent magnitude scale, consistent with the method used for the MV calculations in Section 1.4.

These figures represent the incremental cost of brightness mitigation only, excluding baseline satellite manufacturing, launch, and operations. For a typical 100-satellite LEO constellation with an estimated programme cost of £100–200M, this compliance uplift represents approximately 1-2% of total expenditure. This is a significant but not necessarily a prohibitive burden for operators pursuing regulatory alignment. Its commercial viability depends on the scope and scale of safety and sustainability related design considerations and their consolidated cost to deliver resilient systems and sustained operating environments.

The success, however, is contingent upon an annualised investment of approximately £0.92- 1.33M per year over 7-year operational lifetime, and critically, upon every optimistic assumption in the model holding true.

3.2.6 Critical Limitations of the Model

The passing score demonstrated above is highly fragile. It rests entirely on idealised assumptions, and since the underlying BEC model is conceptual, it is susceptible to real world failures that must be addressed before any regulatory implementation.

1. First, the passing score relies entirely on the unrealistic assumption of zero material degradation. In the LEO environment, dark coatings are exposed to atomic oxygen erosion, ultraviolet radiation, thermal cycling between extreme heat and cold and micrometeorite abrasion. These effects are cumulative and well documented in materials science, though degradation rates for specific brightness- mitigation coatings under operational LEO conditions have not yet been published. In practice, material fading and geometric effects mean the satellite's apparent magnitude may drift below MV= 7.0 well within its intended operational lifetime, turning a marginal pass into a definitive failure.

   
   

2. Second, public cost data for satellite brightness mitigation remains confidential. No operator has disclosed how much of their satellite manufacturing budget is attributable to brightness reduction. SpaceX has not published a price for their dielectric mirror film to operators. Coating suppliers such as Surrey NanoSystems do not list pricing for their Vantablack products. Because verified figures are unavailable, the AIC values used in this analysis are scenario-based estimates, not confirmed market prices. The AIC also excludes costs that would increase the true compliance burden, such as higher insurance premiums for unproven materials and the added expense of qualifying complex deployable mechanisms like visors. Actual costs may differ significantly once real manufacturing data becomes available.

3. Third, achieving and maintaining the high Δm values assumed in Table 7 requires continuous verification and costly process adjustments that are not accounted for in the initial AIC figure.The model excludes mandatory budgets for in-orbit diagnostics and ground-based photometric monitoring campaigns. The very programmes needed to confirm that claimed effectiveness persists throughout the mission lifetime rather than degrading silently.

   
   

4. Finally, the model assumes operators will maintain brightness-compliant configurations throughout the mission. In practice, operational priorities may evolve over time. SpaceX has acknowledged that constraints including power generation and antenna coverage can prevent satellites from always maintaining their lowest-brightness orientations (SpaceX, 2022). A new service contract, for example, might require satellites to occupy orbital positions or attitudes that increase brightness to meet coverage requirements. These adjustments may be temporary and operationally justified, yet they represent a departure from the environmental performance assumed at the licensing stage. The challenge for regulators is to distinguish between operators who sustain their commitments and those whose configurations shift in response to changing commercial circumstances. This uncertainty reinforces the need for ongoing, independent brightness monitoring rather than reliance on initial compliance declarations alone.

3.3 CCT Taxonomy

The CCT is a foundational component of the BEC Framework. It standardises the financial commitment required for satellite operators to achieve and maintain the MV = 7 standard providing companies and investors with clear categories for risk and expenditure. The taxonomy organises all costs into three essential, interconnected categories.

The first bucket is CAPEX, which covers the upfront money needed for hardware and setup, such as purchasing visor modules, qualifying dark paint, procuring test equipment, and conducting research for system integration.

The second bucket is OPEX, which covers the ongoing running costs incurred year after year. This includes paying for forecasting software, maintaining data-sharing infrastructure, handling regulatory reporting, and employing the staff needed to maintain the lowest-brightness harm commitment in line with the organisational standard operating procedure (SOP).

The third is the Regulatory Risk Cost (RRC), which represents the financial exposure from non-compliance. Converting this inherent risk into a clear monetary figure allows for better budgeting and comprehensive risk management. The RRC includes exposure to fines and penalties imposed by regulators, economic costs associated with operational disruption such as delays in licensing or mandated halts to operations, and higher insurance fees resulting from the increased liability profile assumed by insurers when an operator fails to mitigate known regulatory risks.

Evidence base

The CCT draws its credibility from five converging lines of evidence, each reinforcing the case that brightness compliance must be treated as a quantifiable, auditable financial commitment rather than an aspirational design goal.

1. The starting point for design is BRDF modelling. This computational simulation allows engineers to calculate the expected brightness of a satellite based on the materials, surface geometry, and physical shape. The step is not optional. It turns material choices into a sky brightness budget, which is the only way to support regulator-ready performance claims and allows companies to optimise their designs before committing to launch (Lu, 2024). Without this modelling, operators are effectively guessing whether their satellites will comply, and by the time in orbit observations reveal the answer, the fleet design is already in place.

   
   

2. Real-world measurements and case studies confirm that physical hardware fixes are helpful but have limitations. The extreme brightness events reported for the BlueWalker 3 satellite highlight the danger of relying on hardware alone (Nandakumar et al., 2023), as these measures do not in isolation provide the necessary brightness reductions. This reinforces the need for operators to combine dark coatings with smart operational planning to address the absolute brightest, worst-case situations. Conversely, the Vera C. Rubin Observatory offers a practical example of operational adaptation. By predicting when satellites will pass and adjusting observation schedules accordingly, the observatory demonstrated it could minimise data loss, particularly when data is shared openly (Walker et al. 2020, Osborn et al. 2022). However, this scheduling approach, while adequate as a short-term stopgap, would be wholly insufficient alongside a projected four-fold increase in total satellites and unabated brightness growth by 2030.

   
   

3. The governance landscape is maturing rapidly. Global policy bodies consistently argue that new rules must be built on a safety-by-design approach and demand proven, measurable results for regulation to be credible. The IISL has established a dedicated working group on light pollution from a space law perspective (International Institute of Space Law, 2023). At the international level, a significant step came in 2024 when the Scientific and Technical Subcommittee of the UN Committee on the Peaceful Uses of Outer Space (COPUOS) agreed to include 'Dark and quiet skies, astronomy and large constellations: addressing emerging issues and challenges' as a dedicated agenda item for its sessions from 2025 to 2029 (IAU CPS, 2024). In February 2025, twenty member state delegations took the floor during the first substantive discussion under this item, and a Conference Room Paper co-signed by ten country delegations and seven observer organisations set out actionable recommendations largely aligned with IAU CPS positions (IAU CPS, 2025). In December 2025, the United Nations Office for Outer Space Affairs and the SKA Observatory co-hosted a workshop that brought together astronomers, the satellite industry, and space agencies to share mitigation best practices and identify regulatory gaps. These are not abstract diplomatic exercises. They represent the building of an international consensus that will eventually produce enforceable norms. The EU has the potential to lead this process by promoting standardised brightness metrics and transparent data sharing. This effort builds upon existing international frameworks, notably the 2007 UNESCO-IAU Declaration in Defence of the Night Sky and the Right to Starlight, which established that 'the sky, our common and universal heritage, forms an integral part of the total environment perceived by mankind' (UNESCO et al., 2007). UNESCO, through its Astronomy and World Heritage Initiative and partnership with the Man and the Biosphere Programme, provides the neutral, global cultural and scientific mandate necessary to establish international norms outside purely economic or regulatory bodies (Hainaut and Moehler, 2024). The institutional infrastructure to support these norms is also strengthening. The IAU CPS secured five-year funding in September 2025, guaranteeing its continued operation through at least 2030. Its SatHub programme now brings together at least fifteen satellite operators to share best practices and understand astronomical concerns. Critically, the IAU CPS has also launched the Satellite Constellation Observation Repository (SCORE), a centralised, open-access database where professional and amateur observers can submit satellite brightness measurements in a standardised format. SCORE represents exactly the kind of shared measurement infrastructure that the BEC Framework requires: a publicly accessible dataset against which operator claims can be independently verified (IAU CPS, 2025).

   
   

4. Ecological research directly connects light brightness to biodiversity, wildlife behaviour, and the overall health of ecosystems. Studies involving satellites such as SDGSAT-1, the Chinese Sustainable Development Goals Science Satellite launched in 2021, demonstrate that its Glimmer sensor can map artificial light at night at 10–40 metre spatial resolution, enabling researchers to quantify the exposure of protected areas to light pollution, assess wildlife corridors and dark refuges in urban areas, and model the visibility of light sources to animals (Weber et al., 2025). This research broadens the policy relevance of brightness mitigation beyond astronomy, supporting a flexible set of rules that can be applied to environmental monitoring and policy debates across sectors.

   
   

5. The broader research on risk management supports the principle of making compliance costs explicit and measurable. Studies consistently find that having clear, auditable cost categories is a recognised best practice that helps companies make better decisions when facing regulatory uncertainty (Jackson et al., 2020). This concept aligns directly with the CCT taxonomy, confirming that the framework's financial component is built on established business principles rather than novel or untested theory.

One concern remains. There is a relative lack of published evidence supporting the high-bar magnitude 7 threshold anticipated by the EU. The threshold originates from the IAU CPS, which derived it from studies on the Vera C. Rubin Observatory's detector artifact limits (Tyson et al. 2020, IAU CPS 2025). While scientifically well-grounded, the absence of a broader evidence base from multiple independent studies creates the possibility of credible legal challenge around the proportionality of the intended regulation. This risk is not hypothetical. If the evidence base is not strengthened, the threshold may face the same weakening that has affected other aspects of the EU Green Deal when confronted with industry opposition.

3.4 World-Scale Relevance and Cross-Border Governance

The challenge of light pollution from megaconstellations is not a local or regional issue. It is a fundamental global problem demanding a governance solution that transcends any single jurisdiction. A satellite launched from Florida or French Guiana orbits the entire planet. Its reflected light affects observers in Chile, South Africa, and Australia equally, unless geostationary. No unilateral regulation can address a problem that, by its physical nature, has no borders. A flexible methodology driven instrument such as the BEC Framework and CCT taxonomy offers a direct pathway to effective cross-border regulation by establishing a common language that any national regulator can adopt regardless of their existing legal system.

This global approach is essential because local mitigations are often insufficient and, in some cases, ethically problematic. Operational Scheduling, the OPEX based mitigation of manoeuvring satellites to avoid visible passes over specific observatories or regions, is a case in point. When an operator adjusts satellite attitudes to achieve local compliance over one region, they effectively transfer the resulting brightness harm to observers elsewhere in the world or to different time windows. A satellite dimmed over the European Southern Observatory in Chile may be brighter over radio-quiet zones in South Africa or optical facilities in Australia during the same orbit. This practice solves the problem locally by creating a global burden, which is why international standards must enforce a universal reduction in intrinsic brightness Δm rather than permitting the localised time-shifting of the problem.

The imperative for global governance extends well beyond the concerns of professional astronomers. Satellite brightness touches on critical cross-cutting sustainability issues shared across all nations like ecology, public health, tourism, and the cultural value of the night sky. These wider interests make a globally adaptable framework highly appealing, as it allows countries to protect these shared resources while keeping the safety-by-design principle alive, ensuring compliance is embedded in the satellite from its earliest design phase (Weber et al. 2025, European Commission 2025, International Institute of Space Law 2023).

However, mitigations designed to solve the astronomy problem introduce a complex and under-discussed challenge for space safety. Space Situational Awareness (SSA) systems and astronomical monitoring both benefit from accurate brightness data and reliable trajectory predictions, but dark coatings and shields designed to reduce optical brightness simultaneously complicate remote tracking. NASA guidance notes that high-albedo materials allow satellites to be 'more easily detected by ground-based systems' (NASA, 2025), which implies that low-albedo coatings have the opposite effect. Dark coatings and visors therefore present two distinct challenges for terrestrial SSA. First, the reduced signal-to-noise ratio for optical tracking telescopes makes dimmed objects harder to detect and catalogue. Second, the diminished optical signal forces SSA operators to rely more heavily on alternative sensing modalities, primarily radar, which measures radio backscatter and remains unaffected by a satellite's optical brightness, or more expensive and less commonly deployed infrared telescopes. Maintaining adequate orbital coverage therefore requires either significantly higher sensor fidelity or a fundamental shift in the sensor mix deployed by SSA providers (Bastida Virgili et al., 2016).

This tension is not hypothetical. As of 2026, the U.S. Space Surveillance Network, the most extensive tracking system in the world, is already straining under the burden of cataloguing the rapidly growing number of objects in orbit. Military officials have acknowledged that Cold War-era tracking infrastructure and manual processing are falling behind the pace of commercial launches. Making satellites deliberately harder to see optically adds a further layer of complexity to an already overstretched system. The challenge is especially acute for non-cooperative operators who neither share manoeuvre information nor coordinate with international tracking bodies.

The need for cross-border data sharing increases when sensor modalities and capabilities diverge across jurisdictions. Organisations such as the Space Data Association (SDA), which bring together satellite operators to support 'the controlled, reliable and efficient sharing of data critical to the safety and integrity of the space environment' (Space Data Association, 2025), provide a practical model for how shared measurement standards and interoperable data formats can bridge these gaps. In September 2025, the SDA awarded a contract to GMV, a Spanish technology provider, to build a next-generation Space Safety Portal designed to improve conjunction assessment and collision warning services, explicitly addressing the challenges posed by non-cooperative operators who fail to share manoeuvre data. The SDA also signed the ESA Zero Debris Charter in December 2024, aligning its mission with the European Space Agency's ambition to achieve zero debris by 2030. With over 700 satellites currently contributing data to its platform, including approximately half of all active geostationary spacecraft, the SDA demonstrates that industry-led, non-profit data-sharing infrastructure can work at scale, and that its model could be extended to brightness data if the regulatory incentives are aligned (Walker et al., 2020).

Given the global nature of megaconstellations, governance must be a living framework rather than a static rulebook. The IISL and other policy bodies advocate for brightness standards, auditable reporting, and regular updates to reflect new photometric findings and technological developments. The phased transition toward formal standards recommended in Section 1.5 is designed to accommodate regional differences in regulatory capacity while enabling global learning. Countries with advanced space sectors can lead by implementing the BEC Framework and publishing their results. Countries with emerging space programmes can adopt the methodology without needing to build verification infrastructure from scratch, drawing instead on shared resources like the IAU CPS SCORE database and the SDA's data-sharing platform. The goal is convergence, not a single global regulation, which is politically unrealistic, but a common measurement language and compliance methodology that makes results comparable across borders (Walker et al. 2020, International Institute of Space Law 2023, IAU CPS 2025).

4.   Limitations of the Report

The most significant weakness of this entire study and the conceptual BEC Framework is its foundational optimism. The methodology gains utility where it secures greater market transparency. This requirement is aligned to the principles of ESG disclosure but would require a sector-wide culture shift historically aligned toward both defence security and corporate confidentiality.

The entire CCT presently represents a theoretical construct because actual CCT figures require verified, firm-level industry data, including component prices, supplier contracts, and internal operational forecasts. Similarly, the BEC Framework depends on being able to measure and audit all three layers consistently. If any one of the four essential inputs to the BEC Score is distorted, selectively disclosed, or masked by proprietary data, the resulting score may lose credibility for regulatory decision-making.

While future cooperation and candid disclosure remain uncertain, this is not a reason to abandon high standards. The automotive industry provides a clear example. When Volkswagen was found to have systematically falsified diesel emissions test data through defeat devices in 2015, regulators did not weaken emissions standards. Instead, the EU strengthened enforcement by introducing Real Driving Emissions (RDE) testing, which measures pollutants under actual driving conditions rather than in controlled laboratory settings, and by tightening type approval protocols across the association (ICCT, 2015). The regulatory response did not stop at new testing regimes. In May 2025, a German court in Braunschweig convicted four former Volkswagen executives of fraud of their roles in scandal, handing down sentences including four and a half years of imprisonment (Euronews, 2025), a decade after the deception first came to light. The scale of fraud, which affected approximately 11 million vehicles worldwide, demonstrated what happens when an industry is allowed to self-certify compliance without independent real-world verification (CREA, 2025). The lesson for the space sector is not that satellite brightness carries equivalent consequences, but the regulatory principle is the same. When companies are trusted to report their own performance without independent checks, the incentive to overstate compliance becomes structural. The MV = 7 brightness threshold should remain the standard, with efforts focused on stronger verification rather than lower expectations. If regulators soften requirements every time an industry claims compliance is too hard, the standard ceases to function as a standard.

Independent verification can help address the risk of unreliable operator data. Ground-based observatories could help measure satellite brightness directly and compare it against operator claims. If an operator overstates the brightness reduction from a coating or visor, systematic observatory measurements would reveal the discrepancy. Such verification may require observers to have access to satellite BRDF characteristics and a standardised conversion model to translate measurements taken at arbitrary viewing geometries back to a common reference condition, such as zenith. Without this correction protocol, raw observations remain incomparable. With it, independent monitoring becomes a powerful check against inflated compliance claims.

Data standardisation remains an unresolved vulnerability. As detailed in Section 1.3, the apparent brightness of a satellite varies dramatically with viewing geometry, and without a universally adopted protocol for BRDF corrected reporting at zenith, the framework’s core input Δm cannot be meaningfully compared across operators, observatories, or jurisdictions. Until such a protocol is formalised and widely adopted, BEC scores derived from different data sources risk being incomparable, undermining the very cross operator benchmarking the framework is designed to enable (Bassa, Hainaut and Galadí-Enríquez, 2022, Lu 2024, IAU CPS 2025).

The framework's current methodology is also limited by its reliance on a deterministic compliance score. Layered mitigations do not guarantee consistent brightness in all conditions, which means the framework needs to incorporate adaptive thresholds and contingent decision rules for edge cases. The model currently assumes zero material degradation, which makes the compliance score fragile over time. To address this, a degradation coefficient could be incorporated into future iterations. The logic is straightforward. Setting the coefficient = 1.0 at mission start would represent no degradation, with values decreasing toward zero as reflectance performance declines. Initially, the coefficient can be assumed constant across the mission lifetime, but that assumption creates an immediate opportunity. Near-term materials testing programmes to generate empirical degradation curves for specific coatings and visor materials under simulated LEO conditions, including atomic oxygen exposure, UV cycling, thermal stress, and micrometeorite abrasion. As these curves become available, they can replace the default assumption, enabling time-dependent compliance scoring that accounts for the natural fading of coatings and the mechanical wear of deployable structures over a seven-year mission lifetime (Zhi, Jiang and Wang 2024, Nandakumar et al. 2023, Halferty et al. 2022).

Finally, the pace and scope of standards development will differ regionally, and the framework must remain a living document with a formal update cadence to reflect new photometric findings, evolving governance norms, and technological progress. Some degree of governance lag is inevitable, regulation rarely precedes the problem it addresses. The greater challenge is not the lag itself but assembling sufficiently strong evidence to justify intervention in the most effective way, at the earliest opportunity. Without a coordinated effort to generate and disseminate robust photometric data, cost evidence, and degradation studies, regulators will lack the foundation to act decisively. The framework's value therefore depends not only on periodic revision, but on an active programme of evidence-building that can inform and accelerate regulatory responses before fleet-wide design choices become locked in (Bastida Virgili et al. 2016, Walker et al. 2020, International Institute of Space Law 2023).

5.  Conclusions

The core finding of this report is clear. Meeting the mandated MV = 7.0 invisibility threshold requires a Layered Mitigation Strategy that combines physical design measures, such as visors and dark coatings, with operational tools like scheduling and brightness forecasting. No single measure achieves compliance on its own. Hardware visors deliver the largest individual brightness reduction but still leave a satellite visible to the naked eye. Dark coatings are the most cost effective per magnitude but achieve less total dimming. Operational scheduling is the cheapest option but also the weakest, and it carries an ethical problem that other measures do not.

The strength of the BEC Framework lies in its ability to quantify this strategy. By calculating the CUE, the framework enables the sector to objectively rank mitigation options and ensure that every pound invested delivers the maximum brightness reduction. This is essential for avoiding the ‘Good Enough’ trap, where premature or partial fixes become locked into fleet-wide designs for decades, potentially wasting capital and leaving the night sky permanently degraded. The CCT taxonomy complements this by making the full financial burden of compliance explicit, breaking it into CAPEX, OPEX, and RRC, so that operators, investors, and regulators can all see the same picture. Together, these tools enforce cost efficiency, forcing accountability from the initial design phase rather than relying on promises made at the licensing stage.

The implications of this work extend far beyond astronomy. Light pollution from megaconstellations is a global, cross-sector issue that affects ecosystems, public health, tourism, and the cultural value of the night sky. The framework’s global relevance matters because local solutions are ethically incomplete. A satellite dimmed over one observatory may be brighter over another facility on the same orbit. Only intrinsic brightness reduction, embedded in a satellite’s design from conception, solves the problem universally. This necessitates a global embrace of intrinsic brightness reduction. Even the dark coatings themselves create a tension with space safety by making satellites harder to detect for collision avoidance systems. There are no cost-free solutions. Every mitigation involves trade-offs, and the BEC Framework exists to make those trade-offs visible and comparable.

The analysis identifies two critical limitations, each a potential point of catastrophic failure if left unaddressed, demonstrating that the BEC Framework is only as reliable as the data it receives. The first is the fragile nature of current compliance assumptions, particularly the unrealistic expectation that materials will experience zero degradation over their mission lifetime. In the LEO environment, atomic oxygen, thermal cycling and others are constant. A margin pass of initial brightness magnitude at launch could drift into definitive failure well before end of life. The second is the challenge of standardising complex photometric data, especially when relying on advanced techniques such as BRDF corrections.

Addressing these gaps requires a shared commitment to a phased operational programme. For industry leaders, this means acknowledging that the BEC is not a shortcut or a magic solution, it is a commitment, and the first step toward a zero-harm space operating environment. Just as aviation and maritime sectors evolved from unregulated activity to comprehensive safety regimes, the space sector must now embed environmental accountability into its operating culture. The BEC Framework provides the measurable foundation upon which such a regime can be built. They must move beyond voluntary measures and adopt a structured approach that includes auditable reporting and integrates RRC into financial planning from the outset. For regulators, it means applying the EU Space Act's safety-by-design principle to implement performance-based standards that can evolve alongside technological developments. The BEC Framework is not a perfect instrument, no applied science framework is. It represents a deliberate and controlled simplification, designed to enable market adoption rather than await unattainable precision. Like all best-practice methodologies, it accepts manageable trade-offs in exchange for practical utility. A working tool, that can be refined over time is more valuable than a theoretically flawless model that never leaves the page. With industry cooperation and regulatory commitment, the framework provides a credible pathway from the current ungoverned baseline toward measurable, enforceable environmental accountability in space operations.

6.  Associated Features & Publications

ROOM Space Journal of Asgardia - Panluek - DarkSkies - Jan 2026.pdf

Download PDF • 5.03MB

The EU Space Act Deleted Its Brightness Limit — Here's Why That Matters - Orbital Today

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