Bringing Starlink connectivity to Sri Lanka has stirred up much discussion in recent months. While the promise of high-speed internet from space sounds revolutionary, especially for rural and underserved areas, it also raises a crucial question that goes far beyond national borders – Just how many satellites can we sustainably place in orbit? In light of new scientific findings, we must pause to consider the long-term viability of our skies, particularly as they become increasingly crowded with commercial satellite constellations.

Recent research from the Massachusetts Institute of Technology (MIT) reveals a hidden consequence of our global climate crisis, one that reaches beyond the earth's surface and into the fragile edges of space. Greenhouse gas emissions, it turns out, are not only warming our planet but also changing the very environment where satellites like Starlink are meant to operate. And, the consequences could affect everything from communication systems and navigation to the future of global space access.

A shrinking thermosphere

At the heart of this research lies the thermosphere, a region of the earth's atmosphere that starts around 80 kilometres (km) above the surface and stretches up to 600 km. It is home to the International Space Station and the majority of operational satellites.

Unlike the greenhouse effect closer to earth, which traps heat and warms the surface, in the thermosphere, greenhouse gases such as carbon dioxide and methane radiate heat into space, cooling this atmospheric layer. This cooling causes the thermosphere to contract, reducing its density. While this might seem like a benign process, its consequences are anything but.

A thinner thermosphere exerts less atmospheric drag on objects in orbit. Drag is a natural, albeit gradual, mechanism that slows down satellites and space debris, eventually causing them to re-enter the denser layers of the atmosphere where they burn up. With less drag, these objects linger far longer in space. This prolonged orbital lifetime increases the risk of collisions, which in turn generate even more debris, a scenario known as the Kessler Syndrome, a cascading chain reaction of collisions that could make entire regions of space unusable for decades, if not centuries.

From ecology to orbital carrying capacity

Drawing on ecological principles, MIT researchers introduced a novel framework: the concept of ‘carrying capacity’ in space. Traditionally applied to ecosystems to denote the number of individuals that an environment can sustain, this term was repurposed to assess how many satellites a specific orbital shell can safely support without triggering catastrophic collision cascades.

By running simulations under various emissions, scenarios including those developed by the Intergovernmental Panel on Climate Change (IPCC), the team found that greenhouse gas-induced thermospheric shrinkage could reduce the carrying capacity of key satellite altitudes by 50-66% percent by the year 2100.

That means that unless emissions are curbed, only a third to half as many satellites can be safely deployed in critical orbital zones compared to what would have been feasible under year-2000 atmospheric conditions.

The satellite boom

The implications of this research are especially urgent in light of the dramatic surge in satellite launches over the past decade. From 2019 to last year (2024) alone, the number of active satellites has skyrocketed, thanks in part to the rise of megaconstellations, large networks of small satellites deployed by companies like SpaceX (Starlink), OneWeb, and Amazon (Project Kuiper) to provide global internet coverage.

According to MIT, “More satellites have been launched in the last five years than in the preceding 60 years combined.” And, this is only the beginning. SpaceX alone plans to launch over 42,000 satellites in the coming years.

This surge is taking place in an environment that is growing increasingly hostile not due to natural space hazards, but because of changes in the earth’s own atmosphere driven by human behaviour. As the thermosphere thins and drag decreases, space debris will remain in orbit longer, and once satellite populations exceed safe thresholds, runaway instability could make certain orbits unusable.

In other words, if we continue our current trajectory of unregulated satellite launches combined with unchecked greenhouse gas emissions, we risk turning the earth’s orbital real estate into a graveyard of defunct satellites and dangerous debris.

Climate change and space sustainability

This research offers a stark lesson in unintended consequences. For years, the climate crisis was considered a terrestrial issue, one that affected oceans, forests, ice caps, and communities. Now, we are beginning to understand that climate change is planetary in the truest sense. The interconnectedness of earth’s systems extends all the way to space.

The upper atmosphere’s role in orbital sustainability has often been overlooked in the discourse around climate change. The MIT’s findings serve as a wake-up call that preserving the earth’s atmospheric integrity is not only vital for life on the ground but also for the systems that we rely on high above it.

Moreover, space sustainability is not just about scientific exploration or corporate ventures; it has profound implications for global security, economic stability, and human resilience. Satellites underpin the global financial system, weather forecasting that saves lives during disasters, and the communications infrastructure that we rely on every day. Jeopardising satellite operations means jeopardising all these services.

The policy and tech implications

This study arrives at a crucial moment when space governance is becoming more urgent. National and international regulatory bodies, including the United Nations Office for Outer Space Affairs and national space agencies, must now factor climate-related impacts into space traffic management and satellite licensing procedures.

Efforts to develop debris removal technologies such as nets, harpoons, lasers, and robotic arms are in progress, but none are yet scalable enough to handle the scale of the problem. Meanwhile, new frameworks around satellite end-of-life protocols, de-orbit timelines, and collision avoidance systems are needed.

In parallel, climate mitigation must now be seen as a strategy not just for the earth but for preserving access to space. Reducing emissions, adopting sustainable energy sources, and curbing industrial pollutants is not just about protecting coral reefs or air quality, it is about preserving the orbits that hold the infrastructure of modern civilisation.

What happens if we ignore this?

Should greenhouse gas emissions continue unabated and satellite launches remain unregulated, the consequences could be catastrophic.

• Key orbital regions could become inaccessible by the end of the Century.
• Global satellite services could be severely disrupted, affecting communication, navigation, internet access, and weather forecasting.
• Increased space militarisation risks may emerge as nations compete over the remaining viable orbital slots.
• Insurance premiums for space missions could skyrocket, pricing out smaller nations and companies and increasing inequality in access to space-related services.
• Scientific missions and climate monitoring from space could be delayed or made impossible due to debris-related risks.

A final frontier 

These researches and studies shine a bright and urgent light on a domain that few people associate with climate change – the space above our heads. But, as the earth warms, its influence extends outward. The atmosphere, once our guardian against space junk, is thinning. And, unless we act, we may find ourselves locked out of space altogether.

This is not just a technical challenge, it is a moral one. Humanity must now consider sustainability not only in forests and oceans but in the skies and beyond. By recognising that climate action extends past our planetary surface, we can start building a truly resilient future, one where space remains accessible, safe, and sustainable for generations to come.

(The writer is an electronics engineer with a background in information technology and sustainability)

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The views and opinions expressed in this article are those of the author, and do not necessarily reflect those of this publication