Â鶹ÒùÔº

A Dyson swarm made of solar panels would make Earth uninhabitable, suggests study

As civilizations become more and more advanced, their power needs also increase. It's likely that an advanced civilization might need so much power that they enclose their host star in solar energy-collecting satellites. These Dyson swarms will trap heat so any planets within the sphere are likely to experience a temperature increase. A new paper explores this and concludes that a complete Dyson swarm outside the orbit of Earth would raise our temperature by 140 K.

The concept of a Dyson swarm is purely a hypothetical concept, a theorized megastructure consisting of numerous satellites or habitats orbiting a star to capture and harness its energy output. Unlike the solid shell of a Dyson sphere, a swarm represents less of an engineering challenge, allowing for incremental construction as energy needs increase. The concept, first popularized by physicist Freeman Dyson in 1960, represents one of the most ambitious yet potentially achievable feats of astroengineering that could eventually allow a civilization to use a significant fraction of its host star's total energy output.

While presently only the stuff of theory and science fiction, it has inspired real scientific research. It's an idea that presents a potential solution for the enormous energy needs as we take tentative steps toward traveling beyond our solar system. If we, or any advanced civilizations that might be out there succeed, then they would be classed as Type II on the Kardashev scale. The scale is used to articulate a civilization's level of technological advancement based on the amount of energy it is capable of harnessing and using.

Dyson swarm structures are likely to use photovoltaic technology to convert stellar radiation into usable energy. Their efficiency in energy conversion is highly dependent on the temperature of the solar cells, and unlike Earth-based equivalents, they must balance thermal exchanges with the sun, outer space and the enormous surface area of their structure. Temperature regulation of the structure is one of the challenges that must be overcome, since it must remain cool for optimal operation.

It's not just the temperature of the structures that poses problems, asserts Ian Marius Peters from the Helmholtz Institute Erlangen-Nurnberg for Renewable Energy. In a research paper, he explores the environmental changes of planets within a swarm or sphere. The research examines whether such a megastructure could be built using materials available in our solar system while still preserving Earth's habitability, balancing the goal of stellar energy capture with the need to maintain conditions that support life on our planet.

The findings are in the journal Solar Energy Materials and Solar Cells.

The paper concludes that a Dyson sphere surrounding the sun would significantly impact Earth's climate. Small spheres positioned inside Earth's orbit prove impractical, either becoming too hot for their own efficiency or having too great an impact on solar energy arriving on our planet. While large spheres enable efficient energy conversion, they would raise Earth's temperature by 140 K, making Earth completely uninhabitable.

A compromise might involve creating a partial structure (the Dyson swarm) at 2.13AU from the sun. This would harvest 4% of solar energy (15.6 yottawatts, or 15.6 million billion billion watts) while increasing Earth's temperature by less than 3K—comparable to current global warming trends. It's still quite an engineering feat though, requiring 1.3×10²³ kg of silicon.