Could a giant umbrella in space help cool Earth? At the Next Frontiers conference in Stuttgart one topic stood out for its sheer scale: Tharshan Maheswaran from the Institute of Space Systems (IRS) at the University of Stuttgart provided insights into his research on the possibility of protecting Earth from solar radiation from space.
As global temperatures continue to rise and international climate targets drift further out of reach, researchers are exploring ideas once considered pure science fiction. One of them is the International Planetary Sunshade System (IPSS), a proposed space-based structure designed to reduce the amount of sunlight reaching Earth just enough to potentially halt global warming. At the conference, aerospace engineer and climate researcher Tharshan Maheswaran presented the concept as part of a broader discussion about climate engineering. In an interview after the event, he described the IPSS not as a replacement for climate policy, but as a possible emergency measure if current efforts fail.
“We’re not saying that this is the magic solution,” Maheswaran explaines. “we want to understand if it could become part of a larger response to the climate crisis.”
The concept belongs to the field of geoengineering – large-scale technological interventions designed for influencing Earth’s climate system. Unlike similar proposals like releasing particles into the atmosphere to reduce radiation, the IPSS would operate in space. In effect, it would be a gigantic solar sail that lightly shades the entire globe, blocking a tiny fraction of incoming solar radiation. Positioned at the nearest point in space where the Earth’s and our Sun’s gravity balance out, the Sunshade would need only minimal maneuvering once in place. One of the biggest challenges of the project is that this point, the L1 Lagrange point, is roughly 1.5 million kilometers away from Earth. Building Sunshade of over a million square kilometers in size that far away simply isn’t feasible when using materials launched from Earth, scientists agree. The project would therefore require large scale mining and manufacturing closer to the L1 point, in a place where launching material is much easier: the Moon.
What may sound like far fetched a science fiction, scientists like Maheswaran judge to be worth the effort. According to scientific studies, reducing solar radiation by less than one percent could already produces significant cooling effects. Maheswaran and researcher Sebastian Fix outlined technological and governance challenges of such a system in their 2021 publication Roadmap for an International Planetary Sunshade (IPSS).
Supporters argue that the concept could buy time while societies continue transitioning away from fossil fuels. Critics, however, warn that geoengineering risks distracting from our responsibility for reducing emissions and expanding renewable energy. Maheswaran rejects the idea that the system should replace climate policy. “It is a tool among many, not a replacement.”
The debate reflects a broader frustration within climate politics. Reports by the Intergovernmental Panel on Climate Change (IPCC) continue to show that current global policies remain insufficient to meet the Paris Agreement targets. At the same time, many countries remain economically dependent on fossil fuels, making rapid transitions politically difficult. Maheswaran argues that the energy transition is mainly driven by changes in society.
Technologically, we have been sufficiently capable for a long time. Rather than imagining the IPSS as a single megaproject, researchers envision gradual development over decades through prototypes, material testing and orbital infrastructure projects. Public support would be essential for that process. That support may become more realistic as the private space sector grows. Companies such as SpaceX have lowered launch costs through reusable rockets, while NASA’s Artemis program and increasing investment in research are contributing to what many analysts call the “New Space Economy.”
“It’s like a gold rush, only this time in space.”
Tharshan Maheswaran
Supporters also point to possible technological spin-offs. Research into lightweight materials, autonomous manufacturing and orbital energy systems could massively benefit industries far beyond climate engineering. Some concepts even envision the sunshade functioning partly as a solar-energy collector.
Still, major concerns remain. One of the largest is governance. International law regarding space infrastructure and resources remains fragmented. Critics fear that future orbital systems could concentrate enormous power in the hands of corporations or individual states. Maheswaran acknowledges these risks openly. According to him, any technology can be misused if managed incorrectly. How you go about governing something that has the potential to protect the entire globe is arguably the most delicate part.
Others worry that a planetary sunshade could visibly darken Earth’s skies or disrupt ecosystems. Researchers involved with the concept argue that the reduction in sunlight would likely be imperceptible to humans and carefully controlled. Even Maheswaran acknowledges that the IPSS would require decades of research, international cooperation and massive investment. Geoengineering alone also would not solve related problems such as biodiversity loss or ocean acidification. Still, he argues that investigating backup options is increasingly critical as climate risks intensify. As he puts it, researchers hope humanity never needs a system like this. “But if we wait until we are desperate, it will already be too late to start researching it.”
Whether planetary sunshades ultimately become reality or remain speculative, the debate at Next Frontiers demonstrated how quickly once-fictional climate ideas are entering serious scientific discussion.
Sources:
- Maheswaran, T.; Fix, S.: Roadmap for an International Planetary Sunshade (IPSS), IAC-21-D4.1.6, 72nd International Astronautical Congress, Dubai, United Arab Emirates, 2021.
- https://www.ipcc.ch/assessment-report/ar6/
- https://www.fraunhofer.de/de/forschung/artikel-2026/new-space-economy.html
- https://www.pnas.org/doi/10.1073/pnas.0608163103
- https://www.nasa.gov/wp-content/uploads/2020/12/artemis_plan-20200921.pdf
- Interview with Tharshan Maheswaran
Project Contact
Tharshan Maheswaran, Research Associate at the Institute for Space Systems (IRS) at the University of Stuttgart, Department of Space Transportation Technology