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When it comes to the climate crisis, political discussion often rests on the assumption that a technological solution will save us from ourselves and the greenhouse emissions that we continue to pump into the atmosphere. These solutions are far from ready to be deployed, but progress and proposals are being made. Now, scientists have put forward a novel idea suggesting it would be easier to reduce the amount of sunlight getting to our planet than curb emissions: hang a giant sun shade on a nearby asteroid.
The approach sees the deployment of a solar shield, an interplanetary parasol that would sit at L1. This a special gravitational region that is always between the Earth and the Sun, but it moves with our planet as Earth goes around our star. It is crucial that it stays in that position or it won’t work. But to stay there, it needs to be massive, or the pressure of sunlight will push it away.
The traditional estimate for such a sun shield is 3.5 million tons. That would be like launching half of the Great Pyramid of Giza into space. But something massive is very expensive and complicated to send into space. So far, launch vehicles can send about 100 tons of payload into space. That would be 35,000 launches needed.
An astronomer from the University of Hawaiʻi Manoa has been able to massively reduce such requirements by proposing a radical solution: Instead of having a massive shield, how about having a cosmic umbrella with a light parasol part and a heavier counterweight, in this scenario a captured asteroid?
"In Hawaiʻi, many use an umbrella to block the sunlight as they walk about during the day. I was thinking, could we do the same for Earth and thereby mitigate the impending catastrophe of climate change?" István Szapudi said in a statement.
The approach is a lot more feasible than the previous approach but it still requires a large number of launches, the ability to move an asteroid to L1, and also a way to tether the asteroid to the shield like graphene nanotubes. So more feasible, but not yet doable.
The paper is published in the journal Proceedings of the National Academy of Sciences.
