As humanity emits increasing amounts of greenhouse gases, the Earth’s atmosphere traps more and more of the sun’s energy, leading to a steady rise in our planet’s temperature. For decades, scientists have considered using screens or other objects to block enough of the sun’s radiation (about one to two percent) in order to mitigate the effects of climate change. Now, a team of researchers led by Harvard University and the University of Utah has explored another strategy – the potential of using moon dust to shield sunlight.
The researchers investigated different properties of dust particles, quantities of dust, and the orbits which would be best suited for shading the Earth. They discovered that launching dust from Earth to a way station located at the so-called “Lagrange point” – the closest point between Earth and the sun where the gravitational forces are balanced and where objects tend to stay along a path between the two celestial bodies – would be the most effective strategy. This approach, however, would require enormous costs and efforts. To overcome these problems, the experts have proposed using moon dust as an alternative.
“It is amazing to contemplate how moon dust – which took over four billion years to generate – might help slow the rise in the Earth’s temperature, a problem that took us less than 300 years to produce,” said study co-author Scott Kenyon.
According to the researchers, planet formation is a messy process, kicking up astronomical dust that forms rings around host stars. Such rings intercept light from the central star and re-radiate it in ways that can be easily detected. “That was the seed of the idea; if we took a small amount of material and put it on a special orbit between the Earth and the sun and broke it up, we could block out a lot of sunlight with a little amount of mass,” said study lead author Professor Ben Bromley.
The scientists found that a sunshield’s effectiveness would depend on its capacity to sustain an orbit that casts a shadow on the Earth. “Because we know the positions and masses of the major celestial bodies in our solar system, we can simply use the laws of gravity to track the position of a simulated sunshield over time for several different orbits,” said study co-author Sameer Khan.
Since the inherent properties of lunar dust are perfect to effectively work as a sunshield, the scientists proposed to shoot this dust from a platform on the surface of the moon towards the sun – a cost-effective strategy due to the fact that much less energy is needed to launch dust from the moon than from the Earth. “It is astounding that the Sun, Earth, and Moon are in just the right configuration to enable this kind of climate mitigation strategy,” Kenyon said.
However, the researchers emphasize that this study only explores the potential impact of such a method, rather than evaluating whether this strategy is logistically feasible.
“We aren’t experts in climate change, or the rocket science needed to move mass from one place to the other. We’re just exploring different kinds of dust on a variety of orbits to see how effective this approach might be. We do not want to miss a game changer for such a critical problem,” concluded Bromley.
The study is published in the journal PLOS Climate.
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