In a study published in the PLOS Climate journal on February 8th, three scientists discuss the scenario of blocking sunlight reaching Earth by deploying reflective dust into space. Through computer simulations, the research team discovered the potential use of Moon dust for this purpose. They proposed shooting dust from the Moon’s surface into space to temporarily dim the Sun.
Benjamin Bromley, a theoretical astrophysicist at the University of Utah and the lead author of the study, emphasizes that his team does not aim to develop climate solutions as they are not climate scientists. His usual research area focuses on planetary formation. During this process, Bromley and his two computer science students, Sameer Khan and Scott Kenyon, at the Smithsonian Astrophysical Observatory found inspiration. They realized that a relatively small amount of dust could block starlight and considered dust as a potential solution to dim the Sun.
Bromley shares that the proposed simulation would be based on a small Ice Age period during the reign of Louis XIV of France. Blocking about 1-2% of sunlight requires a substantial amount of dust. One of the initial ideas from the research team was to position a dust-spewing array in space at the Lagrange Point L1, located 1.4 million kilometers away, between Earth and the Sun. At this point, objects remain fixed due to the gravitational forces of the two celestial bodies.
However, the challenge arises from the fact that Sun dust would quickly be blown away from the L1 point. It is not stable enough to maintain a dust shield. Therefore, the research team considered a location closer to Earth—specifically, the Moon. They created a simulation demonstrating that launching dust from the Moon to the L1 point is the most promising solution. “Moon dust is chosen for two reasons. First, it effectively deflects sunlight, and second, it has the highest concentration of particles on the Moon’s surface,” explains Bromley.
Nevertheless, the issue lies in determining the required amount of dust. Regularly launching rockets filled with dust to the dust-spewing array at the L1 point would be expensive, making the Moon a second advantage. If humans establish infrastructure on the Moon’s surface, it would be much easier to launch dust from there due to the Moon’s weaker gravitational pull compared to Earth. Simulation results indicate that dust particles would not fall back to Earth after being deployed into space. Instead, they would drift away from the Sun.
Bromley and his colleagues’ proposal is not the only space-based solar shield concept. A similar proposal utilizing Moon dust was introduced by researcher Curtis Struck at the University of Iowa in 2007. Last year, scientists at the Massachusetts Institute of Technology proposed constructing a sunshade in space placed at the L1 point. All of these solutions have the drawback of not being quickly implementable enough to counteract the current rise in temperatures. However, Bromley emphasizes that Moon dust remains an avenue worth exploring if we need to dim the Sun, despite various technical challenges.