He global warming It is one of the most pressing problems facing human beings. That is why, from multiple areas, different solutions are proposed to combat or mitigate it. One of the latest proposals -and one of the most exotic- is the one proposed by researchers from the University of Utah, who have prepared a study in which they detail a system by which dust is used as a kind of ‘global umbrella’ lunar shot directly from our satellite. The conclusions have just been published in the journal ‘PLOS Climate’.
The authors first focused on the dust itself: they looked at different properties of the dust particles, and the amount that would have to shoot into space from our terrestrial domains for these particles to serve as a screen. Thus, they discovered that throwing dust from the Earth to a way station in the ‘Lagrangian point‘ between the Earth and the Sun (L1) would be the most efficient; however, there is a catch: it would require astronomical cost and effort. Therefore, the best alternative is to use lunar dust. The authors argue that launching regolith from the satellite itself could be a cheap and effective way to shade the Earth.
The idea is born with the planets
The authors are dedicated to studying the dust that is created during the formation of planets around their stars. In this chaotic process many of these particles are formed that can form rings around the host star. These rings intercept the light from the central star and radiate it back so that we can detect it on Earth. One way to discover stars that are forming new planets is to look for these dusty rings.
«That was the seed of the idea; if we take a small amount of material and put it in a special orbit between the Earth and the Sun and break it up, we could block a large amount of sunlight with a small amount of mass,” he explains in a statement.Ben Bromley, professor of physics and astronomy and lead author of the study. “It’s amazing to see how lunar dust – which took more than 4 billion years to create – could help slow the rise in Earth’s temperature, a problem that took us less than 300 years to produce,” he says. Scott Kenyonco-author of the study from the Harvard Smithsonian Center for Astrophysics.
The overall effectiveness of a shield depends on its ability to maintain an orbit that casts a shadow on Earth. Sameer Khan, a university student and co-author of the study, led the initial exploration of which orbits could hold the dust in position long enough to provide an adequate shadow. Khan’s work demonstrated the difficulty of keeping powder where it is needed.
“Since we know the positions and masses of the major celestial bodies in our solar system, we can use the laws of gravity to track the position of a simulated sunshade over time in different orbits,” explains Khan.
Two potential scenarios
Two scenarios turned out to be promising. In the first, the authors located a space platform at the L1 Lagrange point, the closest point between the Earth and the Sun, where the gravitational forces are balanced. Objects located at Lagrange points tend to stay on a path between the two celestial bodies, which is why the James Webb Space Telescope (JWST) is located at L2, a Lagrange point on the opposite side of Earth.
In computer simulations, the researchers fired test particles along the L1 orbit, including the position of Earth, the Sun, the Moon and other planets in the solar system, and tracked where the particles scattered. The authors found that, thrown with precision, the dust would follow a path between the Earth and the Sun, creating a shadow, at least for a while. Unlike the JWST, which weighs 5.8 tons, the dust was easily knocked off course by solar winds, radiation, and gravity within the solar system. Any L1 platform would need to create an endless supply of fresh batches of dust to launch into orbit every few days after the initial spray dissipates.
“It was pretty hard to get the shield to stay on L1 long enough to cast a significant shadow. Although this should not surprise us, since L1 is an unstable equilibrium point. Even the slightest deviation in the sunshade’s orbit can cause it to move rapidly out of place, so our simulations had to be extremely accurate,” explains Khan.
moonshot
In the second scenario, the authors shot lunar dust from the Moon’s surface towards the Sun. They found that the inherent properties of lunar dust were just right to function effectively as a solar shield. The simulations tested how lunar dust dispersed along various paths until they found excellent L1-directed trajectories that served as an effective solar shield.
These results are good news, because it takes much less energy to launch dust from the Moon than it does from Earth. This is important because the amount of dust from a sun shield is large, comparable to the output of a large mining operation here on Earth. In addition, the discovery of the new solar shielding trajectories means that lunar dust may not need to be transported to a separate pad on L1.
The authors stress that this study only explores the potential impact of this strategy, rather than assessing whether these scenarios are logistically feasible.
“We are not experts in climate change or the rocket science required to move mass from one place to another. We’re just exploring different types of dust in a variety of orbits to see how effective this approach is. We don’t want to miss the opportunity to be a game changer on such a critical issue,” says Bromley.
One of the biggest logistical challenges, replenishing dust streams every few days, also has an advantage. In the end, solar radiation scatters the dust particles throughout the solar system; the solar shield is temporary and the particles of the shield do not fall on Earth. The authors say their approach would not create a permanently cold and uninhabitable planet, as in the science fiction story “Snowpiercer.”
“Our strategy could be an option to address climate change,” Bromley said, “if more time is what we need.”