Cheap and Effective Solution for Earth’s Climate Crisis: Launching Lunar Dust from the Moon

A US scientific study has explored the possibility of launching moon dust into space to block the sun’s rays and slow down global warming. It may seem like a concept from a science fiction film, but the researchers have calculated the feasibility of this idea.

For many years, researchers have wondered if it could be possible to reduce the impacts of global warming by employing objects, screens, or dust to block between 1 and 2% of the sun’s light.

A research sponsored by the University of Utah investigated the possibility of deploying dust to block sunlight. They examined various dust particle characteristics, dust concentrations, and the optimal orbits for shady Earth.

The authors discovered that releasing dust from Earth to a way station at the “Lagrange Point” between Earth and the sun (L1) would be most successful, but would be very expensive and time-consuming. You might also try moondust. The authors contend that an inexpensive and efficient technique to shade the Earth would be to throw lunar dust from the moon.

The group of astronomers used a method that is usually used to study how planets form around faraway stars. The chaotic process of planet creation produces a great deal of cosmic dust, which may eventually create rings around the host star. These rings block the light coming from the main star and reflect it back to us so that we can observe it. These dusty rings are one way to find stars that are making new planets.

Ben Bromley, professor of physics and astronomy and study’s lead author, said that this was the inspiration for 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.”

According to Scott Kenyon, co-author of the study from the Center for Astrophysics | Harvard & Smithsonian, “it is amazing to contemplate how moon dust—which took over four billion years to generate—might help slow the rise in Earth’s temperature, a problem that took us less than 300 years to produce.”

The study was released by PLOS Climate journal today.

The effectiveness of a shield depends on how long it can stay in an orbit that casts a shadow on Earth. The study’s co-author and undergraduate student Sameer Khan oversaw the first investigation into whether orbits may keep dust in place for long enough to produce sufficient shade. Khan’s experiment revealed the challenge of containing dust to the desired location.

“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,” adds Khan.

Two possibilities seemed to be promising. The L1 Lagrange point, which is the closest point between Earth and the sun where the gravitational forces are balanced, is where the authors placed a space station in the first scenario. Objects at Lagrange points tend to follow a course that connects the two celestial bodies, which is why the James Webb Space Telescope (JWST) is positioned at L2, a Lagrange point on the other side of the Earth.

The researchers launched test particles along the L1 orbit while simulating the positions of Earth, the sun, the moon, and other planets in the solar system, and they then observed where the particles dispersed. When launched exactly, the authors discovered that the dust will follow a route between Earth and the sun, essentially generating shadow for a while. The dust was readily blown off course by the solar winds, radiation, and gravity inside the solar system, unlike the 13,000-pound JWST. Any L1 station would need to continuously produce fresh batches of dust to launch into orbit after the first spray had dissipated.

“It was rather difficult to get the shield to stay at L1 long enough to cast a meaningful shadow. This shouldn’t come as a surprise, though, since L1 is an unstable equilibrium point. Even the slightest deviation in the sunshield’s orbit can cause it to rapidly drift out of place, so our simulations had to be extremely precise,” Khan explains. 

The authors’ second scenario included shooting lunar dust from the moon’s surface toward the sun. They discovered that the natural characteristics of lunar dust were ideal for it to function as a solar screen. The simulations examined how lunar dust dispersed along different paths until they discovered good trajectories that functioned as an efficient solar screen and were directed toward L1. These findings are encouraging since launching dust from the moon requires a lot less energy than launching it from Earth. This is significant because the output of a huge mining operation on Earth is similar to the volume of dust in a solar shield. Also, since the new sun-shielding trajectories were found, it may not be necessary to send the lunar dust to a separate platform at L1.

The authors are very clear that this study only looks at the possible effects of this strategy and doesn’t try to figure out if these scenarios are even possible.

“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,” points out Bromley.  

Refilling dust streams every few days is one of the most difficult logistical tasks, but it also has a benefit. Dust particles are eventually dispersed across the solar system by the sun’s radiation; the sun shield is transitory and particles do not fall on Earth. The authors guarantee that their method will not result in a persistently frigid, inhospitable world, as depicted in the science fiction tale “Snowpiercer.”

If we need more time, then our approach to combating climate change could be a viable one, according to Bromley.

Source: 10.1371/journal.pclm.0000133

Image Credit: Ben Bromley/University of Utah