Moon dust cloud against climate change – New Scientist

Placing a million tons of lunar dust between Earth and the sun would reduce Earth’s sunlight by 1.8 percent, and the temperature would drop. But the risks associated with such a megalomaniac plan are as yet unclear.

To reduce global warming, we could launch a cloud of dust from the moon to block some of the sunlight. The development of such a plan requires more than ten years of research, and the risks are still unclear. There would be consequences for agriculture, ecosystems and water quality in different parts of the world.

The idea itself is older, but now have astrophysicist Benjamin Bromley of the University of Utah and his colleagues devised a solution to how such a dust cloud forms, they write PLOS Climate. He proposes that we continuously launch a stream of lunar dust from the north pole of the moon at a speed of 2.8 kilometers per second.

Stable cloud

It concerns more than 100 million tons of dust that is placed between the earth and the sun, casting a shadow on the earth. The dust would absorb and scatter some of the sunlight’s energy. To achieve this, the dust cloud must be placed 1.5 million kilometers from Earth. There is a place where the gravitational forces of the sun and the earth cancel each other out, so that objects remain suspended. This location is called the first Lagrange point, or L1.

Several research groups propose to place dust on L1. However, dust would not stay there permanently: charged particles from the sun, the so-called solar wind, would gradually blow it away.

Million tons

The researchers propose to continuously replenish the cloud from the moon. From thousands of computer simulations, they conclude that this is a better approach. The simulations took into account the gravitational pull of the sun, Earth and other planets, as well as effects such as the solar wind.

They point out that each dust particle launched blocks sunlight for about five days before drifting away into the solar system. If we managed to keep a dust shield with a mass of 1 million tons close to L1 for a year, the Earth’s sunlight would decrease by 1.8 percent, which is equivalent to blocking all sunlight for six days.

We should keep the material flow going long enough to take other measures to reduce CO in the meantime₂ remove from the atmosphere. In this way we can reduce the CO₂offset the increase since the industrial revolution, says earth scientist Ben Kravitz from Indiana University in the US.

Railgun on the moon

‘If this method works, it can lower the temperature on Earth. But it’s hard to say whether it’s worth it, given the effort and resources required,” says Kravitz. The simulations say nothing about how and with what technology we would launch the lunar dust to L1.

For example, it is possible to have a railgun on the lunar north pole, an electric gun that shoots conductive objects between two rails, says Bromley. The energy for this device could be supplied by “a few square kilometers of solar panels near the launch site,” he says.

Far-reaching effects

There are still some snags to the plan. Darkening the Earth will lead to different effects in different regions, Kravitz says. “Temperature, precipitation, wind and many other things change, in different places in different ways,” he says. ‘These changes naturally have an impact on agriculture, ecosystems and water quality.’

Before a dust gun is put on the moon, large-scale studies must first be carried out by several agencies in different countries. The United Nations will also have to pass judgment on the plan, says astronomer Curtis Struck from Iowa State University.

Another bottleneck is that inaccuracies occur in the launch and scattering of the dust. It is unknown what effect they have. ‘Would more micrometeorites fall to Earth? Or would there be more damage to orbiting satellites?’ says Struck. “These and many other questions have not yet been studied in the necessary detail.”

Moreover, futuristic plans like this should not replace efforts to curb emissions on Earth. “We have to continue to reduce the amount of greenhouse gases in our own atmosphere no matter what,” says Bromley. “Our dust shield solution would just buy a little more time.”