Giant ‘sun umbrella’ tethered to asteroid may help fight climate change: Study

As we continue to witness record-breaking heatwaves and other extreme weather events which researchers previously said have been exacerbated by human-induced climate change, several ideas have been pitched to mitigate the dire challenge but this one is out of the world (literally).

About a giant ‘sun umbrella’

Astronomer István Szapudi of the University of Hawaiʻi Institute for Astronomy believes that a solar shield to reduce the amount of sunlight hitting Earth could help mitigate the problem. However, this is not the first time that the idea of a space-based solar radiation management (SRM) shield or shade has been proposed.

What makes this one different is the plan to tie the giant shield to a captured asteroid as a counterweight. The potential solution was published in the Proceedings of the National Academy of Sciences (PNAS) journal.

So far, the idea of a solar shield, in theory, can cool down the Earth by shading it from some of the sun’s rays but the issue was the large amount of weight needed to make a shield massive enough to balance gravitational forces and prevent solar radiation pressure from blowing it away.

Therefore, the US-based astronomer’s idea involves a tethered counterweight instead of just a massive shield and the use of a captured asteroid to counter said weight to avoid launching such a big mass from Earth to hold the “sun umbrella”.

What makes this idea almost achievable?

Szapudi’s approach brings the idea into the realm of possibility with greatly reduced cost as well as lowering the difficulty of implementation. “In Hawaiʻi, many use an umbrella to block the sunlight as they walk about during the day,” the astronomer explained in a statement.

He added, “I was thinking, could we do the same for Earth and thereby mitigate the impending catastrophe of climate change?”

Previous research has suggested that even if we managed to lower solar radiation by 1.7 per cent it could prevent a catastrophic rise in global temperatures.

In line with this, Szapudi proposed two ideas – the first one would involve placing a tethered counterbalance toward the Sun could reduce the weight of the shield. The second is a counterweight of approximately 3.5 million tonnes, which would be over 100 times lighter than previous estimates for an untethered shield.

While the 3.5 million tonnes might sound like a lot of mass, only one per cent of it would account for the actual shield, around 35,000 metric tonnes and the remaining would be the asteroid.

The plan is to launch the counterweight, which will be attached to the solar shield by a strong graphene tether, and then slowly open once in space, allowing it to gradually fill with lunar dust or asteroid material.

Since the asteroid material that would act as ballast would already be in space it would not need to be launched from Earth. However, some of the largest rockets can carry about 50 tons to low Earth orbit, which poses a big challenge to this particular SRM plan.

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