Mitigating climate change on Earth is such a big problem that scientists are seriously exploring every option they can think of. Astronomer István Szapudi from the University of Hawaii's Institute of Astronomy thinks we could capture an asteroid, park it in front of the Earth and tie an umbrella to it to block some of the Sun's light.

Sounds a bit crazy, doesn't it? But it's not out of the realms of possibility.

The sun shield is not a new idea. But Szapudi's modifications will greatly reduce the cost and difficulty of implementation, bringing it one step closer to accessibility.

"In Hawaii, many people use umbrellas to block sunlight when walking during the day," he explains. "I was wondering if we could do the same thing for Earth and thereby mitigate the impending climate change catastrophe."

The idea of a solar shield is not unjustified at all. If it blocks only a small percentage of the sunlight constantly irradiating the Earth, it might be enough to counteract rising temperatures; maybe not an absolute solution, but a workaround to buy us some time to work on things here on the surface.

The problem is that the sail would need a fair amount of mass to keep it from being blown away by the solar wind and radiation pressure, and as ballast for gravitational stability, and transporting that much mass into space would be difficult and expensive.

But what if the mass is already out there? That's where capturing an asteroid and attaching an umbrella to it comes in.

Szapudi calculated that placing a counterweight in the L1 Lagrangian towards the Sun would reduce the total mass of the shield and counterweight to just 3.5 million tonnes.

However, this idea may be more realisable than previously thought. NASA has shown that we can redirect an asteroid. Much more work needs to be done, but Szapudi thinks that if we start research and development work now, we could make it a reality before it's too late for the climate. And there are other potential benefits.

While it has been calculated that blocking about 1 to 2 per cent of sunlight would be enough to cool the planet, Szapudi argues that "a more cautious approach would use historical data".

Szapudi's idea is therefore scalable, reducing light by as little as 0.24 per cent while increasing it by as much as 1.7 per cent. It would also need to be easily reversible. "Depending on the parallel and intertwined development of graphene, tether and orbital technologies, a tethered shield could initially be faster and cheaper to realise than a heavier structure," he writes in his paper.

"However, the latter could eventually serve as a source of solar energy for Earth or Solar System exploration."

 

Source: https://www.sciencealert.com/