With an idea that sounds like it was torn from the pages of a science fiction novel, a University of Hawaii astronomer has proposed a solution to the global warming crisis that uses a solar shield to reduce the amount of sunlight hitting Earth.
While the concept isn’t exactly new, the proposal by Istvan Szapudi of UH’s Institute for Astronomy suggests stabilizing the shield in space by manipulating the orbit of an asteroid and harnessing its power as a counterweight at the end of a tether in a move to counteract the forces of solar
radiation.
The concept was unveiled Monday in a peer-reviewed paper, “Solar radiation management with a tethered sun shield,” and published in Proceedings of the National Academy of Sciences.
The paper comes as scientists report that July was Earth’s hottest month on record and as hundreds of millions of people around the world are exposed to dangerous heat waves.
In a video interview from his childhood home of Hungary, Szapudi said he would prefer that humans get their act together to drastically reduce greenhouse gases to combat climate change.
“I agree that holding back CO2 emissions is the best way forward, but so far it isn’t happening. So we have to think about everything,” he said.
Szapudi has been traveling in Europe this summer and has seen the climate
crisis with his own eyes.
“There was a heat wave that, coming from Hawaii, was almost unbearable,” he said. “Last week I was in
Milan at a conference, and it was just hell.”
Szapudi, who joined the university in 2001, is a theoretical cosmologist who spends much of his time thinking about abstract concepts and larger ideas spanning time and space.
He came up with his latest idea as he thought of the many people in Hawaii who use an umbrella to block the sunlight as they walk about during the day.
“I was thinking, Could we do the same for Earth and (avert) the impending
catastrophe of climate change?” he said.
The idea of reducing the global temperature to shade Earth from a fraction of the sun’s light with a solar shield has been proposed before. In June the Biden administration released a report mandated by Congress that endorsed studying how to block sunlight from hitting Earth’s surface as a way to limit global warming.
Up to now the large amount of weight needed to make a shield massive enough to balance the sun’s gravitational forces and prevent solar radiation pressure from blowing it away has made the umbrella concept practically impossible to realize because no one on Earth has figured out a way to launch that much weight into space.
Szapudi’s paper, however, offers a couple of innovative ideas to help deal with the weight: a tethered counterweight instead of just a massive shield, making the total mass more than 100 times less, and the use of a captured asteroid as the counterweight to avoid having to launch most of the mass from Earth.
“My idea makes it doable when previously it was
science fiction,” he said.
If lassoing an asteroid, changing its orbit and attaching a tether to it sounds fantastical, well, it is. But Szapudi said scientists are working on this, and it actually appears quite feasible.
Szapudi’s paper starts with the goal of reducing solar radiation by a mere 1.7%, an estimate of the amount needed to prevent a catastrophic rise in global temperatures.
It calls for placing a tethered counterbalance toward the sun, which would reduce the weight of the shield by about 3.5 million tons and make it about one hundred times lighter than previous estimates for such a shield.
With today’s largest rockets able to lift only about
50 tons to low Earth orbit, the weight is still far beyond current launch capabilities. But only 1% of the total, or about 35,000 tons, would account for the shield itself, and that is the only part that needs to be launched from Earth.
And with emerging, lighter materials such as graphene, the mass of the shield can be reduced
even further, he said. The graphene would also make for a tether that is lightweight yet strong.
The rest of the mass needed for the counterweight would come from the asteroid — and possibly from the excavation of lunar dust and rocks for added weight.
Although prior concepts were basically unachievable, Szapudi’s approach brings the idea into the realm of possibility, even with today’s technology.
All of this, of course, is not going to be cheap. Szapudi said a rough estimate puts the price tag at trillions of dollars.
“It’s very, very expensive but it’s doable,” he said. “If global warming is costly, humanity might consider doing something costly, too, to defend the inhabitants of the earth from the consequences.”
He said the next project he wants to do is a collaboration with experts on asteroids and solar sails to study practical ways to manipulate the orbit of an
asteroid.
Szapudi said he’s planted a seed and hopefully it will grow. It will take decades to develop, he said, and hopefully a space company like SpaceX or Blue Origin or maybe the U.S. government takes an interest.
“We need something like this sooner than later because the crisis of climate change is upon us,” he said.
