Hawaii

[IceWizard]

Sun ‘umbrella’ tethered to asteroid might
help mitigate climate change








Earth is rapidly warming and scientists are developing a variety of approaches to reduce
the effects of climate change. István Szapudi, an astronomer at the University of
Hawaiʻi Institute for Astronomy, has proposed a novel approach—a solar shield to reduce
the amount of sunlight hitting Earth, combined with a tethered, captured asteroid as a
counterweight. Engineering studies using this approach could start now to create a
workable design that could mitigate climate change within decades.

One of the simplest approaches to reducing the global temperature is to shade the Earth
from a fraction of the Sun’s light. This idea, called a solar shield, has been proposed before,
but 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 makes even
the lightest materials prohibitively expensive. Szapudi’s creative solution consists of two
innovations: a tethered counterweight instead of just a massive shield, resulting in
making the total mass more than 100 times less, and the use of a captured asteroid
as the counterweight to avoid launching most of the mass from Earth.

“In Hawaiʻi, many 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 thereby mitigate the impending
catastrophe of climate change?” Szapudi said.



Incorporating a tethered counterbalance


Szapudi began with the goal of reducing solar radiation by 1.7%, an estimate of the
amount needed to prevent a catastrophic rise in global temperatures. He found that
placing a tethered counterbalance toward the Sun could reduce the weight of the shield
and counterweight to approximately 3.5 million tons, about one hundred times lighter
than previous estimates for an untethered shield.

While this number is still far beyond current launch capabilities, only 1% of the
weight—about 35,000 tons—would be the shield itself, and that is the only part that
needs to be launched from Earth. With newer, lighter materials, the mass of the shield
can be reduced even further. The remaining 99% of the total mass would be asteroids
or lunar dust used as a counterweight. Such a tethered structure would be faster
and cheaper to build and deploy than other shield designs.

Today’s largest rockets can only lift about 50 tons to low Earth orbit, so this approach
to solar radiation management would be challenging. Szapudi’s approach brings the
idea into the realm of possibility, even with today’s technology, whereas prior concepts
were completely unachievable. Also, developing a light-weight but strong graphene
tether connecting the shield with the counterweight is crucial.

Maybe we need to employ a couple of clowns on uni-cycles to
put these umbrellas on space rocks ...

Barnum/Bailey 2023