To assist combat the results of world warming, scientists are toying with an revolutionary idea to shield our planet from the sun with a spaceborne “umbrella” of sorts.
“In Hawaii, many use an umbrella to dam the daylight as they walk about through the day,” István Szapudi, an astronomer on the University of Hawaii Institute of Astronomy, said in an announcement. “I used to be considering, could we do the identical for Earth and thereby mitigate the approaching catastrophe of climate change?”
The explanation carbon dioxide and other greenhouse gases contribute to global warming is that they trap sunlight around our planet that needs to be released back into space, ultimately resulting in rising temperatures. Nevertheless it’s the sun, and never greenhouse gases, that creates the warmth to start with. That opens up the concept of constructing Earth a shade.
So, Szapudi drew up an “umbrella” of his own. It could rest on the L1 Lagrange point between the sun and Earth, hypothetically joining sun- or solar-wind-observing probes akin to the Solar and Heliospheric Observatory (SOHO) and Advanced Composition Explorer (ACE) that dwell there today. In theory, a large-enough solar shield could effectively block around 1.7 percent of solar radiation at L1, enough to forestall a catastrophic rise in Earth’s temperatures.
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Nevertheless, any type of solar shade is sure to face a stark engineering challenge: At L1, they’d be subject to each the sun’s and Earth’s gravities while experiencing a relentless torrent of solar radiation. A viable shade would thus should be massive — weighing thousands and thousands of tons — and fabricated from a fabric sturdy enough to remain in place and stay intact. Simply, we don’t have a practical way of launching that much stuff into orbit.
But to get around that issue, Szapudi proposed, much of the fabric itself can come from space — from a captured asteroid and even lunar dust. That matter could theoretically function a counterweight, tethered to a much smaller shield weighing only around 35,000 tons. Right away, even such a smaller shield can be far too heavy for a rocket to lift, but with advances in materials, Szapudi’s study suggests we could manage the feat in several a long time.
Szapudi’s apparatus falls under the, well, umbrella of solar geoengineering: the controversial idea of alleviating global warming by physically reducing the quantity of sunlight that reaches Earth’s surface. Other solar geoengineering ideas include pumping aerosols into the atmosphere and editing clouds to reflect more sunlight away into space.
The study was published on July 31 within the journal Proceedings of the Natural Academy of Sciences.