Scientists outline satellite sunshade to cool Earth

A giant swarm of satellites could reflect sunlight away from Earth and slow its warming, according to a new analysis by the nonprofit Planetary Sunshade Institute, reported by ERR. The proposals, compiled from several experts including NASA scientists, remain hypothetical rather than projects set to begin construction.

The most promising plan would place more than 5,000 satellites between Earth and the Sun. Each rotating satellite would be 40 kilometres wide and shaped like a giant windmill with paper-thin blades. Blocking just 1% of sunlight could lower Earth’s temperature by one degree, the researchers estimate.

Building the shade would require about 70 million tonnes of material. To reduce costs, researchers propose mining and assembling the satellites on the Moon, where weaker gravity would make launching heavy loads into space several times cheaper and easier.

An alternative proposal would send an artificial cloud of dust into space, with specialised spacecraft using electric fields to keep it in position.

Despite the detailed calculations, the ideas remain speculative and are not an imminent plan to intervene. The researchers’ proposals are discussed in the journal Nature.