Space mirrors: Reflecting light where the sun doesn’t shine

Space mirrors were once considered a way to direct sunshine towards Earth’s darker regions. Today, scientists are rekindling the concept as one of the more extreme options for tackling climate change.

In the 1990s Russian space scientists attempted a series of experiments to deploy mirrors into space. 

The Znamya Project is the focus of a new film being screened as part of the 2023 SCINEMA International Science Film Festival.

For the Russian space agency (now Roscosmos), the ultimate goal was to beam solar power to Earth, bringing daylight to Earth in mid-winter.

In 1992, the agency successfully deployed one 20-metre diameter space mirror, producing a five-kilometre diameter bright spot in Europe. However, the project was abandoned after a subsequent, larger mirror tore after being caught on its spacecraft’s antenna.

Yet today scientists are reviving the notion of space mirrors for the opposite reasons: to cool down our planet.

Sunshades and space mirrors are being considered among a group of ‘geoengineering’ technologies for tackling climate change.

Geoengineering involves the use of large-scale, high-consequence technologies designed to affect the climate system. The science and the social and environmental risks of geoengineering solutions are considered complex and uncertain: the flow-on effects of these technologies are incredibly difficult to assess.

Methods designed to reflect the Sun’s heat away from Earth are broadly grouped under the term ‘solar radiation management’ (SRM).

Options considered include injecting particles (sulphur dioxide or salt) into the atmosphere to make it more reflective, covering oceans or deserts with reflective material or sending mirrors or shades into space.

An expert review of SRM was released this year by the UN Environment Programme. 

The review found while SRM techniques are not a substitute for emissions reduction, these technologies are the only current options capable of cooling the planet within years. 

“The estimated direct costs for deploying SRM, without considering costs of possible adverse impacts, may be tens of billions of US dollars per year per 1oC of cooling,” the report states.

The review says potential risks have not been fully assessed, but could include damaging the ozone layer, overcompensating for climate change and decreased sunlight for photosynthesis.

The technologies would need to be maintained for decades, because the methods “if abruptly terminated, would lead to rapid climate change that would increase risks for humans and ecosystems”.

Find out more at the 2023 SCINEMA International Science Film Festival

Watch the 2023 SCINEMA International Science Film festival entry, The Znamya Project, by registering to view it for free on the SCINEMA website. 

SCINEMA runs from 1 August to 31 August.

Register for scinema 2023

SCINEMA runs from August 1 to August 31 every year. Register now to be part of the festival and watch the films for free. REGISTER NOW.

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