A Zero-Radiation Pressure Sunshade for Supporting Climate Change Mitigation

TL;DR

This paper introduces a lightweight, zero-radiation pressure sunshade using diffractive metamaterials, significantly reducing mass and cost, potentially making space-based geoengineering a viable complement to terrestrial climate mitigation efforts.

Contribution

The paper proposes a novel, lighter sunshade design that eliminates radiation pressure constraints through diffractive metamaterials, drastically reducing mass and deployment costs.

Findings

Mass of the proposed sunshade is approximately 620,000 tons.

Deployment requires 100 to 1,000 launches over ten years.

Cost reduction makes space-based geoengineering more competitive.

Abstract

Limiting climate change to within the 2 {\deg}C limit requires net zero emissions of CO2 by 2050. However, the window of opportunity is closing fast. Geoengineering as the intentional and large-scale manipulation of the environment and in particular the climate is increasingly discussed as a complement to ongoing mitigation efforts. As a particular geoengineering approach, space-based geoengineering blocks or dissipates a fraction of incoming sunlight via many occulting membranes, located close to the Sun-Earth Lagrange 1 point. However, the mass of the proposed sunshades, around $10^7$-$10^8$ tons, and their associated cost render them about $10^3$ times more costly than terrestrial alternatives. In this article, we propose a novel sunshade concept, which is between $10^2$ to $10^3$ times lighter than the lightest existing sunshade concepts. This is achieved via a net zero-radiation pressure design, based on the use of diffractive metamaterials, removing one of the major constraints to reducing sunshade mass. The whole sunshade system has a total mass of approximately $6.2 \times 10^5$ tons and its deployment requires between $10^2$ to $10^3$ annual launches during a ten-year period. The achieved cost reduction might render space-based geoengineering competitive to terrestrial geoengineering approaches.