As climate change accelerates and politicians continue to argue, scientists are exploring radical new ways to protect our planet. One of the most ambitious concepts under development is a Planetary Sunshade System (PSS), essentially a massive space based umbrella designed to reduce the amount of sunlight reaching Earth and help stabilise global temperatures.
The proposed sunshade is part of a research project led by Marina Coco from the Department of Mechanical and Aerospace Engineering at the Polytechnic University of Turin. The team suggest the solution wouldn't orbit Earth like a typical satellite. Instead, it would be positioned at a special location called the photo-gravitational equilibrium point, situated approximately 2.36 million kilometres from Earth, at its L1 Lagrange point.
At this location, the gentle but constant push of sunlight helps keep the sunshade aligned ensuring it casts a consistent shadow on our planet. This clever use of physics means the system could theoretically operate for extended periods without requiring large amounts of conventional propellant.
Image of Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft (Credit : NASA)
Before deploying a full-scale system, researchers have designed a precursor mission to test the critical technologies involved. Their plan centres around a 12U CubeSat – roughly the size of a large briefcase and equipped with a 144 meter solar sail. Despite weighing only 15-20 kilograms, this small spacecraft would demonstrate all the key technologies needed for the larger system.
The mission has several crucial objectives. First, it will test whether specialised optical shielding materials can survive the harsh space environment over long periods. Space presents challenging environmental issues including intense radiation, extreme temperature fluctuations, and bombardment by microscopic debris.
Second, the mission will demonstrate solar sailing as a viable propulsion method. Just as wind powers sailing ships on Earth's oceans, photons from the Sun can provide thrust to spacecraft. This sustainable propulsion technique would be essential for maintaining the position and orientation of a full scale sunshade without depleting fuel reserves.
Artist impression of IKAROS, the first space-probe with a solar sail in flight, featuring a typical square sail configuration of almost 200 m2 (Credit : Andrzej Mirecki)
One of the most complex aspects of the mission though involves testing autonomous control systems. Operating millions of kilometres from Earth, the spacecraft must be capable of making real time adjustments to its position and orientation without waiting for commands from ground control, which could take over 10 seconds to arrive. Perhaps most importantly, the mission will provide data on spacecraft formation flying capabilities which would be essential for coordinating the thousands of individual components that a full planetary sunshade system would require.
At an estimated cost of $10 million, this test mission represents a relatively modest investment in potentially game changing technology. The researchers plan to leverage ride-share launch opportunities, where their CubeSat would accompany other payloads to space, significantly reducing launch costs and making the mission more economically viable.
While a full scale planetary sunshade system remains years or decades away, this test represents a crucial first step in developing space based climate intervention capabilities. The data collected will help refine designs, validate technologies, and assess the overall feasibility of using space-based systems to help address climate change.
Success could pave the way for larger demonstration missions and eventually operational systems capable of providing measurable climate benefits. As traditional approaches to climate change struggle to keep pace with rising global temperatures, innovative solutions like planetary sunshades may become increasingly important tools in humanity's effort to maintain a habitable planet.
Source : Planetary sunshade for solar geoengineering: Preliminary design of a precursor system and mission
