'Runs on radiation': This tiny cosmic object will travel through interstellar space at astonishing speeds
Produced by Tarun Mishra
Produced by Tarun Mishra
Lightsails operate by harnessing radiation pressure from a light source, such as the Sun or lasers, to propel a spacecraft. Though photons have no mass, they transfer momentum upon impact with a surface, generating thrust. This method eliminates the need for conventional chemical propulsion.
Researchers at Caltech are exploring the use of high-energy laser beams to push lightsails more efficiently than sunlight. A continuous laser beam could provide sustained pressure, allowing spacecraft to achieve speeds greater than those possible with traditional propulsion methods.
Caltech’s team, led by Harry Atwater, developed a test platform to measure how lasers exert force on a thin silicon nitride membrane. The membrane, acting as a miniature sail, vibrates when struck by a laser, allowing researchers to quantify the force exerted by light.
To accurately measure these forces, researchers built a common-path interferometer that cancels out background noise, such as vibrations from lab equipment and conversations. This setup helps detect minute movements in the membrane, providing precise data on how light interacts with the material.
A key challenge in lightsail development is ensuring that the material can withstand heat and maintain stability under radiation pressure. Researchers aim to integrate nanomaterials and metamaterials to improve the sail’s structural integrity and prevent deviations from the laser beam.
The test platform can measure side-to-side motion and rotations, which could inform future designs capable of self-correction. A stable lightsail could maintain its trajectory along the laser beam, reducing the risk of drifting off course during long-distance space travel.
While various lightsail projects are in progress, including a NASA-deployed solar sail, mechanical challenges remain. The Caltech team’s research contributes to refining sail designs, with the long-term goal of enabling small spacecraft to travel across interstellar distances efficiently. The findings were published in Nature Photonics on 30 January.
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