Original title: Project Setu: 3D Multi-Physics Design and Spaceflight-Validated Framework for a 0.20c Relativistic Lightsail
Prashant Suresh Kamble · September 2026
Standard chemical rockets are too heavy to reach relativistic speeds for deep-space missions beyond our solar system. To solve this, researchers designed a 4.0-meter circular lightsail pushed purely by light from a 100 GW ground laser array. Beaming intense laser light onto the reflective sail transfers momentum from photons, which are light particles, accelerating the craft without carrying any fuel onboard. Using detailed computer simulations, the team found the sail reaches 0.166c at 180 s and hits its target speed of 0.20c at 227 s. The sail endures peak stresses of 530.88 MPa, stabilizes at a temperature of 923.02 K safely below its material sublimation point, and avoids destructive laser vibrations during acceleration.
Imagine holding a giant, super-thin trampoline while a high-pressure hose sprays water at it from the ground. The trampoline must be tough enough to not tear, cool enough to not burn up, and so transparent that almost none of the water gets absorbed—only pushes. Here, the laser beam is the water, the lightsail is the trampoline, and the computer model makes sure it won't rip, melt, or vibrate apart before reaching 20% of light speed.
Interstellar travel right now is impossible because rockets are too heavy and slow. This paper designs a 4-meter sail pushed by a ground laser that could reach 20% of light speed, fast enough to probe nearby star systems within a human lifetime. If realized, it would change how we explore space beyond our solar system.
The abstract does not address how to build a 100 GW laser array on the ground, how to aim it precisely over interstellar distances, or how to decelerate at the destination. It also does not validate the framework against experimental lightsail data—only against solar sail telemetry from slower missions.
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Project Setu: 3D Multi-Physics Design and Spaceflight-Validated Framework for a 0.20c Relativistic Lightsail — Prashant Suresh Kamble
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.