Caltech Team Measures 70-Femtonewton Lightsail Force for 20-Year Alpha Centauri Concept
Updated
Updated · spacedaily.com · Aug 7
Caltech Team Measures 70-Femtonewton Lightsail Force for 20-Year Alpha Centauri Concept
2 articles · Updated · spacedaily.com · Aug 7
Summary
A 2025 Caltech-led experiment directly measured about 70 femtonewtons of radiation pressure on a tethered microscopic lightsail membrane, giving researchers new data on how beam angle and edge scattering affect sail motion.
Those measurements target a central Breakthrough Starshot challenge: keeping an ultrathin reflective sail stable and cool under a laser beam powerful enough to accelerate a gram-scale probe to about 20% of light speed.
At that speed, a flyby probe could cross the 4.2-light-year gap to Proxima Centauri in just over 21 years, versus roughly 75,000 years at Voyager 1-like speeds, though first data would still take about 26 years from launch to reach Earth.
The result does not mean a mission is near: engineers still need a huge phased laser array, durable nanometre-scale sails, dust-hardened electronics and ultra-light communications systems.
Starshot, launched in 2016 as a $100 million research program, was reported on hold in 2025, but related work continues even without a confirmed launch date.