Solar heliostats may help detect asteroids from Earth after dark

A scientist at Sandia National Laboratories, John Sandusky, is investigating a novel approach to detecting near-Earth asteroids after dark by repurposing heliostats—mirrors typically used to reflect sunlight for solar power generation. Since heliostats remain idle at night, Sandusky’s method involves using these mirrors to detect extremely faint light (femtowatts) reflected off asteroids, potentially enabling earlier identification of near-Earth objects (NEOs) and improving preparedness for possible impacts. Unlike traditional telescopes that rely on long-exposure imaging to spot asteroids, this technique measures the relative speed of asteroids against stars, which could reduce both time and costs associated with asteroid detection. Using the National Solar Thermal Test Facility’s 212 heliostats, Sandusky conducted nighttime experiments demonstrating that heliostats can effectively track stars by sweeping slowly back and forth. Although no asteroids were detected during initial tests, the results validated the concept’s feasibility. Beyond asteroid detection, the