NASA Eyes Light-Levitating Tracers to Sense Atmosphere 30–100 km Up

Rarified Technologies has proposed a novel atmospheric sensing method targeting the largely under-monitored 30–100 km altitude range. The concept involves deploying lightweight tracers that use photophoresis — a process where sunlight exerts force on particles — to remain suspended for potentially months at controlled heights. Unlike natural aerosols, these engineered tracers are designed to produce strong, trackable signals. They would be monitored remotely using satellite-based lidar or radar systems. The proposal was submitted to NASA as part of efforts to improve data collection in a region of the atmosphere that is difficult to study with conventional tools.