A flowing, replenished column of micron-scale particles centered on the Sun–Earth line near L1. Instead of a rigid shade, the cloud slightly attenuates sunlight (target ~1.5–2%) before it reaches Earth, with density maintained by controlled injection and gentle field shaping.

We work with celestial mechanics, not against them. Particles follow stable ballistic paths through a target zone; we regulate how many pass through per second. No massive structure to hold in place, easier scaling, and inherently reversible by stopping the feed.

Multiple “fountain” injectors stream dust along trajectories that traverse the desired column. Small, local electromagnetic fields and radiation-pressure shaping nudge particles for better coverage and uniformity—like lane guides for traffic rather than a barrier.

Fountain injectors (near L1 or offset stations), guidance/shepherd craft, solar-power and comms, and a real-time control loop tied to optical/infrared sensors. Early stages use Earth-launched material; later phases can source from the Moon or small asteroids.

We tune the cloud’s effective optical depth by adjusting injection rate, grain size distribution, and trajectory mix. Seasonal or emergency controls are possible: increase flow for extra cooling, reduce or pause for rapid roll-back.

Space-based spectrometers and imagers continuously measure column density and angular extent. A simple controller compares measured attenuation to the target and updates injector settings automatically, with human-in-the-loop governance.

Silicate or glassy grains from lunar regolith analogs are promising; alternatives include engineered dielectric or carbon-based particles. Micron-scale grains balance scattering efficiency with controllability; mixes can be tailored for performance and lifetime.

The stream is shaped to avoid Earth-orbital traffic lanes and to minimize long-lived debris. If we stop injection, solar radiation pressure and gravity disperse the cloud on short to moderate timescales (weeks–months depending on grain size), providing a hard failsafe.

Begin with a small column whose integrated attenuation is equivalent to a ~1-km disk. Objectives: validate injection/guidance control, measure real attenuation vs. predictions, exercise the governance switch-off, and refine scaling laws for full deployment.