micrometeoroid

Micrometeoroids are natural solid particles in interplanetary space, typically ranging in diameter from about 10 micrometers to 1 millimeter. They originate from a variety of sources, including comet tails, asteroid collisions, and other processes that produce fine cosmic dust. In the inner solar system, they orbit the Sun and intersect planetary environments, contributing to the ongoing background of interplanetary dust.

These particles travel at high speeds relative to Earth and spacecraft, commonly tens of kilometers per second, with a wide distribution that can extend from roughly 11 to 72 km/s depending on direction. Even very small particles carry enough kinetic energy to damage exposed surfaces on spacecraft, erode materials, or create craters upon impact. To mitigate risk, spacecraft shielding such as a Whipple shield is used, and engineers design components to tolerate or withstand micrometeoroid impacts.

Micrometeoroids are studied through a combination of in-situ measurements by dust detectors on spacecraft, analysis of impact craters on the Moon and other airless bodies, and remote sensing of the zodiacal dust cloud. Their flux varies with location in the solar system and over time, influenced by planetary gravity, solar radiation pressure, and the distribution of source material. In Earth’s atmosphere, micrometeoroids typically burn up as meteors; a small portion may reach the surface as micrometeorites. Understanding micrometeoroids is important for predicting risk to space missions and for insights into the Solar System’s dust population.