The hidden danger of lunar micrometeoroid storms

The moon has no significant atmosphere, no weather, and no wind. Yet it faces an invisible bombardment more relentless than any terrestrial storm, a constant rain of micrometeoroids, tiny fragments of rock and metal traveling at speeds up to 70 kilometers per second. As NASA’s Artemis program prepares to establish a permanent lunar base, understanding this silent threat has become critical to keeping future astronauts safe.

A new analysis led by Daniel Yahalomi posted to the arXiv preprint server quantifies just how intense this bombardment will be. Using NASA’s Meteoroid Engineering Model, the researchers calculated impact rates for a hypothetical lunar base roughly the size of the International Space Station. The numbers are sobering—between 15,000 and 23,000 impacts per year from particles ranging from a millionth of a gram to 10 grams.

These aren’t gentle collisions. Even a particle massing just 1 microgram which would be invisible to the naked eye, strikes with enough energy to crater metal and potentially puncture equipment. Unlike Earth, where our thick atmosphere vaporizes most debris before it reaches the ground, the moon’s vacuum offers no such protection. Every micrometeoroid that approaches the lunar surface makes contact at hypervelocity.

The threat isn’t uniform across the lunar landscape, though. Yahalomi’s team found that impact rates vary by location, with the lunar poles experiencing the lowest bombardment, which is welcome news since NASA has targeted the south pole for its first Artemis base. The highest impact rates occur near the sub-Earth longitude, the region that perpetually faces our planet. Between these extremes, impact rates vary by a factor of roughly 1.6.

Why does location matter? The answer lies in the moon’s complex relationship with Earth and the sun. The moon’s orbit shields certain regions from meteoroid streams, while other areas remain more exposed. Understanding these patterns helps mission planners choose sites that offer natural protection alongside other necessities like water ice access and communication with Earth.

Protection systems will be essential regardless of location. The researchers modeled how aluminum Whipple shields, the same multi-layer bumper systems used on the International Space Station, would perform on the moon. These shields work by fragmenting incoming particles on a sacrificial outer layer, spreading the impact energy before it reaches critical equipment or habitat walls.

The analysis provides mission designers with a mathematical relationship describing how many impacts would penetrate shielding based on the shield’s specifications and location. This allows engineers to calculate the precise thickness of protection needed to reduce risk to acceptable levels without adding unnecessary mass to structures launched from Earth.

For astronauts living months at a lunar base, this mostly invisible rain of debris will become part of daily life, a reminder that even on our closest celestial neighbor, space remains fundamentally hostile to our presence.