regolith

plural regoliths

1. countableuncountablegeographyThe layer of loose rock, dust, sand, and soil, resting on the bedrock, that constitutes the surface layer of most dry land on Earth, the Moon, and other large solid aggregated celestial objects. Submarine regolith also exists.

   The structures on the surface were gone from normal view, pulverized into regolith across a span of aeons.

   2020 [1992], Vernor Vinge, chapter 1, in A Fire Upon the Deep, 1st edition, New York: Tor Essentials, →ISBN, page 19

   2 more examples

   The soil sample, called LZS-1, is the latest in a list of lunar regolith simulants of varying quality that have been developed to help Nasa and other space agencies around the world prepare for missions to the Moon.

   2023 April 25, Dhananjay Khadilkar, “Why scientists are making fake Moon dust”, in BBC

   What Interlune is trying to do [the startup aims to develop robotic lunar mining camps] is far from child’s play. Helium-3, an industrially prized cousin of the isotope of the gas we use to fill party balloons, is rare on Earth. […] Even if Interlune can find lunar regions with higher concentrations, collecting a commercially viable amount of helium-3 means developing and transporting to the moon machines that can chew through millions of tons of regolith, the loose debris that covers the lunar surface from billions of years of micrometeorite impacts. Autonomously. With no boots on the ground to repair them as they kick up dust more abrasive than anything on Earth. […] Interlune expects less than 1% of the gas they’ll get when they crush lunar regolith will be helium-3 – it’s estimated to exist only in the single- to double-digit parts per billion. To separate it from balloon helium and hydrogen, they’re cooling it all beyond negative 450 degrees Fahrenheit, at which point the other gases will liquefy and the helium-3 can be siphoned off.

   2025 September 2, Jeremy Bogaisky, “This Startup Is Racing To Be The First To Mine Helium On The Moon”, in Forbes