One might consider why there are more or less of a particular type of particle in the universe.

The relative mix of particles on a statistical basis generally over a volume element, is often referred to as stoichiometry.

Mars Surface Topology

If for example the particle collections we commonly refer to as planets are found to be formed covariantly with stars, from the same "broth" so to speak, one might wonder why the stoichiometry is not roughly the same.

Earth Moon Surface Topology

Generally only the surface layers of large particle collections are readily accessible to sensors.

A preliminary survey of possible resources might start with drill core sampling of larger impact crater centres, in hopes of finding high concentrations of useful elements or molecules.

Drilling on Earths' moon for example might be somewhat problematic due to the mass of equipment and drill pipe segments required.