A team of “European planetary geologists and young scientists” is assembling a mineral library to help future astronauts identify rocks on other worlds. “The goal,” according to the European Space Agency, “is to create a database of all known rocks and minerals on the Moon, Mars and meteorites surfaces for easy identification.”
This collection, assembled in anticipation of discoveries made far from Earth, can then be used as a basis of forensic identification and formal comparison. We will know future worlds through anticipatory fragments we have collected here on Earth.
Although this particular “library” appears to be part of a specific training course, the ESA blog post about it links onward to what I believe is a separate institution, one called—incredibly—the Planetary Terrestrial Analogues Library.
There, the chemical spectra of rocks are analyzed to help understand “the mineralogical and geological evolution of terrestrial planets.” This, again, prepares humans and their robotic intermediaries to encounter landscapes so alien they cannot be understood at first glance, yet similar enough to our home world we can still work out what they’re made of.