Melpomenia

Melpomenia is a planet in the novel Foundation and Earth, one of the fifty Spacer worlds colonized by the first wave of settlers from Earth and the nineteenth to be settled. When Golan Trevize, Janov Pelorat and Bliss reach it while searching for humanity's planet of origin, it is an old, dead world with a very thin atmosphere and almost no trace of civilization beyond some ruins. One ruin is the Hall of the Worlds, whose wall lists the names, coordinates and settlement dates of all fifty Spacer worlds; Pelorat later uses it to work out the approximate position of Earth. A moss that lives on the faintest traces of carbon dioxide survives there.