  Due to its absence of an atmosphere and relative geological inertness, the
Moon's surface records past impacts of objects from the Solar system and
beyond. We examine the prospects for discovering extrasolar material near the
lunar surface and predict that its abundance is $\mathcal{O}(10)$
parts-per-million (ppm). The abundances of extrasolar organic carbon and
biomolecular building blocks (e.g., amino acids) are estimated to be on the
order of $0.1$ ppm and $< 0.1$ parts-per-billion (ppb), respectively. We
describe strategies for identifying extrasolar material and potentially
detecting extrasolar biomolecular building blocks as well as molecular
biosignatures of extinct extraterrestrial life. Thus, viewed collectively, we
argue that \emph{in situ} lunar exploration can provide vital new clues for
astrobiology.
