The Apollo-era Biostack experiment was a NASA-run bioscience experiment flown aboard Apollo 16 (launched April 16, 1972) and Apollo 17 (launched December 7, 1972). The goal of these experiments was to study the effects of high-energy cosmic rays on biological materials. The experiments contained various biological materials including bacterial spores, seeds, and the eggs of a variety of species. The principal investigator was H. Bücker of the University of Frankfurt.