Cosmic Ray Astrophysics and Hadronic Interactions

Research in cosmic rays is now nearly a century old, but most of the fundamental questions in this field remain unanswered, on the other hand the perspectives of future studies in the next decade are very bright. New detectors will provide higher quality data in the entire energy range from 10^8 to 10^{20} eV (or more if particles of higher energy have non negligible fluxes), moreover cosmic ray astrophysics must now be considered, together with gamma, neutrino and gravitational wave astronomy, as one of the subfields of high energy astrophysics, and using information from these four "messengers" there is the potential of a detailed understanding of the origin of the high energy radiation in the universe. High energy cosmic rays are measured indirectly observing the showers they generate in the atmosphere, and a correct and detailed interpretation of these measurements will require an improved understanding of the properties of hadronic interactions. The new collider experiments, and in particular the LHC project at CERN offer the unique possibility to perform measurements of great value for cosmic ray astrophysics. It is of great importance for cosmic research that this possibility is fully exploited with the appropriate instrumentation and analysis.