Main results of the PAMELA space experiment after 5 years in orbit

After five years of data taking in space, the experiment PAMELA is showing very interesting features in cosmic rays, namely in the fluxes of protons, heliums, electrons, that could have significant implications on the production, acceleration and propagation of cosmic rays in the galaxy. In addition, PAMELA measurements of cosmic antiproton and positron fluxes are setting strong constraints to the nature of Dark Matter. PAMELA is also measuring the radiation environment around the Earth, and has recently discovered an antiproton radiation belt. The study of particles related to the Solar activity is part of the scientific program of PAMELA too, providing important improvements in the comprehension of the solar modulation mechanisms. In this paper PAMELA main results are reviewed.