Cosmic Rays from the Knee to the Ankle – Status and Prospects

Recent progress in cosmic ray physics covering the energy range from about 10 eV to 10 eV is reviewed. The most prominent features of the energy spectrum are the so called ‘knee’ at E ≃ 3 · 10 eV and the ‘ankle’ at few 10 eV. Generally, the origin of the knee is understood as marking the limiting energy of galactic accelerators and/or the onset of increasing outflow of particles from the galaxy while the ankle is considered to mark the transition from galactic to extragalactic cosmic rays. Alternative theories do exist and shall be sketched. A key observable to answer the still open questions about the cosmic ray origin and to discriminate between various models is given by measuring the chemical composition or – more directly – by measuring energy spectra of individual cosmic ray mass groups. The status of present analyses is critically discussed and new experimental endeavors carried out in order to improve both the statistics and the quality of data particularly at energies above the knee will be summarized.