Sources of UHECRs in view of the TUS and JEM-EUSO experiments
  The origin of ultra-high-energy cosmic rays (UHECRs) is one of the most intriguing problems of modern cosmic ray physics. We briefly review the main astrophysical models of their origin and the forthcoming orbital experiments TUS and JEM-EUSO, and discuss how the new data can help one solve the long-standing puzzle. 
N. N. Kalmykov, B. A. Khrenov, G. V. Kulikov, M. Yu. Zotov
astro-ph.HE