  GAMMA-400 is a new space mission which will be installed on board the Russian
space platform Navigator. It is scheduled to be launched at the beginning of
the next decade. GAMMA-400 is designed to study simultaneously gamma rays (up
to 3 TeV) and cosmic rays (electrons and positrons from 1 GeV to 20 TeV, nuclei
up to 10$^{15}$-10$^{16}$ eV). Being a dual-purpose mission, GAMMA-400 will be
able to address some of the most impelling science topics, such as search for
signatures of dark matter, cosmic-rays origin and propagation, and the nature
of transients. GAMMA-400 will try to solve the unanswered questions on these
topics by high-precision measurements of the Galactic and extragalactic
gamma-ray sources, Galactic and extragalactic diffuse emission and the spectra
of cosmic-ray electrons + positrons and nuclei, thanks to excellent energy and
angular resolutions.
