Nuclear astrophysics is an extremely rich field, strongly correlated with many other research fields like observational astronomy, stellar modelling, neutrino physics, cosmology, nuclear physics etc. One of the most ambitious task of nuclear astrophysics is to explain the origin and relative abundances of the elements in the Universe, formed through different nuclear processes in different astrophysical scenarios. Therefore, nuclear fusion reactions are the core of nuclear astrophysics since they determine the formation of the elements in the earliest stages of the Universe (Big Bang nucleosynthesis, BBN) and in all the objects formed thereafter and control the energy generation, neutrino production and evolution of stars. After 25 years of measurements on the cross section of key reactions belonging to BBN or Hydrogen burning, the LUNA collaboration is going to start a new ambitious program devoted to Helium and Carbon burning using the new 3.5 MV “LUNA MV” accelerator which will be installed in the underground laboratory of Gran Sasso next year. After a general introduction on nuclear astrophysics and underground techniques, the scientific goals of the LUNA MV project for the first five years and its present status will be described.