  SIMBOL-X is a hard X-ray mission, operating in the ~ 0.5-70 keV range, which
is proposed by a consortium of European laboratories in response to the 2004
call for ideas of CNES for a scientific mission to be flown on a formation
flying demonstrator. Relying on two spacecrafts in a formation flying
configuration, SIMBOL-X uses for the first time a ~ 30 m focal length X-ray
mirror to focus X-rays with energy above 10 keV, resulting in a two orders of
magnitude improvement in angular resolution and sensitivity in the hard X-ray
range with respect to non focusing techniques. The SIMBOL-X revolutionary
instrumental capabilities will allow to elucidate outstanding questions in high
energy astrophysics, related in particular to the physics of accretion onto
compact objects, to the acceleration of particles to the highest energies, and
to the nature of the Cosmic X-Ray background. The mission, which has gone
through a thorough assessment study performed by CNES, is expected to start a
competitive phase A in autumn 2005, leading to a flight decision at the end of
2006, for a launch in 2012. The mission science objectives, the current status
of the instrumentation and mission design, as well as potential trade-offs are
presented in this paper.
