The discovery of X-ray emission from cosmic sources in the 1960s has opened a new powerful observing window on the Universe. In fact, the exploration of the X-ray sky during the 70s–90s has established X-ray astronomy as a fundamental field of astrophysics. Today, the emission from astrophysical sources is by large best known at energies below 10 keV. The main reason for this situation is purely technical since grazing incidence reflection has so far been limited to the soft X-ray band. Above 10 keV all the observations have been obtained with collimated detectors or coded mask instruments. To make a leap step forward in Xray astronomy above 10 keV it is necessary to extend the principle of focusing X ray optics to higher energies, up to 80 keV and beyond. To this end, ASI and CNES are presently studying the implementation of a X–ray mission called Simbol-X.
Taking advantage of emerging technology in mirror manufacturing and spacecraft formation flying, Simbol-X will push grazing incidence imaging up to ~ 80 keV and beyond, providing a strong improvement both in sensitivity and angular resolution compared to all instruments that have operated so far above 10 keV. This technological breakthrough will open a new highenergy window in astrophysics and cosmology. Here we will address the problematic of the development for such a distributed and deformable instrument. We will focus on the main performances of the telescope, like angular resolution, sensitivity and source localization. We will also describe the specificity of the calibration aspects of the payload distributed over two satellites and therefore in a not “frozen” configuration.
SIMBOL-X is a space-based X-ray telescope operating from 0.5 keV up to 80 keV providing an improvement of roughly two orders
of magnitude in sensitivity and angular resolution compared to the instruments that have operated so far above 15 keV.
This breakthrough is reached thanks to the use of Wolter-I optics based on shells working in grazing incidence combined with a large
focal length (20 meters). With these characteristics, the size and the mass of a classical monolithic instrument would be well beyond
the capacity of the most powerful launchers. For that reason SIMBOL-X is the first operational mission relying on two satellites
flying in formation. The so-called mirror satellite carries the mirror of the telescope, while the detector satellite drives the detector
assembly. The first one moves freely on a high elliptical orbit controlling its attitude towards the target, while the latter controls its 3-
axis position and attitude so as to keep the detector assembly right at the mirror focal point and perpendicular to its axis.
This promising concept of formation flight raises a variety of problematics, such as relative navigation, communications, operations,
safety, simulation and performance evaluation. After a successful concept study, the current feasibility phase provides answers to
each of these issues.
The SIMBOL-X project is a cooperation between the French Space Agency (CNES) and the Italian Space Agency (ASI). The design
of the instrument involves a number of laboratories in France (CEA, CESR, APC), in Italy (INAF, IASF) and in Germany (MPE,