Abstract: A measurement method is presented for the determination of low levels of optical absorption in any material, with at least a quasi-simultaneous detection of the transmission intensities of a measurement light beam and a reference light beam, the wavelengths of which are different, such that, essentially, the measurement light is absorbed by the material to be tested, and with a joint analog acquisition of the detected measurement and reference signals, taking into consideration the natural difference in intensities between the measurement light beam and the reference light beam.

Abstract: A satellite adapted to be spin-stabilized in geostationary orbit having, coaxial with a spin rotation axis, a satellite surrounded with a solar generator. At least two equipments including an apogee maneuver system are disposed along the rotation axis. A set of generally annular antennas including at least one picture transmission antenna is disposed on one of the NORTH and SOUTH faces of the satellite so as to leave at its center a cylindrical space along the spin rotation axis to house one of the equipments. The other of the equipments is disposed on the other of the NORTH and SOUTH faces.