The planetary Fourier Spectrometer for MarsExpress

This paper summarizes some of the activities performed to qualify the interferometric unit of the PFS instrument to the MarsExpress requirements. The Planetary Fourier Spectrometer, PFS, is a Fourier Spectrometer, originally conceived for the orbiter of the Russian Mars’96 mission. After the failure of the Mars’96 launch the European Space Agency has approved a mission to Mars that includes, in its orbiting platform, the most scientifically interesting payloads of the Mars’96, among them the PFS. PFS has been conceived (and built) by an international team of scientific institutions. The mechanical and thermal designs of the interferometric module are under responsibility of CISAS-Università di Padova, with contributions from Politecnico di Milano. PFS-MarsExpress PI is Prof. Vittorio Formisano of Rome’s IFSI-CNR, CNR is also responsible for the design and manufacturing of the electronic units for data handling and interferometer management and control. The power converter unit and the pointing device are under responsibility of a polish team of SBRC, Warsaw. Interferometer optical issues are care of the Dipartimento di Fisica-Università di Lecce with contributions from DLR. At last scientific and technical participation are provided by many national teams from Russia (IKI-Moscow), Germany (DLR-Berlin), France and US. The first ESA mission to Mars has been named MarsExpress because of the unusually short development time; in fact it had the official start in 1999 with the signing of the contract with the Spacecraft Prime contractor and the launch is foreseen for 2003. The rational for such tight schedule is that the mission uses as far as possible already developed instruments and technologies, that is in particularly evident for the payloads derived from Mars’96. The idea of the mission as a simply re-flight in case of the PFS however has soon proved to be strongly misleading because, the mechanical (and thermal) environment foreseen for the new mission is strongly different from that of the Russian one. The initially specified mechanical environment at launch was especially severe with vibration amplitudes ranging from 5 to 10 times those foreseen in the Mars’96. Although the qualification to the new mission environment is not concluded yet, the instrument has already past the mechanical tests at qualification levels with a tolerable degradation of the optical alignment, allowing proceeding with the building of the flight model.