FIFI LS getting ready to fly aboard SOFIA

FIFI LS is the German far-infrared integral field spectrometer for the SOFIA airborne observatory. The instrument consists of two independent integral field spectrometers for two different wavelength bands (45-110 μm and 100-200 μm). A dichroic filter enables simultaneous observation of two different spectral lines in the same field-of view. This allows very efficient mapping of extended regions with FIFI LS in many important far-infrared cooling lines with line ratios sensitive to temperature and density. FIFI LS will become a facility instrument for SOFIA. In the next two years it will become a fully commissioned facility instrument. After its commission, FIFI LS will be available for general observing with a large science potential. In this paper, we will also discuss the science of FIFI LS.