THE CASSINI COMPOSITE INFRARED SPECTROMETER (CIRS) MID-INFRARED OBSERVATIONS OF TITAN ATMOSPHERE PROVIDED UNIQUE INFORMATION ABOUT ITS THERMAL STRUCTURE CHEMICAL COMPOSITION AND DYNAMICS [FLASAR ET AL. 2004 2005]. IN THIS STUDY WE WILL FOCUS ON THE ANALYSIS OF CIRS LOW-RESOLUTION MID--INFRARED SPECTRA TAKEN IN LIMB GEOMETRY FOR TANGENT HEIGHTS LARGER THAN 350-400 KM AIMED AT RETRIEVING KINETIC TEMPERATURES PRESSURES AND TRACE GAS DENSITIES IN TITAN'S MESOSPHERE. AT THESE ALTITUDES BOTH FOR DAY AND NIGHT CONDITIONS THE BREAKDOWN OF LOCAL THERMODYNAMIC EQUILIBRIUM (NON-LTE) HAS SIGNIFICANT IMPACT ON THE FORMATION OF THE MID-INFRARED ROVIBRATIONAL BAND EMISSIONS OF METHANE AND VARIOUS TRACE GASES [YELLE 1991]. HOWEVER TO OUR KNOWLEDGE NO STUDIES WERE PERFORMED UP TO NOW TOWARDS RETRIEVING TEMPERATURES AND GASEOUS CONCENTRATIONS FROM CIRS OBSERVATIONS AT THE ALTITUDES WHERE NON-LTE EFFECTS PREDOMINATE. IN THE PROPOSED WORK WE WILL EMPLOY THE ALI-ARMS (FOR "ACCELERATED LAMBDA ITERATIONS FOR ATMOSPHERIC RADIATION AND MOLECULAR SPECTRA") NON-LTE CODE PACKAGE SUCCESSFULLY APPLIED RECENTLY FOR RETRIEVING MESOSPHERIC AND LOWER THERMOSPHERIC TEMPERATURES PRESSURES AND COMPOSITION FROM THE EARTH'S LIMB SPECTRAL RADIANCES MEASURED BY THE CRISTA/ASTROSPAS EXPERIMENT BROADBAND RADIANCES OF SABER/TIMED INSTRUMENT AS WELL AS FOR THE INTERPRETATION OF THE SPECTRAL LIMB MARS GLOBAL SURVEYOR/TES OBSERVATIONS. WE WILL PERFORM DETAILED COMPARISON OF RETRIEVED TEMPERATURES PRESSURES AND GAS DENSITIES IN TITAN'S MESOSPHERE WITH RESULTS OF OTHER OBSERVATIONS SUCH AS CIRS HIGH-RESOLUTION MID-INFRARED LIMB OBSERVATIONS VOYAGER AND UVIS OCCULTATION MEASUREMENTS GROUND-BASED MILLIMETER HETERODYNE OBSERVATIONS AS WELL AS WITH THE MODELS OF CHEMICAL COMPOSITION. OUR WORK WILL CONTRIBUTE TO THE UNDERSTANDING OF THE LOWER PART OF WHAT IS SOMETIMES CALLED THE "AGNOSTOSPHERE OF TITAN" WHICH IS THE REGION BETWEEN 500 KM AND 1000 KM THAT IS DIFFICULT TO PROBE WITH CASSINI'S INSTRUMENTS. WE WILL BE ABLE TO STUDY THE THERMAL STRUCTURE AND COMPOSITION OF TITAN'S MESOSPHERE WHICH STILL NEED FURTHER INVESTIGATION. THIS WORK WILL PROVIDE NEW CONSTRAINTS FOR DEVELOPING GCMS AND CHEMICAL COMPOSITION MODELS INVOLVING TITAN'S MIDDLE ATMOSPHERE. IT WILL ENHANCE THE SCIENCE RETURN OF THE CASSINI MISSION AND IS DIRECTLY RELEVANT TO THE SPECIFIC GOALS OF THE CDAP PROGRAM AND NASA'S OVERALL OBJECTIVES IN THE REALM OF SOLAR SYSTEM SCIENCE.