63 rd International Astronautical Congress, Naples, Italy. Copyright ©2012 by the International Astronautical Federation. All rights reserved. IAC-12- A3,5,13.p1,x12886 Page 1 of 7 IAC-12- A3,5,13.p1,x12886 EFFECT OF NOSE CAVITY ON THE HEAT FLUXES TO REENTRY VEHICLE IN TITAN'S ATMOSPHERE Karthik Sundarraj University of Petroleum and Energy Studies, India, karthik_sundarraj@yahoo.com Linsu Sebastian University of Petroleum and Energy Studies, India, linsusebastian@gmail.com Rajesh Yadav University of Petroleum and Energy Studies, India, upes.rajesh@gmail.com Sourabh Bhat University of Petroleum and Energy Studies, India, spbhat@ddn.upes.ac.in Gurunadh Velidi University of Petroleum and Energy Studies, India, guru.velidi@live.in Ugur Guven University of Petroleum and Energy Studies, India, drguven@live.in The effective exploration of the outer reaches of our solar system is one of the most important objectives in the various space programs of the world. One of the more interesting objectives of such an exploration is a robotic space probe mission to Titan. There are various observational data to suggest that Titan may hold the key to various key raw elements and this can be varied with a mission that has an objective of a successful re-entry to Titan's atmosphere. A typical probe for Titan's entry with forward facing axisymmetric cavity is investigated numerically for peak heat fluxes using commercially available Computational Fluid Dynamics code. The cavities investigated are circular in shape with rounded lips while the lip radius is varied from 20 cm to 80 cm. The Martian entry vehicle chosen for the simulation is 60-deg sphere cone probe with a projected diameter of 2.7m and nose radius of 1.25 m. The flow conditions simulated in the investigation are that of ballistic descent through the Titan's atmosphere with free stream Mach No., pressure and density of 18.86, 15.62 Pa and 0.000296 kg/m3 respectively. A two dimensional axisymmetric computational fluid dynamic analysis is done for ideal gas condition and will be extended to non- equilibrium chemically reacting gas assumptions with non-catalytic wall in the further study. The non-equilibrium chemistry is simulated using thirteen species with 24 step reaction of Gokcen. The presence of large cavity at the nose is likely to reduce the maximum heating rates at the stagnation region which is extremely desirable for safe delivery of payloads. It is the objective of this paper to ensure to suggest relevant design parameters for a successful reentry mission to Titan so that it can set the trend for similar missions in the future. INTRODUCTION Titan is said to be formed in the Saturn sub- nebula. With the help of a model of comet nuclei, it is noticed that Titan’s nitrogen and methane makes up 50% of its mass which is in the form of ice. Thus it is assumed that as a result of accretion of icy planetesimals (i.e. particles and lumps made of rock and ice) the Titan has originated in Saturn’s sub- nebula. [1] There is no direct measurement of the composition of these planetesimals. Titan’s atmosphere is produced by degassing of the icy planetesimals. Until modern instrumentation was employed it was not revealed that Titan had unusual nature. With advances in infrared instrumentations the composition shown in Table:1 was revealed in the Titan’s atmosphere. [2] Titans Atmospheric profiles as explained by Ralph D. Lorents [3] considering Huygens Engineering Sensors gives a very good understanding of Density, Pressure and Temperature variation with respect to Altitude. A.James Friedson et.al in his paper (A global climate model of Titans atmosphere and surface) gives a very clear comparison between the temperature variation with pressure. He also explains the Heating/cooling rate with increase in altitude. Tobias Owen in his work provides a detailed insight on the recent advancement in the atmospheric findings of Titan and also gives a detailed explanation to the presence of each gas in the atmosphere of Titan and the behavior of these gasses in accordance to many parameters. An excellent result produced by Bobby Kazeminejad et al on Entry and Descent through Titans Atmosphere provides an