Aerothermochemical analysis of the Orion capsule in rarefied transitional flow regime during Mars entry.

• The present paper evaluates thermochemical effects on Orion at the beginning of an entry path. • Effects of chemical reactions and of typology of entry trajectory (direct and orbit) are evaluated. • Heat flux associated to the surface recombination reactions is also estimated. It is well known that NASA developed the Orion project, besides for a rescue shuttle for the International Space Station, also for the transportation of instruments and astronauts to Moon, Mars and beyond. The forthcoming use of Orion for Mars landing stimulated Zuppardi to compute global aerodynamic coefficients in rarefied, transitional flow along a high altitude entry path. A Direct Simulation Monte Carlo (DSMC) code computed the coefficients at the altitudes of 80, 90 and 100 km, in the range of angles of attack 0–180 deg. The aim of the present paper, that can be considered as the logic follow on of the previous paper by Zuppardi, is to evaluate, in high altitude entry path, the influence of: 1) chemical reactions on the flow field and on some local quantities (temperature, pressure and heat flux) along the Orion surface, 2) typology of entry trajectory (direct and orbit) on both local quantities and drag coefficient, 3) heat flux associated to the surface recombination reactions. Computations were carried out in axisymmetric flow and in the altitudes interval 60–100 km by means of a home made code for the computation of the entry trajectories and of the powerful and advanced two-dimentional/axisymmetric DSMC code (DS2V) for the solution of the flow field around Orion. [ABSTRACT FROM AUTHOR]