SACOMAR

The success of future exploration missions to the surface of Mars strongly depends on an appropriate evaluation of thermal loads on the entry vehicle during atmospheric entry. Determination of heat fluxes during entry is one of the most challenging problems in vehicle design. A more accurate prediction could help to reduce design margin and increase the scientific pay load, but it requires improvements to the physical models which are currently used in numerical simulation tools.

SACOMAR logo . Material sample in Martian atmosphere flow .

The improvement of experimental and numerical tools to study aerodynamic problems of Martian entry is one of the main objectives of the SACOMAR project which is part of the European Commission’s Seventh Framework Programme and is run on behalf of the commission by DLR in cooperation with the following partners:

• CIRA: Italian Aerospace Research Center (Italy), 
• TAS-I: Thales Alenia Space Italia S.p.A (Italy),
• EADS Astrium GmbH (Germany),
• TsNIIMash: Central Research Institute for Machine Building (Russia),
• TsAGI: Central Aerohydrodynamic Institute (Russia),
• IPM: Institute for Problems in Mechanics (Russia),
• ITAM: Institute of Theoretical and Applied Mathematics (Russia).

Further objectives are the achievement of a better understanding of physical phenomena and the creation of a data base. The SACOMAR project brings together for the first time the key institutions of Western Europe and Russia in the field of Martian entry technologies. The involvement of two industrial partners allows definition of technical requirements based on flight relevant references.

The definition of requirements on experimental investigations, physical modelling and numerical simulations is based on the needs of the EXOMARS mission which currently prepared for lift-off to Mars in 2016. The test setup for experimental investigations will directly be derived from the specified requirements. Several types of high enthalpy ground test facilities will be applied to cover all important thermochemical regimes. Tests in short duration facilities will allow to simulate thermal and chemical relaxation phenomena in close comparison to typical Martian entry flight. Stagnation heat flux rates in thermal and chemical equilibrium and in frozen conditions will be obtained from long duration ground test facilities, i.e plasmatron and arc heated facilities. Additionally, these facilities allow for a detailed flow field characterization using sophisticated spectroscopic measurement techniques. These measurements can provide a correlation between measured heat flux rates and local flow properties behind the bow shock as well as in the free stream.

SACOMAR work logic

In parallel to the experiments the potential for improving the existing thermochemistry models with respect to non-equilibrium effects, transport properties and surface chemistry will be evaluated. Compared to Earth the thermochemical modelling of Martian atmosphere is more complex and due the low pressure and density levels significant deviations from equilibrium have to be considered. Useful information about the sensitivity of modelling to numerical results will be obtained from code-to-code comparisons. There will be several iterations between modelling and numerical simulation. At the end, the improved models will be used for numerical rebuilding of the experiments in the high enthalpy facilities. The SACOMAR project will end up with a synthesizing analysis of the achieved improvements with respect to future Martian entry missions.