Water on Mars in best analyzed in two broad classifications: the portions of Mars that are at or close to thermodynamic equilibrium and those that are in long-term disequilibrium. In considering martian equilibrium conditions, the repeatability of thermal inertia results from data set to data set suggests that numerical thermodynamic models are generally accurate to better than a few degrees during most seasons and are even more accurate on an annual average. Comparison between Mars Odyssey Gamma Ray Spectrometer (GRS) measurements and theoreti

A modal test was performed on the six-meter Hypersonic Inflatable Aerodynamic Decelerator (HIAD) test article to gain a firm understanding of the dynamic characteristics of the unloaded structure within the low frequency range. The tests involved various configurations of the HIAD to understand the influence of the tri-torus, the varying pressure within the toroids and the influence of straps. The primary test was conducted utilizing an eletrodynamic shaker and the results were verified using a step relaxation technique. The analysis results show an increase in the structure's stiffness with respect to increasing pressure. The results also show the rise of coupled modes with the tri-torus configurations. During the testing activity, the attached straps exhibited a behavior that is similar to that described as fuzzy structures in the literature. Therefore extensive tests were also performed by utilizing foam to mitigate these effects as well as understand the modal parameters of these fuzzy sub structures. Results are being utilized to update the finite element model of the six-meter HIAD and to gain a better understanding of the modeling of complex inflatable structures.

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