Air flow velocity and fluctuations can be measured by HW based on the detection of rapid changes in the transferred heat from a tiny sensor (wire typically 5 μm in diameter) to the flow. This technique has got a very high state of development, offering high quality in measuring flow velocities and especially for study of turbulent flows. Thermal anemometry, usually named as hot wire (HW) technique, is a well-established measurement technique introduced in the first half of twentieth century from the study carried out by King after investigating the thin cylinders heat transfer. For example, an experiment of the same velocity requires a subscaled model of 1/35th scale, while a reduction to 1/2 of flow velocity requires a reduction of approximately 1/18th in all dimensions of the rover model to be tested in Earth. Because velocity can be slightly reduced, but length can be modified in a large range, this way will be followed by wind tunnel testing. But, if we are trying to simulate the problem by wind tunnel testing in Earth atmospheric conditions, flow velocity and length in Earth will be reduced in the same quantity of kinematic viscosity ratio, in order to verify the same Reynolds number in both planets. E6Ĭonsequently, the Reynolds number in Earth is approximately 35 times higher than these to be expected in Mars surface, when Earth conditions corresponds to standard atmospheric conditions therefore, Reynolds in Earth only can be equal when using same gas and same thermodynamics conditions as those present in Mars. Re Earth Re Mars = ν Mars ν Earth = 35.4. On the other hand, quality measurements of the wind in Mars could provide a better understanding of the geophysical phenomena occurring in Mars such as dust devils, carving intracrater layered deposits, and changes on dunes or any other eolian processes due to the wind-driven particle mobility. On one hand, in situ propulsion will be necessary for long-term planetary surface missions, and the wind energy could be the power to push wind-driven craft for exploration. The importance of studying the wind in Mars is manifold. MEDA wind sensors are inspired in the design of the wind sensor of Rover Environmental Monitoring Station (REMS) that was embarked on the Mars Science Laboratory (MSL) Curiosity rover. MEDA sensors will provide information about both ambient and ground, such as wind speed and its direction, temperature, pressure, relative humidity, ultraviolet radiation, and size and shape of dust. The Mars Environmental Dynamics Analyzer (MEDA) is the contribution of Spain to the Mars Exploration Program, and it was designed as a mobile environmental station to be transported by Mars 2020 rover. Satellites orbiting Mars provide remote sensing data for the study of Martian atmosphere, but a higher resolution data must be obtained by means of investigation surface vehicles. The investigation of the environmental factors is an overriding aspect to get insight and a better understanding of the meteorological processes in Mars atmosphere. This mission is conceived for the exploration of Mars, and additionally, it provides a way to demonstrate novel technologies addressed to the future Martian human expeditions. The Mars 2020 rover mission is a part of NASA’s Mars Exploration Program.
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