Aeolian behavior of dust in a simulated Martian environment
Aeolian behavior of dust in a simulated Martian environment
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DOI：
10.1029/97je01753
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发表时间：
1997-11
影响因子：
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通讯作者：
B. White;B. M. Lacchia;R. Greeley;R. Leach
中科院分区：
文献类型：
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作者：
B. White;B. M. Lacchia;R. Greeley;R. Leach
在模拟的火星环境中分析了直径为1 - 2微米（μ m）的风尘的行为。研究了三个主要领域：（1）确定火星微粒和自然风吹陆地尘埃的光谱和风成特性，以确定合适的替代火星尘埃;（2）在模拟火星环境中放置物质;（3）在火星表面风洞中进行实验程序和测试。研究的第一阶段涉及选择一种与火星尘埃非常相似的陆地尘埃。从各种来源积累的数据表明，火星尘埃是来自玄武岩母体物质的风化，绿脱石粘土是一个很好的候选成分。一种商业粘土，卡本代尔红粘土（CRC），被确定为合适的替代火星尘埃。使用压缩空气粉尘喷射系统，产生空气夹带的粉尘云，其沉降以覆盖MARSWIT中的测试部分。这种方法最好地复制了假定存在于火星上的自然acrodynamic沉降过程。低压实验是在位于加州莫菲特场NASA艾姆斯研究中心的MARSWIT设施中进行的。两个单独的风洞地板用于这些实验;一个提供空气动力学光滑表面流，另一个是空气动力学粗糙表面流。初始和瞬间的颗粒运动记录在摩擦速度低至2米/秒。然而，粉尘从未达到流体跃变阈值，因为小于10 μ m的单个颗粒通常不会跃变，而是进入悬浮液。当摩擦速度为2m/s时，尘埃通量为3.7 × 10 - 7g/cm2 s。这种通量每秒可以在火星表面悬浮大约10，000公吨的尘埃。在火星条件下，光滑表面上的灰尘行为与粗糙表面上的灰尘行为明显不同。将上述过程应用于火星环境表明，在岩石表面首先会发生尘埃悬浮，而平滑的平原则需要更高的风速才能夹带尘埃。
The behavior of aeolian dust, particles 1-2 microns (μm) in diameter, was analyzed in a simulated Martian environment. Three main areas have been investigated: (1) characterizing spectral and aeolian properties of Martian particles and natural wind-blown terrestrial dust in order to identify a suitable surrogate Martian dust, (2) emplacement of the material in the simulated Martian environment, and (3) experimental procedures and testing in the Martian Surface Wind Tunnel (MARSWIT). The first phase of the study involved choosing a terrestrial dust that closely resembled Martian dust. Data accumulated from various sources suggest that Martian dust is derived from the weathering of basaltic parent material, nontronite clay being a good candidate composition. A commercial clay, Carbondale Red Clay (CRC), was determined to be an appropriate surrogate Martian dust. Using a compressed air-dust ejection system, an air-entrained dust cloud was generated which settled to cover the test section in the MARSWIT. This method best replicated the natural acrodynamic settling process presumed to exist on Mars. Low-pressure experiments were performed in the MARSWIT facility located at the NASA Ames Research Center, Moffett Field, California. Two separate wind tunnel floors were used for these experiments; one provided an aerodynamically smooth-surface flow, and the other was an aerodynamically rough-surface flow. Initial and momentary particle movement was recorded at friction velocities as low as 2 m/s. However, the dust never reached fluid saltation threshold because individual particles less than 10 μm typically do not saltate, but pass into suspension. An estimated dust flux of 3.7 x 10 -7 g/cm 2 s was determined for a friction velocity of 2 m/s. This flux could suspend about 10,000 metric tons of dust per second over the surface of Mars. The dust behavior on the smooth surface was markedly different than on the rough surface under Martian conditions. Application of the processes described above to the Martian environment suggests that on rocky surfaces dust suspension would first occur, whereas smooth plains would require higher wind speeds for dust entrainment.