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arXiv 1402.0541astro-ph.EP
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CRISM南极测绘:第一个火星观测年

CRISM south polar mapping: First Mars year of observations

Adrian J. Brown, Wendy M. Calvin, Patrick C. McGuire, Scott L. Murchie

摘要:

我们报告的火星南极地区的地图使用的数据从紧凑型侦察成像光谱仪火星(CRISM)仪器。我们的观察导致了以下发现:1。水冰以极地绕圈云的形式存在,起源于环希腊地区,在Ls=162之前开始,在Ls=200-204时明显减少。2.先前已经通过温度测量来推断(Titus等人,2003)和CO2-H2O混合物光谱模型(Langevin等人,2007年),表面水冰在升华的最后阶段存在于神秘区域。CRISM的高分辨率揭示了只有水冰存在的区域(而不是CO2-H2O冰的混合物)。这种水冰在Ls=252时完全消失,并且可能是CRISM在Ls=240-260之间的南纬度观测到的水蒸气的来源(Smith等人,本期)。3.我们估计了南极剩余冰帽(SPRC)和季节性CO2冰帽,整个夏季,春季和夏季覆盖它的表面CO2冰粒度分布。我们的分析表明,晶粒尺寸在Ls=191-199处达到峰值,表观晶粒尺寸为~7 +/-1 cm。到夏季结束时,我们的分析表明,在SPRC中占主导地位的最小表观粒度为~5 +/-1 mm。4.细粒CO2冰从Ls=0-40凝结,并对称地延伸远离地理极点,延伸超过80 ° S的Ls=4-10。没有证据表明不寻常的CO2沉积过程中的隐藏区域观察到LS=16。

英文摘要:

We report on mapping of the south polar region of Mars using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument. Our observations have led to the following discoveries: 1. Water ice is present in the form of pole-circling clouds originating from the circum-Hellas region, beginning prior to Ls=162 and diminishing markedly at Ls=200-204. 2. It has previously been inferred by temperature measurements(Titus et al., 2003) and CO2-H2O mixture spectral models (Langevin et al., 2007) that surface water ice was present in the Cryptic Region in the final stages of sublimation. The high resolution of CRISM has revealed regions where only water ice is present (not a CO2-H2O ice mixture). This water ice disappears completely by Ls=252 and may be the source of water vapor observed by CRISM in southern latitudes between Ls=240-260 (Smith, et al., this issue). 3. We have estimated surface CO2 ice grain size distributions for the South Pole Residual Cap (SPRC) and the seasonal CO2 ice cap that covers it throughout summer spring and summer. Our analysis suggests that grain sizes peak at Ls=191-199 with an apparent grain size of ~7 +/-1 cm. By the end of the summer period our analysis demonstrates minimum apparent grain sizes of ~5 +/-1 mm predominate in the SPRC. 4. Fine grained CO2 ice condenses from Ls=0-40, and extends symmetrically away from the geographic pole, extending beyond 80 deg S by Ls=4-10. No evidence for unusual CO2 depositional processes in the Cryptic Region is observed up to Ls=16.

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