| Project/Area Number |
05833003
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
惑星科学
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| Research Institution | University of Tokyo |
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Principal Investigator |
MTSUI Takafumi Univ.of Tokyo, Dept. Earth&Planetary Physics, Assoc.Prof., 大学院・理学系研究科, 助教授 (80114643)
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| Co-Investigator(Kenkyū-buntansha) |
HORAI Ki-iti Meteoritical Research Institute, Senior Scientist, 地震火山研究部, 研究部長
宝本 帰一 東京大学, 気象研究所・地震火山研究部, 研究部長
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Mars / heatflow / thermal conductivity / thermal diffusivity / 粉体 / 粘土鉱物 / 火星探査 / 火星表層環境 / 探針法 / 熱伝導率測定 / 月面疑似物質の熱伝率 / ガラスビーズの熱伝導率 / 火星表層疑似物質の熱伝導率 / 火星の熱流量測定 |
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| Research Abstract |
Thermal conductivity of a simulated Martian surface material was measured under the simulated Martian surface conditions, namely at temperatures ranging from 200 to 300K,and the interstitial gaseous pressure of CO_2 ranging from 10 to 10^5 Pa. The primary purpose of the study is to provide basic data relevant to a Martian heat flow measurement that is expected in the future. The measurement of thermal conductivity was made by means of the needle probe technique on the sample of bentonite with the grain size ranging from 1 to 10mum that was used as a simulant of the Martian surface material. The thermal conductivity of the sample decreases as the pressure of gas filling the sample's interstices is reduced from 10^5 Pa to 1 Pa. The thermal conductivity is most sensitive to the change of pressure around 8 hPa that is the Mars' average atmospheric pressure at the surface. For the interstitial gaseous pressure held constant, the thermal conductivity of dry bentonite is rather insensitive to
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the change of temperature as it increases slightly for the temperature raised from 200 to 300 K.The effect of moisture is remarkable, however. Under a constant interstitial gaseous pressure of CO_2 the thermal conductivity increases and becomes more sensitive to temperature change as the sample's water content is increased om 5 to 13 weight percent. Contrary to the thermal conductivity, the thermal diffusivity of wet bentonite is less temperature dependent. Thermal skin depth of the Martian surface layr, calculated from the data of thermal diffusivity taken at 290K of temperature and 9 hPa of interstitial gaseous pressure, was 5 and 79cm, respectively, for the diurnal and annual variations of the Martian surface temperature. At290K of temperature and 7.9hPa of interstitial gaseous pressure, thermal inertia of the sample is 97 Jm^<-2>s^<-1/2>K^<-1> or 2.32x 10^3 cal cm^<-2>s^<-1/2>ﾟC^<-1> that is close to the lower of the two peak values observed on the low to middle latitude areas that have a relatively high albedo as revealed by the Viking thermal mapping of the Martian surface. Less
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