【单选题】
Mars Probe Watches Water-ice Fade
The pictures acquired by a NASA、orbiter(卫星) show white material exposed by flesh meteorite impacts fading over time-behaviour expected of ice on Mars.An onboard instrument also detected the tell-tale chemical signature of water.
To date, exposed water-ice has only been seen at very high latitudes. The US space agency’s (NASA、recent Phoenix probe famously dug into water-ice at its" highArctic" landing site. The implication, even with the small set of examples scientists now have, is that broad deposits of ice sit just below the red top-soil of Mars. "There’s a consistent picture starting to emerge now that these broad sheets may be common on Mars," observed ShaneByme of the University ofArizona, a member of the team running the HiRISE、camera on NASA’s Mars Reconnaissance Orbiter (MRO).
"The volume of water is probably comparable to the volume that we would have in the Greenland ice sheet on theEanh-in the buried ice deposits that stretch from each pole to mid-latitudes. "
MRO has produced" earlier" and" later" images at five fresh impact sites made in 2008. These were all halfway between the North Pole and the equator on Mars.
The craters (环形山, 陨石坑) were small, just a few metres across, gouged out by incoming space rocks that may have been no more than 10cm in size. The bright, white deposits uncovered by the impacts were seen to wither over time, something exposed water-ice cannot help but do in the low-pressure Martian atmosphere. It is bound to sublimate-to tum directly from a solid into a Vapour.
However, the length of time it took to fade was a good indication that the ice was very pure. Had it contained a lot of dirt mixed in with it, the ice would have sublimated much quicker, scientists saiD、
The discoveries made by MRO are said to indicate that Mars had a more humid climate in the relatively recent past, within the last 10,000 years. Scientists suspect much of this ice came out of the atmosphere. Water vapour in the atmosphere will diffuse through the particles of the soil until it gets to a certain depth where it then freezes.
The locations of the exposed ice fit with the models used to predict where ground ice might be stable, i. e. from mid up to high latitudes.
"The more humid the Martian atmosphere, the more extensive the area of this stable ice. " explained ShaneByme. "Based on the locations of these craters, we are able to say something about how much water was in the Martian atmosphere recently, and that turns out to be a lot more than is in the atmosphere today—maybe almost double what’s in the atmosphere today. \
What new findings has NASA、acquiredA、new planet
B．Creature on Mars
C．Broad deposits of ice sit below the Martian surface
D．Large-scale water
网考网参考答案：C
网考网解析：
The pictures acquired by a NASA orbiter(卫星)show white material fading over time -behaviour expected of ice on Mars. The US space agency’s (NASA) recent Phoenix probe Famously dug into Water-ice at its "high Arctic" landing site. 由文章第一段以及第二段我们可以得知：一颗美国宇航局卫星获得的图片显示由于新的陨石撞击而外露出的白色物质正随着时间的流逝而消失，凤凰号探测器在火星北极高纬度着陆时恰好插入水冰，虽然这些例子不多，但已经暗示了就在火星表层土下藏有大量的冰块。所以本题正确答案为C。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
The pictures acquired by a NASA、orbiter(卫星) show white material exposed by flesh meteorite impacts fading over time-behaviour expected of ice on Mars.An onboard instrument also detected the tell-tale chemical signature of water.
To date, exposed water-ice has only been seen at very high latitudes. The US space agency’s (NASA、recent Phoenix probe famously dug into water-ice at its" highArctic" landing site. The implication, even with the small set of examples scientists now have, is that broad deposits of ice sit just below the red top-soil of Mars. "There’s a consistent picture starting to emerge now that these broad sheets may be common on Mars," observed ShaneByme of the University ofArizona, a member of the team running the HiRISE、camera on NASA’s Mars Reconnaissance Orbiter (MRO).
"The volume of water is probably comparable to the volume that we would have in the Greenland ice sheet on theEanh-in the buried ice deposits that stretch from each pole to mid-latitudes. "
MRO has produced" earlier" and" later" images at five fresh impact sites made in 2008. These were all halfway between the North Pole and the equator on Mars.
The craters (环形山, 陨石坑) were small, just a few metres across, gouged out by incoming space rocks that may have been no more than 10cm in size. The bright, white deposits uncovered by the impacts were seen to wither over time, something exposed water-ice cannot help but do in the low-pressure Martian atmosphere. It is bound to sublimate-to tum directly from a solid into a Vapour.
However, the length of time it took to fade was a good indication that the ice was very pure. Had it contained a lot of dirt mixed in with it, the ice would have sublimated much quicker, scientists saiD、
The discoveries made by MRO are said to indicate that Mars had a more humid climate in the relatively recent past, within the last 10,000 years. Scientists suspect much of this ice came out of the atmosphere. Water vapour in the atmosphere will diffuse through the particles of the soil until it gets to a certain depth where it then freezes.
The locations of the exposed ice fit with the models used to predict where ground ice might be stable, i. e. from mid up to high latitudes.
"The more humid the Martian atmosphere, the more extensive the area of this stable ice. " explained ShaneByme. "Based on the locations of these craters, we are able to say something about how much water was in the Martian atmosphere recently, and that turns out to be a lot more than is in the atmosphere today—maybe almost double what’s in the atmosphere today. \
What new findings has NASA、acquiredA、new planet
B．Creature on Mars
C．Broad deposits of ice sit below the Martian surface
D．Large-scale water
网考网参考答案：C
网考网解析：
The pictures acquired by a NASA orbiter(卫星)show white material fading over time -behaviour expected of ice on Mars. The US space agency’s (NASA) recent Phoenix probe Famously dug into Water-ice at its "high Arctic" landing site. 由文章第一段以及第二段我们可以得知：一颗美国宇航局卫星获得的图片显示由于新的陨石撞击而外露出的白色物质正随着时间的流逝而消失，凤凰号探测器在火星北极高纬度着陆时恰好插入水冰，虽然这些例子不多，但已经暗示了就在火星表层土下藏有大量的冰块。所以本题正确答案为C。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
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