The terrain where Phoenix set its three legs is relatively flat with polygon-shaped patterns in the ground likely caused by the expansion and contraction of underground ice.

菲尼克斯放置三个支架的地形相对来说比较平坦，地面上多角形图案看起来好像是由于地下永冻土的扩张和收缩形成的。

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The spacecraft will use its 2.5-meter robotic arm to scoop up soil samples and collect underground ice, or permafrost, to see whether there's evidence life ever existed on the Red Planet.

探测器将借助2.5米长的机械手臂挖掘土壤样本，采集地下冰，或者永久冻土，来研究这个红色星球上是否有生命迹象存在。

youdao

The translucent columns also resemble giant pillars of ice but are warmed by superheated air leaking up from underground magma Chambers.

这些剔透的柱体就像巨大的冰柱，但又被过热的空气熔化，这些空气来自地下的岩浆房。

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He saw that an underground spring flowed under the ice at that spot.

VOA: special.2010.05.01

Also on board Mars Odyssey is a neutron spectrometer that registers evidence for underground ice in the same regions of the planet.

BBC: Ice reservoirs found on Mars

But Shell says it has a solution for that, a giant underground wall of ice.

NPR: Industry Seeks to Extract Oil from Rocky Mountain Shale

It could identify soil types, verify the presence of water ice and dry ice at the poles, and even track traces of water underground.

NEWYORKER: The Martian Chroniclers