托福听力30天备考计划:第5天备考内容

2022-06-11 20:10:33

  1) trying to pinpoint the moon’s age

  2) studying an enormous impact crater

  3) This color-coated image of the SPA Basin,those aren’t its actual colors obviously

  4) Its orbits enableit to send back data to create this topographical map of … well, the greyand white area towards the bottom is the South Pole, the purples and blues inthe middle correspond to low elevations - the SPA Basin itself, the oranges and reds around it are higher elevations.

  5) The basin measures an amazing 2,500 km in diameter, and its average depth is 12 km.

  6) and in this case,we especially want to know if any of the mantle, the layer beneath the crust,was exposed by the impact.

  7)Not everyone agrees,but some experts are convinced that whatever created the SPA Basin did penetrate theMoon’s mantle.

  8) If we had rocksamples to study, we’d know whether the small craters were formed by impactsduring the final stages of planetary formation, or if they resulted from later meteor showers.

  9) such crudeestimates

  10) the wall of thesouth-polar crater was more reflective than expected.

  11) data from a latermission indicates significant concentrations of hydrogen and by inference water less than a meter underground at both poles.

  12) We think meteors that crashed into the moon or tails of passing comets may have introduced water molecules.

  13) Any water molecules that found theirway to the floors of craters near the moon’s poles, that water wouldbe perpetually frozen, because the floors of those craters are always in shadow.

  14) if the water ice was mixed in with rock and dust, it would be protected fromevaporation.

  15) So water ice couldenable the creation of a self-sustaining moon base someday, a mining camp perhaps or adeparture point for further

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