亚太SAT考试考情速递真题回忆5

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第五篇

题目：

1. 全文的主要目的是什么? 选择月球上新的发现质疑之前的假设理论

2. 为什么作者说发现新的长方形地貌的时候还要提及 geologic plumbing sysyem?是为了进一步说明该地域的地址形态

3. Hannah是如何评价之前的陨石撞击导致盆地理论的

4. NASA飞船GRAIL给Hannah团队提供了什么样的帮助

5. GRAIL提供的信息和什么有关

6. Hannah对于信息后的分析如何评价

7. 寻证题

8. 结合以上内容，Dark Spot到底应该是如何形成的

9. 为什么一开始认定OP是陨石冲击形成的

10. 寻证题

11. 作者为什么给出宇宙中一些其他天体的例子，比如土星的卫星.

文章原文：

Ancient magma plumbing found buried below moon'slargest dark spot

By Eric HandOct. 1, 2014 ,1:00 PM

Scientists have found a nearly squarepeg underneath a round hole—on the moon. Several kilometers below OceanusProcellarum, the largest dark spot on the moon’s near side, scientists havediscovered a giant rectangle thought to be the remnants of a geologicalplumbing system that spilled lava across the moon about 3.5 billion years ago.The features are similar to rift valleys on Earth—regions where the crust iscooling, contracting, and ripping apart. Their existence shows that the moon,early in its history, experienced tectonic and volcanic activity normallyassociated with much bigger planets.

“We’re realizingthat the early moon was a much more dynamic place than we thought,” saysJeffrey Andrews-Hanna, a planetary scientist at the Colorado School of Mines inGolden and lead author of a new study of the Procellarum’s geology. Thediscovery also casts doubt on the decades-old theory that the circularProcellarum region is a basin, or giant crater, created when a large asteroidslammed into the moon. “We don’t expect a basin rim to have corners,”Andrews-Hanna says.

The work isbased on data gathered by GRAIL (Gravity Recovery and Interior Laboratory), apair of NASA spacecraft that orbited the moon in 2012. Sensitive to tinyvariations in the gravitational tug of the moon, GRAIL mapped densityvariations below the surface (because regions of higher density produceslightly higher gravitational forces). Below known impact basins, GRAIL foundthe expected ringlike patterns, but underneath the Procellarum region, themysterious rectangle emerged. “It was a striking pattern that demanded anexplanation,” Andrews-Hanna says.

Scientistsalready know that the Procellarum region is rich in radioactive elements thatbillions of years ago would have produced excess heat. The study team theorizesthat as this region cooled, the rock would have cracked in geometricalpatterns, like honeycomb patterns seen on Earth in basalt formations, but on amuch larger scale. In a study published today in Nature, the researcherspropose that these cracks eventually grew into rift valleys, wheremagma from the moon’s mantle welled up and pushed apart blocks of crust. Lava spilledout and paved over the Oceanus Procellarum, creating the dark spot that is seentoday. The extra weight of this dense material would have caused the wholeregion to sink slightly and form the topographic low that has made theProcellarum seem like a basin.

With thediscovery, the moon joins Earth, Mars, and Venus as solar system bodies withmapped examples of rifting. There are also similar features near the south poleof Enceladus, the moon of Saturn that is spewing water into space from cracksin an ice shell.

Andrews-Hannaand colleagues have made a good case, says Herbert Frey, a planetary scientistat NASA’s Goddard Space Flight Center in Greenbelt, Maryland, even though thenewly described features are surprising. The moon is not big enough to have thesame strong convective cooling process that Earth has in its interior, heexplains, and ordinarily convection is one of the main mechanisms thought tolead to large-scale rifting. So just what caused the rifting remains unclear.“It just means the moon continues to surprise us,” he says. Frey adds that aremaining mystery is why the rectangular features were found only beneathOceanus Procellarum. Even if the rifting is explained by the excess radioactiveelements, there is still no definitive explanation for why only the near sideof the moon ended up enriched.

The discoverycould also be a death knell for the impact theory for Oceanus Procellarum, anidea first put forth in the early 1970s. A basin there would have been thelargest on the moon—larger than the South Pole–Aitken Basin—and second in thesolar system only to the Borealis Basin on Mars, which covers the planet’sentire northern hemisphere.

RyosukeNakamura, a researcher at the National Institute of Advanced Industrial Scienceand Technology in Tsukuba, Japan, is still not convinced that an impact can beruled out. In 2012, he and his colleagues published a paper in NatureGeosciencethat found compositional evidence for an impactwithin Procellarum—a type of pyroxene mineral that is found in other, knownimpact basins such as South Pole–Aitken and is associated with the melting orexcavation of mantle rock from an asteroid impact.

In response tothe current study, Nakamura says that the features in the southwestern cornerof the Procellarum region look to be circular rather than rectangular, andstill consistent with an impact. But Frey, who has long been skeptical of theimpact theory, says that the features are as clear as day, and not what you’dexpect underneath a basin. “That looks like a rectangle to me.”

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