「首发」沃邦名师3月10日亚太SAT考试考情速递(19)

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.