The gravitational shield of the giant outer planets, while highly efficient, must occasionally fail to protect Earth.

巨大的外行星的引力护盾虽然效率很高，但偶尔也会无法保护地球。

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The absence of oxygen on other planets means that those planets lack an ozone shield to protect life forms against UV radiation.

其他行星上没有氧气，这意味着这些行星缺乏保护生命体免受紫外线辐射的臭氧层。

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The absence of an oxygen atmosphere on Mars and other planets in our solar system means that these planets also lack an ozone shield that would protect surface-dwelling life from UV radiation.

在火星和我们太阳系的其他行星上没有氧气，这意味着这些行星也缺乏保护地表生物免受紫外线辐射的臭氧层。

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The United States says the missile shield would protect against rogue states such as Iran and North Korea.

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But the EFSF only runs until 2013, so France and Germany are arguing for a permanent shield to protect the eurozone.

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Then it can expand the shield to protect the allies and lead the way to a new era in which defenses promote global stability.

CENTERFORSECURITYPOLICY: Center For Security Policy