Lengthy delays like this are one of the key challenges for NASA, according to an April 2011 report from the USNational Academy of Sciences.
美国国家科学院于2011年4月的报告称，这样的长时间延误是美国航空航天局面临的主要挑战之一。
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The USNational Center for Atmospheric Ressearch has already suggested that the proposal to inject ulphur into the atmosphere might affect rainfall patterns across the tropics and the Southern Ocean.