The European Space Agency (ESA), the Russian Federal Space Agency (RKA) and Nasa have each poured billions of pounds into such a craft without success.

欧洲航天局，俄罗斯联邦航天局和美国宇航局已分别投入到这样一门手艺没有成功数十亿英镑。

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The U.S. General Services Administration (GSA) is adopting changes to its standard lease language to enhance energy and water efficiency in the more than 190 million square feet of office space the federal agency leases across the United States.

FORBES: GSA Goes Deep Green With Next-Gen Green Leasing Standards

In the speech, the president did not change the broad outline of the vision for the US space agency he first expounded in his 2011 federal budget request.

BBC: Obama sets Mars goal for America

Energy Star exemptions: Federal agencies are required to lease space in U.S. Environmental Protection Agency ENERGY STAR-labeled buildings.

FORBES: GSA Goes Deep Green With Next-Gen Green Leasing Standards