It is a brilliant hot morning in the desert north of Tucson,Ariz.,and the sun blazes down on a dozen or so people as they went their way through a savanna and around a marsh,an ocean,and miles of pipes,channels,steel struts and glass panels.

• 这是亚利桑那州图森市以北的沙漠中一个炙热的早晨，阳光烘烤着正在步行的十几个人。他们穿行于热带稀树大草原。沼泽地、人造海以及绵延数里的管道、水道、金属支柱和玻璃嵌板中间。