It might be that some massive network of communications, or some shield against asteroidal impact, or some huge astro-engineering project that we can't even begin to conceive of, could generate signals at radio or optical frequencies that a determined program of searching might detect.
它可能是巨大的通信网络， 或者是防御天体碰撞的护罩， 甚至超出我们想像力的宏伟的空间机械工程， 产生出可能被持久的搜索计划 侦测到的无线电信号或光学频率。