They're currently building what they call a " space fence" , which is just a radar-based space surveillance system that will allow the Air Force to better track space debris and artificial satellites.

他们目前正在建造所谓的“太空围栏”，这是一个基于雷达的太空监视系统， 可以让空军更好地跟踪太空碎片和人造卫星。