SIERRA VISTA — Many keen-eyed residents may have noticed that one of the common sights of the local skyline, the aerostat on Fort Huachuca, has been missing from the skies above Sierra Vista for the last several weeks. After five years of serving as an important link in a chain of detection spanning the length of the international border, the most recent iteration of the Tethered Aerostat Radar System (TARS) has been brought down for regular comprehensive maintenance after reaching the end of its life cycle, said Robert Brown, TARS program manager for U.S. Customs and Border Protection (CBP), which...