Welcome to today's Space Briefing -- a biweekly roundup of the latest national security space news. Top Story OPIR architecture report designates MDA as lead for HBTSS, reveals new interagency AQ team A new report on the Defense Department's overhead persistent infrared architecture offers insight into the Pentagon's plans for future space-based missile tracking and warning capabilities -- a response to lawmakers' calls for a clear strategy that addresses concerns about duplication and oversight across the enterprise. News & Notes...