Navigation and guidance experts at Argon ST Inc. in Fairfax, Va., are building on previous company research to develop a prototype sensor fusion system for land, sea, and airborne applications that can accept inputs from several kinds of navigation sensors so that warfighters can maintain navigation capability with or without global positioning system (GPS) satellite navigation. Argon ST won a $2 million contract for the U.S. Defense Advanced Research Projects Agency (DARPA) All Source Positioning and Navigation (ASPN) Phase 2 program, designed to develop algorithms and a prototype sensor-fusion system to enable low-cost navigation for military users on any operational platform and in any environment, with or without GPS. Argon ST won a $1.9 million first-phase ASPN contract early last year, and focused on developing navigation algorithms and a navigation software architecture. Also participating in the first phase of the ASPN program was the Charles Stark Draper Laboratory Inc. in Cambridge, Mass. With the addition of Argon ST, the number of ASPN Phase 2 contractors grows to six. SAIC Inc. in McLean, Va., won the initial contract in late January, and other ASPN Phase 2 contractors are Vesperix Corp. in Arlington, Va.; SRI International in Menlo Park, Calif.; Systems & Technology Research in Woburn, Mass.; and the Northrop Grumman Corp. Navigation and Maritime Systems Division in Woodland Hills, Calif.