[SatNews] The 50th Space Wing has completed phase one of a two phase Global Positioning System constellation expansion known as “Expandable 24.”
When fully complete, this expansion will increase global GPS coverage and provide civil, military and commercial GPS users with more robust satellite availability and a higher probability of signal acquisition in terrain challenged environments. The GPS constellation consists of 24 operational slots positioned within six equally-spaced orbital planes surrounding the Earth. This plane/slot scheme and enhanced satellite placement ensure GPS users receive the most accurate navigation data at any time, at any place around the world. Expandable 24 is a U.S. Strategic Command commander directed initiative, executed by the wing, specifically the 2nd Space Operations Squadron, to reposition six satellites in the current GPS constellation. Given the strength and number of satellites in the current constellation, Air Force Space Command was in a unique position to enact this revolutionary strategy to benefit global users. AFSPC acted on this opportunity to increase the robustness of satellite availability by expanding three of the baseline 24 constellation slots.
Phase one of Expandable-24 began on Jan. 13, 2010 when 2 SOPS performed maneuvers to reposition three GPS satellites, one of which took 351 days to maneuver. The last of the satellites completed repositioning on Jan. 18, 2011. Phase two of Expandable-24 began in August 2010 and is expected to be complete in June 2011. During Phase two, three other GPS satellites will be repositioned. When complete, the GPS constellation will attain the most optimal geometry in its 42 year history, maximizing GPS coverage for all users.