Satellite repositioning to boost GPS accuracy

Government Security News website story by Mark Rockwell

The US Air Force has repositioned six satellites to boost global positioning accuracy for civilian and military use worldwide.

The 50th Space Wing, part of the Air Force Space Command said Jan. 19 it completed the first of two phases in an expansion of a Global Positioning System satellite constellation. When fully complete, the "Expandable 24" operation 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, said the wing.

The GPS constellation consists of 24 operational slots positioned within six equally-spaced orbital planes surrounding the earth, according to the Space Wing. The 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, it said.

“Expandable 24” is a US Strategic Command-directed initiative, executed by the wing, specifically the 2nd Space Operations Squadron, to reposition six satellites in the current GPS constellation, said a statement from the Strategic Command. “Given the strength and number of satellites in the current constellation, Air Force Space Command [AFSPC] 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,” it said.

Phase one of Expandable-24 began Jan. 13, 2010 when three GPS satellites were repositioned, one of which took 351 days to maneuver. The last of the satellites completed repositioning on Jan. 18, 2011, it said.

Phase two of Expandable-24 began in August 2010 and is expected to be complete in June 2011. During Phase two, three more 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, it said.

"Our primary focus is to execute flawless operations to maintain GPS as the world's gold standard for positioning, navigation, and timing," said Lt. Col. Mike Manor, director of operations for the 2nd Space Operations Squadron. "By repositioning a handful of our satellites to optimize their locations in space, we’ve not only improved the accuracy for military users in disadvantaged terrain like Afghanistan, but also improved the accuracy for all GPS users worldwide."