WASHINGTON — The U.S. Air Force’s space acquisition arm is officially looking for possible challengers to Lockheed Martin to build the service’s next batch of positioning, navigation and timing satellites.

But there is a caveat, according to a June 4 notice on the Federal Business Opportunities website: Challengers must offer an alternative to the Exelis-provided payload that will fly on the eight GPS 3 satellites under contract to Lockheed Martin Space Systems.

Exelis Geospatial Systems’ struggles developing that payload prompted Lockheed Martin to consider switching suppliers beginning with the ninth satellite in the GPS 3 series. Lockheed Martin says five companies responded to its solicitation last year seeking information on alternate suppliers. 

In its June 4 “sources sought” notice, the Air Force Space and Missile Systems Center said it plans to award as many as two contracts in 2015 to see if a production ready GPS space vehicle, equipped with an alternate payload, can be completed in time to square off with Lockheed Martin’s GPS 3 platform in a competition for up to 22 follow-on navigation satellites.

“For every block of GPS satellites over the past 40 years, the primary risk has been the navigation payload,” the notice said.

The first phase of the contract would include two firm-fixed price contracts worth about $100 million to $200 million to demonstrate a competitor to GPS 3. The Air Force stipulated that the satellite be ready to launch by 2023 and that the competitors be able to produce two to three satellites per year.

The second phase features a competition between Lockheed Martin and one or more other companies for as many as 22 satellites. A final contract award would be made in 2017 or 2018. 

Boeing, which built the current generation of GPS satellites, has said it likely would bid if the Air Force opts to hold a new GPS competition. Boeing built the platform and major payload components for the GPS 2F satellites.

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Mike Gruss is a senior staff writer for SpaceNews. He joined the publication in January 2013 to cover military space. Previously, he worked as a reporter and columnist for The Virginian-Pilot in Norfolk, Va. and The Journal Gazette in Fort Wayne, Ind. He...