By Andrea Shalal

PALMDALE, Calif., Dec 11 (Reuters) - Northrop Grumman Corp this week said it would bid if the U.S. Air Force opens a fresh competition for next-generation GPS satellites next year, as expected, and perhaps later on a new ground control system.

Tom Vice, president of Northrop's Aerospace Systems division, said he expects the Air Force to launch a competition for new Global Positioning System (GPS) satellites, and Northrop was ready to participate. Northrop already builds satellites for the U.S. intelligence community and is building the powerful new James Webb telescope for NASA.

Air Force officials have said they expect to start early work in 2016 on a competition for a next batch of GPS satellites, followed by a formal request for proposals in 2018.

Lockheed Martin Corp is under contract to build the first eight GPS III satellites, and the Air Force has options for two more.

GPS satellites provide critical timing and navigational data to the U.S. military and commercial users worldwide.

Lockheed now expects to deliver the first GPS III satellite for launch in May 2017, more than two years after the initial target due to issues with the main navigational payload for the satellite that was built by Exelis Corp, which is now owned by Harris Corp.

Boeing Co and Northrop have both expressed interested in competing for what would be a multibillion-dollar program, as have several companies that build sensors for satellites, including General Dynamics Corp.

Vice said Northrop could also bid to build a new ground control system for the GPS satellites, if the Air Force decided to open that system to competition at some later date. He said the company would need to ensure that the requirements for the new system were clear and stable, and that it had sufficient time to develop a suitable proposal.

The Pentagon this week said it was sticking with Raytheon Co to build a new ground control network for GPS satellites despite years of cost overruns and schedule delays, but would revise its contract with the company to reflect an additional two-year delay.

Major General Roger Teague, director of space programs for the Air Force's acquisition chief, said the Air Force and Pentagon planned aggressive oversight of the ground control program, but could pursue an alternate system in case it failed to improve.

(Reporting by Andrea Shalal; Editing by Lisa Shumaker)