Delta IV launch to continue modernizing GPS fleet

CAPE CANAVERAL — After lofting four Global Positioning System satellites into orbit last year, the Air Force and United Launch Alliance will pick up where they left off this week.

A ULA Delta IV rocket is targeting a 2:36 p.m. ET Wednesday liftoff from Launch Complex 37 at Cape Canaveral Air Force Station, at the opening of an 18-minute window.

On top of the 206-foot rocket is the ninth in a series of 12 Boeing-built GPS satellites known as IIF, or 2F, that are modernizing a constellation with more than 30 active spacecraft.

The satellite labeled GPS IIF-9 is the first of three GPS launches planned this year.

The launch would be the third in 25 days from Cape Canaveral.

Until recently it was expected to be the fourth. SpaceX, however, postponed its planned launch of a communications satellite Saturday.

Company officials reported finding a problem with components used to pressurize propellant tanks on Falcon 9 rockets. The problem originated in a factory, not on the rocket being readied for launch .

The mission for Thales Alenia Space is now planned after SpaceX's next launch of cargo to the International Space Station, which is targeted for no earlier than April 10.