The launch of a new GPS satellite was postponed for one day Tuesday because of an unspecified problem with the SpaceX Falcon 9 rocket that will put the satellite in orbit.
Liftoff was rescheduled for Wednesday at Cape Canaveral, Florida.
SpaceX said Tuesday's launch was scratched because of sensor readings on the rocket's first stage. Neither the company nor the U.S. Air Force provided details.
This will be the first GPS satellite launch for SpaceX.
The rocket will carry a GPS III satellite, the first of new generation of GPS orbiters designed to be more accurate, secure and versatile than predecessors. Lockheed Martin is building the new satellites outside Denver.
GPS III satellites will have a stronger military signal that's harder to jam. They also will provide a new civilian signal compatible with other countries' navigation satellites. That means civilian receivers capable of receiving the new signal will have more satellites to lock in on, improving accuracy.
But some of those features will not be fully available until 2022 or later because of problems in a companion program to develop a new ground control system for the satellites, government auditors said.
GPS is best known for its widespread civilian applications, from navigation to time-stamping bank transactions. The Air Force estimates that 4 billion people worldwide use the system.
GPS was developed by the U.S. military, which still designs, launches and operates the system. The Air Force controls a constellation of 31 GPS satellites from a high-security complex at Schriever Air Force Base outside Colorado Springs.