The launch of a secret reconnaissance satellite from Vandenberg AFB has been delayed 24h due to unspecified problems with the Boeing Delta IV launch vehicle's upper stage.

The Delta IV in medium-plus configuration was due to launch NROL-25, a National Reconnaissance Office (NRO) satellite, from Vandenberg AFB, California, on 29 March.

"During close out for launch, the team observed an upper stage engine condition that will require additional time for review."

The launch is rescheduled for 30 March, but forecasts predict a 70% chance of unacceptable high-altitude winds.

United Launch Alliance (ULA), providers of the missile, had no immediate comment on the matter.

NROL-25, a National Reconnaissance Office (NRO) radar satellite, is due to launch four additional payloads in 2012 and at least three more in 2013. The agency, which designs and operates surveillance satellites for the US intelligence community, is in the midst of an "aggressive" launch schedule.

Source: Flight International