CAPE CANAVERAL, Fla. (June 29, 2012)--An unmanned Delta IV-Heavy rocket lifted off Friday morning from Cape Canaveral, Fla., carrying a satellite for the National Reconnaissance Office.

The reconnaissance office isn’t talking about the satellite's purpose.

It was the second rocket launch for the NRO in the last two weeks.

An Atlas V rocket carrying another secret satellite was launched June 20.

The launch was delayed a day because of concerns about weather conditions caused by Tropical Storm Debby earlier in the week.

Because of several technical issues with a sticky valve, the Friday morning launch was delayed three hours, but the rocket went off without a hitch once it was cleared for flight.

The Delta IV-Heavy is the largest of the Delta rockets.