James Dean

FLORIDA TODAY

11 A.M. UPDATE

The forecast remains excellent for today's planned 1:45 p.m. launch of an Atlas V rocket with a classified National Reconnaissance Office satellite from Cape Canaveral Air Force Station.

An update in advance of fueling continued to show only a 10 percent chance that thick clouds could become a problem during the launch window, whose duration has not been disclosed.

The same is true if the launch should slip to Friday.

Today, the temperature at launch time is expected to be about 73 degrees with light winds, no precipitation and no lightning threat. Some thin clouds may form but are not considered much of a threat, according to the mission's weather officer.

PREVIOUS REPORT

A nearly 200 foot Atlas V rocket this morning is counting down to a 1:45 p.m. blastoff from Cape Canaveral Air Force Station with a classified intelligence gathering satellite.

The weather forecast is excellent, with a 90 percent chance of favorable conditions at Launch Complex 41. The precise launch window for the National Reconnaissance Office mission, and details about the payload, are classified.

Launch teams plan to begin pumping super-cold liquid oxygen and liquid hydrogen into the United Launch Alliance Atlas booster and Centaur upper stage around noon, when you can join us for live countdown coverage.

This is only the second flight of this version of the Atlas V known as "541," indicating a five-meter diameter payload fairing, four solid rocket boosters strapped to the first stage and a single engine for the upper stage. The first mission using the same rocket configuration launched NASA's Curiosity to Mars.

PREVIOUS REPORT

What may be a first-of-its-kind U.S. spy satellite is set to lift off from Cape Canaveral Air Force Station at 1:45 p.m. today atop an Atlas V rocket.

The countdown is set to begin this morning after a more than two-week delay because of damage to an Air Force tracking radar needed to ensure public safety during the flight.

The 19-story United Launch Alliance rocket and its classified National Reconnaissance Office payload returned to their Launch Complex 41 pad on Wednesday morning, repeating a trip they made March 24, the same day an electrical short disabled the tracking radar located on Kennedy Space Center.

Today, Air Force meteorologists expect near-perfect launch weather, with only a 10 percent chance that thick clouds could pose a problem.

Launch windows are not disclosed for NRO missions, but weather forecasts showed it may extend about 40 minutes. The Air Force's posted a hazard area that boaters should avoid is active until 3:15 p.m.

The NRO also does not discuss what it is launching.

A ULA poster for the mission shows an electric blue Pegasus striding over Earth's horizon and the Latin phrase "In Scientia Opportunitas," or "In knowledge, there is opportunity."

Amateur astronomers who make a hobby of tracking satellites, including secret missions, suspect the payload is a signals intelligence, or SIGINT, satellite bound for a geosynchronous orbit more than 22,000 miles above the equator.

Signals intelligence satellites are designed to detect transmissions from broadcast communications systems such as radios, as well as radars and other electronic systems, according to an overview from the Federation of American Scientists.

The analysis is based on the type of rocket being used, the satellite's estimated mass, the flight's eastward trajectory from Cape Canaveral and public knowledge about previous NRO missions.

Those factors provide "strong evidence" for a next-generation signals intelligence spacecraft headed for geosynchronous orbit, Toronto-based Ted Molczan wrote in a recent post on the SeeSat-L electronic mailing list, updating one he titled "NRO payload guesses."

The Atlas V is flying in one of its most powerful configurations, with four solid rocket motors strapped to the first-stage booster, and may be equipped with a special package intended to extend the life of the Centaur upper stage.

That would allow the rocket to place the satellite — estimated to weigh roughly 8,000 pounds — directly into its final orbit instead of the satellite maneuvering itself into position, consistent with past NRO practice for these types of missions.

ULA will air a webcast starting 20 minutes before liftoff, but it will go black about four minutes into flight to help preserve the mission's secrecy.

The launch is proceeding after the Air Force reactivated a backup tracking radar to replace the damaged one, which is still being repaired. The launch is the first of two planned within four days, with SpaceX targeting a Monday afternoon launch of cargo to the International Space Station.

Contact Dean at 321-242-3668 or jdean@floridatoday.com.

Today's launch:

» Rocket: United Launch Alliance Atlas V (541 configuration)

» Mission: Classified National Reconnaissance Office satellite (NROL-67)

» Launch time: 1:45 p.m.

» Launch window: Classified

» Launch complex: 41 at Cape Canaveral Air Force Station

» Weather: 90 percent "go"