The last in a long line of communications satellites for the U.S. Navy heads for space Monday night aboard a Lockheed Martin Atlas 3B rocket.

Launch from Cape Canaveral's pad 36B is scheduled for 9:38 p.m. EST (0238 GMT). The evening's launch window extends exactly two hours.

File image of Atlas 3B launching. Photo: Lockheed Martin TV

Riding solely on the power from the Russian-made RD-180 main engine, the 176-foot tall rocket will fly for three minutes on the kerosene/liquid oxygen first stage. After the engine shuts down, the spent stage separates from the Centaur upper stage at T+3 minutes, 7 seconds.

The Centaur's liquid hydrogen/liquid oxygen-fed RL10 engine, built by Pratt & Whitney, will perform a pair of firings, separated by a 10-minute coast period, to inject the 6,705-pound Ultra-High Frequency Follow-On F11 satellite into geosynchronous transfer orbit.

After a 32-and-a-half-minute flight, the satellite cargo will be deployed into an orbit with a high point of 19,387 nautical miles (35,908 km), a low point of 155 nautical miles (287 km) and inclination of 27 degrees to the equator.

An artist's concept of UHF spacecraft. Photo: Boeing

A Boeing 601-model satellite, the UHF F11 will boost itself into geostationary orbit where it will join a network of similar craft providing tactical mobile communications. Users of the system span all branches of the U.S. military as well as the White House, the State Department and the Department of Homeland Security, officials said.

"There are some 20,000 UHF satellite terminals currently in use. Many of these are small and portable enough to be carried deep into military theaters of operation," the Navy says.

The F11 satellite features an ultra-high frequency and extremely-high frequency communications payload.

"The UHF frequency offers the capability of penetrating jungle foliage and inclement weather, as well as urban canyons. U.S. military personnel on the front lines of battle count on UHF communications provided by the UFO spacecraft.

"The EHF subsystem carried on F4 and subsequent satellites provides enhanced antijam telemetry, command, broadcast, and fleet interconnectivity communications, using advanced signal processing techniques."

The mission poster for this launch. Credit: ILS

"Over the life of this highly successful 15-year program, the UFO payloads have evolved to meet the customer's changing needs, and the 11th spacecraft's added capabilities will provide new UHF channels that are critically needed by U.S. forces in active military operations," said Dave Ryan, vice president and general manager of Boeing Satellite Systems. "We take great pride in our role on this program because the UHF mobile service is the backbone of global military communications today, supporting warfighters on land, at sea and in the air."

This is the 11th and final UHF Follow-On satellite to launch. It was built to sustain the constellation until the next-generation Mobile User Objective System becomes available. All 11 UHF Follow-On spacecraft have flown aboard Atlas rockets.

Monday's launch will be the fifth and final Atlas flight in 2003, the fourth to occur from Cape Canaveral and the second using an Atlas 3-series rocket.

See our Mission Status Center page for live play-by-play updates during Monday's countdown and launch. Also, we will post a status report on Saturday morning following the completion of mission managers' Launch Readiness Review that gives final approval to proceed with the countdown.