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Atlas 5 stacked for Navy satellite launch in July

Posted: June 11, 2013

The most powerful version of the United Launch Alliance Atlas 5 rocket has been assembled at Cape Canaveral to deploy the second satellite in the Navy's new mobile communications system.

File image of solid boosters being attached to Atlas 5. Credit: NASA-KSC
The massive rocket, equipped with five strap-on solid-fuel boosters, will lift the 15,000-pound Mobile User Objective System satellite into orbit July 19 during a morning window of 8:51 to 9:35 a.m. EDT (1251-1335 GMT).

It will be the year's fifth Atlas, the third for the Pentagon and the first using the expansive five-meter-diameter nose cone and solid motors.

This rocket is known as the 551 configuration of the multi-varient Atlas 5 family, which is tailored with different sized nose cones and strap-on solids to match the cargo's mass, size and targeted destination.

ULA provided this cutaway illustration that shows the elements of the rocket.

Previous uses of the high-energy configuration have hurled NASA probes on paths to Pluto in 2006 and Jupiter in 2011 and successfully heaved the first MUOS satellite to space last year.

ULA technicians began stacking this latest rocket at the Vertical Integration Facility with erection of the first stage on May 29. Its RD-180 main engine will burn a highly refined kerosene fuel and liquid oxygen.

Known as the Common Core Booster, the 106.6-foot-long stage was rotated vertical, then maneuvered into the building and stood upright on the mobile platform that rolls to the pad for launch.

The next several days were spent installing the five solid rocket boosters to the attachment fixtures on the first stage. Built by Aerojet, the motors ignite at liftoff to deliver a power boost in thrust.

In the case of MUOS, the solids enable the Atlas to carry a much heavier payload than is otherwise possible.

Once the interstage hardware was set in place, workers on Tuesday hoisted the 41.5-foot-long Centaur upper stage atop the first stage. It will be enclosed within the rocket's large nose cone for the initial minutes of ascent through the atmosphere.

File image of Centaur upper stage being attached to Atlas 5. Credit: NASA-KSC
Centaur's single RL10 engine, fueled by liquid hydrogen and liquid oxygen, will perform three burns to reach the desired geosynchronous transfer orbit for deployment of MUOS 2.

The spacecraft is undergoing processing at its own cleanroom facility for final testing, fueling and encapsulation in the rocket's nose cone.

After the Atlas goes to the pad at the end of this month for a countdown dress rehearsal, it will be brought back to the assembly building to be fitted with the MUOS 2 satellite in early July.

Built by Lockheed Martin, the MUOS 2 spacecraft will continue the orbital construction of the Navy's planned five-satellite fleet to provide cellphone-like communications.

MUOS will offer 10 times greater communications capacity to the mobile warfighter over the Navy's current generation of Ultra High Frequency Follow-On spacecraft to relay narrowband tactical information such as voice calls, data messaging, file transfers and email.

The sophisticated MUOS system was designed around the commercial third-generation cellular telephone architecture to substantially increase the number of users and amount of communications that can be routed to military forces.

"MUOS 2 will add on-orbit military satellite communication that is heavily in demand. Our first space vehicle has performed exceptionally on orbit, providing legacy payload voice calls at full capacity. In fact, we recently demonstrated mobile data and voice transmissions using our advanced payload," said Iris Bombelyn, vice president of Narrowband Communications at Lockheed Martin.

The upcoming launch will be ULA's 72nd since its formation in December 2006.