ULA prepares for third Oct. 2015 Atlas launch with GPS IIF-11
United Launch Alliance (ULA) is gearing up for the third launch this month of an Atlas V 401 rocket. The mission will see the 11th Block IIF navigation satellite for the United States Air Force’s Global Positioning System. Preparations to send the Atlas V booster that will loft the satellite to orbit are in full swing.
At present, the launch is scheduled for Oct. 30 from Space Launch Complex 41 (SLC-41) at Cape Canaveral Air Force Station in Florida. The launch window will open at 12:17 p.m. EDT (16:17 GMT) – and extends for 19 minutes.
“We are currently processing the launch vehicle for an Oct. 30 launch. We still have many milestones to reach before launch, reviews such as the Launch Readiness Review, and roll to [the] pad,” Lyn Chassagne, ULA spokesperson told SpaceFlight Insider.
The Atlas V, in its most commonly used “401” configuration, will have about a 90 percent chance of favorable weather conditions for launch.
After igniting its Russian-made NPO Energomash RD-180 rocket engine, the booster will soar into space until cutoff and second stage separation have occurred – about four minutes into the flight. The Centaur second stage, after completing its three-burn trip to space, lasting approximately three hours and 23 minutes, will then deploy the satellite into its designated orbit.
GPS IIF-11 is the next-to-last planned spacecraft of the next-generation GPS satellites. It will incorporate various improvements to provide greater accuracy, increased signals, and enhanced performance for users. The spacecraft will be placed into a semi-synchronous circular orbit.
The GPS IIF satellites deliver second civil signal (L2C) for dual-frequency equipment, and a new third civil signal (L5) to support commercial aviation and safety-of-life applications. Capable of providing jam-resistant military signals in hostile environments, the GPS IIF satellites are designed to replace the GPS Block IIA spacecraft, which were launched between 1990 and 1997. The first Block-IIF satellite was originally scheduled to launch in 2006, but it was delayed due to program setbacks and technical problems until it was finally launched in 2010.
“The ULA team is focused on attaining perfect product delivery for the GPS IIF-11 mission, which includes a relentless focus on mission success (the perfect product) and also excellence and continuous improvement in meeting all of the needs of our customers (the perfect delivery),” Jim Sponnick, ULA vice president of Atlas and Delta Programs said in a statement.
The planned service life of the GPS Block IIF series of satellites is 12 years. Users equipped with suitable receivers can utilize the signals from the satellites to determine position, time, and velocity. The accuracy of the signals is precise enough that time can be measured to within a millionth of a second, location can be established to within a meter, and velocity to within a meter per second. Various types of GPS receivers have been manufactured and integrated into aircraft, ships, land vehicles, and hand-held devices.
The Global Positioning System (GPS) is a space-based navigation system operated and controlled by the U.S. Air Force’s 50th Space Wing, located at Schriever Air Force Base, Colorado, under the name Navstar – Navigation System Using Timing and Ranging. The system is a constellation of satellites providing freely available navigation data to military and civilian users around the world.
The Atlas V 401 rocket employed for the Oct. 30 launch has a Common Core Booster (CCB) as its first stage; it is 12.5 ft. (3.81 m) in diameter and 106.5 ft. (32.46 m) in length. An RD-180 engine – a single engine with two thrust chambers – provides the propulsion for the first stage, delivering 860,200 lbf (3826.36 kN) of thrust at sea level. The RD-180 uses RP-1 (Rocket Propellant 1 – a highly refined kerosene) for fuel, and liquid oxygen as the oxidizer.
The Atlas V 401 second stage is a Centaur with a single (denoted by “1” in 401) RL10C engine generating 22,900 lbf (101.86 kN) of thrust. The Centaur second stage is 10 ft. (3 m) in diameter and 41.5 ft. (12.65 m) in length. The inertial navigation unit (INU) is located in the Centaur’s avionics system and provides guidance, flight control, and vehicle sequencing functions for both the booster and Centaur phases of the ascent.
The upcoming mission will be the 59th Atlas V launch and the 29th liftoff of this booster in “401” configuration. It will be also the third GPS mission ULA launches in 2015.
The next GPS satellite, designated GPS IIF-12, is planned to be launched on Feb. 3, 2016, also atop an Atlas V 401 launch vehicle.
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