Thursday, October 22, 2015

ULA Prepares for GPS IIF-11 Satellite Launch

Artist's impression of a Block IIF GPS satellite in orbit. Image Credit: USAF

United Launch Alliance (ULA) gears up for the upcoming launch of the newest navigation satellite, designated GPS IIF-11, for the U.S. Air Force. The preparations of the Atlas V booster that will loft the satellite into space, are in full swing before the liftoff scheduled for Oct. 31 from the Space Launch Complex-41 at Cape Canaveral Air Force Station in Florida.

“We are currently proceeding the launch vehicle for an Oct. 30 launch. We still have many milestones to reach before launch, including payload mate, reviews such as the Launch Readiness Review, and roll to pad,” Lyn Chassagne, ULA spokesperson told SpaceFlight Insider.

Atlas V, in the most commonly used “401” configuration, will start its mission during a 19-minute launch window opening at 12:17 p.m. EDT. After igniting its Russian-made RD-180 engine, the booster will soar into space until cutoff and second stage separation about four minutes into the flight. Completing its three-burn trip to space lasting approximately three hours and 23 minutes, the Centaur second stage will deploy the satellite into a designated orbit.

GPS IIF-11 is one of the next-generation GPS satellites, incorporating various improvements to provide greater accuracy, increased signals, and enhanced performance for users. The spacecraft will be put 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 satellites, which were launched between 1990 and 1997. The first Block-IIF satellite was originally scheduled to launch in 2006, but 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 GPS IIF series have a design life of 12 years. With the proper equipment, users can receive these signals to calculate time, location, and velocity. The signals are so accurate that time can be measured to within a millionth of a second, velocity within a fraction of a mile per hour, and location to within feet. Receivers have been developed for use in aircraft, ships, land vehicles, and to hand carry.

The Navstar Global Positioning System (GPS) is a constellation of satellites that provides navigation data to military and civilian users worldwide. The system is operated and controlled by Air Force’s 50th Space Wing, located at Schriever Air Force Base, Colorado.

The Atlas V booster employed for the Oct. 30 launch is 12.5 ft. in diameter and 106.5 ft. in length. The rocket’s propulsion is provided by the RD-180 engine system - a single engine with two thrust chambers. The RD-180 burns RP-1 (Rocket Propellant-1 or highly purified kerosene) and liquid oxygen, and delivers 860,200 lbs. of thrust at sea level.

The Centaur second stage is 10 ft. in diameter and 41.5 ft. in length. It uses a single RL10C engine producing 22,900 lbf of thrust. The Atlas V booster is controlled by the Centaur avionics system, which provides guidance, flight control, and vehicle sequencing functions during the booster and Centaur phases of flight.

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.

Next GPS satellite, designated GPS IIF-12, is planned to be launched on Feb. 3, 2016, also atop Atlas V 401 launch vehicle.

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