GPS IIF-7 satellite successfully launched atop Atlas V
CAPE CANAVERAL, Fla. — The GPS IIF-7 satellite lifted off from Space Launch Complex 41 (SLC-41), marking the third successful GPS launch of 2014. The satellite was carried into orbit atop a United Launch Alliance (ULA ) Atlas V rocket at the very opening of an 18-minute launching window at 11:23 p.m. EDT (0323 GMT).
The United States Air Force manages the Global Positioning System (GPS), with GPS IIF-7 being the latest upgrade, replacing a seventeen year-old satellite. Originally design for military use, the GPS system was created in 1970 and provides civilians and military personnel with accurate location, time and speed information.
The initial GPS spacecraft, dubbed Block I satellites, were actually prototypes. They showed the benefits of a satellite constellation in medium-Earth orbit for navigational purposes. A prior program, the Transit program, utilized a satellite constellation in low-Earth orbit — a system making global coverage impossible.
The GPS system was originally called the Navigation System using Timing and Ranging (NAVSTAR) and operates with 24 satellites in six separate orbital planes, providing accurate coverage across the globe. Between 1978 and 1985, eleven prototype satellites were launched, with ten successfully reaching orbit. Then between 1989 and 1997, the first operational satellites, Block II and Block IIA, were launched atop Delta II rockets.
In 1994, the constellation was fully operational with the launch of USA-100, also known as GPS II-24 or GPS IIA-15). In 1997, the Block II Replenishment (GPS IIR) suffered an initial launch failure, but recovered quickly and launched satellites to upgrade and replace aging Block II and Block IIA satellites. Thirteen were launched, with an additional eight satellites converted to Block IIRM. In August 2009, the last Block IIRM, known as USA-206), was launched.
The Block IIF series of satellites are designed to upgrade and replace the IIA and IIR series satellites and provide consumers with enhanced capabilities. In 2016, the next generation GPS satellite, GPS IIIA-1, is slated to be launched.
“We are providing our Air Force partner and GPS users with a steady supply of advanced GPS IIFs,” said Craig Cooning, president of Boeing Network & Space Systems. “Our robust launch tempo requires vigilance and attention to detail, and mission success is our top priority. We continue to partner with the Air Force and ULA to effectively execute the launch schedule.”
The current mission, GPS IIF-7 is the seventh in a series of twelve Block IIF satellites. It is the third GPS IIF mission to launch this year, with its predecessors GPS IIF-5 and GPS IIF-6 both launched atop a Delta IV in February and in May. The next satellite slated to go up is the GPS IIF-8 atop an Atlas V this October.
GPS IIF satellites are lighter than previous satellite models, each with a mass of 3,590 pounds (1,630 kilograms). The current launches rely on ULA’s Delta IV and Atlas V rockets. Each GPS IIF satellite is designed to operate for a period of twelve years and GPS IIF-7 will be taking slot 3 in the F plane, replacing USA-132 (GPS IIR-2). USA-132 will then move on to replace the GPS fleet’s second-oldest satellite, USA-83 (GPS IIA-5 or II-16).
“This launch marks the third time this year ULA has successfully launched two missions within a week,” said ULA’s Vice President of Atlas and Delta Programs Jim Sponnick. “The ULA team’s focus on mission success, one launch at a time, allows us to be ready when our customers are ready to launch.”
The Atlas V, Delta II and Delta IV series of rockets are operated by United Launch Alliance (ULA), a collaboration between Lockheed Martin and Boeing. Formed in 2006, ULA provides Evolved Expendable Launch Vehicles (EELV) to the United States Government and also serves as a subcontractor for various commercial missions.
The launch of GPS IIF-7 marks the eighty-sixth for ULA since it first carried the NROL-21 (USA-193) into orbit for the National Reconnaissance Office in 2006. The Atlas V rocket was flown in its most common configuration, the 401, which consists of two stages, a common core booster and a Centaur upper stage. The 401 configuration does not use solid rocket boosters (SRBs) and utilizes a four meter fairing.
First introduced in 2002, this mission marks the forty-seventh launch of an Atlas V and the twenty-third launch in the 401 configuration. GPS IIF-7 was launched from SLC-41, which was built in the 1960s, SLC-41 was first used for the Titan IIIC rocket. Twenty-eight Altas V rockets have lifted off from SLC-41, with the remaining nineteen launching from California’s Vandenberg Air Force Base Space Launch Complex 3.
Powered by a single RD-180 engine, the first stage Common Core Booster (CCB) burned for approximately four minutes and six seconds after igniting at T-2 seconds. Liftoff occurred at T+1 second.
The Atlas booster then performed a series of yaw, pitch and roll maneuvers to ensure it was on the proper trajectory needed for orbital insertion.
Rocket and spacecraft were flying downrange and achieved Mach 1 at approximately 78 seconds after liftoff, with the rocket reaching the region of maximum dynamic pressure (max q) at T+90 seconds. This point in the booster’s ascent is the most dangerous as both the rocket’s speed along with the outside pressure of Earth’s atmosphere place the Atlas V under the greatest amount of stress.
Booster Engine Cutoff (BECO) occurred around the four minute mark, with the first stage jettison following six seconds later.
The second stage, a single-engine Centuar, is powered by an RL10-A-4-2 engine. The engine ignited approximately ten seconds after staging and payload fairing separation occurred sixteen seconds into the second stage burn.
Centaur’s first burn, designed to establish an orbital parking spot, lasted for 12 minutes and 49 seconds. At the end of this first burn, the mission entered a three hour coast phase. After the coast phase, a second circularization burn was initiated, lasting two minutes eight seconds. Approximately four minutes and 45 seconds later, spacecraft separation occurred.
GPS IIF-7 is now in a semi-synchronous orbit at an altitude of 12,700 miles (20,460 kilometers) and a 55 degree inclination. The satellite will orbit the Earth once every twelve hours. This mission is the fifth Atlas V launch this year and the ninth of 15 planned ULA launches for 2014. The Colorado-based firm conducted the GPS IIF-7 flight a mere four days after sending a Delta IV Medium rocket and its payload of three AFSPC-4 satellites to orbit on July 28.
Next up on ULA’s manifest is the August 13 launch of another Atlas V 401 with the WorldView-3 imaging satellite from Vandenberg Air Force Base.
“Congratulations to the U.S. Air Force and all of our mission partners on the successful launch of the Atlas V carrying the GPS IIF-7 satellite,” Sponnick said. “ULA launch vehicles have delivered all of the current generation of GPS satellites, which are providing ever-improving capabilities for users around the world.”
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