Final GPS IIF Launched

Discussion in 'Defense Industry & Policy' started by Pathfinder, Feb 4, 2016.

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  1. Pathfinder

    Pathfinder Lieutenant Colonel

    Dec 17, 2015
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    Final GPS IIF satellite moves to next processing phase toward launch


    When a space vehicle is loaded with 320 pounds of hydrazine, the 45th Space Wing's Airmen-led GPS processing team knows they are in their final stages toward launching a premier capability to the warfighter.

    All of the intricate processing steps from delivery of the satellite to launching into orbit are part of their standard operations at Cape Canaveral Air Force Station, Florida. But, it’s a bitter sweet moment when the team reflects on the extensive years of history they have processing GPS systems for the Air Force.

    "GPS II processing at the Cape started while the Shuttle program was here, when the Air Force was still launching Delta IIs and the Cold War was still going on," said Capt. Trung Nguyen, the field program manager for GPS IIF at the 45th Launch Support Squadron. "The GPS processing program has been a staple at the Cape. There are engineers and technicians here who worked on the first GPS II block satellite. Some have launched over 20 satellites. Some have been with the program since 1989."

    The 45th LCSS processing team received its 12th and final Air Force GPS IIF model on Oct. 8 and unpackaged it in the NAVSTAR Processing Facility, where successful functional tests of the system made sure the satellite operates as expected when it is in orbit next month. The team is currently in the next phase of preparation for launch at the DSCS Processing Facility where major milestones occur, such as fueling.

    "The NPF portion of the campaign lets the customer know that the satellite they paid for works," Nguyen said. "For this final mission, we executed the functional testing like we've always done."


    Before they began tests, the team unpackaged the satellite and watched Air Force contracted partners give it a good shake down to ensure the satellite didn't suffer any inadvertent deviations during its transportation from the factory, delivery and transition into the NPF. A team carrying flashlights inspect every nut and bolt to make sure things are in order.

    "Just because it looks like the final one, it is not exactly the same; each spacecraft is built by hand and thus is a little different from every previous unit," said Scott Chappie, the lead Air Force responsible engineer for GPS IIF-12, who has processed the previous four satellites that launched.

    The Air Force team mounts the satellite to a test stand where an extensive suite of electronic tests are performed to verify the functionality and performance of each unique space vehicle. This process in the spacecraft control room can take up to 10 days with an Air Force mission responsible on station 24/7 to monitor the data received from a variety of cables plugged into the satellite. They don't install batteries until they know everything is operating as expected.

    During this functional testing, proper operation of the subsystems is demonstrated, and the test procedure is designed to detect any malfunctions or failures that may have an impact on the satellite while in orbit.

    "We also take a photo of every inch of the space craft in case we need to refer to it to trouble shoot something while it is in orbit," said Chappie, who has worked in military space for 20 years before coming to the Cape Canaveral AFS last year. "This forces us to look at every piece again. It is an extremely detailed procedure designed by the contractor - what to do, in what order and what tools are needed."

    The closer the team gets to launch day, the higher the value of the satellite. This means there is less room for risk as they move forward. The Air Force team provides independent mission assurance to constantly monitor all launch site processing and assess the risk of those operations on spacecraft mission success.


    In the final processing phase at the NPF, the space vehicle propulsion system is pressurized to the maximum expected operating pressure using gaseous nitrogen, which verifies that the reaction control system is working properly without any leaks in a simulated fueling test before it is transported and unpackaged at the DSCS Processing Facility.

    Although the GPS moved to another location to continue processing, the control room remained at the NPF and is in contact with the satellite through every other phase of processing until the moment the rocket lifts off from Cape Canaveral AFS.

    The DSCS Processing Facility is configured to handle fueling operations safely with minimum personnel in the trench-lined hangar bays. Once fueled up and ready, the satellite can be mated to United Launch Alliance's Ground Transport Vehicle and encapsulated in the payload fairing. During this time, multiple electrical tests occur to ensure that all electrical paths are still operating nominally. Then the satellite will be transported to the Vertical Integration Facility, where it is mated to the top of an Atlas V rocket.

    "We are here to protect the interests of the warfighter in this critical national asset," Chappie said. "We verify the satellites functionality and performance before we commit to launch."

    T-minus two days from launch the integrated team is on console ready for power configuration to launch. Using fiber optic cables they can test their ability to communicate with the satellite. On the day of launch, they are ready to assist with any situation that may come up with close eyes on the telemetry data.

    Following the completion of the processing and launch of the last of the GPS IIF Block spacecraft, the Air Force team looks forward to launching the GPS III spacecraft, which are already being built at a contractor factory.

    Compared to other spacecraft, GPS IIF-12 is a modest size platform weighing in at 3,600 pounds, Chappie said. Although the design is impressive, the engineer said the impact it has is astonishing.

    "That space craft is going to touch the lives of hundreds of millions if not billions of people on a daily basis," he said. "It not only vastly increases our military's position, navigation and timing capabilities all over the world, but so many people and business activities have also come to depend on GPS. This is a stunningly, successful program -- the way the Air Force conceived it and the way they continue to manage and implement the program."

    Members of the mission assurance team, ranging from young military officers to career enlisted troops to seasoned civilians, look forward to the Atlas V's scheduled launch with GPS IIF-12 on board Feb. 5.


    Once the satellite is on orbit, it communicates with the GPS Master Control Station, operated by the 50th Space Wing's 2nd Space Operations Squadron at Schriever Air Force Base, Colorado. This squadron is responsible for monitoring and controlling the GPS as a 24-satellite system, consisting of six orbital planes, with a minimum of four satellites per plane. There are currently 40 vehicles in the GPS constellation.

    GPS satellites serve and protect U.S. warfighters by providing navigational assistance and timing standards for military operations on land, at sea, and in the air.
    Last edited: Feb 4, 2016
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  2. Pathfinder

    Pathfinder Lieutenant Colonel

    Dec 17, 2015
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    Deliver sustained, reliable GPS capabilities to America's warfighters, our allies and civil users. GPS provides positioning, navigation and timing service to civil and military users worldwide.


    In 1996, the GPS IIF contract was awarded to The Boeing Company for the development and production of 33 space vehicles (SVs). In 2000 the United States Air Force modernized the contract, increasing capabilities and reducing the number of SV's delivered to twelve. On 27 May 2010, the first GPS IIF satellite was launched from Cape Canaveral Air Force Station, Fla.


    GPS IIF SV's continue to modernize the GPS constellation while bringing new capabilities to both military and civilian users. GPS IIF SV's will bring into service the dedicated civil signal (L5) as part of the modernization effort that began with GPS IIR-M. GPS IIF also brings improved accuracy, greater security and anti-jam capabilities over previous blocks while maintaining baseline legacy GPS performance.

    · Development and Production Contract
    o Development of modernized GPS IIF is complete
    o Delivering 12 SVs
    o Develop Ground Control System

    · Mission Support
    o Provide on-site vehicle launch processing and launch support at Cape Canaveral AFS
    o Monitor on-orbit GPS IIF satellites from Schriever AFB
    o Support 2 SOPS in day-to-day control and maintenance
    o Provide expertise in resolving anomalies/out-of-family conditions


    · Next Generation of GPS satellites
    o Legacy signals: L1 C/A, L1/2 P(Y)
    o Dedicated civilian signals: L5I, L5Q
    o Multiple civil/military signals: L1M, L2M, L2C
    o Improved anti-jam
    o Improved accuracy


    · Orbit: Six orbit planes at 55 degree inclination
    · Altitude: 10,898 nautical miles
    · Design life: 12 years
    · On-orbit weight: 3,230 lb
    · Size: 98 in wide, 80 in deep, 88 in high
    · Position accuracy: 1.5 meters, with daily updates from the control segment
    · Electrical Power Subsystem
    o Solar array: 3-Panel Improved Triple Junction GaAs Solar Arrays, 1900 watt capacity
    o Battery system: NiH2, rechargeable
    · Attitude Determination and Control
    o Zero momentum, 3-axis stabilized, Earth-oriented, Sun-nadir pointing
    o Attitude reference control: Static Earth sensor, Sun sensor, reaction wheels/magnetic coils
    · Propulsion Subsystem
    o Propellant: Monopropellant N2H4
    o Propellant capacity: 320 lbs
    o Thrusters: Twelve 1.0-lb REAs and four 5.0-lb REAs
    · Navigation Payload
    o Two Rubidium clocks & one Cesium clock, radiation-hardened design, high stability timing
    o RH32 central processor, ADA HOL, integral baseband processor, full message encoding and processing, real-time Kalman filter
    o Improved Crosslink performance with Narrow Band Crystal filter
    · Structure and Thermal
    o Structure: Six aluminum honeycomb panels mounted to a central aluminum core
    o Thermal control: Blankets, thermal coatings, radiators and electrically controlled heaters
    · Tracking, Telemetry and Command
    o S-band, SGLS transponder Security architecture: Encrypted data links, redundant RH32 control processor, centralized command decoding and telemetry communications
    Prime Contractor: The Boeing Company
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