Artist’s concept of a GPS III satellite in orbit, courtesy of Lockheed Martin.
Air Force Orders GPS III Satellites 05 and 06 from Lockheed Martin
A December 12 contract modification provided Air Force funding to Lockheed Martin to complete the fifth and sixth GPS III space vehicles (SV 05-06). Lockheeed originally received funding to procure long-lead parts for satellites five through eight (SV 05-08) in February 2013.
The $200,700,415 cost-plus-incentive-fee modification (P00276) on an existing contract (FA8807-08-C-0010) for GPS III space vehicles 05 and 06 means that work will be performed at Littleton. Colorado and Clifton, New Jersey, and is expected to be completed by Dec. 14, 2017 for space vehicle 05 and June 14, 2018 for space vehicle 06. The Air Force Space and Missile Systems Center Contracting Directorate, Los Angeles Air Force Base, California, is the contracting activity.
Galileo Achieves First Airborne Tracking
The European Space Agency’s Galileo satellites have achieved their first aerial fix of longitude, latitude, and altitude, enabling the inflight tracking of a test aircraft.
ESA’s four Galileo satellites in orbit have supported months of positioning tests on the ground across Europe since the first fix in March. Now the first aerial tracking using Galileo has taken place, determining the position of an aircraft using only its own independent navigation system.
The milestone took place on a Fairchild Metro-II above Gilze-Rijen Air Force Base in the Netherlands on November 12. It was part of an aerial campaign overseen jointly by ESA and the National Aerospace Laboratory of the Netherlands, NLR, with the support of Eurocontrol, the European Organisation for the Safety of Air Navigation, and LVNL, the Dutch Air Navigation Service Provider.
A pair of Galileo test receivers was used aboard the aircraft, the same kind employed for Galileo testing in the field and in labs across Europe. They were connected to an aeronautical-certified triple-frequency Galileo-ready antenna mounted on top of the aircraft.
Tests were scheduled during periods when all four Galileo satellites were visible in the sky. The receivers fixed the plane’s position, as well as determining key variables such as the position, velocity, and timing accuracy; time to first fix; signal-to-noise ratio; range error; and range–rate error.
Testing covered both Galileo’s publicly available Open Service and the more precise, encrypted Public Regulated Service, whose availability is limited to governmental entities.
Flights covered all major phases: take off, straight and level flight with constant speed, orbit, straight and level flight with alternating speeds, turns with a maximum bank angle of 60 degrees, pull-ups and push-overs, approaches and landings.
The flights also allowed positioning to be carried out during a wide variety of conditions, such as vibrations, speeds up to 456 km/h, accelerations up to 2 ghorizontal and 0.5–1.5 gvertical, and rapid jerks. The maximum altitude reached during the flights was 3,000 meters.
GPS III Prototype Proves Constellation Compatibility
The Lockheed Martin prototype of the next-generation GPS satellite, the GPS III, has proven that it is backwardly compatible with the existing GPS satellite constellation in orbit.
During tests concluded on October 17, Lockheed Martin’s GPS III testbed successfully communicated via cross-links to Air Force simulators of the current GPS constellation in orbit. The current GPS constellation includes GPS IIR, GPS IIR-M, and GPS IIF satellites.
Testing also demonstrated the ability of an Air Force receiver to track navigation signals transmitted by the GPS III Nonflight Satellite Testbed (GNST). The GNST is a full-sized, functional satellite prototype at Cape Canaveral Air Force Station.
“These tests represent the first time when the GNST’s flight-like hardware has communicated with flight-like hardware from the rest of the GPS constellation and with a navigation receiver,” explained Paul Miller, Lockheed Martin’s director for GPS III Development. “This provides early confidence in the GPS III’s design to bring advanced capabilities to our nation, while also being backward-compatible.”
The first flight-ready GPS III satellite is expected to arrive at Cape Canaveral in 2014, for launch by the Air Force in 2015.
GPS III satellites will be the first GPS space vehicles with a new L1C civil signal designed to make it interoperable with other international global navigation satellite systems.
The GNST has helped to identify and resolve development issues prior to integration and test of the first GPS III flight space vehicle (SV 01). It has gone through the development, test, and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance, and lowering overall program costs.
The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center.
Lockheed Martin is the GPS III prime contractor, with teammates including ITT Exelis, General Dynamics, Infinity Systems Engineering, Honeywell, ATK, and other subcontractors.
Good News for Users and Manufacturers
The U.S. Air Force is directing transmission of continuous CNAV message-populated L2C and L5 signals starting in April 2014. The move is designed to help development of user equipment compatible with the civil signals. Full text of the CNAV memo appears below.
Galileo FOC Satellites Endure Simulated Space Tests
The European Space Agency’s newest Galileo satellite has emerged from five weeks of simulated space conditions. On November 29, a hatch slid open to end its thermal-vacuum test, a milestone on the way to orbit.
The satellite was placed in the 4.5-meter-diameter Phenix chamber in ESA’s ESTEC Test Centre in Noordwijk, the Netherlands, in late October. Once inside, the air was pumped out to create a space-quality vacuum. Temperature extremes were also reproduced, with the six copper walls of the thermal tent cooled by liquid nitrogen down to –180°C.
A second Galileo vehicle has been undergoing the same rigors at the site, along with a vibration and shock test to reproduce separation from the launcher. Thermal-vacuum testing on the second model will begin in early 2014. The two satellites will be launched on a Soyuz rocket from Europe’s Spaceport in French Guiana in mid-2014.
The next satellite is expected to arrive at ESTEC in March, with further satellites following every seven weeks or so. A total of 22 FOC satellites are being built by OHB in Germany, with navigation payloads being delivered from Surrey Satellite Technology Ltd. in the UK.
The first Galileo Full Operational Capability satellite emerges from the Phenix test chamber after five weeks of thermal–vacuum testing.
Raytheon Intelligence and Information Systems has been awarded a change order for work that costs up to $8.5 million on its existing contract to ensure that the new military signal, M-code, works with the GPS Operational Control System, according to an announcement from the Pentagon as reported by Space News.
Raytheon is building the ground station (OCX) for a new generation of satellites that will bring more safety and precision to GPS. The contract modification is to assure implementation of M-code capabilities across OCX Block 1 and 2. M-code is the new highly secure, anti-jam signal designed for the GPS III constellation. The current GPS ground control system lacks M-code capability.
The OCX is designed to work with the advanced GPS III positioning, navigation and timing satellites, slated to start launching in 2015, and also will be backwardly compatible with existing GPS satellites.
Raytheon won the $886.4 million prime contract to develop the OCX in February 2010. Work will be performed at Raytheon’s facility in Aurora, Colorado, and is expected to be completed by August 31, 2016.
The Air Force Space and Missile Systems Contracting Directorate, Los Angeles Air Force Base, California, is the contracting agency.
Details on the contract change order: Raytheon Intelligence and Information Systems, Aurora, Colo., has been awarded an unpriced change order (P00112) with a not-to-exceed of $8,595,748 on an existing contract (FA8807-10-C-0001) for M-Code Implementation on the Operational Control System. The contract modification is to assure implementation of M-Code Capabilities across OCX Block 1 and 2. Work will be performed at Aurora, Colo., and is expected to be completed by Aug. 31, 2016. Fiscal 2014 research and development funds will be obligated at definitization. The Air Force Space and Missile Systems Contracting Directorate, Los Angeles Air Force Base, Calif., is the contracting activity.
During the August test, the GPS III Non-flight Satellite Testbed (GNST) proved that it could connect with and receive commands from the Launch and Check Out System.
Lockheed Martin Corporation has been awarded $200 million to produce GPS III satellites SV05 and SV06 by the U.S. Air Force. Lockheed Marin originally received funding to procure long-lead parts for satellites five through eight (SV05-08) in February.
The award is a $200,700,415 cost-plus-incentive-fee modification (P00276) on an existing contract (FA8807-08-C-0010). Work will be performed at Littleton, Colorado, and Clifton, New Jersey.
Work is expected to be completed by December 14, 2017, for space vehicle 05, and June 14, 2018, for space vehicle 06.
Fiscal 2013 missile procurement funds in the amount of $200,700,415 are being obligated at time of award. The Air Force Space and Missile Systems Center Contracting Directorate, Los Angeles Air Force Base, California, is the contracting activity.
By Colonel William T. “Bill” Cooley, U.S. Air Force, Director, Global Positioning System
The cliché “time flies when you’re having fun” accurately describes how quickly the past six months have passed for me. In a program as challenging, rewarding, and mission-critical as GPS, it is full-speed ahead all the time. As the GPS director, I am acutely aware of the importance of time — particularly high-accuracy time. Since declaring initial operational capability in December 1993, the extremely precise time service delivered by GPS has enabled numerous technological advances around the globe. While extremely proud of the accomplishments over the past 20 years, I look forward to the next 20 years, as GPS brings on new signals and continues to deliver on its promise of a worldwide free positioning, navigation, and timing (PNT) service. This article elaborates on the GPS Directorate commitment, along with the 2nd Space Operations Squadron (2 SOPS), to provide unparalleled space-based PNT accuracy, availability, and reliability to the civil community.
The first commitment, arguably the most important for users everywhere, is the commitment to high accuracy for space-based PNT. After speaking at the ION GNSS+ conference and meeting many of you in Nashville this September, I realized that some users remain worried that selective availability (SA) — the intentional degradation of public GPS signals — could return and negatively impact GPS signal quality. SA was discontinued in May 2000 to provide an increased level of accuracy to all users around the globe. Since that time, the U.S. government has adopted a policy to no longer use SA and, furthermore, in 2007 removed that function from the upcoming GPS III satellites. The GPS Performance Standard for the Standard Positioning Service reflects our commitment to accuracy by ensuring the signal-in-space (SIS) user range error remains low: better than 4-meter accuracy. Figure 1 shows the record-setting SIS accuracy and how GPS meets and far exceeds this guarantee: consistently better than 1-meter accuracy! The 2 SOPS operators who command and control the GPS satellites do a masterful job ensuring global PNT accuracy is as good as it can be.
Figure 1. Standard Positioning Service signal-in-space performance.
The quality of these services, however, does not permit the GPS enterprise to rest in the comfort of past success. We are dedicated to updating and modernizing the program.
The second commitment I’d like to highlight includes the GPS pledge for constellation sustainment and service availability. This is a guarantee to maintain a constellation of at least 24 satellites continuously broadcasting the GPS signals, providing a low dilution-of-precision value around the globe. Current efforts to meet this commitment range from replenishing unhealthy satellites to deploying improved, modernized satellites and corresponding ground support. For example, the GPS IIF satellites are rapidly becoming an integral part of the GPS constellation. With four IIFs on-orbit and a fifth soon to be launched, the constellation continues to exceed the 24-satellite requirement.
The third commitment — to modernize the GPS constellation with new signals — is best illustrated by, but not limited to, the modernized GPS IIF and GPS III satellites that are beginning to populate the constellation. In addition to four GPS IIF satellites now on orbit, the remaining GPS IIFs are either ready for launch or in final testing.
Down the road, GPS III satellites are completing development and progressing through early production. They will add the fourth civil signal, L1C, for civil users worldwide. Earlier this year, the GPS III program shipped the GPS non-flight satellite testbed (an engineering development unit) to Cape Canaveral; it successfully communicated with the next-generation operational control system (OCX), essentially as it would for launch and on-orbit check and control of functional GPS III satellites. The operational portion of the GPS ground segment, OCX Block 1 is on track to begin operations in 2016, modernizing the control segment by providing mission operation control of all legacy signals, as well as L2C and L5; later, OCX Block 2 will support L1C.
GPS civil users will soon be able to take advantage of the L2C and L5 signals that broadcast the modernized civil navigation message (CNAV); this will effectively eliminate the need to access the L1 and L2 P(Y) signals through codeless or semi-codeless techniques. These codes permit civil users to access dual-frequency solutions for precision applications (using dual-frequency enables ionospheric corrections for highly accurate PNT solutions). Compared to the L1 C/A signal, L2C features faster signal acquisition, enhanced reliability, and greater operating range. L5 will provide for increased safety-of-life applications with broadcast power even greater than L1 C/A and L2C combined, increased bandwidth, and advanced signal design. Regardless of the early availability of L2C and L5, semi-codeless users will be able to access P(Y) code — unhindered and unaffected by fully tested and vetted flex-power operations — until the end of 2020. Overall, these modernization efforts emphasize a commitment that availability surpasses simply putting satellites on orbit.
Finally, the GPS Directorate is committed to providing a high-quality service that is highly reliable. We achieve this by fielding first-rate satellites, conducting extensive test campaigns before deploying new capabilities or launching new satellites, and working closely with the operators at 2 SOPS, ensuring our constellation delivers top-quality PNT signals. An example of diligent testing is the recent live-sky test of the CNAV message on all GPS IIR-M and IIF satellites this past June. An example of a modernization feature that will enhance reliability is the capability of GPS III satellites to autonomously monitor the atomic clocks that drive the signal, thereby protecting users from clock instability and resulting signal errors.
Our demonstrated commitment to deliver accurate, available, and reliable space-based PNT allows innovators around the world to invest confidently in the creation of a multitude of GPS and GPS-enabled technologies that shape the way we live. GPS and its related technologies go far beyond letting you find the deli down the street and “checking in” to let your friends know what you’re up to on Facebook; it tracks financial transactions, enables precision farming, and allows accurate real-time updates on natural disasters such as earthquakes and tsunamis with capabilities that organizations like the NASA Jet Propulsion Laboratory and the International GNSS Service provide using GPS. The GPS Directorate is keenly aware that innovators invest their time and talent because they know they can depend on GPS availability. Our commitments are not just “feel-good” words; they are our mission and promise to the world.
I am very proud of the men and women in the GPS Directorate and thrilled to be part of this great team as the new GPS program director. The commitments listed here provide a glimpse into the services provided by the GPS enterprise. I am excited about bringing modernized signals to the world, but more excited to learn how the PNT community will use these signals to develop new innovative and useful applications. The world is easier to navigate because of GPS and GPS-enabled technologies, all of which rely on services the GPS enterprise provides: accuracy, availability, and reliability. We are committed to delivering these services as we modernize and improve the enterprise to continue GPS as the gold standard of space-based PNT.
Colonel William L. cooley is Director, Global Positioning Systems (GPS) Directorate, Space and Missile Systems Center, Air Force Space Command, Los Angeles Air Force Base, California.
The GNST arrives at Cape Canaveral Air Force Station, Florida, in July.
The Lockheed Martin prototype of the next-generation GPS satellite, the GPS III, has proven that it is backwardly compatible with the existing GPS satellite constellation in orbit.
During tests that concluded on October 17, Lockheed Martin’s GPS III testbed successfully communicated via cross-links to Air Force simulators of the current GPS constellation in orbit. The current GPS constellation includes GPS IIR, GPS IIR-M, and GPS IIF satellites.
Testing also demonstrated the ability of an Air Force receiver to track navigation signals transmitted by the GPS III Nonflight Satellite Testbed (GNST). The GNST is a full-sized, functional satellite prototype at Cape Canaveral Air Force Station.
“These tests represent the first time when the GNST’s flight-like hardware has communicated with flight-like hardware from the rest of the GPS constellation and with a navigation receiver,” explained Paul Miller, Lockheed Martin’s director for GPS III Development. “This provides early confidence in the GPS III’s design to bring advanced capabilities to our nation, while also being backward-compatible.”
Lockheed Martin is under contract to produce the first four GPS III satellites (SV 01-04), and has received advanced procurement funding for long-lead components for the fifth, sixth, seventh, and eighth satellites (SV 05-08). The first flight-ready GPS III satellite is expected to arrive at Cape Canaveral in 2014, for launch by the Air Force in 2015.
Testing took place with the GNST — a test version of the GPS III — at Cape Canaveral.
GPS III, a critically important program for the Air Force, will replace aging GPS satellites in orbit while improving capability to meet the evolving demands of military, commercial and civilian users. GPS III satellites will deliver three times better accuracy; provide up to eight times more powerful anti-jamming capabilities; and include enhancements to extend spacecraft life 25 percent further than the prior GPS block. It will be the first GPS satellite with a new L1C civil signal designed to make it interoperable with other international global navigation satellite systems.
An innovative investment by the Air Force under the original GPS III development contract, the GNST has helped to identify and resolve development issues prior to integration and test of the first GPS III flight space vehicle (SV 01). Following the Air Force’s rigorous “back-to-basics” acquisition approach, the GNST has gone through the development, test, and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance, and lowering overall program costs.
The GNST arrived at the Cape on July 19 to test facilities and pre-launch processes in advance of the arrival of the first flight satellite. On August 30, the GNST successfully established remote connectivity and communicated with the GPS Next Generation Operational Control System (OCX), being developed by Raytheon.
Before shipment to the Cape, the GNST completed a series of high-fidelity activities to pathfind the integration, test and environmental checkout that all production GPS III satellites undergo at Lockheed Martin’s GPS III Processing Facility (GPF) in Denver, Colo.
The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Lockheed Martin is the GPS III prime contractor, with teammates including ITT Exelis, General Dynamics, Infinity Systems Engineering, Honeywell, ATK, and other subcontractors. Air Force Space Command’s 2nd Space Operations Squadron, based at Schriever Air Force Base, Colo., manages and operates the GPS constellation for both civil and military users.
Raytheon Company reached several milestones recently in its development of the GPS Next -Generation Operational Control System (GPS OCX). Lockheed Martin’s GPS III Non-flight Satellite Testbed (GNST) — a full-sized, functional satellite prototype currently residing at Cape Canaveral Air Force Station — successfully established remote connectivity and communicated with OCX during pre-flight tests.
GNST proved that it could connect with and receive commands from Raytheon’s Launch and Check Out System (LCS), a part of OCX that supports the satellite and mitigates risks prior to launch. The GNST received commands from Lockheed Martin’s Launch and Checkout Capability (LCC) node in Newtown, Pennsylvania via the OCX servers at Raytheon’s facility in Aurora, Colorado; the system then returned satellite telemetry to the control station. The tests mirror launch and early orbit testing planned for all flight vehicles.
“While we have connected OCX with ground-based simulators before, these tests were the first time that OCX and a GPS III satellite have actually communicated,” said Keoki Jackson, vice president for Lockheed Martin’s Navigation Systems mission area.
Ahead of Schedule. Raytheon received Interim Authorization to Test (IATT) security certification from the U.S. Air Force for OCX LCS four months ahead of schedule. The company received a one-year certification with no liens, meaning the government does not require any changes.
“Typically, IATT certification is given for six-month increments,” said Matthew Gilligan, Raytheon’s GPS OCX program manager and a vice president in Raytheon’s Intelligence, Information, and Services business. “The LCS one-year accreditation speaks to the quality of the information assurance design and threat protection.” The IATT not only includes the LCS, but also Lockheed Martin’s GPS III satellite support systems, Exercise and Rehearsal Training Tool, and Upload Generation Tool.
OCX is being developed in two blocks. There are seven iterations in Block 1 and one in Block 2. LCS is the fifth Iteration of Block 1; it successfully completed Critical Design Review in June 2013.
Early Orbit Exercises. Lockheed Martin and Raytheon also completed the third of five planned launch and early orbit exercises to demonstrate launch readiness of GPS III and OCX.
Exercise 3 demonstrated space-ground communications; first acquisition and transfer orbit sequences; orbit-raising maneuver planning and execution; and basic anomaly detection and resolution capabilities. In addition, the industry and Air Force GPS Directorate teams jointly executed mission planning activities, such as orbit determination and the generation of upload command files.
Two additional readiness exercises and six 24/7 launch rehearsals are planned before launch of the first GPS III satellite. The first flight GPS III space vehicle (SV-01) is expected to be available for launch in 2014, and launched by the U.S. Air Force in 2015.
Exelis Encryptors. Exelis delivered the first three of a planned 14 ground-based encryptors to Raytheon Company for OCX. Designed to automatically code and decode GPS signals, encryptors facilitate the exchange of user information by securely transmitting navigation payload data between the OCX ground station and the orbiting constellation of satellites.
Delivery followed successful thermal, electromagnetic interference and security verification testing. Exelis provides critical elements of software in the navigation processing subsystem that will enable controllers to better understand the exact position of GPS satellites. This helps ensure accurate navigation information is securely broadcast to users. In addition to encryptors, Exelis is building high-precision receivers for use in GPS ground monitoring stations and satellite signal simulators for testing purposes.
Exelis is also on contract with Lockheed Martin to provide the payloads for the GPS III satellites.
Europe Tests Galileo Public Regulated Service
European Union member states began their independent testing of the Public Regulated Service (PRS) broadcast by the four Galileo navigation satellites in orbit. Transmitted on two frequency bands with enhanced protection, PRS offers a highly accurate positioning and timing service, with access strictly restricted to authorized users, such as government defense, security, and emergency services.
PRS access was initially considered for Galileo’s Full Operational Capability phase, but it has been enabled in 2013 in response to the strong interest of member states in this service. To allow early access to PRS during the current phase, the European Commission and ESA began the joint project PRS Participants To IOV (PPTI) in July 2012.
ESA ensured the availability of several tools developed under ESA contracts, including test receivers and other qualification equipment. ESA’s PRS Laboratory, based at the Agency’s ESTEC technical centre in Noordwijk, the Netherlands, provided training, demonstrations and sample data.
“Belgium, France, Italy, and the UK have now performed independent PRS acquisition and positioning tests. In parallel, ESA, through collaboration with Dutch and Italian authorities, is conducting PRS fixed and mobile validation in several locations in the Netherlands and Italy,” said Miguel Manteiga Bautista, head of ESA’s Galileo Security Office.
The PRS tests have demonstrated a current autonomous positioning accuracy of less than 10 meters when in the correct geometrical configuration. This is an impressive result considering the small number of Galileo satellites in orbit and the limited ground infrastructure so far deployed.
Italy has developed its own PRS receiver, and tests have confirmed the feasibility of independent PRS receiver development and verification based on specifications provided by ESA.
“The PPTI project is still ongoing to test more advanced functionalities this coming autumn and to run the first aeronautical PRS tests in collaboration with the Dutch authorities. Other member states have also expressed their willingness to join the IOV PRS experimentation campaigns soon,“ concluded Miguel Manteiga.
The project is a first step to ensure use of the PRS as soon as it becomes operational. It will be complemented by PRS pilot projects, focused on PRS applications, which are currently under definition in a common effort between European agencies.
The United States has submitted a request to be able to use Galileo’s PRS. Other non-EU countries have also expressed a desire to be associated with the program.
System Briefs
Way to Go GAO, Part II. The Air Force should come up with better cost estimates and options for new GPS satellites, according to a September 9 report from the U.S. Government Accountability Office (GAO). The GAO was responding to an Air Force study on lower-cost space solutions for GPS.
“More information on key cost drivers and cost estimates, and broader input from stakeholders would help guide future investment decisions,” the GAO concluded. Specifically, the key cost drivers include dual-launch capability, navigation satellites (smaller GPS-type satellites yet to be developed), and a nuclear detection capability.”
New Birds by Fall. Galileo satellite-builder OHB AG said it should know by late September whether tests of the first Full Operational Capability (FOC) Galileo satellites are proceeding well enough to permit their delivery later this year. The first FOC satellite began testing at ESA’s European Space Research and Technology Centre in May, and the second arrived August 9.
The OHB satellites either “bear a strong resemblance” or “are identical” to the four in-orbit validation spacecraft now in medium-Earth orbit, depending on the source. However, the on-board power of the OHB spacecraft exceeds that of the validation satellites built by a different manufacturer. According to one source, Galileo managers made the modification in part to enable Galileo’s encrypted Public Regulated Service signal to overcome a signal frequency overlap issue with China’s BeiDou constellation.
Raytheon Company reached several milestones recently in its development of the GPS Next -Generation Operational Control System (GPS OCX). Lockheed Martin’s GPS III Non-flight Satellite Testbed (GNST) — a full-sized, functional satellite prototype currently residing at Cape Canaveral Air Force Station — successfully established remote connectivity and communicated with OCX during pre-flight tests.
GNST proved that it could connect with and receive commands from Raytheon’s Launch and Check Out System (LCS), a part of OCX that supports the satellite and mitigates risks prior to launch. The GNST received commands from Lockheed Martin’s Launch and Checkout Capability (LCC) node in Newtown, Pennsylvania via the OCX servers at Raytheon’s facility in Aurora, Colorado; the system then returned satellite telemetry to the control station. The tests mirror launch and early orbit testing planned for all flight vehicles.
“While we have connected OCX with ground-based simulators before, these tests were the first time that OCX and a GPS III satellite have actually communicated,” said Keoki Jackson, vice president for Lockheed Martin’s Navigation Systems mission area.
Ahead of Schedule. Raytheon received Interim Authorization to Test (IATT) security certification from the U.S. Air Force for OCX LCS four months ahead of schedule. The company received a one-year certification with no liens, meaning the government does not require any changes.
“Typically, IATT certification is given for six-month increments,” said Matthew Gilligan, Raytheon’s GPS OCX program manager and a vice president in Raytheon’s Intelligence, Information, and Services business. “The LCS one-year accreditation speaks to the quality of the information assurance design and threat protection.” The IATT not only includes the LCS, but also Lockheed Martin’s GPS III satellite support systems, Exercise and Rehearsal Training Tool, and Upload Generation Tool.
OCX is being developed in two blocks. There are seven iterations in Block 1 and one in Block 2. LCS is the fifth Iteration of Block 1; it successfully completed Critical Design Review in June 2013.
Early Orbit Exercises. Lockheed Martin and Raytheon also completed the third of five planned launch and early orbit exercises to demonstrate launch readiness of GPS III and OCX.
Exercise 3 demonstrated space-ground communications; first acquisition and transfer orbit sequences; orbit-raising maneuver planning and execution; and basic anomaly detection and resolution capabilities. In addition, the industry and Air Force GPS Directorate teams jointly executed mission planning activities, such as orbit determination and the generation of upload command files.
Two additional readiness exercises and six 24/7 launch rehearsals are planned before launch of the first GPS III satellite. The first flight GPS III space vehicle (SV-01) is expected to be available for launch in 2014, and launched by the U.S. Air Force in 2015.
Exelis Encryptors. Exelis delivered the first three of a planned 14 ground-based encryptors to Raytheon Company for OCX. Designed to automatically code and decode GPS signals, encryptors facilitate the exchange of user information by securely transmitting navigation payload data between the OCX ground station and the orbiting constellation of satellites.
Delivery followed successful thermal, electromagnetic interference and security verification testing. Exelis provides critical elements of software in the navigation processing subsystem that will enable controllers to better understand the exact position of GPS satellites. This helps ensure accurate navigation information is securely broadcast to users. In addition to encryptors, Exelis is building high-precision receivers for use in GPS ground monitoring stations and satellite signal simulators for testing purposes.
Exelis is also on contract with Lockheed Martin to provide the payloads for the GPS III satellites.
During the August test, the GPS III Non-flight Satellite Testbed (GNST) proved that it could connect with and receive commands from the Launch and Check Out System.
The prototype for Lockheed Martin ‘s next generation GPS III satellite reached a major milestone on August 30 when it successfully established remote connectivity and communicated with the GPS Next Generation Operational Control System (OCX), being developed by Raytheon, during a series of pre-flight tests.
During the Compatibility and Integration (C&I) Tests, Lockheed Martin’s GPS III Non-flight Satellite Testbed (GNST) — a full-sized, functional satellite prototype currently residing at Cape Canaveral Air Force Station — proved that it could connect with and receive commands from Raytheon’s Launch and Check Out System (LCS), part of the next-generation OCX that supports the satellite and mitigates risks prior to launch.
The GNST received commands from the LCC node at Lockheed Martin’s facility in Newtown, Pennsylvania, via the OCX servers at Raytheon’s facility in Aurora, CO, the system then returned satellite telemetry to the control station. The tests mirror launch and early orbit testing planned for all flight vehicles.
“The GNST is essentially a non-flying, functional GPS III satellite. While we have connected OCX with ground-based simulators before, these C&I tests were the first time that OCX and a GPS III satellite have actually communicated,” explained Keoki Jackson, vice president for Lockheed Martin’s Navigation Systems mission area.
Matthew Gilligan, a vice president with Raytheon’s Intelligence, Information and Services business and Raytheon’s GPS OCX program manager, stated, “This was an invaluable early opportunity to demonstrate command and control of the GPS III satellite with LCS, proving the end-to-end system capabilities well before putting an actual GPS III in orbit. The positive results tell us that we are right on track for the first GPS III launch.”
The LCS works hand-in-hand with Lockheed Martin’s Launch and Checkout Capability (LCC) contract, which brings online some of OCX’s GPS III-specific capabilities early to provide on-orbit checkout and control of the satellites.
The GNST has been at the Cape since July dry-running launch base space vehicle processing activities and pre-launch testing that all future flight GPS III satellites will undergo. The first flight GPS III space vehicle (SV-01) is expected to be available for launch in 2014, and launched by the U.S. Air Force in 2015.
Prior to shipment to the Cape, the GNST was developed and then completed a series of high-fidelity activities to reduce program risks, improve efficiencies and pathfind the integration, test and environmental checkout that all production GPS III satellites undergo at Lockheed Martin’s new GPS III Processing Facility in Denver, Colo.
An innovative investment by the Air Force under the original GPS III development contract, the GNST has helped to identify and resolve development issues prior to integration and test of SV-01. Following the Air Force’s rigorous “Back-to-Basics” acquisition approach, the GNST has gone through the development, test and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance and lowering overall program costs.
The Lockheed Martin-developed GPS III satellites and Raytheon’s OCX are critical elements of the U.S. Air Force’s effort to modernize the GPS enterprise more affordably while improving capabilities to meet the evolving demands of military, commercial and civilian users worldwide.
GPS III satellites will deliver three times better accuracy; provide up to eight times more powerful anti-jamming capabilities; and include enhancements which extend spacecraft life 25 percent further than the prior GPS block. The GPS III also will carry a new civil signal designed to be interoperable with other international global navigation satellite systems, enhancing civilian user connectivity. The spacecraft bus and antenna assemblies for the first GPS III satellite have been delivered to Lockheed Martin’s GPS III Processing Facility and are in the integration and test flow leading to the planned space vehicle delivery in 2014.
Lockheed Martin is currently under contract for production of the first four GPS III satellites (SV 01-04), and has received advanced procurement funding for long-lead components for the fifth, sixth, seventh and eighth satellites (SV 05-08).
OCX will revolutionize GPS command and control and mission management capabilities, controlling all legacy and new military and civil signals, providing protection against evolving cyber threats and ensuring continuity of operations during cyber attacks, and reducing operation and sustainment costs through efficient software architecture, automation and performance-based logistics. OCX represents a quantum leap in capabilities over the current Operational Control System and provides flexibility and adaptability to meet future GPS mission needs. Raytheon is the OCX prime contractor and is on track to deliver the final Launch and Checkout System in 2014.
The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Lockheed Martin is the GPS III prime contractor with teammates ITT Exelis, General Dynamics, Infinity Systems Engineering, Honeywell, ATK and other subcontractors. Raytheon is the GPS OCX prime contractor with teammates ITT Exelis, Boeing, Braxton, Infinity Systems Engineering, and NASA’s Jet Propulsion Laboratory. Air Force Space Command’s 2nd Space Operations Squadron (2SOPS), based at Schriever Air Force Base, Colo., manages and operates the GPS constellation for both civil and military users.
Artist’s concept of the nextgen GPS III satellite (courtesy of the USAF).
Lockheed Martin and Raytheon Company successfully completed the third of five planned launch and early orbit exercises to demonstrate the launch readiness of the world’s most powerful and accurate Global Positioning System (GPS), the U.S. Air Force’s next-generation GPS III satellite and Operational Control System (OCX).
Successful completion of Exercise 3, on August 1, was a key milestone demonstrating Raytheon’s OCX software meets mission requirements and is on track to support the launch of the first GPS III satellite, being produced by Lockheed Martin. Two additional readiness exercises and six 24/7 launch rehearsals are planned before launch of the first GPS III satellite in 2015.
Using new installments of Raytheon’s OCX software and Lockheed Martin’s GPS III Launch and Checkout Capability (LCC), the Air Force Global Positioning System Directorate and the industry team completed a launch and early orbit exercise over a three-day period in late July. Exercise 3 demonstrated space-ground communications; first acquisition and transfer orbit sequences; orbit-raising maneuver planning and execution; and basic anomaly detection and resolution capabilities. In addition, the industry and customer teams jointly executed mission planning activities, such as orbit determination and the generation of upload command files.
Exercise 3 expands on two previous exercises, with a longer mission timeline, and the introduction of simulated vehicle and ground anomalies to evaluate the combined response capabilities of the control segment, satellite and operations crew. “Successful completion of Exercise 3 clearly demonstrates that OCX is on track to support the first GPS III satellite launch,” stated Matt Gilligan, a vice president with Raytheon’s Intelligence, Information and Services business and Raytheon’s GPS OCX program manager. “The system responded as designed, and met all of the launch exercise success criteria and successfully demonstrated our anomaly response.”
“Exercise 3 demonstrated that the cross-organizational operations team is on track to support successful GPS III launch and on-orbit checkout missions from our Newtown facility,” said Keoki Jackson, vice president of Lockheed Martin’s Navigation Systems mission area. “I look forward to the team’s continued success as they progress through the complex mission readiness program towards the first GPS III launch.”
The Lockheed Martin-developed GPS III satellites and Raytheon‘s OCX are critical elements of the U.S. Air Force’s effort to modernize the GPS enterprise more affordably while improving capabilities to meet the evolving demands of military, commercial and civilian users worldwide.
GPS III satellites will deliver three times better accuracy; provide up to eight times more powerful anti-jamming capabilities; and include enhancements which extend spacecraft life 25 percent further than the prior GPS block. The GPS III also will carry a new civil signal designed to be interoperable with other international global navigation satellite systems, enhancing civilian user connectivity. The spacecraft bus and antenna assemblies for the first GPS III satellite have been delivered to Lockheed Martin’s GPS III Processing Facility and are in the integration and test flow leading to the planned space vehicle delivery in mid-2014.
OCX is being developed in two Blocks using a commercial best practice iterative software development process, with seven iterations in Block 1 and one iteration in Block 2. Exercise 3 was conducted using the recently completed Iteration 1.4 software. Exercise 4, scheduled for early 2014, will use Iteration 1.5 software, which includes the Launch and Checkout System capability as well as all critical information assurance features needed to support launch of the first GPS III satellite.
From left: James J. Miller and John LaBrecque, NASA Headquarters; A.J. Oria, Overlook Systems Technologies
By James J. Miller and John LaBrecque, NASA Headquarters, and A.J. Oria, Overlook Systems Technologies, Inc.
Satellite laser ranging (SLR) and the results of combining SLR with GPS in the future will translate into significant performance advancements for generations to come, once it is fully implemented as part of the GPS III architecture. Simply put, SLR techniques will improve GPS signal performance by enhancing the accuracy of GPS orbit and clock estimates, allowing for the correction of systematic errors and limitations inherent in current GPS radiometric solutions.
This will produce higher levels of positioning and timing as new information is processed and used to update orbital models and reference frames over a period of time. Eventually this will enable user accuracy in the centimeter range, orders of magnitude better than the 1-meter average user-range accuracies accessed today. Every GNSS constellation under development will provide for SLR, because not doing so would limit their systematic accuracy and diminish the potential of their PNT services.
This SLR initiative progressed over the past decade from technical engineering exchanges to senior-level reviews and policy deliberations under the aegis of the PNT EXCOM (see Sidebar), with GPS III now poised to have laser retro-reflector arrays (LRAs) placed on board all space vehicles, beginning with number 9 (GPS-III-SV9).
The National Aeronautics and Space Administration (NASA), National Geospatial-Intelligence Agency (NGA), National Oceanic and Atmospheric Administration (NOAA), and the U.S. Geological Survey (USGS), among others, strongly support the decision by Air Force Space Command to proceed with the placement of LRAs on board GPS III satellites to enable SLR. These agencies will work together to ensure that the derived science benefits all PNT EXCOM agencies and our many constituents and users around the world.
How Satellite Laser Ranging Works
SLR to any orbiting body involves firing repetitive laser pulses towards an object equipped with some form of LRA. The laser roundtrip time is then translated into distance or range measurements (Figure 1). In our case, SLR data collected from lasing to GPS and other GNSS constellations is compared with radiometric data collected at GPS/GNSS ground monitoring stations.
Figure 1. SLR operations description.
Radiometric monitoring and SLR each have their respective strengths. Radiometric monitoring stations are inexpensive and can be densely deployed, but are susceptible to systematic errors that cannot easily be identified. SLR is a high-accuracy method, independent of radiometric positioning, that can be used to identify some of these systematic errors. The two techniques in concert will provide more accuracy to the determination of satellite orbits and clocks, strengthening the societal benefits of GPS through improved performance and more precise applications over time.
Societal Benefits of Space Geodesy
Geodesy is the science of the Earth’s shape, gravity, and rotation, and their variations over time. Modern geodetic measurements rely upon GNSS technology and techniques to understand and respond to evolving geo-hazards such as earthquakes, volcanic eruptions, debris flows, landslides, land subsidence, sea-level change, tsunamis, floods, storm surges, hurricanes, and extreme weather. In recent years, GPS radio occultation data from satellites is used by weather services to improve the accuracy of forecasts. Other benefits include the use of regional differential networks to monitor crustal movements in near real time, and guide farm machinery and construction equipment with centimeter-level accuracies.
An essential element is the ability to relate geodetic measurements to one another in space and time through a stable and accurate reference frame. Most global terrestrial reference systems set their origin to the Earth’s center of mass or geocenter. Precise knowledge of the reference frame geocenter and its relative change are needed to study regional and global sea-level fluctuations and ocean-climate cycles like El Niño, the North Atlantic Oscillation, and the Pacific Decadal Oscillation.
Reference Frames
GPS satellite ephemerides are derived from ranging based on pseudorandom noise signals and carrier-phase variations, referenced to onboard atomic clocks and a ground network of GPS monitor stations expressed in the World Geodetic System 1984 (WGS 84) reference frame. The WGS 84 reference frame is determined using the analysis of GPS satellites, and must be periodically updated by the National Geospatial-Intelligence Agency (NGA) due to geophysical processes such as tectonic-plate motion. NGA works to maintain the tightest alignment between the WGS 84 and the International Terrestrial Reference Frame (ITRF) using GPS reference sites common to both.
The more ambitious ITRF is obtained using a global network of instrumentation — GPS, SLR, Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) — and geodetic satellites such as LAGEOS and LARES. These data are gathered and analyzed through an international cooperative effort by the services of the International Association of Geodesy (IAG) within the framework of the Global Geodetic Observing System (GGOS) (Figure 2).
Figure 2. Structure and products of the Global Geodetic Observing System related to GPS performance.
The integration of SLR and radiometric tracking of all GNSS constellations will improve multi-GNSS performance and interoperability as tools and techniques are co-located and data combined into various products that enable PNT service providers to improve system models.
Geodetic Requirements. GPS is a critical component in the determination of the ITRF geodetic reference frame and serves as the principal means of positioning relative to the reference frame. Though the current accuracy of the ITRF and WGS 84 reference frames marginally meets most current operational requirements, emerging scientific requirements in Earth observation demand more accuracy than core geodetic systems, including GPS and the ITRF, can deliver.
There is thus a growing GPS capability gap that can only be met with systematic improvements such as SLR will enable. In this manner, today’s scientific needs for positioning and timing often become tomorrow’s operational capabilities. If GPS is to continue as the primary geodetic reference system, we must ensure that GPS continues to evolve its system accuracy as well (Figure 3).
Figure 3. Evolution of GPS accuracy versus civil and scientific requirements assuming a factor of ten per decade improvement in accuracy.
Presently, the accuracy of both the ITRF and the WGS 84 is estimated to be on the order of 1 part per billion (6.4 millimeters at the Earth’s surface), with observed regional drifts on the order of 1.8 mm/year, and errors in the colocation of geodetic stations exceeding 5 mm/year. There is also little to verify this estimated accuracy of the reference frames, because successive estimates of the ITRF are retrospective and utilize the same historical data sets, except for the addition of more recent data and new analysis approaches. All determinations of the ITRF are therefore inter-related and not independent, allowing some errors to remain embedded.
Although such drifts and errors are acceptable for meter-level positioning, we must address these significant instabilities if we are to meet the growing geodetic requirements demanded by science and society. The GGOS and the National Research Council have called for a significant improvement in the accuracy and stability of the ITRF, including the goal for 1 mm of accuracy and 0.1 mm/year of stability.
Getting Laser Reflector Arrays aboard GPS III
In 2006, a working group of representatives from multiple U.S. civil and military government agencies identified a set of anticipated geodetic requirements for GPS to meet future geodesy and science needs. An analysis of alternatives (AoA) concluded that the only practical solution to correct for systematic errors in satellite coordinates and reference frames is optical laser ranging, as has been demonstrated on board GPS block IIA SV-35 and -36. These were equipped with LRAs thanks to the effort of Ron Beard of the U.S. Naval Research Laboratory (NRL).
In 2007, the geodetic requirements and AoA were submitted to the GPS Interagency Forum for Operational Requirements (IFOR), along with formal endorsement letters from NASA, NGA, NOAA, and USGS. The goal of the GPS IFOR is to ensure that new features on GPS adhere to U.S. PNT Policy objectives, and that any proposed technical enhancements do not degrade core GPS performance, schedule, signals, or services. Between 2007 and 2012, interagency IFOR discussions and studies continued and subsequently were elevated to a special multi-agency study group led by AFSPC and NASA. In December 2012, after reviewing the results of these technical deliberations, NASA Administrator C. Bolden, AFSPC Commander Gen Shelton, and U.S. Strategic Command’s Gen Kehler agreed on a plan for installation of LRAs on all GPS III vehicles beginning with SV9.
Laser-Ranging Operations
GPS laser ranging will be accomplished through the International Laser Ranging Service (ILRS), and NASA will ensure all operations adhere to a set of standards and procedures. All ILRS GPS laser ranging will use 532- or 1064-nanometer wavelengths, and the reflectivity of LRAs will be optimized for these two “colors.” To support operations and accommodate this level of control and situational awareness, the ILRS has defined minimum standards for GNSS LRA cross-sections to optimize ranging to the satellites by ILRS stations.
The design of the LRA for GPS III, funded by NASA and currently being developed by the NRL, easily exceeds the ILRS recommended standards. Some satellites tracked by the ILRS are to be ranged subject to certain basic restrictions and conditions to ensure the science data gained is optimal for all stakeholders. The ILRS has developed policies and procedures for controlled tracking, and laser ranging to GPS III will be performed on a schedule issued by the ILRS Central Bureau located at the NASA Goddard Space Flight Center in Greenbelt, Maryland.
The laser-ranging schedule will be coordinated considering ground-network capabilities, GPS operational requirements, and the tracking frequency required for accurate orbit determination. Only certified/approved ILRS stations will be authorized to perform laser ranging following a predetermined assessment, using approved laser-ranging stations operating within set technical parameters (color, power, and so on). The ILRS will issue digital keys once confirmation is received that all conditions have been met, with AFSPC and NASA maintaining a role.
Summary
A positive way forward has been established to allow for the implementation of laser ranging to the GPS-III constellation beginning with SV-9 in the 2019 timeframe. The laser ranging to GPS III, followed by post-processed analysis and mitigation of systemic errors, will contribute significantly to achieving the goal of a more accurate ITRF. These applications will also be augmented by an ongoing and significant international investment in the global geodetic infrastructure of the GGOS observing networks and analysis systems. Laser ranging of GPS III will also encourage further international investments and industry innovations as higher precisions are further introduced to the world community.
Sidebar
The PNT EXCOM
The U.S. National Space Based, Positioning, Navigation, and Timing (PNT) Policy, formally unveiled in December 2004 and supported through two administrations, strengthened GPS by creating a deputy-secretary-level PNT Executive Committee (EXCOM) to coordinate federal agency oversight of this critical national asset. The PNT EXCOM is co-chaired by the Department of Defense (DoD) and Department of Transportation (DOT), with representation by the deputy secretaries, or their equivalents, from other agencies and departments. The PNT Policy maintains the U.S. Air Force (USAF) as the DoD Executive Agent for Space.
This policy also designated newer responsibilities for other agencies. The NASA administrator, in coordination with the Department of Commerce and DOT, is responsible for developing requirements for the use of GPS and its augmentations in support of civil space systems. This level of collaboration is enabled by high-level interagency stakeholder discussions on all aspects of civil GPS activities. This is vital in the age of GPS modernization among other emerging constellations, as it allows individual PNT EXCOM agencies to develop and fund new capabilities. This multi-agency collaboration is very appropriate for GPS, since PNT is a suite of services used by all federal agencies to serve the public, providing greater safety, efficiency, and economy for a multitude of governmental missions.
Collaboration through the PNT policy has allowed NASA to optimize the use of GPS-based PNT services to fulfill a variety of science missions with ever-expanding societal benefits, ranging from space operations, exploration, Earth observation, and weather forecasting, to all manner of environmental monitoring including ice-melt and sea-level fluctuations. These data are increasingly important for governments to be able to plan for and respond to changes affecting human health, economy, and security. NASA therefore continues to work closely with the USAF and other PNT EXCOM agencies to improve the performance of GPS and its products through science initiatives.
One such initiative is known as GPS Satellite Laser Ranging (SLR), and is described here, along with its implementation aboard GPS III satellites.
Acknowledgments
The authors thank these individuals for their contributions in developing a way forward for the implementation of LRAs on GPS III, clearly showing the high level of interagency interest and coordination required to make this initiative happen overly nearly a decade of work. We are especially grateful to the U.S. Department of Defense, and in particular to U.S. Air Force Space Commander General Shelton, for leadership and support in enabling NASA and our partners to realize this important contribution to GPS in years to come: Honorable Charles Bolden, Honorable Lori Garver, Gen William Shelton, Gen Robert Kehler, Letitia Long, Maj Gen Martin Whelan, Chris Scolese, Badri Younes, Michael Freilich, Jack Kaye, Barbara Adde, Norm Weinberg, Craig Dobson, Mike Moreau, David Carter, Stephen Merkowitz, Yoaz Bar-Sever, Scott Pace, Ray Yelle, Scott Wetzel, Major Janelle Koch, Col (Ret.) David Buckman, Col (Ret.) Allan Ballenger, Col (Ret.) David Madden, Col (Ret.) Bernard Gruber, Col James Puhek, Steve Malys, Thomas Johnson, Ron Beard, Linda Thomas, Mark Davis, Larry Hothem, Ken Hudnut, Hank Skalski, James Slater, Vaughn Standley, Mike Pearlman, Erricos Pavlis, Kirk Lewis, Maj Gen (Ret.) Robert Rosenberg, and the National Space-Based PNT Advisory Board co-chaired by Honorable James Schlesinger and Col (Ret.) Bradford Parkinson.
James J. Miller is deputy director of the Policy & Strategic Communications Division with the Space Communications and Navigation (SCaN) Program at NASA. He is a commercial pilot with master’s degrees in public administration from Southern Illinois University and international policy and practice from George Washington University.
John LaBrecque is lead of the Earth Surface and Interior Focus Area within NASA’s Science Mission Directorate, managing NASA’s Global Geodetic Network that provides PNT products in support of NASA’s Earth Observation program. He received his doctorate in marine geophysics from Columbia University.
A.J. Oria works for Overlook Systems Technologies, Inc., supporting NASA headquarters in the area of GPS and PNT technology. He has a Ph.D. in astronautics and space engineering from Cranfield University, UK.
The GPS III Non-Flight Satellite Testbed completed pathfinding activities at Lockheed Martin’s GPS III Processing Facility outside of Denver prior to it shipping to Cape Canaveral Air Force Station to test facilities and pre-launch processes there in advance of the arrival of the first GPS III flight satellite. Photo: Lockheed Martin
Lockheed Martin has delivered a full-sized, functional prototype of the next-generation GPS satellite to Cape Canaveral Air Force Station to test facilities and pre-launch processes in advance of the arrival of the first GPS III flight satellite.
The GPS III Non-Flight Satellite Testbed (GNST) arrived at the Cape on July 19 to begin to dry run launch-base space-vehicle processing activities and other testing that future flight GPS III satellites will undergo. The first flight GPS III satellite is expected to arrive at the Cape in 2014, ready for launch by the U.S. Air Force in 2015.
The GNST arrived at the Cape by Air Force C-17 aircraft from Buckley Air Force Base near Lockheed Martin’s GPS III Processing Facility (GPF) in Denver, Colorado. Prior to shipment, the GNST was developed and then completed a series of high-fidelity activities to pathfind the integration, test and environmental checkout that all production GPS III satellites undergo at Lockheed Martin’s new satellite manufacturing facility.
An innovative investment by the Air Force under the original GPS III development contract, the GNST has helped to identify and resolve development issues prior to integration and test of the first GPS III flight space vehicle (SV 01). Following the Air Force’s rigorous “back-to-basics” acquisition approach, the GNST has gone through the development, test and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance and lowering overall program costs.
“We call the GNST a ‘pathfinder’ because it has truly blazed the trail for every one of our GPS III processes from initial development, production, integration and test, and now pre-launch activities,” explained Keoki Jackson, vice president for Lockheed Martin’s Navigation Systems mission area. “All future GPS III satellites will follow this same path, so the GNST was a smart initiative to help us discover and resolve any issues in advance, implement production efficiencies, and ultimately save a tremendous amount of time and money in the long run.”
GPS III is a critically important program for the Air Force, affordably replacing aging GPS satellites in orbit, while improving capability to meet the evolving demands of military, commercial and civilian users. GPS III satellites will deliver three times better accuracy, include enhancements which extend spacecraft life 25 percent further than the prior GPS block, and a new civil signal designed to be interoperable with international global navigation satellite systems.
Lockheed Martin is currently under contract for production of the first four GPS III satellites (SV 01-04), and has received advanced procurement funding for long-lead components for the fifth, sixth, seventh and eighth satellites (SV 05-08).
Lockheed Martin has completed and is preparing to install the navigation, communication, and hosted payload antenna assemblies for the first satellite of the next-generation GPS III.
Seven antenna assemblies, produced at Lockheed Martin’s Newtown, Pennsylania, facility were delivered to the company’s GPS III Processing Facility (GPF) near Denver, Colorado, on June 14. The antennas will be installed on the first GPS III space vehicle (SV01), which Lockheed Martin will deliver to the U.S. Air Force on schedule, “flight-ready,” in 2014.
The new antennas for GPS III SV01 will provide the satellite’s capability to send and/or receive data for Earth-coverage and military Earth-coverage navigation; a UHF crosslink for inter-satellite data transfer; telemetry, tracking and control for satellite-ground communications; and data acquisition and communication for the nuclear detection system hosted payload. The antenna designs enable three to eight times greater anti-jamming signal power to be broadcast to military users across the globe when compared to previous GPS generations.
“These antennas on the next generation of GPS III satellites will transmit data utilized by more than one billion users with navigation, positioning and timing needs,” explained Keoki Jackson, vice president of Lockheed Martin’s Navigation Systems mission area. “We have become reliant on GPS for providing signals that affect everything from cell phones and wristwatches, to shipping containers and commercial air traffic, to ATMs and financial transactions worldwide.”
GPS III is a critically important program for the Air Force, affordably replacing aging GPS satellites in orbit, while improving capability to meet the evolving demands of military, commercial and civilian users. GPS III satellites will deliver three times better accuracy, include enhancements which extend spacecraft life 25 percent further than the prior GPS block, and a new civil signal designed to be interoperable with international global navigation satellite systems.
The production of the first GPS III satellite continues on schedule. Recent testing of the SV 01 bus — the portion of the space vehicle that carries mission payloads and hosts them in orbit — assured that all bus subsystems are functioning normally and that they are ready for final integration with the satellite’s navigation payload.
This milestone follows February’s successful initial power on of the SV01 spacecraft bus, which demonstrated the electrical-mechanical integration, validated the satellite’s interfaces and led the way for functional electrical hardware-software integration testing.
Lockheed Martin is under contract for production of the first four GPS III satellites (SV01-04), and has received advanced procurement funding for long-lead components for the fifth, sixth, seventh and eighth satellites (SV05-08).
The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Lockheed Martin is the GPS III prime contractor with teammates ITT Exelis, General Dynamics, Infinity Systems Engineering, Honeywell, ATK and other subcontractors. Air Force Space Command’s 2nd Space Operations Squadron (2SOPS), based at Schriever Air Force Base, Colorado, manages and operates the GPS constellation for both civil and military users.
