While investigators continue to search through the debris of the failed launch of three Russian GLONASS navigation satellites, the United States and Europe have announced progress with their fleet of upcoming GPS spacecraft. The first Galileo Full Operational Capability (FOC) satellite is now undergoing testing in Holland, while Lockheed Martin’s GPS III program passed a major development milestone.
GPS was created by the US Department of Defense (DoD) and became fully operational in 1994. Serving both the military and the public alike, the use of GPS has rocketed in recent years, not least via the use of navigation aids in personal mobile devices.
The Americans lead the way with their GPS satellite fleet, with the most recent launch coming via the successful deployment of the fourth Block IIF GPS satellite – GPS IIF-4 – the sixty-fourth GPS satellite overall.
The next generation of navigation satellites – known as GPS III – is on track for a 2014 launch, with Lockheed Martin currently under contract for production of the first four GPS III satellites (SV 1-4), while they have also received advanced procurement funding for long-lead components for the fifth, sixth, seventh and eighth satellites (SV 5-8).
In preparation for the new fleet, the GPS III Non-Flight Satellite Testbed (GNST) successfully completed a series of high-fidelity pathfinding events, validating the process and facility for vehicle integration checkout, as well as signals interference testing.
The GNST is a full-sized GPS III satellite prototype, used to identify and resolve development issues prior to integration and test of the first GPS III space vehicle (SV 1).
During this latest milestone, the GNST successfully completed thermal vacuum (T-Vac) chamber trail blazing, demonstrating facility, mechanical and electrical ground equipment integration, and ran a series of vehicle integration test procedures.
The GNST also completed Passive Intermodulation (PIM) and Electromagnetic Compatibility (EMC) testing, which assures that multiple high-powered signals generated from the satellite’s navigation downlink transmissions, or transmitted from the hosted nuclear detection system payload on the satellite, do not interfere with each other or themselves.
“As the GNST serves as a pathfinder for the GPS III program, its successful completion of this testing validates that development risks have been retired and our engineering and technology is sound for the flight vehicles being built,” explained Keoki Jackson, vice president for Lockheed Martin’s Navigation Systems mission area.
The GNST is now being prepared for shipment to Cape Canaveral Air Force Station for more risk reduction activities related to launch.
GPS III satellites will deliver three times better accuracy and – to outpace growing global threats that could disrupt GPS service – up to eight times improved anti-jamming signal power for additional resiliency. Notably, GPS III will include enhancements adding to the spacecraft’s design life and a new civil signal designed to be interoperable with international global navigation satellite systems.
For a variety of reasons, including the need to avoid reliance on specific GPS constellations, other nations – such as Russia and China – have been launching their own fleets of GPS satellites into orbit to provide a
system that is under their control.
The Chinese continue to launch and upgrade their BeiDou Navigation Satellite System – otherwise known as Compass – consisting of two separate satellite constellations.
A limited test system has been operating since 2000, while a full-scale global navigation system is currently under construction.
The long-term goal is to develop a global navigation satellite network similar to the GPS and GLONASS by 2020, eventually consisting a constellation of 35 vehicles, including 27 MEO (21,500 km orbits) satellites, three IGSO satellites (inclined at 55 degrees) and five GSO satellites.
India also began the deployment of their own navigation system, with the recent launch of the IRNSS-1A satellite becoming the first of seven spacecraft that will make up the Indian Regional Navigation Satellite System (IRNSS).
Their GPS constellation will consist of four satellites in geosynchronous orbits inclined at 29 degrees, with three more in geostationary orbit.
The Russian GLONASS Global Navigation Satellite System – operated by the Russian Aerospace Defence Forces – is the only alternative to the US GPS fleet in operation that has global coverage of comparable precision.
Development of GLONASS began in the Soviet Union in 1976. By the turn of the this decade, GLONASS had achieved 100 percent coverage, with the full orbital constellation of 24 satellites operational in 2011.
Three GLONASS-M satellites were set to join the constellation this month, but were lost when their Proton-M launch vehicle dramatically failed during launch.
With the wreckage crashing back to Earth just a short distance from launch pad, investigators have been examining the remains of the rocket for a root cause of the failure.
According to Russian media outlet “Interfax”, a source has claimed human error may be to blame for the failure, related to this Proton-M’s production, noting the angular velocity sensors appear to have been installed upside down.
Meanwhile, Europe are pressing on with the construction of what will become the Galileo navigation system.
With the first first four Galileo In-Orbit Validation (IOV) satellites already in orbit – providing the core of the new constellation – the first Galileo Full Operational Capability (FOC) satellite was delivered to ESA’s ESTEC technical centre in Noordwijk, the Netherlands last month.
The satellite – which is identical to its IOV sisters in orbit – is undergoing testing in simulated space conditions. A second Galileo FOC satellite is due to join its predecessor at ESTEC later this summer, preparing for a launch scheduled for later this year.
The 700 kgs birds sport two Passive Hydrogen Maser atomic clocks; two Rubidium atomic clocks; Clock monitoring and control unit; Navigation signal generator unit; L-band antenna for navigation signal transmission, C-band antenna for uplink signal detection, two S-band antennas for telemetry and tele-commands and a search and rescue antenna.
A total of 22 FOC satellites have been procured by ESA, with the satellite’s prime contractor OHB based in Bremen, Germany, while the navigation payloads are being produced by Surrey Satellite Technology Ltd in Guildford, UK.
(Images via Lockheed Martin, ESA, ChinaDaily, Tsenki TV and ISRO).