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The System: Galileo Turning Ten

September 30, 2015  - By
Galileo 9 and 10 lift off. (Credit: ESA)

Galileo 9 and 10 lift off. (Credit: ESA)

Galileo satellites 9 and 10 are functioning perfectly, and the initial series of flight operations is continuing as part of the critical launch and early orbit phase, according to a European Space Agency Rocket Science blog by Daniel Scuka, senior editor for Spacecraft Operations at ESOC, ESA’s European Space Operations Centre, Darmstadt, Germany.

Galileo 9 and 10 lifted off together on Sept. 11 from Europe’s Spaceport in French Guiana atop a Soyuz launcher, bringing the total number of Galileo satellites in orbit to 10.

“The pair are being stepped through an intense series of check-outs, confirmations, mode changes, configurations and health verifications by the joint ESA/CNES mission team working around the clock at ESOC, Darmstadt, Germany,” according to the blog. “The team are now focusing on conducting a series of thruster burns designed to start the drift of the two satellites toward their target orbital positions.”

“Following the burns performed during the LEOP (launch and early orbit phase), the satellites will continue naturally drifting, ending up in their final desired operational orbits at about 23,222 km after another set of thruster burns, planned to achieve fine positioning in orbit, around the end of October,” said Liviu Stefanov, co-flight director from ESA.

With the excellent performance of the spacecraft and the ground teams, the LEOP is expected to wrap up soon.

All the Soyuz stages performed as planned during the September 11 launch, relieving anxieties tied to a faulty Soyuz launch in September of last year. The Fregat upper stage released the satellites into their target orbit close to 23,500 km altitude, around 3 hours and 48 minutes after liftoff.

“The deployment of Europe’s Galileo system is rapidly gathering pace,” said Jan Woerner, director general of the European Space Agency (ESA). “By steadily boosting the number of satellites in space, together with new stations on the ground across the world, Galileo will soon have a global reach. The day of Galileo’s full operational capability is approaching. It will be a great day for Europe.”

Two more Galileo satellites are scheduled for launch by end of this year. These satellites have completed testing at ESA’s ESTEC technical centre in Noordwijk, the Netherlands, with the next two satellites also undergoing their own test campaigns.

More Galileo satellites are being manufactured by OHB in Bremen, Germany, with navigation payloads coming from Surrey Satellite Technology Ltd in the UK, in turn utilizing elements sourced from all across Europe.

“Production of the satellites has attained a regular rhythm,” said Didier Faivre, ESA’s Director of Galileo and Navigation-related Activities. “At the same time, all Galileo testing performed up to now — including that of the ground segment — has been returning extremely positive results.

“And while the continuing deployment of Galileo remains our priority, along with exploitation of EGNOS — Europe’s already operational satellite navigation augmentation system — ESA is also looking farther ahead.

“With the European Commission, we are doing the technical work to ensure Galileo goes on forever — locking in continuity of Europe’s navigation services into the long term, to meet performance on a par with the other global satellite navigation systems.”

Next year Galileo deployment will be boosted by operation of a specially customized Ariane 5 launcher that can double, from two to four, the number of satellites that can be inserted into orbit with a single launch.

European SBAS Advances, Improves

After extensive ground and space testing, the SES-5 GEO satellite has entered into the European Geostationary Navigation Overlay Service (EGNOS) operational platform, broadcasting EGNOS Signal-In-Space (SIS). Replacing Inmarsat-4F2, SES-5 will ensure reliable EGNOS services until 2026, and will enable a range of performance improvements. In particular, EGNOS will offer even greater stability during periods of high ionospheric activity.

“SES-5 is the first step of the complete renewal of the EGNOS Space Segment, securing the EGNOS services for the next decade and the future transition to the dual-frequency multi-constellation services,” said Carlo des Dorides, European GNSS Agency executive director. “It will be completed by the introduction of the ASTRA-5B signals and the procurement of a new EGNOS payload which are both planned for 2016.”

SES-5, carrying EGNOS L1 and L5 band payloads, was launched in July 2012. The integration of a second EGNOS SBAS L1/L5 band payload on SES ASTRA-5B GEO satellite is currently ongoing. The introduction of the second SES GEO satellite for EGNOS is planned at the end of 2016.

GAO Report Spotlghts OCX Delays, Cost Increases

According to a report released by the U.S Government Accountability Office (GAO) on Sept. 9, titled “Actions Needed to Address Ground System Development Problems and User Equipment Production Readiness,” the Air Force has experienced significant difficulties developing the GPS next-generation operational control system (OCX). According to the report, completion of OCX will require $1.1 billion and four years more than planned to deliver OCX. The report Highlights section states, “The Air Force began OCX development in 2010,” and “accelerated OCX development in 2012 to meet optimistic GPS III satellite launch timeframes even as OCX development problems and costs grew, and then paused development in 2013 to address problems and resolve what it believed were root causes.

“However . . . OCX cost and schedule growth have persisted due in part to a high defect rate, which may result from systemic issues. Further, unrealistic cost and schedule estimates limit OSD visibility into and oversight over OCX progress. “ The full report may be read online.

During the course of development the Air Force made changes, updating the specifications for connections to other government systems and in the M-code signal requirements. Officials for Raytheon, the prime OCX contractor, estimated that, as a result of various modifications “nearly two-thirds of the requirements baseline as of [preliminary design review] had changed by mid-2012.” Subsequent software updates and modifications contributed to a high defect rate in the OCX software. “

If you have requirements change at the same time you’re developing the software, it’s more likely that you could have a higher amount of defects that you have to change after the fact,” said Matthew Gilligan, Raytheon’s vice president for navigation and environmental solutions.

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About the Author:

Alan Cameron is the former editor-at-large of GPS World magazine.

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