Three Years After Launch, SES-5 Operational for Navigation Service
PARIS — The agency managing Europe’s Galileo and EGNOS satellite navigation programs on Sept. 2 said it had only recently certified as operational the SES-5 satellite despite the satellite’s successful launch three years ago.
The agency also said it is evaluating bids from prospective satellite operators to host a navigation payload to be launched to geostationary orbit in 2019. A decision is expected by the end of the year.
The lengthy SES-5 delay, which has consumed two years of the 12-year contract with satellite fleet operator SES of Luxembourg, was at first the result of a suspected defect onboard SES-5, and later due to an upgrade of the elaborate ground network serving EGNOS, the European Geostationary Navigation Overlay Service.
The Prague-based European GNSS Agency (GSA) said the L-band navigation payload on the SES-5, stationed at 5 degrees east, is performing well and will replace the payload on an Inmarsat satellite that London-based Inmarsat plans to relocate.
A second navigation terminal, on the SES-owned Astra 5B satellite launched in March 2014, is still undergoing tests and is planned to enter EGNOS service by late 2016, GSA said.
SES won separate contracts for the navigation service in 2007 and 2008, each valued at about 75 million euros ($83 million) and covering the cost of integrating the navigation payloads into SES-owned commercial telecommunications satellites, launching them and hosting the service for 12 years.
While it was judged healthy by SES for its main commercial mission, SES-5’s navigation signal did not immediately satisfy the EGNOS contract specifications. It took a year from the launch before it was judged fit for service, and SES began to receive annual contract milestone payments in August 2013.
Astra 5B, located at 31.5 degrees east, had a smoother path to acceptance, and contract payments began in June 2014, just three months after launch.
EGNOS is analogous to the U.S. Wide Area Augmentation System and similar overlays in Japan and India. All receive information from ground stations on the performance of the U.S. GPS constellation in medium Earth orbit and relay the information to users.
EGNOS is being upgraded to keep up with GPS satellite improvements, and will be modified further to provide similar reliability and integrity data for Europe’s Galileo constellation.
For now, EGNOS relies on two Inmarsat satellites — Inmarsat-3 F2 at 15.5 degrees west and Inmarsat-4 F2 at 25 degrees east. Use of the European Space Agency’s aging Artemis data-relay satellite as an in-orbit spare was ended.
Jean-Marc Pieplu, EGNOS exploitation program manager for GSA, conceded that three years to declare a satellite ready for service is exceptionally long, and that most of the time has been spent making ready the upgrade of the EGNOS ground network to higher-precision guidance instrument approaches at European airports.
The upgrade — called LPV-200, for localizer performance with vertical guidance — will permit higher-precision flight paths and afford fuel and time savings for European air travelers.
In a Sept. 2 interview, Pieplu said that because the Inmarsat spacecraft have remained in good health, there was no urgency to placing SES-5 into service beyond using it as a test satellite until the LPV-200 upgrade was completed.
One of the two Inmarsat satellites now used for EGNOS, Inmarsat-4 F2, will be relocated by Inmarsat in the coming months. The second will be used as the in-orbit spare once Astra 5B is brought into service.
Anticipating the time when the Inmarsat spacecraft are no longer available, GSA this summer began preparations for a third geostationary payload to add to the two SES spacecraft.
In a preparatory document sent to industry, GSA said it plans to enter into a 15-year contract with the winning bidder for a payload to be launched around 2019 — just before the EGNOS network is next upgraded in preparation for the Galileo constellation.