ESA GPS Navigation: Work begins to strengthen EGNOS against solar storms

This illustration shows a CME blasting off the Sun’s surface in the direction of Earth. 

This left portion is composed of an EIT 304 image superimposed on a LASCO C2 coronagraph. 

Two to four days later, the CME cloud is shown striking and beginning to be mostly deflected around the Earth’s magnetosphere. 

The blue paths emanating from the Earth’s poles represent some of its magnetic field lines. The magnetic cloud of plasma can extend to 30 million miles wide by the time it reaches earth. These storms, which occur frequently, can disrupt communications and navigational equipment, damage satellites, and even cause blackouts.

Credits: ESA/NASA - SOHO/LASCO/EIT

Europe’s European Geostationary Navigation Overlay Service (EGNOS) satnav augmentation service, employed for an ever-increasing range of uses such as guiding aircraft landings, will be strengthened against the effects of solar storms and its design ‘future-proofed’. The new work order was signed on Friday.

EGNOS uses geostationary satellites and a Europe-wide network of ground receivers to sharpen the accuracy and reliability of US GPS signals over the continent.

EGNOS signals are potentially vulnerable, however, to the effects of high solar activity on the ionosphere – the electrically active upper layers of our atmosphere – which can cause signal ‘scintillations’ and time delays.

And an increase in solar storms is being experienced as the Sun enters the active phase of its 11-year cycle.

This new effort will increase system robustness and service availability against severe ionospheric severe effects that began last year and are expected to continue until the peak of the solar cycle expected in 2013–14.

In addition, while EGNOS began its general service in 2009 and its ‘Safety-of-Life’ signal for aircraft vertical landing approaches became available a year ago this month, the overall system was designed almost a decade ago, so work is also needed to upgrade elements of its communication system to manage technology obsolescence.

The work order also covers planned EGNOS mission evolution, including keeping pace with GPS modernisation, provision of vertical guidance for aircraft landings and extending the EGNOS network to cover North Africa and the Middle East.

This new work order is part of a framework contract signed with Thales Alenia Space France in May 2011.

EGNOS ranging station

About EGNOS

Along with Galileo, EGNOS is the other pillar of Europe’s navigation programme. ESA designed the EGNOS system in cooperation with the EC and Eurocontrol. EGNOS informs users about the current accuracy and integrity (level of reliability) of the system based on the GPS satellites’ orbits, atomic clock accuracy and ionospheric delay.

If the accuracy of the signal falls below a given threshold, users are warned within six seconds.