Space blog

Technical update - Europe's first Galileo navigation signals were transmitted from space by the GIOVE-A satellite at 17:25 GMT this afternoon 12th January.

























The satellite payload was commanded 'on' from the SSTL Mission Control Centre and the Galileo signals were successfully received using the 25-metre dish antenna at CCLRC Chilbolton Observatory (Andover) and the ESA Station in Redu (Belgium). The Galileo E5 and L1 channel signals were successfully decoded at the SSTL groundstation using a Galileo navigation receiver.

GIOVE-A payload switch-on at Mission Control at SSTl:



















SSTL & ESA team celebrate reception of first Gailileo signals:


















These milestone transmissions from GIOVE-A mark Europe's independent entry into global positioning, navigation and timing services - intended to work alongside the US GPS and provide enhanced performance.

Galileo signal spectrum received in the UK from GIOVE-A:








Gailileo navigation signals decoded alongside GPS at SSTL:












Following launch from Baikonur on 28th December, the GIOVE-A spacecraft in-orbit checkout and commissioning progressed extremely well and had been completed by Friday 6th January. These activities on GIOVE-A involved the co-operation of the ground stations deployed at RAL (UK), Bangalore (India) and Kuala Lumpur (Malaysia), which supported SSTL during the upload of the On-Board Computer software and the deployment of both solar panels, placing the satellite in Sun Acquisition Mode.

On Monday 9th January, the on-board atomic clocks and signal generating systems were checked by the SSTL Mission Control Centre and found to be performing nominally. An ESA team then travelled to the Chilbolten groundstation in the UK to prepare to analyse the first Galileo signals to be transmitted from the GIOVE-A satellite.

The different modes of Galileo signals will now be generated sequentially using the GIOVE-A first payload chain to perform the frequency filing activities. Once these frequency filing activities are completed (expected by the end of January 2006), the payload commissioning will resume with the checkout of the second and third payload chains, assumed to be performed by mid-February 2006. Additional measurement campaigns will then be carried out to assess the Medium Earth Orbit (altitude of 24,000 kilometres) radiation environment, characterise the performance of on-board clocks and perform signal-in-space experimentations.

The 660 kg GIOVE-A satellite, built by SSTL for ESA in just 30 months and 28M Euros, has three mission objectives. First, it secures use of the frequencies allocated by the International Telecommunications Union (ITU) for the Galileo system. Second, it demonstrates critical technologies for the navigation payload of future operational Galileo satellites. Third, it is characterising the radiation environment of the orbits planned for the eventual full Galileo constellation.

GIOVE-A carries two small European rubidium atomic clocks, each with a stability of 10 nanoseconds per day, and two signal generation units, one able to generate a simple Galileo signal and the other a more representative Galileo signal. These two signals are broadcast through an L-band phased-array antenna designed to cover all of the visible Earth under the satellite. Two instruments monitor the types of radiation to which the satellite is exposed during its two year mission. The Galileo signals broadcast by GIOVE-A are being carefully analysed by ground stations to make sure they satisfy the criteria of the ITU filings.

SSTL website