Airbus Defence and Space

A voyage to the heart of the ‘GAIActic empire’

Gaia, the most advanced astrometry satellite ever built in Europe, is due to be launched from Kourou in December. We meet Alexandre Affre, a ‘gaiactic empire’ enthusiast, on site in Kourou.

Mechanical engineer Alexandre Affre has been involved in the Gaia project since 2009, when flight model integration activities began in Toulouse, after joining Airbus Defence and Space for a three-year college placement in 2006. He is now taking part in the launch campaign in Kourou.

“I arrived at the Guiana Space Centre on 21 August, the day of my 29th birthday and two days prior to the departure of Gaia from Toulouse, so that I would be there ready to take delivery of the satellite when it arrived on board an Antonov transport plane. I am lucky enough to have been involved in the project since the beginning of the integration process and will stay with it right up to coupling with the Fregat stage of the Soyuz launcher. We have just completed electrical testing and are entering the stage of final mechanical work on the satellite with the DSA (Deployable Sunshield Assembly), a 10-metre diameter deployment system which insulates the satellite from the sun once in orbit.

“My job is to take delivery of the flight parts, assemble them and then test them. We work to the nearest micron (a centimetre now seems like a metre to me!) and in close collaboration with the optical and thermal engineers.

“Gaia is packed with incredible technology. Take for example the use of silicon carbide (SiC), a ceramic material that is incredibly lightweight and resistant to deformation arising from temperature changes. Using this material will enable Gaia to operate at ultra-low temperatures (-110°C) and ensure its stability (thermal instability less than 0.1°C) and longevity. The one billion-pixel image sensor comprising 106 charge-coupled devices (CCD), the electronic equipment for high-speed data transmission and the cold gas (nitrogen) micro-thrusters that will allow the satellite to correct its position at any time are also admirable feats.

“I will leave Kourou four days before the launch because only Airbus Defence and Space electricians and a skeleton standby team will be involved after that. Once launched, the satellite will undergo a transit period of one month, travelling 1.5 million kilometres to arrive at the L2 Lagrange point. Then we will go over the settings and final adjustments in orbit to make sure that everything is in working order, so that we can deliver Gaia to our customer, ESA.

The Gaia mission has really sparked my enthusiasm, not only in terms of the subject matter itself and its extraordinary technology (it is estimated that it will take 15 years for scientists to analyse all the data collected!) but also because of the teamwork involved. Some 400 engineers and technicians from Airbus Defence and Space have worked on the project alongside around 50 manufacturers across Europe. I owe so much of what I have learnt to them, from the very first day I arrived at Airbus Defence and Space for my college placement and was assigned to my first mission: setting the clocks to the right time in the cleanroom!”

GaiaSpaceUniverseSpace Exploration