1.) After the deployment test the sunshield (DSA) has to be moved back into launch position. This has actually happened already as you can see in this photo series of ESA: http://t.co/9DOtyUOY1D. It is also visible that some of the Multi-Layer Insulation (MLI) had to be removed for this process. It needs to be reinstalled to the DSA structure. The 12 pyrobolts that are connecting the sunshield to the satellite during launch were destroyed during the deployment test. Thus, they need to be replaced with new bolts containing two explosive charges each.
2.) During the next few days Gaia will be moved to a different building as some delicate operations need to be done. Both, the Chemical Propulsion System (CPS) and the Micro-Propulsion System (MPS) will be fueled in the HPF (Hazardous Payload Facility). The HPF is located in building S5A. Therefore, Gaia needs to be moved from the cleanroom in the S1B building to the HPF in the S5A building for this fueling processes. The technicians performing the fueling process will need to wear protective suits as you can see in the image of the fueling process for the Planck satellite of ESA. An additional task will be performed in the S5A building: Gaia will be connected to the Payload Adapter System (PAS). This is a standardized system that will connect Gaia with the Fregat upper stage. The entire processing in the S5A building is expected to take up to 2 weeks.
3.) In the next step Gaia will be moved to the S3B building for the meeting with the Fregat Upper stage that will propel it on course to its final destination – an orbit around the Lagrange point L2. Therefore the Gaia-PAS combination will be lifted by a crane and mated on top of the Fregat stage, which is already fueled. As you can see in the image above (showing a Fregat mated with tho Galileo satellites) the Fregat is also packed in golden MLI. Thus the Fregat and Gaia will form a really golden combination – with some solar panels visible.
4.) Then both halfs of the payload fairing will be installed around the Gaia-Fregat combination (shown here for a Fregat stage with the four O3B satellites ) in the cleanroom of the S3B building. During this process the dusk cap and the protective covers of both telescopes of Gaia will need to be removed. The atmosphere in the fairing needs to be carefully controlled to avoid any contamination of the mirrors of the telescopes.
5.) Finally, the Gaia-Fregat-fairing combination (called the Upper Composite – UC) will be loaded on a transporter. This transporter will move the Upper Composite to the launch zone very few days before the launch date. At the launch pad the 3-stage Soyuz launcher is waiting already to be connected with the Upper Composite. These launch pad operations I will described in a future post.
All images used are copyrighted to ESA/CNES/Arianespace.
Update: There is now a version of this article in French available with some additional information thanks to Isabelle from Astrium, Toulouse. She is working for the Gaia launch campaign and is currently in Kourou. Here you can find the article: http://reves-d-espace.com/2013/10/21/gaia-les-prochaines-etapes-a-venir-en-campagne-de-tir/ .
Update 2: Please read also the new post on the official Gaia blog from Giuseppe Sarri, Gaia Project Manager: http://blogs.esa.int/gaia/2013/10/21/the-pieces-of-the-puzzle-are-coming-together/ .