1.) There is a new post by the Gaia Project Manager Giuseppe Sarri in the ESA Gaia blog explaining some interesting details about the issues with the transponders of Gaia leading to the delay of the launch from November 20 to December 20. You can read about transponders flying in the business class, but no champagne was served, among other things.
One month ago, on October 19, about one month before the planned launch on November 20, it was discovered that some components that had failed on another spacecraft already in orbit are also installed in both transponders of Gaia. It was decided to send the transponders back to the factory in Italy for exchanging these components. The repairs took about three weeks and were “challenging”, what probably means more complicated and time consuming than expected. Today is November 19, and the launch is now planned for December 20. It is reported that the transponders are currently installed into the spacecraft. Some testing will be needed, the service module still needs to be closed as well as the opening in the sunshield allowing the access to the service module. This will take several days. If this is the case then the launch processing is a little bit behind schedule – the old schedule. There is a new schedule for sure to allow a launch on December 20. As it is said in the article – “we are back” on track.
Enjoy the article at: http://blogs.esa.int/gaia/2013/11/19/we-are-back/.
Update: More details about this story can be find in the blog of the QA engineer of Gaia giving the view from the Astrium launch processing team: http://reves-d-espace.com/2013/11/20/gaia-retour/. It confirms, among many other things, that the transponders are already back mounted inside the service module and that the launch processing will be back in normal mode at the end of this week.
2.) For the case that you missed it, ESA has also published a long list of frequently ask questions about the Gaia mission – with all the answers. Here they are: http://www.esa.int/Our_Activities/Space_Science/Gaia/Frequently_Asked_Questions_about_Gaia!