Tuesday April 28th 2009. Launch -16 days and Counting.


The “relaxed” period lasted less than one day. Here we go again!


So, to start with the good news: we have a launch date! I repeat, we have a launch date. D-Day is May 14th, a date that had been widely speculated about for a couple of weeks. This means that the countdown has given another little jump downwards. This has happened because some launch preparation activities continued, even though we had no official launch date.


What happened? There were two issues, one trivial, one potentially more serious. The trivial one was some minor damage to the fairing that covers Herschel and Planck during launch. This got repaired while other problems were being fixed. More serious was that the thrusters on the upper stage of the Ariane had to be replaced after a fault was found in testing in some other thrusters that had been manufactured in the same batch. There was no reason to suspect that our own thrusters were faulty, but it is a standard precaution. When Herschel and Planck are released the thrusters have to carry out a series of manoeuvres to re-orientate the space craft: first Herschel is released, then the thrusters point the upper stage in a different direction so that the Scylda support that Herschel rests on can be released and then they manoeuvre again so that Planck can be released safely. If the thrusters were to fail, there is the potential that Planck, which goes on a faster trajectory, could rear-end Herschel after release, which would be embarrassing to all concerned.


Last week’s tests showed some bugs in the new software, but also that it is good enough to use for launch if we can fix the problems in time. So, this week is bug-fixing week and next week, taking advantage of the extra week before launch, we will have the grandly named “Science Ground Segment Downlink End-to-End Test 1” – a name that really trips off the tongue. The idea of the test is to check that all the important bugs have been fixed and to see if there are any others hidden deeper in the software. By the end of the week we should, barring nasty surprises, be able to certify Herschel Common Science System 1.0 ready to fly. This is something that we had never expected. In fact, this software was only expected to become available some weeks after launch. Score one to the Good Guys!


However, having thought that my Test Coordinator role would disappear and that I could go into reasonably honourable retirement, it seems that I have been volunteered for a final encore. So, next week, I will be working on two major tasks at once. When this became apparent yesterday afternoon my stress level shot back up to an unhealthy degree.