Monday March 23^rd 2009. Launch -?? days.

The end of the test. I feel drained. Many of my colleagues look drained. Today, surprisingly, the traffic was very light in the morning. One of the nicest parts of working at the weekend is the feeling that one is not dicing with death a every turn [having had two near misses with lunatic drivers in one day last week, this is a pleasing prospect] as there are not many other road users. A Monday usually means a return to having eyes in the back of one’s head and being prepared to take emergency measures at any moment: when you are a cyclist you get a wonderful realisation of just how vulnerable you are… I would make all drivers cycle in heavy traffic occasionally so that they understand what it’s like. Today, in contrast, there seemed to be far few cars than usual and the ride was much more relaxing.

This morning we had a long run through of the test and our impressions of it. Most were strongly positive. After several tests where it felt as if we were never truly in control and always reacting to events, this time the system was quite docile and we were just fine-tuning. We now have 4 weeks of consolidation and fixing the things that still need to be fixed. The Boss said that we have a “success-orientated plan”, which is quite true. We depend on numerous elements that we want to add to the system being added with no great problems; if there are big problems, we will not be able to do everything that we want to do. However, we can still go back to the old system at any point because it has been tested and we know that it works.

Over the weekend the spacecraft has been fuelled-up with hydrazine. Someone asked about hydrazine fuel over lunch, leading to an interesting discussion. There are numerous variants of hydrazine, but what they all have in common is that they are incredibly unstable and violently reactive. Hydrazine is often used as a hypergolic fuel – add hydrazine or one of its derivatives and another liquid like methanol, or nitrogen tetroxide and you don’t need to think about doing anything else to the mixture because they explode on contact. You need do nothing more sophisticated or subtle than simply putting the two in the reaction chamber at the same time and “BOOOOOM!!!!” It is really nasty stuff because it is poisonous and also reacts violently with organic matter – Messerschmitt pilots in World War Two would literally be dissolved in the cockpit if there was a fuel leak. Missiles that used dimethyl hydrazine and nitrogen tetroxide as fuel produced an exhaust that was almost as unpleasant if you were nearby as the cargo at the top of the rocket. In Herschel we use it in the reaction jets, as the Apollo capsules did: spray a little hydrazine on a catalyst and it will decompose instantly into incredibly hot gas. This makes it ideal for thrusters for manoeuvring in space. Once the fuelling-up is finished we cannot imagine that it will be long before a final launch decision is taken.

While people are still getting over these tests, we are already preparing the next and, we hope, last. At lunch there was some gallows humour as we pondered, in the case of a further launch delay, what test number eight (rather than number three) might be like. Our conclusion is that we will never know because there will be a mass suicide before it ever happens. I have been discussing the draft test plan with various interested parties and making some adjustments and modifications based on a series of very perceptive suggestions that people have made about how it can be made most useful and focussed. Tomorrow I need to send out an agenda for the first planning Videocon. No peace for the wicked…