In this month's Prospect, Stephen Eales reported from inside command HQ on the nerve-wracking launch of the Ariane 5 space rocket. Stephen is leading two of the surveys that the mission is hoping to carry out which, if successful, could help solve some of the deepest questions about how stars and galaxies are formed, and why the universe expanded so rapidly after the first split second of the big bang. The rocket launch was a success but, as his diary continued here reveals, there are an endless number of things that could still go awry...
Launch+3 days: I have never seen Matt Griffin nervous before. Matt, a tall, calm Irishman, has seemed to effortlessly manage a massive budget and a huge international team, including a large number of prima donna astronomers (his words), with remarkably little stress. He even claims that he wasn't too nervous during the launch, because if it all went wrong it wouldn’t be his fault. But now he’s about to set off for the European Space Operations Centre in Germany to supervise the switching-on of SPIRE, the camera he has spent 15 years of his life building. If it doesn’t work, it will be his fault. And since Herschel is now further away than the Moon, if SPIRE doesn’t switch on because of some dodgy connection, he won’t be able to go out and shake it.
Launch+5 days: One of the SPIRE team just passed me in the corridor. The word from Germany is that SPIRE has been switched on successfully.
Launch+7 days: Herschel is now twice as far away as the Moon. For a moment this did not make a lot of sense to me because it will take Herschel 60 days to reach the second Lagrangian point, which is only four times the distance to the Moon, but then I realised the solution was a piece of GCSE physics: Newton’s Law of Gravity. Herschel is gradually slowing down because of the Sun’s gravitational field.
Launch+13 days: A piece of space-speak I have grown to dislike is"single-point failure." When I asked Matt before launch how many single-point failures there were in Herschel—things that if they failed would scupper the whole mission—he was rather coy. He also didn’t make me particularly confident by claiming that Herschel would be the most complex telescope ever to be sent into space. The next potential single-point failure for SPIRE is when they try to cool it down tomorrow. At the moment, it is 4 degrees above absolute zero (that's a cool -269 degrees centigrade), but for SPIRE to work properly it needs to be only 0.3 degrees above absolute zero—otherwise radiation from the camera itself will swamp the faint emission from stars and galaxies that the camera is supposed to detect.
Launch+14 days: SPIRE is now the coldest place in space. This is because everything in space is bathed in radiation that was emitted shortly after the big bang, which keeps everything at a minimum temperature of 2.7 degrees above absolute temperature, unless, as in the case of SPIRE, it is actively cooled down with a refrigerating system. Therefore, unless there are some extra-terrestrials out there who have also invented refrigeration, SPIRE is now the record holder for the entire universe.
The final possible single-point failure is when they take the cover off the telescope in about ten days time. If that doesn’t work, we will have some beautifully working instruments but nothing to point them at.
To be continued...
