I meet Mathieu at 10am for a late breakfast – it’s already two and a half hours since I got up. So many things and so many photos to share!
Guillaume Blanchard is our first guide today, and he takes us to visit his realm, the MMB – the mirror maintenance building. Like all mirrors, those on telescopes are covered by a thin coating of metal, which tarnishes and attracts dust. So regularly, every 18-24 months, this metal coating has to be replaced. Guillaume shows us his most impressive machines, the ones designed to handle the 8.2-metre diameter VLT mirrors.
First, there is this machine, which removes the mirror from its mount:
Then this one, which reminds me of a centrifuge, but which is in fact nothing other than a giant dishwasher, which cleans with acid and caustic soda, and removes the residues left from the previous coating:
And last of all, a vacuum chamber on the roof of which Guillaume takes us to admire the cryogenic pumps that create the vacuum.
It’s in this chamber that the new coating, with a thickness of 0.1 microns, is applied to the mirror. Knowing that each of these telescope mirrors that together make up the VLT weighs 23 tonnes for a thickness of just 17 centimetres, and a price estimated at 50 million euros, I leave it to you to imagine the responsibility that weighs on Guillaume, who is forever testing new methods. I’m pretty sure he even used the term ‘cuisine’ at one point – experimental cuisine no doubt.
In a previous post, I talked about the future ELT and its 800 segments that will form a single mirror of almost 40 metres in diameter. Knowing that each of these 800 mirrors will have to be recoated every 18 months, he will presumably have to supervise the removal, cleaning, renovation and replacing of two mirrors every day. This reminds me of the Sisyphean labours imagined by the ancient Greeks!
After lunch, we head off to visit another workshop – a mechanical one, this time. Mechanics, carpentry, painting, welding – in fact, all the trades are present at Paranal.
From design to construction, everything is done internally, no matter what the final destination of the item is: maintenance of the residence or a specific requirement for a telescope. For the astronomers to do their work in the best of conditions, many unseen hands must work in the background. Paranal is so isolated that this independence is just common sense. The observatory is only tied down, really, by an optical fibre.
Since Mathieu needs to check that everything is ready in terms of logistics for the live videoconference with ESO Headquarters tomorrow – which will be broadcast online – we head up to the VLT platform, ever so stunning.
And the view…
We go back down again to the VISTA telescope (Visible and Infrared Survey Telescope for Astronomy), which boasts a 4-metre mirror and a wide field of view.
VISTA is located on a separate platform, a little lower down than the VLT’s, and it offers a new viewpoint over the surrounding desert.
On the picture above, Armazones, where the European – Extremely Large Telescope (E-ETL) and its 40 meters diameter mirror will be located.
Free time comes next, and I take advantage of it by going for a swim under the residence’s cupola. Some of its panes have been opened up, letting me see the blue sky. I clock up some lengths doing back-stroke for half an hour, and the feeling is divine! Some aspects of the residence remind me of a holiday camp, even if the astronomers’ nights are long, very long… not far off 12 hours.
I catch up with Mathieu again just after 7pm, for another sunset from the VLT platform.
Like yesterday, we see – without hearing – the VLT telescopes open up, but we waited in vain for the auxiliary telescopes to open, as they were undergoing technical checks that night.
Never mind, it’s time to go and talk to Henri Boffin about the details of the next morning’s planned live observations. Everybody seems ready and eager to participate in the event.
To finish the day, I take advantage of the fact that the Moon has not yet risen to take some photos of the Milky Way and Magellanic clouds. I also see four meteors, though obviously I don’t manage to take any pictures of them.
Nous redescendons à la Résidence tout juste à temps pour attraper un repas, il est déjà passé 22h30, je ne m’endormirai que plusieurs heures plus tard, pas si longtemps avant que le réveil ne sonne à 4 heures du matin…
We head down to the residence just in time to get a meal – it’s already 10.30pm, I’ll finally get to sleep only after a few more hours of writing and checking picture, and the alarm clock is set for 4am tomorrow morning.
- Translation provided by ESO.