Friday, 5 October 2012

MIRI is not alone anymore

This week, I have been mostly preparing for the second part of our James Webb Space Telescope teacher CPD which we run annually with the National Science Learning Centre.

We held the first part shortly before I left for Chile, and 28 secondary science teachers and technicians from across the UK came to Edinburgh to learn all about the telescope and the UK's involvement.

Just before the workshop, the Mid-Infrared Instrument (MIRI) had been safely delivered to NASA Goddard - a real milestone in the project, and particularly significant for us at the Royal Observatory. Professor Gillian Wright, the director of STFC's UK Astronomy Technology Centre is the Principal Investigator for MIRI and has led a European consortium of 10 different European countries in this project.

During the workshop, we treated the teachers to a live link-up with NASA Goddard, and Martyn Wells, UK ATC optical engineer. Martyn, who had been involved in our JWST CPD the previous year, was unable to be there in person this year as he had to be at Goddard for some of the initial testing of MIRI.

You can find out more about some of the people involved in MIRI here.

On Monday, we hold the second part of the CPD in York, and I'm very much looking forward to seeing what the teachers have done since we last met and how they have been inspired by their trip to the Royal Observatory Edinburgh.

But, what has happened with JWST since then?

Well, MIRI was the first of the instruments to be delivered, and it has gone through all the necessary NASA checks since delivery and everything works as expected! Also, MIRI is no longer alone out there. Late July, the second instrument was delivered and is currently going through the same tests as MIRI did.

Even before it left the UK, MIRI had to undergo serious testing at STFC's RAL Space, including vibration testing which you can see more about in this video clip:

More recently, 2 of the mirror segments have been delivered. You can find out more about the segments in this BBC News article

Next year, all of the instruments will be tested together in a giant cryogenic chamber.

Wednesday, 22 August 2012

The last of KMOS leaves Edinburgh

Today, the final parts of KMOS left the UK ATC for their journey by air to Chile. The Cable Rotator left back in mid-July when I was still out there, and now the cryogenic unit has left too. But both deliveries will arrive at roughly the same time as the first went by boat - a 6 week journey.

There were 2 large lorries on site to pick up the 21 (!) boxes and take them on their journey to the airport.

A tight fit for the lorry through the gates!
One of the many boxes ready to go

Inside these various boxes are a selection of electrical cabinets, electrical and mechanical components, pipes, pumps, documents and manuals to name but a few things. And, of course, the cryostat itself - this box weighing in at a whopping 3.7 tonnes!

On Sunday, 3 of the UK ATC team will head out to Chile too, for at least 6 weeks, to test the instrument after its journey, put it all back together and to be there to fit it to the telescope.

The guys heading out are Alasdair Fairley, Project Manager; Phil Rees, systems engineer; and George Davidson, Technician. Out at Paranal, they will be joined by 2 electrical engineers and 1 software engineer from Germany and a mechanical engineer from Durham.

Some of those on the KMOS team

Wednesday, 25 July 2012

Universidad de Concepcion - Astronomy Outreach

On Monday and Tuesday I had been invited by Paulina Hernandez Jara, of the Universidad de Concepcion, to observe their public astronomy activities, for the winter holidays.

I arrived at the university on Monday late morning, and after a little bit of asking around, I found Paulina in the hall with the planetarium. It was lovely to meet her and she proceeded to introduce me to various different people from the Astronomy Department.

Me and some of the Concepcion outreach team

Paulina has worked as the outreach officer for the Astronomy Department for a couple of years and is a journalist by background. She had organised 2 weeks of public activities, following on from a very successful 1 week of activities in the past summer.

The programme of activities was fantastic - something for everyone, a great variety. The previous week they had 'Astro-Cine' and had shown various films, like 'Contact' and '2001 - A Space Odyssey'. Throughout the whole 2 weeks they also had various courses on different topics like black holes, exoplanets, stars and galaxies - given by professors of the department. They also had arranged for the Cerro Tololo Observatory outreach team to come with their planetarium and do shows each day for 1 week, as well as various other workshops and talks - including a workshop for pre-school children. They also had the IYA 2009 exhibition From Earth To The Universe on display. Also, each day, a post-grad or masters student would give a short talk on a different topic, like the history of astronomy, astrobiology and astronomy in different wavelengths.

The team providing the activities were a mixture of professors, post-docs and post-grads, as well as various undergrads helping out with the administration of the activities.

All the activities, bar the courses, were provided for free to the public. I asked Paulina how they got the funds for such a programme, and she told me that within the University there is an Arts and Culture department who fund activities for the public, but normally focussing more on the Arts side of things.

After chatting for a while with various people, and having a spot of lunch together with Paulina and Marcela (the department secretary) I went to the spectroscopy workshop which was being provided by Juan Sequel Beecher.

There were around 20 people who had booked in for this workshop, and they were a mixture of adults and children.

Juan started with an introduction to himself and the Cerro Tololo Observatory and made the very good point that there are many different people who work at observatories, not just astronomers. He himself is a mechanical engineer by background, and moved into outreach later.

He then continued to give a brief description of how our eyes work, comparing the sensors in our eyes to the sensors of a camera, and explaining that our eyes don't see colour well at night because of one of the cone cells.

After this he went on to explain a little about spectroscopy and the sequence of stars, and how we can find out information about the chemical composition of the stars by studying the light emitted, and using spectroscopy.

Juan had a selection of different lamps at the front of the room, and gave each member of the audience a handheld spectroscope and proceeded to go through each lamp in turn, so people could see the difference between the spectra. It was great and the audience were really getting it. He then did a great demonstration of what it's like looking at the stars - he switched on all of the lamps at the same time, so the people could see that there was a lot of information, as the spectra overlap. He explained that even though there is lots of information from one star, scientists are still able to distinguish the different chemicals.

Looking at the spectra of different lamps

Next, Juan used a portable spectroscope he had with him to show the line spectra on the screen. This was great as he had already explained that our eyes only see in the visible region (400 - 700nm) so he was able to then talk about energy efficiency of the different lamps. For example, the halogen lamp is not very efficient as much of the light it emits is in the infrared (i.e. the lamp gets very hot) so is wasting a lot of the light. Also, he showed a white LED and showed that it has a large peak in the blue region of the spectrum, where our eyes don't pick up a lot of light either. I loved this and could really see this working very well in schools.

After the workshop, I headed to the lecture theatre to see Matias Blaña, one of the post-grad students, give a talk on the history of astronomy. Of course, it was in Spanish, so I didn't understand all of it, but I really enjoyed it and he got a lot of questions afterwards, so clearly the rest of the audience were very engaged too.

At the end of the day, Paulina took me to talk to Dr Ricardo Bustos, who works with the GAVRT project, a NASA initiative for schools. Chile is the only other country outside of the USA to participate in the project, which involves pupils in schools remotely controlling the Goldstone Apple Valley Radio Telescopes in California. In Chile, this project has double value - as well as being beneficial to the pupils' science learning, it also helps them with their English as they have to communicate with the controllers in the states. The pupils can choose what they want to observe - satellites and planets for example. I really like the fact they can observe satellites as there is so much scope for then expanding the topic to different areas of physics and engineering.

Ricardo is the coordinator for Chile and currently there are 6 schools involved with the project. He is keen to get more teachers involved, but part of the requirement is that the teachers first go to California for 5 days of introductory courses and background information about the telescopes, which has to be paid by the school. Also, it is not financially viable for the GAVRT people to run the course for less than 6 people, so Ricardo has to get at least 6 people to go along. Another reason for having 6 is that following on from the course, not all of them will continue with the project, normally roughly 1 out of 6 will continue.

I could see similarities between this project and the likes of the projects involving robotic telescopes - Faulkes and Bradford - which are active in the UK. The benefit of course with this project is that it's a radio telescope, so the weather isn't quite so much of an issue and the timing of the observations isn't dependent on it being night-time.

On Tuesday, I met Paulina at about 9:30am, with Prof. Ezequiel Triester, and we headed off for one of the regional television channel studios! Ezequiel was being interviewed on a live morning show (a bit like 'Lorraine'!) all about the astronomy activities. It was fun to be in a TV studio and really funny to watch the piece before Ezequiel - the presenters were interviewing some kids, not sure exactly about what, but one little girl was in her tutu and doing ballet demonstrations which the presenters were copying!

In the TV studio

The coverage the activities got was fantastic. There was a short piece of pre-filmed footage, showing nice astronomical images and people coming out of the planetarium very happy. Then they interviewed Ezequiel, which I couldn't hear very well, but the whole piece was probably about 10 minutes long. I told Paulina that in Scotland, the TV companies are only really interested in our activities if it's a really big activity, with a particularly large audience. She has had excellent media interest for her activities, both regional and national TV companies had been in touch and along to film the activities.

Once we got back to the university, I met up with a group of about 6 post-grad students who are all really keen and active in outreach within the department.

I showed them our Deep Space activities and explained the thinking behind them, and how to run a workshop for a class. They were really enthusiastic and are very keen to use the resources. Paulina says they will translate them into Spanish and trial them with some schools, probably by the end of the year. She'll be giving me a copy of the translated worksheets, so hopefully I can get them going in Spain too.

The students asked me more about my job and the observatory, and I told them lots about the Curriculum for Excellence in Scotland. They particularly liked the fact that the Deep Space resources encourage the class to discuss their findings together, and I explained that one of the outcomes of the curriculum in Scotland is that they should be effective contributors.

After a lovely chat with them, Paulina and I headed for lunch with Ricardo, Ezequiel and one of Ezequiel's post-docs.

When we returned to the university, there were another 2 TV crews (nationals this time) who were filming at the planetarium and interviewing Ezequiel. This time though, I also got interviewed! Paulina introduced me to one of the crew and explained who I was and why I was there, and they thought it would be great to include me in their piece! So, I have been on TV in Chile!! It wasn't exactly a long piece, and when I saw it on the TV I was very embarrassed to hear how strong my Scottish accent is when I speak Spanish! But considering I could barely string 2 words together when I first arrived in Chile, I think it's quite an achievement!

I had such a fantastic time at the Universidad de Chile and it was wonderful to share ideas with such enthusiastic people and to hear of all their activities. I have come away with some great ideas too, for Visitor centre public activities. A fantastic end to a wonderful trip around Chile - I'm really glad I could include a visit to Concepcion, and that it coincided with their winter public activities.

A few days off in Valparaiso

After my time in La Serena and Valle de Elqui, I had decided to take a few days out and visit Valparaiso, which I had heard such great things about. Also, it was my birthday, so I figured I deserved a wee treat.

I was not disappointed by Valparaiso - such a cool place. Sadly on the first day I was there it was cloudy and very foggy so I wasn't able to appreciate the spectacular views of this amazing hilly city.

I took a walk to Pablo Neruda's Valparaiso house, La Sebastiana and had the weather been better, I would have been blessed with amazing views down to the port and across the city along the walk. Nevertheless, La Sebastiana was lovely. They have an audio guide so you can wander through at your own pace. It was pretty busy, though which is a shame as a lot of the rooms are quite small so sometimes it was difficult to see everything. Still, a really cool house and I really got a good impression of how Neruda loved the sea and to collect many different objects!

La Sebastiana
After the house, I wandered down towards the Museum of Open Air - an art installation throughout an area of the city, which is made up of lots of different paintings and graffiti on buildings and walls. I didn't see much of it, as even with a map, the streets are really difficult to navigate!

I then took a trip on the oldest of the 'ascencores' in Valparaiso - The Concepcion Ascencor. Built in 1883 and one of the 3 currently working in the city, it was an interesting experience! Thankfully the ride didn't last too long as I was a little worried about how rickety it was!! But still, good to take the trip.

After a spot of lunch in Cerro Concepcion I went to visit the Museo El Mirador de Lukas - a museum of cartoons by the Italian born 'Lukas'. He did cartoon strips for the local newspapers for years, displaying the life and city of Valparaiso as well as the rest of Chile. My Spanish has obviously improved as I could actually understand a lot of the cartoons, which were very funny.

On my second day, which was my birthday, the owner of the hostel took me and 2 German tourists to visit the Casablanca Valley and Isla Negra. This was a great way to spend my birthday - a bit of culture and some lovely wine!

We visited 2 wineries in the late morning - William Cole and Emiliana - and tried a total of 7 different wines. The Casablanca Valley is actually famous for its white wines because of the climate, but they do also grow Pinot Noir grapes, and the Emiliana has some Merlot grapes too. A lot of the wineries also make other wines, like the Carmenere (a favourite of mine), using grapes from other wine regions.

I had a pleasant surprise in both of the tastings. At William Cole, there was a Pinot Noir to try and previously, for example on my numerous vineyard visits in Australia, I hadn't been a fan of this wine. But, wow! The smell of this wine was stunning - full of vanilla and cinnamon - and the taste was lovely too. So, now I know, I can buy Chilean Pinot Noir when I get home and I'll like it!

The second surprise came at the Emiliana winery - organic and biodynamic vineyards. I really did not think for a second I was going to like this one, as I have really disliked it in the past. The Viognier. Again, the smell was totally amazing, this time just like honey. And it tasted delicious!

After the vineyards, we stopped off for lunch and I had a lovely rabbit stew - have been hankering after some rabbit for a while now!

Casa de Isla Negra
Then we headed to Isla Negra to see another of Pablo Neruda's houses, and this one, I think, is the best.

Again, an amazing collection of objects, and the rooms in this house are made out to either resemble a boat or a train carriage! In the first room, there is a huge collection of ship figureheads of all different sorts, some of them absolutely huge!

Pablo Neruda and his 3rd wife are buried here at Isla Negra, but this is a fairly recent thing.

The views from the house were beautiful too. Neruda called the place Isla Negra because, although its not an island, he felt like he was on an island when he looked out to sea and down to the black rocks below.

I loved Valparaiso, and it's definitely a place I'd like to explore more if I ever return to Chile.

Tuesday, 17 July 2012

Observatorio del Pangue

What a fantastic stargazing experience I had at Observatorio del Pangue on Monday evening. I had been in touch with Eric, who runs the observatory, since before I left the UK. Eric is a French astronomer, who, as it turns out, worked at the Royal Observatory Edinburgh for two years, back in the 90s. He and Christian, an astrophotographer from Vicuna, take small groups up to their small observatory approximately 16 km from Vicuna. The road there is mostly a dirt track, through amazing semi-desert landscape - lots of cacti!

There were 5 of us in total this evening - me and a Chilean family of 4. At the observatory, they have a 16 inch motorised Meade telescope, and of course, fantastic dark skies.

I've decided that for this blog post, I'm going to go through every amazing object I got to see...

Alpha Centauri

We started with one of our closest neighbouring stars, Alpha Centauri, just 4.37 light-years from the Sun. It is the brightest star in the constellation of Centaurus and the 3rd brightest star in the whole sky. But, it is not just one star, Alpha Centauri is actually a binary star system - designated Alpha Centauri AB. When you look through the telescope at this system, it looks a bit like a pair of headlights coming towards you! Research shows that actually many stars are binary star systems, or indeed multiple star systems.

Omega Centauri

Credit ESO
After Alpha Centauri we moved to another object in the constellation of Centaurus - Omega Centauri. I had seen this for the first time at Observatorio Mamalluca earlier in my trip and had been blown away by it.

It's quite astonishing to think that Edmund Halley first observed this back in 1677! But it wasn't until the 1800's that John Herschel (not the astronomer who discovered Uranus) correctly recognised it as a globular cluster.

Omega Centauri is about 15,800 light-years from Earth and contains several million stars - a huge cluster. It is of particular interest to astronomers because it is so different from other galactic globular clusters.

Carbon Star

Next, we moved onto something which I really wasn't familiar with at all - a carbon star near the Southern Cross. It was quite difficult to see with the telescope as it's not very bright and there was another bright star in the field of view, but once I had it, it was amazing - such an intense red colour.

Carbon stars are ones which are similar to red giants, and very close to the end of their life. Their atmosphere contains more carbon that oxygen, leading to the combination of the two elements to form carbon monoxide. This leaves carbon atoms free to form other carbon molecules, and leads to the striking red colour.

Swan Nebula

Credit ESO
The Swan Nebula forms part of the Omega Nebula, in the constellation of Sagittarius, between 5000 - 6000 light-years away.

The Omega Nebula itself is around 15 light-years in diameter but the cloud of interstellar matter of which it is a part spans some 40 light-years!

The Sagittarius Arm of our galaxy, where this nebula is, contains a large concentration of nebulae - in other words, is a large star formation region.

I can't honestly say I saw the swan shape of the nebula, but it was beautiful to see.

Jewel Box Cluster

Credit ESO
Next, we moved on to another type of cluster - an open cluster - called the Jewel Box cluster. This was one I had seen at Mamalluca and in San Pedro.

An open cluster is one where the stars have all been born out of the same nebula - like the Pleiades which we see well in the northern Hemisphere.

The Jewel Box is particularly pretty as it has 3 brightly coloured stars, including Kappa Crucis which is bright orange and so contrasts with its bluer neighbours.

It is estimated that the Jewel Box cluster is around 14 million years old - very young compared to the Pleiades at 65 million years old!

47 Tucanae Cluster

Credit ESO
Sticking with clusters, but going back to globular, I got the chance to see the 47 Tucanae cluster.

47 Tucanae is slightly further away than Omega Centauri, around 16,700 light-years away, but almost as bright. It too is made up from millions of stars.

Globular clusters are fairly common in galaxies - our own Milky Way has around 150. They are generally contain many more stars than open clusters, and are older.

Eric said he finds it difficult to choose which of Omega and Tucanae he prefers to observe, and I quite agree. They're both beautiful to look at.

Carina Nebula

Credit ESO
The Carina Nebula is really stunning to look at and is another of the star formation regions in the Sagittarius arm of our Galaxy. The nebula is between 6500 - 10000 light-years from Earth. It is one of the largest diffuse nebulae in the skies, 4 times bigger than the Orion Nebula!

It surrounds various open clusters of stars, and one bright star of particular interest is Eta Carinae - one of the most massive and luminous in our Galaxy.

Eta Carinae. Credit Hubble
Eta Carinae is so interesting because around it is a strange mini-nebula, which is thought to have been caused by an eruption of the star in the 1800's. Christian changed the eye-piece on the telescope to a higher magnification, so we could see this feature.

The star looked a bit like it had Mickey Mouse ears on it, one slightly larger than the other! It was amazing to see this 'broken' star, which really, isn't there any more. I saw something which doesn't exist any more!

Tarantula Nebula

Credit ESO
Something I had been really pleased to see here in the Southern Hemisphere are the Magellanic Clouds. Although I have been in the Southern Hemisphere before, that was before I worked in astronomy. I was always interested in astronomy, but I didn't know to look out for these members of our local group.

So, as I knew this would probably be my last opportunity to see them, I asked if we could observe one of them with the telescope. Eric and Christian obliged to my delight, and focussed the telescope on the Tarantula Nebula, within the Large Magellanic Cloud.

I mentioned this nebula in a previous post as my friend and colleague's research area is super-massive stars and the Tarantula Nebula has some of these, and some which are acting quite strange.

With this nebula, I could definitely see where it gets its name!

Sombrero Galaxy

Credit ESO
I also got another chance to see the Sombrero Galaxy, which I had seen in San Pedro. This time it was better though, as the telescope was larger, so I could really see the shape. In San Pedro it was more of a smudge and quite difficult to distinguish.

28 million light-years from us, it's just amazing that we can see something at this distance with just a 16" telescope!

The Sombrero Galaxy gets its name from the unusually bright nucleus and the dark prominent dust line.

Planetary Nebula

Credit Hubble
We also got to see a planetary nebula - a dying star. The one we looked at is nicknamed 'The Ghost of Jupiter' as when it was first observed, it was thought to be a planet.

A planetary nebula is a late stage in the life of certain types of stars. William Herschel (the one who discovered Uranus) came up with the term, because he thought this type of nebula looked like the planet Uranus through the telescope. Although the nebula has nothing to do with planet formation, the name has stuck.

With the telescope, it looks like a diffuse oval of light - not as pronounced as a planet, much hazier.

Centaurus A

Credit ESO
We also got to see Centaurus A - a collision of galaxies.

At roughly 10 - 16 million light-years distance, Centaurus A is one of the closest radio galaxies and as such has been studied extensively. Studies show that the Sombrero Galaxy is undoing an intensified rate of star formation - something which regularly occurs due to galaxy collisions.

You can clearly see in the telescope, a black bar (dust) going across the brighter object (a spiral galaxy face on) behind.


Saturn, taken with my camera through telescope
To finish the official part of the public event, we saw Saturn. This was by far the best view I've ever had of Saturn and I could even see 5 of its moons, including Titan and Enceladus.

I asked Christian if my camera would be able to capture the image of Saturn through the eye piece of the telescope, and with a bit of fiddling with settings, he was able to get this image.

He also took a couple of video clips of it which are also very cool.

I'm quite pleased that you can even see a little colour in the image too!

I stayed a little later with Eric and Christian after the family had left and played around with my camera trying to get some more good shots of the Galactic centre and even trying to get the Magellanic Clouds. I'm quite pleased with the results I got, which you can see on my flickr account

Whilst I was playing around with my camera, Eric and Christian were doing some more serious work. 3 nights earlier, they had taken a picture of the night sky, towards the Galactic Centre. This evening, they were going to take the same shot again, with the purpose of getting an image of Pluto. They would be comparing the two photos to look for the object which had moved.

It was really exciting to be there and seeing the comparison, especially when they found it! What a fantastic way to finish off my stargazing experience in the Southern Hemisphere - to be able to say I saw an image of Pluto as taken with a 16" telescope!

KMOS Has Left The Building!

As I contemplate the sad fact that I have less than 2 weeks left in Chile, back home in Edinburgh, KMOS started its journey here on Monday.

The delicate job of packing KMOS up began on Monday morning at the UK Astronomy Technology Centre. A huge lorry arrived on site to transport the instrument and cable rotator to Tilbury Docks, London.

The Cable Rotator (CACOR) will be transported by boat and will take 6 weeks to arrive. The instrument itself goes by air and will be at the assembly hall in Paranal in 1 week. So as I fly home, I'll be flying over the CACOR in transportation somewhere on the Atlantic Ocean.

For a more detailed description of what KMOS is and how it will work, have a look at this STFC Backstage Science video clip:

And to find out more about being an instrument scientist, watch this video interview with Michele Cirasuolo, UK ATC Instrument Scientist for KMOS:

UT1 is ready and waiting for KMOS
Whilst at Paranal, I specifically asked to see Unit Telescope 1 (Antu) so I could see where KMOS would go. It was great to see 'the other side'! 

During the 6 years I've been working at the Royal Observatory Edinburgh, I've been seeing all these amazing instruments being created and tested in the Crawford Laboratory. Now, I've actually been able to see where one will go.

It is incredible to think that by the end of this year, KMOS will be getting its first science results, right there, where I stood.

Sunday, 15 July 2012

Paranal Visit

Me and the Very Large Telescope
To say I was excited about the prospect of visiting Paranal would be an understatement. I'm not sure exactly why this visit in particular held so much excitement for me. Perhaps it was because until I had actually started my trip in Chile, I thought I was only going to be able to visit as part of one of the tourist tours. Instead, as things turned out, I was able to have an overnight stay at the infamous Paranal Residencia.

Unfortunately, it was cloudy and extremely windy on the night I stayed over, so I didn't get to see the telescopes opening and operational at night - I barely even saw the stars at night - but still, that didn't stop the visit from being thoroughly enjoyable and hugely interesting.

My host, Laura, whom I had met at the ESO offices in Santiago earlier in my trip, was hosting a French film-making team, which was why I was able to go up and visit too. The French team had been commissioned to make a film for planetarium use, about an astronomer using the VLT and E-ELT to find out more about exoplanets. Specifically, using the E-ELT to try and detect water on an exoplanet.

I spent the night before my visit in a hotel in Antofagasta, and was picked up by the Paranal bus from outside the hotel. There were probably around 10 - 15 people also getting the bus there - mostly engineers.

Life at Paranal

Paranal Residencia
It seems fitting to start with some information about the Residencia, which in itself is a pretty amazing place. You may recognise it from a certain James Bond film, Quantum of Solace - its the building which gets blown up a bit at the end of the film! But enough about that for now.
The Residencia was finished and opened in 2001. It was designed especially so that it would not intrude too much on the surrounding landscape - in fact, when you first arrive on-site, you can barely see it as you're on the roof of it. The colour of the building is not down to paint, instead, pigments have been added to the building materials to blend in with the nature around. It has also been designed to withstand a Richter Scale 10 earthquake, which luckily it hasn't had to stand up to so far, but it has seen some big ones.

Inside the Residencia, the first thing you notice is the swimming pool, and tropical looking garden around it. It looks very luxurious. Not only is the pool there as a health and leisure facility for those working at Paranal, but it also serves a purpose in maintaining the humidity and temperature of the complex. Outside, there is typically 5-10% humidity but inside, thanks to the pool, there is around 30% humidity. By helping to maintain a constant temperature, it also serves for energy conservation - there is very little air conditioning or heating needed in the Residencia. Additionally, the pool helps to maintain the plants which surround it.

Laura explained that often, people who come to visit Paranal think the Residencia is a bit over the top for a workers' hotel. However, when you consider that people generally work shifts (8 days on, 6 days off, or similar) and they are 110km from the nearest small town (Taltal), having a good variety of leisure facilities and as comfortable a residence as possible is necessary.

The Residencia has also been designed to limit light pollution from it as much as possible. As such, the windows are all very small and have blinds on them. Also, the glass doors to the balcony areas have wooden sliding doors behind to be closed at night. Also, the roof above the swimming pool has a cover which automatically closes on sunset and reopens on sunrise.

Typically, there are around 120 people working on-site at any one time. Of those, only about 10% are astronomers, around 40-50 are engineers, and the remaining are contractors who look after the catering, maintenance, logistics, cleaning etc.

Everything has to be brought in from off-site, in particular, water. Around 60,000 litres of water are brought in per day, in 20,000 litre capacity tankers.

One really lovely touch in the Residencia which I particularly liked were the hand-made rugs you can see dotted around the communal areas. The rugs have images of the first science results from the VLT. 

I also particularly liked the fact that all the crockery is branded with 'ESO Paranal' - and the towels too!

It was interesting to hear from Laura that many of the temporary buildings currently being used on the ALMA OSF site for accommodation and facilities, were also used during the construction phase of Paranal.

Why Here?

So why exactly was Paranal chosen as an optimum site for a professional observatory? The Humboldt Current, which comes in from the Pacific Ocean, helps to maintain the excellent atmospheric conditions of the area. The Current maintains the sea temperature at around 14 C, and creates a thermal inversion layer at around 1100m, meaning that normally, the VLT sits above the cloud layer and the atmosphere is very still.
Layer of cloud at 1100m and abnormal clouds higher up!

The Telescopes

After a good look around the Residencia, getting settled in my room and having some lunch, we headed off up towards the telescopes. The film crew were looking for a good spot to film the sunrise the following day, and Laura suggested up near VISTA might be good. VISTA is on a hill which is referred to as the NTT Peak (NTT = New Technology Telescope) as originally the NTT was going to be situated at Paranal. Instead it is at the La Silla really the hill should be renamed the VISTA Peak. That has a much nicer ring to it!

Anyway, whilst the film crew were checking out the view and conditions, Laura took me in to see VISTA.

VISTA - Visible and Infrared Survey Telescope for Astronomy

VISTA is a 4.1m survey telescope, which the UK ATC project managed. It's one of the first projects I remember being completed in my time working at the Royal Observatory Edinburgh. First light for VISTA was in December 2009.

It is a very compact telescope, with not much space between the primary and secondary mirrors - in other words, it has a very short focal length. It has a large field of view, of 1.5 square degrees (roughly the area the full Moon covers) and, due to the size of the primary mirror, can see faint objects too - so a perfect survey telescope.

The primary mirror on VISTA is quite special - it is the most highly curved mirror of this size ever made for a telescope. Also, any deviations on the surface are less than 1/3000th of the thickness of a human hair. As I mentioned in my ALMA OSF post, the precision in the surface of mirrors for infrared telescopes needs to be much greater than it does with ALMA. The level of precision correlates with the wavelength the telescope works at.

The original coating on the VISTA mirror was silver, chosen, as with Gemini, for its good reflectivity in the infrared. However, its durability is not so great and so now the VISTA M1 is coated with aluminium. VISTA has its own coating plant right there in the building - so the mirror doesn't have to be transported far to be re-coated.

The VLT - Very Large Telescope

After some time having a look at VISTA, Laura took me up to the VLT platform. On the platform there are not just the four 8.2m telescopes of the VLT, but also the 4 Auxiliary Telescopes (ATs) used for interferometry and the VLT Survey Telescope.

It was extremely windy by this time and very shortly after we arrived Laura got a message over the radio system saying we were no longer allowed to be out on the platform. Already at this stage, even with a good 3 hours til sunset, the opening of the telescopes was not looking hopeful. Firstly, the cloud layer wasn't looking like it was moving anywhere. Secondly, the gusts of wind were reaching higher than 18m per second - the maximum wind speed of operation.

So, we went indoors and to see UT1, or Antu - the telescope where the UK ATC instrument KMOS will be going. I had specifically asked Laura if I could see this telescope. There is a tunnel system underneath the platform which allowed us to still be able to enter the telescope. The tunnel system, as well as being a passageway for workers, is also where all the cables are for combining the light from the ATs for interferometry.

The Unit Telescopes

Each one of the Unit Telescopes of the VLT has a primary mirror of 8.2m diameter and 17cm thickness - 23 tonnes of glass ceramic! The material it is made from is called 'Zerodur'. This is a very stable material but as the telescope moves, gravity acts on it so active optics compensate for these deformations. There are 150 actuators on the primary mirror, and they move to make corrections roughly every 30 seconds.

The primary mirrors are re-coated roughly every 18 months, and unlike the VISTA mirror, they have to be transported down to base camp for this to be done. This is a particularly delicate operation - after all, it involves handling the most expensive and delicate part of the telescope. There are no spare primary mirrors! So, the mirror is transported down the hill, travelling at 5km/hr. The whole process takes around 1 week from when the mirror is removed from the telescope to when it is replaced.

The mirror of UT1 was covered when we were in to see it - to protect from any dust which might have been blowing around in the high winds. When dust accumulates on the mirror, it may only reduce the reflectivity by a couple of % but every photon is valuable, to preserve the quality of the image. To protect the mirror, when the dome is opened at night, the telescope is tilted to 90°, to prevent anything falling on it.

The tower of the secondary mirror on these telescopes is mechanically the most complicated part of the telescope, as it has to move a lot to maintain the focus of the image. The mirror itself is made from beryllium - making it both light and stiff.

The telescopes are built on altazimuth mounts rather than equatorial. This has the advantage that the enclosures are much smaller than they would be with an equatorial mount. With an altazimuth mount, it does mean the telescope has to move in 2 directions at different speeds to track an object. The NTT (New Technology Telescope - the name makes sense to me now) was actually a prototype for the VLT unit telescopes. It was the first large telescope to be built with an altazimuth mount. It was also a prototype for the active optics on the primary mirror.


Tertiary mirror on UT1
Each of the Unit Telescopes has 3 different instruments and the tertiary mirror sends the light to the chosen instrument. On UT1 there are currently only 2 instruments attached as KMOS will be fitted shortly. In fact, KMOS is getting packed up and shipped on Monday from Edinburgh. Watch this blog for more information on that.

The instruments UT1 has are CRIRES, on Nasmyth A and FORS 2 on the Cassegrain - both different types of spectrograph. KMOS will be fitted to the Nasmyth B position.

The VLT is now onto its second generation of instruments - typically an instrument will last/be used for around 10 years.


The VLT was built with the objective of combining the 4 telescopes together for interferometry. In practise, around 20% of the Unit Telescope time is spent on interferometry, but the Auxiliary Telescopes are used for interferometry all the time.

There are 30 different stations where the ATs can be positioned on the platform, with a maximum distance of 120m, which, by the process of interferometry, means the equivalent of a 120m diameter telescope.

In the interferometer, the combined light has a very complicated path to follow, bouncing off 17 mirrors on its travels. This means that most of the light is lost - only around 30% of the original light is received. Because of this, typically, the interferometry is only done for objects which are visible to the naked eye (approximately magnitude <6).

On the platform, there are certain areas where you are not allowed to walk, as even the smallest vibration can cause disruption to the interferometer.

The Control Room

UT1 control station
We headed back to the control room afterwards and spoke with a couple of the engineers and astronomers there.

Inside the control room, there are separate control stations for each one of the Unit Telescopes of the VLT, the 2 survey telescopes, and the VLT Interferometer - making a total of 6 control stations. There is also a control station already set aside for the European Extremely Large Telescope, but for now all the screens are showing are the weather monitors.

Each observing night, there would normally be 2 people at each control station: one astronomer and one telescope and instrument operator. Sometimes there will be extra people, for example visiting astronomers, or new staff.

On any given night, the number of observations can vary. One observation might be for 6 hours of the night, others can be very brief. To change between the different instruments on the telescopes takes a maximum of 10 minutes, depending on the position of the telescope. The telescope needs to be in the stand-by position to change instruments (i.e. pointing directly upwards) so the further from this position it is, the longer it takes to change instrument.

You could tell there was a mixed sense of disappointment and relief in the control room, since it was looking unlikely the telescopes would be operating. It must be tough working shifts like that - getting a night off must be a welcome relief at times. Although, I'm not sure exactly whether they would really have the night off, or be on-call just in case the weather improved.

Maintenance Buildings

AT1 in for maintenance
One of the ATs was in the maintenance building for routine checks and to have some of its mirrors re-coated. The primary mirrors on the ATs are only re-coated every 5 years. This one was having M2, M3 and M4 re-coated. This was the second of the ATs which they had worked on this year, and in September they would be re-coating the same mirrors on one of the other AT's. I think, by the end of the year, they would have worked on all 4 of them.

Usually, the re-coating is done with the large re-coating machine which is in the maintenance building, but at the moment, they're having some technical problems with this, so the mirrors of the AT were transported up to the VISTA coating plant.

European Extremely Large Telescope

Me and Cerro Armazones
On the Tuesday, the film crew wanted to get some footage of their 'star' astronomer driving through the desert on the way to the E-ELT, so we headed off on the dirt road to Cerro Armazones.

Once built, the E-ELT will be controlled from Paranal - although it is on a mountain around 20km away from Paranal, it is still going to be a Paranal Observatory telescope. 

I still can't quite imagine just how big the E-ELT is going to be - it seems impossible to think of building something that big, having already thought the ALMA dishes were huge!

The E-ELT primary mirror will be made of segments and because there are so many of them (around 800), the re-coating process will be practically continuous. One segment will be re-coated each day, so it is very likely that the E-ELT will have its own coating plant on-site - it wouldn't be very practical to have to transport a segment 20km and back each day!

Although I didn't get to see the opening of the telescopes at Paranal, I still had an amazing time. I think having been to ALMA first, which is still under construction, and then to Paranal, really helped me to imagine both Paranal under construction and what the ALMA site will be like when complete. Just need to make sure I can get out here again to see the E-ELT being constructed!

Friday, 13 July 2012

Valle de la Luna

On Saturday, I had an afternoon trip to the Valle de la Luna, an area where a prototype for a Mars Rover was tested because of the dry and challenging landscape.

Personally, I think it should be renamed Valle de Martes, since to me, the colours more resemble the surface of Mars rather than the Moon. Whichever you want to call it, it certainly does seem 'other worldly'.

It is an incredible place, which has been sculpted by wind and water over the years, and is part of the Salar de Atacama. Salt deposits occur from the water which comes down from the mountains. Over time the deposits built up and became compacted. Tectonic movements over the years have folded the layers and created strange curves of rock, sometimes perpendicular to their original orientation. A mixture of salt, rock and sand, form strange almost man-made looking, structures.

The Three Marias

Me in front of the 'Amphitheatre'
After the Valle de la Luna, we went for a quick look at the Valle de la Muerte. Supposedly, the Belgian  Jesuit missionary, Gustavo Le Paige, actually named it Valle de la Martes (i.e Valley of Mars) but didn't realise that Martes is actually a masculine word, so the name ended up being heard as Valle de la Muerte and has stuck ever since.

Anyway, I feel I'm getting a little too fixated on this valley naming business!

One cool feature there is in Valle de la Muerte, is a layer of volcanic ash, trapped in amongst the rock formations. There are many volcanoes around San Pedro, many of which are now inactive, but had plenty of activity in years gone by. In fact, not too far from San Pedro is the most active volcano in all of Chile - the Lascar Volcano. Apparently, there has been an 'amber' alert of activity on this volcano for the past 2 years.

The white-ish layer is volcanic ash
We headed off in time for the sunset, to watch the colours change over the Valle de la Luna. It wasn't really so much a case of watching the sunset, as the sky wasn't that spectacular, but the colour changes in the valley were quite stunning - from bright rust-red, to brown, to purples and pinks.

While the Sun was still up

And once the Sun had gone down

Stargazing in the Atacama Desert

After our trip to ALMA, Liliana, Olivier and I managed to get the last 3 places on one of the many stargazing trips on offer from San Pedro. We went with Space, whom I had read were the best ones to go with, and whom I had contacted before I left the UK. We did speak to another agency offering a tour, but I was severely put off by the fact the guy was trying to tell us that the fact that the Moon would be up (this tour was happening later in the night than the one we went on) wouldn't be a problem at all. Nonsense. The Moon was in a waning gibbous phase and would have made it more difficult to see the Milky Way, despite the low artificial light pollution levels. It definitely wouldn't have had no effect whatsoever.

Space is run by Alain Maury, an astronomer, who actually used to work at the Royal Observatory Edinburgh. He and his partner, Alejandra, run tours in French, Spanish and English, every night - as long as its not cloudy. And thankfully, we had a lovely clear night.

We got picked up by the bus in the centre of San Pedro and were driven about half an hour out of the town where we found 10 telescopes outside.

There were a few French people in the group, so Olivier went with them, and Alain, for his tour. Liliana and I stayed in the English speaking group which was led by Ale.

Ale did an excellent job of leading us through the night sky, doing the usual sort of guidance, with a laser pointer. Being in this group, and also my experience at Mamalluca earlier in my trip, really did remind me that you shouldn't assume anything with a general public group. By that, I mean that its really important to start with the basics and work up, without being patronising, of course, because you can't assume that everyone knows and understands the difference between the Solar System and the Galaxy, or between a star and a planet.

Some things which Ale did which really impressed me, and which I'd be keen to use at future public events at the observatory:

  1. Making people feel at ease with the notion of using light years as a measure of distance. Ale did this by saying that using time to measure distances really wasn't that uncommon. She asked someone how far San Pedro was from there, and quite naturally, got the response 'about half an hour away'. Such a simple thing but so effective.
  2. Explaining why we see different constellations in the Northern Hemisphere. Many of the group were European, and as such, not so familiar (just like me!) with the Southern Hemisphere night sky. Ale did a great job of explaining that your latitude on Earth, and the fact that the Earth is tilted, dictates what constellations you will see. She used the laser pointer to make some examples, showing where Polaris would be in London for example. I really liked this. We get a reasonable number of tourists visiting the observatory in Edinburgh - maybe not so many from the Southern Hemisphere...but I still think its worth explaining.
We spent around an hour with Ale showing us the various constellations. We even saw the zodiacal light, something I had never seen (knowingly) before.

Liliana with one of the telescopes
After this introduction, Ale took us round the various telescopes. I think this is possibly the one bit which could have been better. As we were such a large group - possibly about 25 of us - Ale took us round each telescope in turn telling us a little about the object the telescope was pointed at. This meant that at each telescope only around 5 people had a look as she was explaining, and then she moved on to the next telescope. Of course, we had time afterwards to go back to the different telescopes, but I just felt, that perhaps people didn't get as much out of it as they could. For example, there were around 20 of us at Mamalluca, and although there weren't as many telescopes, I felt the explainer there did a better job of showing us a few different objects and talked about each one in much more detail.

That said, I still think it was an excellent event, and I did get to see the Sombrero Galaxy for the first time, Alpha Centauri (a binary star system) and I had a better look at the Jewel Box cluster.

Unfortunately, I forgot my mini-tripod so wasn't able to get any fantastic shots of the Milky Way, but I did have a go, just laying my camera on the ground or sitting it on a table. I got a couple of mediocre shots. This one is my favourite although I'm not sure how well you'll be able to see it on your computer. It has Antares and Scorpio in it (well, most of the Scorpio constellation) and at the bottom of the picture is the Milky Way.

After we had all had some extra time to look through the telescopes, we headed inside (except it wasn't really inside - there was no roof, which was very cool!) for a hot drink (nice touch) and a chance to ask Alain any questions we might have. He's a really entertaining guy and gave very clear and interesting answers to the questions he was given.

Sunday, 8 July 2012

ALMA Array Operations Site Visit

An early start on Friday  for our second day of ALMA activities. Liliana and Olivier met me at 7:30am and we met Valeria shortly after 8am at the OSF. At the control at the entrance, I had to do an alcohol test - first time I've ever done one of those!! Of course, I had heeded Valeria's advice and hadn't drunk any alcohol the evening before so I had a reading of 0. The guard explained that before 8am, all drivers must do a breathalyser test (and have a reading of 0) and passengers are subject to random testing too.

Although we had all submitted a medical certificate to say we were fit and healthy to go to the 5000m site, ALMA have a policy to do a quick medical check on everyone before they ascend. This involved checking our blood pressure. Mine was a little higher than usual - normally mine is around 120 over 70, but it was 130 over 80- but still within the limits set by the doctors. Thankfully, Liliana and Olivier were both fine too, so we could all go up!

Whilst we were waiting in the medical room, Valeria had gone to get the oxygen cylinders and some food supplies for us to take up to 5000m. She also got us each an ALMA hat, which I was totally delighted with! I'd seen them in the safety video the day before and quite fancied one!

Then we set off - Valeria drove us there, stopping along the way to get some photos and point out some of the traditional Atacameño features which have been preserved along the roadside. One of these was a stancia - a place where nomadic Atacameño people would stay when up in the mountains with their animals. Valeria explained that before construction began, ALMA took an environmental and cultural responsibility and had employed an ecologist and biologist to ensure that native flora and fauna were protected.  

The view was quite stunning on the road up and we also saw some HUGE cacti!
Valeria and I (with my ALMA hat) and a big cactus
All the way up in the car, we had to monitor our blood oxygen levels and heart rate. We did this by putting a little meter thing on our index finger. If our oxygen levels dropped below 80% we had to take oxygen from the cylinder. Valeria also had to radio in every 10km to base. Valeria's and my oxygen levels did indeed drop below the 80% on the journey up, so I had my first experience of inhaling oxygen from the cylinder.

Once we reached the top, we found that once again we were very lucky - one of the North American antennae was being moved down to the OSF for routine maintenance and we were just in time to see this happening. It's quite an incredible feat. Each antennae weighs around 100 tonnes and the transporters (called Otto and Lore - German machinery of course!) are built to carry one antenna each. The transporters have 14 sets of double wheels which can move independently, meaning it can turn in reasonably small areas, despite its huge size!
 We had missed the antennae first being put onto the transporter, but managed to see all the rest of the procedure. All in all, it takes around 5 hours to transport one antenna from the AOS to the OSF.

Seeing the AOS was incredible. Already, even with just over half of the antennae in place, it seems huge - and it can be even bigger too. There are 250 pads where the antennae can be moved to for different observations. All the proposals requiring the same configuration of dishes will be gathered together and the dishes moved into the positions and the observations done.

I certainly felt the altitude in terms of lack of oxygen - it made me feel very sleepy at times, although it's not really much wonder. My oxygen level at one stage was 65% and my heart rate 94 bpm. So, needless to say, I needed a bit more supplementary oxygen.
Oxygen please!
Once we had watched the antenna being lifted onto the transporter and the transporter started to move off (Olivier and Liliana even had a go in the drivers cabin!) we headed inside to the technical building to speak to some of the computer engineers who handle the correlators.

We met 2 guys, who were attached to a permanent supply of oxygen. I asked if they always had this when working up at the AOS and they said they did. They normally spend around 4 hours there, and because they need to use their brains a lot, they need their oxygen levels to be at a reasonable level.

They showed us the super computers which are the correlators. First the one which is just for the Atacama Compact Array, so only the 16 East Asia dishes, and then the second super computer for the wider array.
Atacama Compact Array correlator
The job of the correlator is to collect all the signals from the antennae. In the 'Base' correlator (the one for the wider array) there are 4 quadrants, each one working in a different wavelength range. Each quadrant has an energy consumption of 40kW per hour. To compare, typically, your television uses 0.2kW per hour. There are 1250 cables for each quadrant (see picture) and each quadrant receives approximately 120gigabytes of data per antennae per second!

The room where the correlators are must be kept at a stable temperature (less than 20°C) and with reasonably high humidity (around 30 - 40%). These conditions help to avoid electrostatic charges.

On our way back down to the OSF we caught up with the transporter and American antenna number 11 on its journey:

Another fascinating day, and so amazing to see the Array Operations Site itself. I really don't know how the people work up there - it is absolutely freezing outside with the antennae and the lack of oxygen made me so tired! Whilst we were up there some of the work actually got stopped because the wind was picking up again. Just a clear example of the challenges this huge project faces.

ALMA Operations Support Facility Visit

On Thursday I had the pleasure of visiting the ALMA Operations Support Facility. I had hired a car to get me there and had 2 passengers to accompany me - Liliana, a Columbian journalist, and Olivier, a French engineering student. They met me at my hostel around 12:30pm and we set off to meet Valeria at the site for lunch. The Operations Support Facility is around a half hour drive from the town of San Pedro, where I've been staying for this week, and is at an altitude of 2900m.

Liliana and I on the road to ALMA OSF
After about 15 minutes driving on the main road, we took the turn off for ALMA and stopped at the control. We had to give our passports in and watch a safety video about being at the site - mainly covering driving rules and safety tips in terms of sun protection. We were given our entry passes and headed off up the dirt road to the OSF.
 The road was very similar to the road to Gemini, so I wasn't too worried about my driving on it. Also, I had another ute to drive, so I was quite happy!

Once we arrived on site, we met Valeria in the canteen and had lunch, chatting to some of the people who work there. Valeria told us that there are around 500 people currently working at the OSF.

ALMA truly is an international project. There are 20 countries involved - the dishes are being made by ESO (14 European countries, plus Brazil), North Americans (USA and Canada) and East Asia (Japan and Taiwan), and of course, Chile is hugely involved. The East Asian companies are making 16 of the antennae (including all eight of the 7m dishes for the Atacama Compact Array), and the Europeans and North Americans are making 25 each of the 12m dishes. The North Americans are due to be finished their dishes by September 2012, and the whole project is due to be complete by the end of 2013.

During lunch, the wind picked up and when I looked out the window I could no longer see anything for the dust! This actually ended up working in our favour.

RAL cryostat
After lunch, Valeria took us into one of the lab areas, where they were testing cryostats - cryostats made by our STFC sister site Rutherford Appleton Laboratory no less. The engineers were testing the cryostats for leaks and making any repairs necessary. We talked with a few of the engineers, and one had actually been at RAL last year helping with the assembly of the cryostats.

One of the cryostats was open as they had discovered a broken piece inside, so were removing the small fragments of plastic. The cryostat looks amazing inside - first time I've ever seen inside one - with lots of copper. The cryostats are used to cool the 'Bands' (I'll come on to them in a little bit) and the central area is cooled to 4K, then there is an outer sleeve at 15K and an outermost sleeve at 110K. The noise in the lab area was very familiar - exactly the noise I've heard many times in the Crawford Laboratory of the UK ATC, of the Helium being pumped in and out of the cryostats.
Inside RAL cryostat

After seeing the cryostats, we went into another lab space to have the 'Bands' explained to us. Unfortunately, this is probably one of the most complicated parts of the technology and it was explained in Spanish, so I definitely didn't catch everything! Having said that, I'm not sure I would have understood it all even if it had been explained in English!

Here is my very simple explanation of what I understood about the Bands. The Bands take the signal from the telescope and they work at different frequencies. In total, when complete, there will be 10 different Bands, and at the moment, I think there are 4 operational, and a further 2 working as prototypes. The Bands need to be cooled, which is what the cryostats are used for.

From what I understood, we are not able to work with the frequency of the signal we receive from the telescopes, so it is mixed with another signal of known frequency and they cancel each other out to produce a frequency which can be worked with. As I said, this really is something I'm not familiar with and having to translate from Spanish didn't help things! Apologies if my explanation doesn't make sense. I'll endeavour to find out more and do a better explanation at a later date.

After the labs, we were taken to meet Christian, one of the European engineers working on the assembly of the antennae. We got into the assembly hall, where 2 antennae were being worked on. I found this part absolutely fascinating.

The European dishes arrive in 2 parts from France, and are glued together at the OSF in the assembly hanger. This process involves around 30 people, takes around 4 hours and is normally done at night, in stable temperature conditions. The glue is like super-glue, and comes in 2 parts. Once mixed together you have a couple of hours before it sets.

During the process, the accuracy of the positioning is checked using a laser and once happy that the position is correct, the bolts are tightened. Lightening protection (copper wiring) is also added to the dish.

The dishes and the cabin beneath are made from carbon fibre and the base and arms are made from steel. Carbon fibre is used for the dish to keep the temperature stable.

Once the dish is stuck together, the reflective panels must be added. The panels come from Italy, and the final reflective coating on the panels is nickel, which is chosen specifically for the wavelengths ALMA works at. Since it is such a large dish, there are many panels - 120 per antenna. Each panel has 5 actuators so it can be positioned with an error of only 12 microns. Although this is extremely precise, because of the wavelengths ALMA is working at, it is not necessary for the positioning of the panels to be as precise as an optical/infrared telescope. For example, the European Extremely Large Telescope, whose primary mirror will also be made up of segments, requires its segments to be positioned with precision on the nanometer scale.
Positioning the panels
We were really lucky to be able to see this process in action, as work had just started positioning panels onto one of the dishes in the hanger. The whole process of adding the panels takes around 2-3 weeks per antenna.

First, the engineers attach the actuators for one panel, and check the accuracy of the position with a laser system - making the tiny corrections as needed. After all 5 actuators are in the correct position, the base of the panel is attached (as in the photo) and finally the panel itself. Even once the panel is in position, it is still possible to adjust the actuators.

In the hanger we also saw one of the holders for the secondary reflector. Inside the holder is a piezoelectric hexapod, allowing the secondary reflector 6 directions of freedom.
Piezoelectric hexapod for the secondary reflector
Christian then took us outside to have a closer look at one of the completed antennae, which was ready for testing. Because of the wind, many of the outdoor operations had been stopped, which meant that we got to see a lot more than we maybe would have otherwise. We even go to go inside one of the cabins of the European antennae - can't believe I've actually stood inside one of the ALMA antennae! It was cool to see where the cryostat would be positioned and to see the gortex shutter system which is used to protect the instrument from dust.

Outside the hanger, there were a few complete dishes, all waiting for their testing - it was incredible to stand next to them and get a real idea of the size of them. It did also leave me totally amazed thinking about how big the E-ELT will be!
A European 12m antenna

Number 24 and the dish of 25
After speaking with Christian, we were extremely lucky as Valeria managed to get us a little time in the North American construction hanger. In the hanger we saw dish number 24 complete, and dish number 25 under construction - so they really are on schedule with finishing by the end of September.

Bill, the lead on the North American construction, explained that there are around 12 people in his team who are there all the time, and all the rest are contractors. They have around 16 - 20 people working there at any one time, and not just from North America - they have contractors from Chile, Guatemala, Brazil and the UK.

Bill explained that each of the contracted construction companies for the antennae have a 2 year warranty period, so they will have to service the antennae during this period. He said once all their dishes are complete and in place, there will still be a small core team on site initially, but after that it may be a case of people coming in as and when required.

Although all the dishes have their slight differences since made by 3 different companies, they all had to comply with certain standards. For example, they all have to be able to plug into the same bases up at the summit - mechanically and electronically. Also, all the antennae have to match up with the transporters so they can be moved at the summit, and down to the OSF for maintenance when required.

After seeing the American hanger, Valeria took us to the control room to speak with one of the astronomers there about their work. Although not all the dishes are in place currently (only 34 in place at the moment) the first science has already been done with ALMA, using 16 dishes. A call went out for proposals some time ago and around 1000 proposals were submitted from scientists around the world. A panel of about 50 people reviewed the proposals and around 100 were selected. The next phase of science, using 32 dishes, is just around the corner. The call for proposals is open just now, and indeed I know of a couple of people who are working on such proposals.

Theodore Nakos, one of the astronomers, explained the control room to us and answered some more of our questions. He explained that all commands are run from the OSF and that currently about half of the time is used for testing and the other half for actual science. At the moment, only the 12m antennae are being used for science, not the 7m dishes of the compact array. In the control room, they have a constant live feed showing the Array Operations Site (AOS) with live weather observations. There are huge climatic challenges with the project - wind, rain, snow, dramatic temperature changes.

By the time we had finished chatting with Theodore, it was around 7pm and getting quite dark, so Liliana, Olivier and I headed back into San Pedro for dinner. We arranged to meet Valeria the next day at the OSF at 8am, for our trip to the AOS.

It was a truly fascinating day at the OSF and I would like to thank all those who answered our questions and explained many parts to us. Lots of food for thought and plenty of ideas swimming round in my head for ways to link to the Physics curriculum in Scotland.