Although it is an ambitious scientific project activities on the ALMA site not only focus on building the world’s most advanced astronomical observatory but also on the historical and environmental aspects in this unique region.
Venus shortly before it moved in front of the Sun (the famous Venus transit) last month on June 5th. At that stage Venus was not visible through optical telescopes because its dark side was turned towards us. ALMA detects millimeter and submillimeter waves which are given off by the hot atmosphere of Venus (and of course even more strongly by the hot surface of the Sun).
The Atacama Large Millimeter/sub-millimeter Array (ALMA) is an array of radio telescopes in the Atacama desert of northern Chile.
When ALMA is completed it will consist of:
a giant array of 12-m antennas with baselines up to 16 km
an additional compact array of 7-m and 12-m antennas to greatly enhance ALMA’s ability to image extended targets
This is located on the Chajnantor plateau at 5000m altitude. Initially, it will observe at wavelengths in the range 3 mm to 400 μm (84 to 720 GHz).
The antennas can be moved around, in order to form arrays with different distributions of baseline lengths. More extended arrays will give high spatial resolution, more compact arrays give better sensitivity for extended sources.
Each antenna weighs: 115 tonnes! Moving these around at 5000m is not an easy feat. Two custom 28-wheel self-loading heavy haulers were developed. Each is 10 m wide, 20 m long and 6 m high, weighing 130 tonnes. They are powered by twin 500 kW diesel engines!
A new window into the Universe has opened with the start of Early Science at the Atacama Large Millimeter/submillimeter Array (ALMA). Watch the world’s most complex ground-based telescope in action and get a first look at its unique views of the Universe.
ALMA (Atacama Large Millimeter/submillimeter Array) scientists have detected a galaxy that is 12.4 billion light-years away! This was detected via looking at the emission line of Nitrogen in the galaxy. At that distance we are looking at a time that is just 1.3 billion years after the big bang. This means that astronomers are able to see if there is any difference between the contents of galaxies not long after the big bang and now. The result of this work shows that the composition was already close to the elemental composition of the present Universe. Thus suggesting that intense star formation activities had occurred in the early Universe.
The ALMA telescope is on a plateau at 5000m altitude in Chile — the same height as the Everest base camp. I got to go up to visit the site in May.
Before my trip up, I’d already spent a few days at the ALMA operations site at 2900m. Even this is high enough that you really notice the effect of altitude — carrying my suitcase the short distance into my room the first night there left my heart pumping. However, 5000m is a lot more serious.
The journey starts with a quick trip to the ALMA medical room, to have my heart rate and bloody pressure checked. After I’ve been passed, its time to make sure I’ve got sunscreen and sunglasses — as well as gloves, a wooly hat and a warm jacket. Its pretty cold up on the site on the day I visit, but the high altitude means the sunlight is a lot stronger than it is at ground level, and you want to keep the UV away.
We also make sure we’ve got blood-oxygen monitors and some cans of compressed air. The oxygen levels at 5000m are low enough that you want to keep an eye on your blood-oxygen level and take regular breaths from the oxygen.
The landscape around the site is amazing, and to someone used to a wet and green Britain the dry Chilean mountains look like an alien landscape. This is a view from a peak overlooking some of the more far-flung ALMA antenna pads — you can just see the roads out to the most distant pads in the left. Once its completed, ALMA will have its dishes spread out around the plateau, with up to 16km between them.
Even though I didn’t have to do anything more physically taxing than walk around for a few minutes, I can feel the effect of the low oxygen as I wander around snapping picture. I have to consciously remind myself to keep taking extra deep breaths, as well as occasional breaths from the cans of oxygen we’ve brought. But people have had to build all the telescope infrastructure in these conditions — roads, power lines, antenna pads, buildings, radio masts, weather stations, all had to be constructed or installed at the high site. As well as an amazing scientific instrument, ALMA is also a hugely impressive engineering project, constructed under very difficult conditions.
Below, you can see an overview of the central region of the ALMA site. The individual dishes are spread out over about 2km in this picture. Once the telescopes construction is finsihed, the massive 12m dishes will be moved around the site regularly — averaging about one dish moving every single day.
We drive back down to the 5000m plateau where the ALMA antennas live to take a close up look at them. In the picture below you can see the antennas clustered together from a lot closer up. The building off to the right of the image contains the ALMA correlator. The correlator is where the signal from each of the dishes are combined together to create one much more detailed image. The level of detail we can see is determined by the size of the distances between the individual dishes instead of by the size of a single dish.
And here’s a close up of some of the 12m dishes. ALMA will eventually have 66 dishes, and as of May this year they already had 33 dishes at the 5000m site! The dishes are a mix of 12m dishes and a few 7m dishes. The 7m ones are placed very close together in the centre of the array, and this helps ensure that ALMA can produce more accurate images. Each of the 12m dishes weighs almost 100 tonnes, and the special transporters that move them to and from the different pads has to have a 28-wheel drive!
After this we head back down to the comfort of the ALMA operations site — after a few hours spent at 5000m, the lower site feels far more comfortable than it did in the morning!
We have finished writing the code (in glorious Python) to get our ALMA demonstrator for the Summer Science Exhibition, so here are a few quick previews….
Here is Adam looking at his best through the eyes of an interferometer:
Note the fake colours, what we are using to make the images is the brightness - then for fun we add the really the garish colour scheme. The redder the brighter. I’m guessing this means that Adam was blushing when he had is photo taken by the webcam :-)
Not looking quite as complete as Adam, probably down to the type of interferometer I made (the more antennas the better), is me:
Can you guess what is on my T-shirt?
John decided to go for the Blue Peter approach, getting out a piece of paper and some Tipp-Ex…
During the exhibition you should take note of our twitpic feed as users will be able to upload their creations for all to see! We hope to see many more interesting images than we have produced so far.
The time is counting down… so see you at the:
The above photo is the exhibition logo as seen through ALMA’s ‘eyes’.
Yes, you read that correctly, there are fully robotic models of the ALMA transporter and antennas made out of LEGO!
The ALMA LEGO Simulator are scale robots of one of the ALMA antennas and the transporter truck. Both devices are controlled remotely via Bluetooth communication and are designed to provide a coordinated movement of the antennas and the rearrangement of the ALMA antennas by rising and moving an antenna with the transporter truck. The transporter is huge, measuring some 20x10x6 meters with a total weight of 130 tons when empty! The LEGO model consists of 4500 LEGO pieces and 2 2 Intelligent Bricks. The antennas model uses about 5000 LEGO pieces, which will create a dish of about 30 centimetres.
Well you’ll be in luck! There are paper models for the 12m antennas available. The paper antenna is movable along the elevation and azimuth axes. If you are careful then you can end up having one just like that made by one of research students at the University of Cambridge, Djelal Osman:
Along with the ALMA antennas you will also find the antenna transporter. So you could build you own “operational” ALMA.
Suddenly things got very busy in the UK ARC Node office last week, not only is the Royal Society’s Summer Science Exhibtion less than a month away (gulp!) but last Thursday saw the second ever ALMA Call for Proposals announced (the deadline for which is just after the Exhibition! Gulp gulp!).
A call for proposals is a period of time in which astronomers around the world metaphorically get down on one knee and ask the telescope of their choice if the telescope will do them the great honour of observing the astronomers favourite object.
The getting down on one knee is replaced by a short document explaining why the observations an astronomer is asking for are scientifically interesting and how the astronomer intends to use the telescope to achieve the observations they are asking for. From the list of proposals submitted a committee at each telescope facility then selects the observations they deem most scientifically interesting and technically feasible.
So why can’t astronomers just get all the time they want? Well once upon a time an astronomer at a particular University (or indeed in the backgarden of his/her manor house or a observatory owned by a monarch) would have a dedicated telescope and could use this as, when and how they saw fit. But as astronomy moved from its early origins and we began to understand the layer after layer of complexity we were observing, the telescopes needed to become more complex and precise making them more expensive.
At approximately $1bn not everyone can afford their own ALMA telescope nor are there many places on Earth where they could build one and have it be as accurate as ALMA. The high costs and technical specifications of an instrument like ALMA require international collaboration and the work of many engineers and scientists at many different institutions. So if the people allowed to use ALMA were just from the institutions which had worked on its construction the demands on its time would already be very high, but with such a groundbreaking instrument it seems unfair to exclude sections of the astronomical community so ALMA like many other large telescope facilities are open to all professional astronomers to ask for observing time.
The astronomy community of the 2010’s is a large and vibrant place meaning when ALMA made its first Call for Proposals last year for every one hour of time available to observe with ALMA there were nine requests wanting that hour! This year there are more hours on the telescope available (less construction is required this year) and also more telescopes available in the array (which reduces the required observing time… ask us how at the exhibition!), but early indications are that demand for ALMA time from this years Call for Proposals are going to be just as high!
So best of luck to all astronomers applying for time, we at the UK ARC Node are here to help!
A day in the life of ... an ALMA Support Scientist.
Seeing as there are many types of people, who do different types of jobs, all working toward producing the ALMA Stand at this years SSE we thought it would be good see what they each do! So to kick this off it’s me, Adam.
I am a Postdoctoral Research Associate at the University of Manchester, and my job title is Support Scientist at the UK ALMA regional centre node (or UK ARC Node for short). This means I typically spend my day providing support to UK astronomers who use ALMA, testing software to process ALMA observations, actually processing ALMA observations and doing a bit of my own research. For example here is a ‘day in the life of Adam’.
08:40 Arrive at the office.
08:45 Having checked my emails, begin work on the interactive display for the Summer Science Exhibition. I got some cool coding done the previous evening whilst reclined on my sofa at home.
09:30 Spend some time discussing travel arrangements with my boss. We’re are both attending a meeting in Paris in a few weeks to discuss future research projects and collaborations.
09:45 Redesign the Array layouts for the interactive display (spoilers!). Whilst intermittently checking the status of an ALMA simulator we host at the UK ARC node.
11:15 I then began tweaking the code of the online ALMA simulator we host here in Manchester, making it ready for the next round of ALMA observing proposals. Observing proposals are the method through which astronomers apply for time on particular telescopes. Those with the best scientific cases and justification for what they wish to achieve with the telescope are awarded time. Using a simulation of a particular ALMA observation lends weight to an ALMA proposal by showing something which is similar to what ALMA will actually observe.
12:45 Lunch! :D:D
13:30 UK ARC weekly meeting. In which we discuss whats being going on in the ARC and with ALMA this week. I won’t bore you with further details!
14:30 Finish off testing the code I was working on before lunch… It works Hurray! (can you tell I like coding yet?)
15:00 Colloquium Time! Each week in our department a visiting astronomer gives a presentation on there research. This week Dr David Jess from Queen’s University Belfast presented “What’s in a name? The controversial nature of waves in the solar atmosphere.” A fascinating talk on different types of wave in the magnetic field lines from the Sun.
16:00 Get back to the office and convert some ALMA data for a group of astronomers in France I was working with last week!
The first images from ALMA are trickling in, and one in particular really shows its power, and demonstrates beautifully why we need to build it. It’s an image of (half of) the dust ring around a nearby star, Fomalhaut, a system we believe may harbour planets. The blue arc shows the glowing dust emission measured by ALMA, and the background image in red/white is the same object but taken by a single 15-m telescope (the JCMT in Hawaii). Where JCMT sees a couple of blobs, ALMA shows a beautiful arc. The much increased resolution of ALMA reveals the details we need to see to understand exactly what is going on around this star. (Note that ALMA hasn’t looked at the lower part of the ring yet!). We think the dust that we see is created continuously by the smashing together of large numbers of comets in the outer part of this system, and this helps us understand how the system formed and evolved, and gives us clues to the nature of our own Solar system’s outer regions.
To achieve high resolution in its images, ALMA has to be a huge telescope. Much of the cost and complexity of the project comes from the need to make a telescope with an effective diameter of 16km, or 10 miles in old fashioned units. ALMA will ultimately function as a 10-mile diameter telescope. We achieve this by combining (in fact, interfering) the radio waves collected by lots of separate antennas, spread over a plateau about 10 miles in size. The separation between a pair of ALMA antennas is called a baseline. Long baselines reveal sharp detail in the images.
But the true collecting area of ALMA is much less than a single telescope 10 miles across. ALMA’s collecting area, basically the total area of reflecting surface we have built, is about that of a football pitch, Upton Park to be precise. The more reflector we build the fainter the objects we can see. But as far as the resolution of the images we can make goes, its the effective diameter (maximum baseline) that matters.
Right now in Chile, the individual ALMA antennas are quite close together, 400m apart at most. So ALMA can currently see as much detail as a 400-m diameter telescope. Next week, the team (including two scientists from Cambridge) are heading to the site to try to connect in an antenna 2km away from the main group of antennas. Over the next year or so, we hope to spread the antennas over ever wider distances, eventually achieving the holy grail of a 16km (10 mile) telescope. This has never been done before at these frequencies, and there are big challenges ahead to make this happen.
It’s incredibly exciting to see the power of interferometry in action: ALMA’s crisp image of the arc of dust reveals so much more about what’s happening in the Fomalhaut system than the JCMT image. And this is only a very low resolution image for ALMA - once we have longer baselines we’ll be able to make better and better images.
For comparison, how much detail can you see with your own personal ‘telescopes’ - your eyes? The human eye is am amazing device. The diameter of the eye’s pupil varies, but typically is only 5mm or so. If you have 20/20 vision, it turns out that the resolution of the human eye is about the same as the JCMT, the 15-m telescope in Hawaii. It’s just good enough to see the headlights of a car as two separate sources when it is a few km away; or distinguish the main features on a human face at a distance of 100 metres or so.
Of course it’s important to remember that ALMA is a radio telescope: we are not detecting normal light, but light with a wavelength one thousand times longer. Nonetheless, we can make perfectly good images, albeit using computers rather than just mirrors and lenses.
When ALMA is finally working with 10-mile baselines, it will have a resolution 5000 times better than the human eye. So it could separate the headlights of a car on the other side of the Earth. Or detect the main features on a face at a distance of over a 100 miles. And this is the key to ALMA making great scientific discoveries.
Such a busy few weeks! After our road trip to Cambridge to plan for the SSE, members of the UK ALMA Regional Centre have been busy busy busy! Adam (the guy who is currently writing this post) went off to Sweden to use the 20m telescope at Onsala for 5 days, (check out the scientist profile video, which I filmed there, coming soon!).
Shortly after that the whole of UK ALMA team were at the National Astronomy Meeting in Manchester, where we lead two ALMA based sessions. Something we’ve been planning for a long time! These sessions included some of the very first science images to come off the telescope. (Sadly, these images belong to the astronomers whose data it is so I can’t post any pictures here… yet!). But you can check out some of the press releases made at NAM here: http://www.alma.ac.uk/media
After that John Richer and Adam were at the Communication training day at the Royal Society itself. Which was loads of fun and very informative!
Finally, as I teased with my first post on this Tumblr here is an updated version of one of the interactive parts of our stand at this years SSE.
As the ALMA stand at this years Royal Society Exhibition is being put together jointly by the University of Manchester and the University of Cambridge telephone calls and emails are happening thick and fast!
But there are somethings you just can’t do over the phone on in an email, so last week two of the team from Manchester (George Bendo and myself), hopped in the car, put the pedal to the metal (strictly obeying speed limits at all times!) and drove down to Cambridge to do some face to face planning with John Richer.
I’d never been to Cambridge before and I can heartily recommend it, a very picturesque city, ideal for any budding photographers. I’m not much of a phototaker but here’s an offering from my iPhone.
I won’t bore you too much with what happened in two days of meetings, but suffice to say we’ve pretty much got a clear idea of what we’ll be bringing to the exhibition this summer and we thoroughly annoyed the staff at a well known high street computing shop by playing with their touch screens for over an hour!