ANALYSIS To read extended versions of these interviews, along with exclusive additional content, please see the digital-only space supplement ‘Space unlimited’: http://digimag.internationalinnovation.com//launch.aspx?eid=56412537-57f3-4040-8e23-d04d47344012 Atacama Large Millimeter/ submillimeter Array

The result of an impressive international collaboration, ALMA is the largest astronomical project in existence. Here, Director Pierre Cox discusses some of the surprising discoveries that have been already made and the incredible potential of a fully- functioning telescope

ALMA antennae bathed in red light.

Could you outline the origins of the Atacama Large Millimeter/submillimeter Array (ALMA) and your role within it?

I have been Director of ALMA since April 2013, and before that I had smaller roles in scientific and advisory committees. Previously, I was Director of the Institut de Radioastronomie Millimétrique (IRAM), which built one of the receivers for ALMA and has had many staff work on the project. individual interests. So The ALMA project started in the 1990s when there were a number of these have to be different ongoing initiatives initially in North America, Europe and Japan. carefully balanced and People realised that combining their efforts could be very valuable because a close watch kept on the by adding more antennas you increase sensitivity, which is a significant fairness of what is done in each advantage. Everybody was looking for a dry site at a high altitude and one region; that goes from technological © ESO/C Malin of the most obvious places on Earth is the Atacama desert in Chile, which cutting-edge developments to the attribution offered many opportunities to build such a facility. of observing time using the facility.

I think it is quite an extraordinary endeavour, particularly as it was the first The Chilean Government estimates that the country project ever run globally, with an equal share between North America and will be home to 70 per cent of the world’s astronomical Europe, and Japan joining later. infrastructure by 2020. What are the reasons for this, and if correct, how will it impact the astronomy community? How are the different research interests and needs of ALMA’s international partners balanced? The high altitudes of the sites in north Chile and the excellent conditions in terms of dryness are the main reasons for this. In the case of ALMA, That is the core question for ALMA and it’s not easy to answer. It has Chajnantor offers a flat plateau at an altitude of 5,000 m, large enough to profound ramifications because there are scientific, technological and also allow us to arrange and rearrange the antennas up to 16 km from each other.

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Artist’s illustration showing the four SKA instruments. © SKA Organisation

In addition, the sites in the northern regions of Chile are exquisite in terms of the sky stability which is essential for observations. This is why for instance the Very Large Telescope (VLT) and, in a few years, the European Extremely Large Telescope are located there. These are some of the features that attract the astronomy community and I think Chile will be the Mecca in astronomy in about 10 years’ time.

I think it will have a positive effect on the community because there will be high-quality instruments in prime locations, and hence the scientific discoveries and the field of astronomy will keep growing. We’ve seen it with the VLT, we see it today with ALMA and we will see it with the new instruments.

Could you highlight some of the most exciting observations to have come out of ALMA so far?

There have been many exciting observations and we have a high rate of publication in prominent scientific journals like Nature and Science. These spectacular results are based on a limited number of antennae – 20 at the most – which shows the potential of a fully functioning ALMA network with all 66 antennas. It is difficult to say what the most exciting observations are, but if you look at cosmology it’s now very easy to measure the distance to galaxies in the early universe by analysing the molecular lines in their spectrum and to study their properties including the morphology and dynamics.

We have been surprised by some of our findings on the material around Square young stars out of which planets are formed. We found that the distribution of matter is asymmetrical, in the sense that the dust seems to be distributed in such a way that there are places in the disc that concentrate a higher proportion of big dust grains; those sites are thought to be the places where Kilometre Array planets form. This discovery was not even foreseen by models. Another very nice recent result is the finding of a lot of dust in a nearby and Organisation recent supernova in the Large Magellanic Cloud, which provides information on how dust is formed through the death of massive stars.

Each time you observe with ALMA you will have surprises, because it has The SKA project, though still in its infancy, has such sensitivity and bandwidth, and this creates lots of potential to find the potential to answer some of astronomy’s wonderful things. biggest questions. Philip Diamond, Director Finally, how do you predict ALMA will develop over the forthcoming decade? General of the SKA Organisation, discusses how international collaboration is fundamental to the The main goal in the next year or two is to have the ALMA facility fully operational with all the observing modes that are foreseen. We are gradually success of such an ambitious initiative ramping up in terms of the number of antennae that are used for science and there are still observing Can you provide a brief overview of the Square Kilometre Array modes that need to be (SKA) project? From what context did the project emerge? tested and commissioned, such as the long baselines of SKA is the next-generation radio telescope – when it’s fully complete it a few kilometres. will be 50 times more sensitive than the current best radio telescope, with a massive ability to survey the sky rapidly and repeatedly. It will I think that with ALMA there be able to see deeper into the Universe and further back in time than © ESO/C Malin are very exciting scientific ever before. results down the road because of the increase in observing The project emerged in the early 1990s when astronomers were looking capability to a level which has at the next big questions in the field. Specifically, it was led by a desire to never been reached before. There’s observe hydrogen all the way back to just after the Big Bang to study the always the question of being evolution of the Universe. sensitive to exploring the fringes, the cutting-edge in science – that’s Have you seen a move towards large-scale international projects over what we want to do. the course of your career? What are the benefits and challenges of working across national boundaries?

The previous generation of radio and optical telescopes were produced by www.almaobservatory.org individual countries. Over the last few decades the complexity and cost of

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projects have grown, requiring international collaboration. Splendor of the Milky There’s definitely still room for small-scale university- SKA will use Way shining in the led innovative projects, but the big facilities need background of a international collaboration. enough optical MeerKAT antenna. MeerKAT is the South fibre to wrap African precursor To date, SKA has 11 members, with other countries telescope to the SKA. aspiring to join. The various governments involved twice around © SKA South Africa in the project all have slightly different agendas and there are challenges of coordination, communication, the Earth openness, transparency and language. These challenges are to be expected, but the ultimate benefit is that a mega-science facility like SKA simply couldn’t be built by a single country. Collaborating at the international level spreads both the financial load and the risk, and science can act as a diplomatic tool at Could you discuss your relationship with other contemporary this scale. instruments, in particular the Atacama Large Millimeter/submillimeter Array (ALMA)? The telescope will produce more than 10 times the data traffic of the internet. Can you explain how signal transport and networks will ALMA focuses on the cold Universe – it operates at higher frequencies than support this volume of data? SKA, very short wavelengths and is very sensitive to emissions from gas, cold gas, dust, etc. In contrast, SKA will look at hydrogen gas, bigger molecules Data management is one of the big challenges of the project and we have and more energetic phenomena; for example, the enormously powerful jets a number of consortia working on this. The University of Manchester, UK, is emitted from black holes or the magnetic fields that are generated across leading a consortium that is designing the fibre optic network that will be galaxies. We are complementary in that we can look at the same objects but integral to SKA. The fibre is off the shelf but the electronics, control systems study different physical phenomena. Astronomers want to observe the whole and electrical fibre interfaces are of a scale that industry hasn’t seen before. wave band, so they’ll use both SKA and ALMA, as well as other instruments. Data will go into a massive digital signal processor that will need to be capable of handling the enormous volume, and another consortium led by Canada is designing this. It will reduce the volume of data by averaging, in both time and frequency, and then pass those data onto a massive supercomputer.

However, data volumes will still be too large to store as raw data, so they will have to be processed continuously. A University of Cambridge- led consortium is designing the software systems that will carry out the automatic removal of bad data, calibration, imaging and depositing in the archive. This is the point at which astronomers, scientists and engineers will access the information. www.skatelescope.org To read International Innovation’s 2013 interview with Philip Diamond, please visit: www.research-europe.com/index.php/2013/04/professor-phil-diamond-direc- tor-general-square-kilometre-array

Stellar science: SKA’s key scientific objectives

To understand the To observe hydrogen – SKA Are we alone? – SKA will be To investigate the origin fundamental physics will allow us to detect and our best chance of detecting and evolution of cosmic behind gravity – we’ll be study in detail the epoch alien signals over the next magnetism – SKA will create using a network of pulsars where the Universe changed 15-100 years, if any. We’ll 3D maps of cosmic magnets (remnant cores of stars that from being neutral to ionised be looking for the molecular to understand how they have exploded) to detect gas. This is when the first signatures of heavy stabilise galaxies, influence the passage of gravitational stars and galaxies were molecules, biomolecules and the formation of stars and waves through the Milky formed, and is a critical amino acids – the building planets, and regulate solar Way as they are the most period in the evolution of the blocks of life – to discover and stellar activity accurate clocks in the Universe. We will be able whether they are out there Universe. Having them in to trace through 13 billion in space orbit around ultra-dense years how galaxies evolved objects like black holes will and became the structures enable us to test Einstein’s we see today theory of general relativity to destruction. We know that at the quantum level Einstein’s ASKAP antenna under a starry night sky. theory probably breaks Currently under commissioning, ASKAP is down but on Earth we can’t one of the Australian precursor telescopes to create such conditions the SKA. © Alex Cherney/terrastro.com

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