An ambitious new European project aims to create the world's largest ground-based telescope. Ireland has a chance to be part of the adventure, writes Dick Ahlstrom
Europe's astronomers have embarked on a remarkable new adventure - to build the world's largest ground-based telescope. This €800 million monster would have a light-collecting mirror almost as big as half a football pitch.
Unfortunately, Ireland may be left behind in the development of the European Extremely Large Telescope (EELT) because we are one of the few western European countries who are not members of the European Southern Observatory (ESO), the body behind the telescope.
"If you want to be part of the adventure, which this really is, you have to be a member," stated the ESO's head of public affairs and new entrant negotiator, Claus Madsen.
Madsen was in Dublin earlier this month speaking at the annual Astro-Expo and meeting astronomers and scientists. The key topic under discussion was Irish membership of ESO.
The Georgia Tech report on Irish membership of science bodies was published several years ago and recommended that Ireland join ESO and several other bodies such as the European Molecular Biology Laboratory (EMBL) and the European Synchrotron Radiation Facility (ESRF). We are now members of EMBL but await a decision on ESO.
Madsen had no meetings with officials but did talk to Irish astronomers anxious to join ESO. "My understanding is the discussions are up again," he says.
There are a number of reasons why Ireland would benefit from membership, he believes. "The issue really is the full and complete integration of Irish science and astronomy into the European Research Area," he suggests. "It builds a lot of prospects for European science."
But this can't happen if some EU members remain outside certain aspects of the research area, be believes. "Ireland should definitely play its role and harvest the benefits of membership."
Not least among these are the commercial opportunities that open up to Irish science and industry given membership of ESO. "This is a completely different league of science you can take part in. These instruments are large machines and very technically advanced. They are built by national institutes in collaboration with industry partners."
This allows much technology transfer between participants across ESO, he says. "This is a way to integrate national programmes into a big international programme."
These industrial linkages, which represent income and jobs for Irish participants, help offset the cost of membership, he says. It would cost us between €14 million and €15 million to join, with an annual cost of about €1.5 million.
Just as important and more difficult to quantify, however, is the impact on society generally. "Astronomy as a science exerts a strong attraction for the public at large and especially among young people," says Madsen. "Astronomy has been very good at raising an interest in science."
This serves the Government's aim to get more students to take science subjects at Leaving Cert and Third Level. ESO also opens up many career opportunities for those who do embrace science as a subject.
"ESO has evolved to become the leading force for ground-based astronomy in Europe and probably in the world," Madsen says. "ESO has a very strong technical record in the design and development of research infrastructure for astronomy."
They don't get much bigger than the EELT, a huge project that hopes to deliver the most sensitive ground-based optical and infrared telescope yet devised by 2017. The ESO council gave the green light for a detailed €57 million study of the EELT on December 11th. This will make it possible to begin construction of the instrument, probably within three years.
The challenge is to produce reflective mirrors that can overcome the difficulty faced by all terrestrial observatories, the fuzziness of stellar images caused as the light passes through the atmosphere. The planned instrument would overcome this "twinkle" by using a set of five different mirrors to capture and clean the faint light coming from the edges of the universe.
The EELT would have a primary mirror some 42m across. It will be more than 100 times more sensitive than the current largest ground-based telescopes such as the 10m Keck telescopes or the 8.2m instruments.
"A telescope of this size could not be built without a complete rethinking of the way we make telescopes," says ESO director general, Catherine Cesarsky. This big a reflective surface is only possible because the primary mirror is actually made of 906 hexagonal segments each 1.45 metres in size.
The light captured by the primary mirror is reflected to a second six metre mirror and then a third of 4.2m. From here the light would be relayed to an "adaptive optics system" involving two mirrors.
One is a 2.5m mirror supported by 5,000 actuators able to distort the mirror's surface 1,000 times per second. This will iron out the twinkle effect caused by the atmosphere.
This adjusted light would then reach the fifth and final 2.7m mirror that would make the final image corrections prior to observation. "This is really the beginning of a new era for optical and infrared astronomy," says Cesarsky.