UK astronomers reach new heights with giant telescope
DR EMILY BALDWIN, REPORTING FROM THE ATACAMA DESERT, CHILE
Posted: 03 October 2011
The Science Technology and Facilities Council (STFC) confirmed today that it will provide UK scientists with £3.5 million to fund development of key instruments for the planned European Extremely Large Telescope (E-ELT), which at 39.3 metres in diameter, will be the biggest optical and infrared telescope in the world.
Artist’s impression of the finished E-ELT. Image: ESO.
It is expected that the European Southern Observatory (ESO) partners will make a final decision on the one billion euro project this December, with construction of the telescope due by the end of the decade. Once operational, the revolutionary telescope, which will be almost as high as Big Ben, will take on the challenge of detecting and characterising Earth-like exoplanets, study the first stars and galaxies in the Universe, and probe the nature and distribution of dark matter.
At present, site engineers are studying the 3,060 metre-high mountain-top location in the Cerro Armazones for its observing and atmospheric quality. Soil testing is also underway – before construction can begin, engineers must level the mountain top using explosives, a procedure that requires intimate knowledge of the local geology.
The planned site of the E-ELT, in the Cerro Armazones, Chile is at an altitude of 3060m metres, seen here from the Paranal Observatory 80 kilometres away. A track is visible leading up to the site. Image: Emily Baldwin.
Gonzalo Argandoña of ESO took Astronomy Now to the remote site via what is currently the only access route, a dirt track through vast boulder-strewn plains that resemble that of Mars. He explained that construction of both the telescope and the required infrastructure in such a remote desert location will not be the most difficult part of the project.
“The main challenge will be maintaining the mirror segments once the telescope is built,” he says. The telescope will comprise five mirrors, with the main mirror consisting of 1,000 hexagonal mirror segments, each 1.4 metres wide. It will gather 100,000,000 times more light than the human eye, and 26 times more light than a single 8.2 metre Very Large Telescope (VLT) unit telescope, the flagship telescopes of Paranal Observatory. “A mirror coating facility like the one in Paranal which is used to recoat the single mirrors of the VLT once every 18 months will be needed, but for so many mirror segments it will be a continuos process of maintaining them.”
The E-ELT’s main control room, from which the telescope’s nightly observations will be operated, will be at the main Paranal Observatory around 80 kilometres away, negating the need for astronomers to live and work in such a remote location.
The telescope will host nine first generation instruments, and STFC’s injection into the UK’s instrument development fund will enable continued studies on various instruments including the construction of HARMONI, a spectrograph that will work at both optical and infrared wavelengths.
“If you imagine an image of a galaxy, then for every point on the galaxy [that you image with HARMONI] you would get a spectrum, which tells you about the chemical composition at that point and the velocity at which that part of the galaxy is moving,” explains Professor Isobel Hook, the UK E-ELT Project Scientist from the University of Oxford. “The UK is also involved in the design of an instrument that is specialised to take images and basic spectra of extra-solar planets. This instrument will have its own very specialised adaptive optics system to provide extremely sharp images needed to separate the planet from its parent star.”
The funding from STFC to continue design studies on a variety of instruments allows the UK to play a central role in the whole project. “In the case of HARMONI it means the UK could lead the work and the team can actually start constructing the instrument,” Hook tells Astronomy Now. “If the E-ELT is approved by ESO Council in December then UK scientists will be in a very exciting position, having access to the whole telescope through our membership of ESO, and expert knowledge and observing time on one of the first instruments.”
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