A €9 million contract for the construction of a near-infrared spectrograph for the European Southern Observatory’s Very Large Telescope (VLT) has been awarded to a group of UK-based engineers and designers. The instrument, which is due for completion in 2019, will allow astronomers to gain a further understanding of how stars and galaxies form and evolve, and probe the structure of our Milky Way.
The MOONS (Multi-Object Optical and Near-infrared Spectrograph) instrument will be designed and built by an international team led by the UK Astronomy Technology Centre (UK ATC) − part of the Science and Technology Facilities Council (STFC) − in Edinburgh for the Very Large Telescope in northern Chile, already the world’s most productive ground-based astronomical facility. It will take around 200 staff five years to complete, at a total of €23 million − €9 million of which is just for the hardware.
As recently as March another spectroscopic instrument was installed on the VLT. The Multi Unit Spectroscopic Explorer (MUSE) combines high resolution imaging with spectroscopy and uses 24 spectrographs to separate light into its component colours to create both 3D images and spectra of selected regions of the sky. The device was developed to further investigate mechanisms of galaxy formation and to study both the motions of material in nearby galaxies and their chemical properties.
The MOONS spectrograph will be more powerful and will enable astronomers to see obscured areas in the Milky Way at a distance of around 40,000 light years away and create a 3D map of our galaxy. Currently, this is extremely challenging because the Earth is in the middle of the Milky Way’s disc; therefore it could be compared to mapping a forest of densely-packed trees from the inside.
‘The team at UK ATC in Scotland have an opportunity with this project to enable all of us to understand why the Milky Way looks the way it does,’ said Professor Gillian Wright, director of the UK ATC. ‘This instrument will act as an intergalactic GPS to help us to navigate through the billions of stars in our galaxy and create a comprehensive map of its structure.’
Like any spectrograph, MOONS will use light emitted by objects to reveal their chemical composition, mass, speed and other properties. By simultaneously observing 1,000 objects using fibre-optic cables to feed visible and infrared light into the instrument, it will survey large samples of objects far faster than any existing instrument and conduct surveys that would be virtually impossible using today’s technologies.
Not surprisingly, the design will pose technical challenges. For example, each of the 1,000-plus fibres will have to move into position very quickly, with great accuracy and without colliding with each other.
The UK ATC’s expertise in fields such as miniaturised mechanics and precision optics will be used to overcome these difficulties. The UK ATC will develop the individual motorised systems that will allow each fibre to move rapidly into position; it will also develop the cryostat system used to cool MOONS down to -170°C.
Partnerships with a range of UK equipment suppliers will also contribute across the project, helping the UK to further strengthen its cutting-edge scientific capabilities in the relevant fields. For example, the University of Cambridge will develop complex cameras capable of meeting the instrument’s demanding performance requirements.
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