Exploring dark energy

UK astronomers and their international team mates have constructed the lenses of a camera that will detect the mysterious ‘dark energy’ component of the universe.

The pieces of glass for the five unique lenses have been shipped from the US to France to be shaped and polished into their final form. The largest of the five is one metre in diameter, making it one of the largest in the world.

Observations suggest that roughly four per cent of the universe is made up from ordinary matter and 22 per cent from dark matter. This leaves 74 per cent unaccounted for and this is known as dark energy.

The Dark Energy Survey (DES) camera will map 300 million galaxies using the

Blanco four metre telescope, which is a telescope with new advanced optics, based at Chile’s Cerro Tololo Inter-American Observatory.

It is hoped that the DES galaxy map will enable the astronomers to measure dark energy far more precisely than current observations.

University College London Astrophysics Group head and UK DES Consortium leader Professor Ofer Lahav said: ‘Dark energy is one of the biggest puzzles in the whole of physics, going back to a concept proposed by Einstein 90 years ago. The DES observations will tell us if Einstein was right or if we need a major shift in our understanding of the universe.’

After polishing, the lenses will be sent to the Optical Science Laboratory at UCL for assembly into the camera and from there to the telescope in Chile, where observations will start in 2011 and continue until 2016.

The Science and Technology Facilities Council (STFC) is providing support for the Dark Energy Survey (DES) collaboration, which involves over 100 scientists from the US, UK, Spain and Brazil. The UK consortium includes members from UCL, Portsmouth, Cambridge, Edinburgh and Sussex universities.