A new telescope euclid being built by the European Space Agency (ESA) will map the shape, brightness and 3D distribution of two billion galaxies covering more than a third of the whole sky and looking back over three-quarters of the history of the universe.
To be launched in 2020, Euclid’s 1.2 metre diameter telescope is the most ambitious mission to date to map the geometry of the universe.
Scientists hope it will help solve key problems in the understanding of the evolution and fate of our expanding cosmos: the roles played by dark matter and dark energy. Dark matter is invisible, but has gravity and acts to slow the expansion. Dark energy, however, seems to be accelerating the expansion seen around us today.
Together, these two components are thought to comprise more than 95% of the mass and energy of the universe, with normal matter and energy making up the remaining small fraction. But what they are remains a profound mystery.
To map the distribution and evolution of dark energy and dark matter in the universe, Euclid requires crisp deep images with sharpness similar to that obtained with the Hubble Space Telescope but over a huge area, some 40% of the sky. It will make high-precision measurements of billions of distant galaxies, using a technique called ‘gravitational lensing’.
The mission will effectively look back in time about 10 billion years, covering the period over which dark energy seems to have accelerated the universe’s expansion.
The eight UK institutions working on the mission have been granted a planned A£8.5 million by the UK Space Agency to develop some of the instruments vital for its mapping task and to support the initial development of the necessary data processing capabilities.
University College London’s Mullard Space Science Laboratory is leading the development of the visible imaging instrument and the Open University is receiving a grant to carry out the radiation testing and verification. “The UK is leading the design and construction of the main camera for Euclid,” said Professor Mark Cropper at Mullard Space Laboratory.
“The camera will have 600 megapixels and will be built in the UK with custom-made UK detectors from e2v in Chelmsford. It will also be one of the largest digital cameras ever launched into space and will provide a fabulous view of much of the sky in incredible detail for everyone.”
Euclid’s infra-red camera will be used to measure distances to many of the galaxies. “These distances give us another view of the dark universe,” says Professor Carlton Baugh at the University of Durham who is responsible for generating detailed Euclid simulations. “Looking at a 3-D picture of the universe is a lot more interesting.”
Nasa recently signed an MOU with ESA, outlining its contribution to the mission. The US agency will provide 20 detectors for the near-infrared instrument, which will operate alongside a visible-wavelength camera. The instruments, telescope and spacecraft will be built and operated in Europe.
Nasa has also nominated 40 US scientists to become members of the Euclid Consortium, who will build the instruments and analyse the science data returned from the mission. The consortium already includes almost 1,000 scientists from 13 European countries and the US.
Euclid is optimised to answer one of the most important questions in modern cosmology: why is the universe expanding at an accelerating rate, rather than slowing down due to the gravitational attraction of all the matter in it? The discovery of this cosmic acceleration in 1998 by teams of US, European and other international scientists was rewarded with the Nobel prize for physics in 2011.