Mapping the universe in extraordinary detail using UCL lenses

A three-dimensional map of the Universe that reaches deeper in space and time than ever before is one step closer as final testing begins on the Dark Energy Spectroscopic Instrument (DESI), designed and built in part by UCL physicists. From early 2020, DESI will observe the light from 35 million distant galaxies and 2.4 million quasars over five years to precisely map their distance from Earth and gauge how quickly they are moving away from us. This is important for accurately measuring and understanding more about dark matter and dark energy, which is driving the mysterious accelerating expansion rate of the universe. Professor Ofer Lahav, (UCL Physics & Astronomy) , chair of the DESI UK consortium of seven universities, said: "By looking back in time by up to about 11 billion years, DESI will expose secrets of the universe's infancy and early development. This new information will help us better understand the physical processes driving the accelerating expansion of the universe, one of the key unsolved questions in physics." DESI is mounted on the four-metre Mayall telescope at Kitt Peak National Observatory near Tucson, Arizona. The telescope's top end has been replaced with DESI's optical corrector, built by a team including  UCL physicists , and a focal-plane system containing 5,000 fiber-optic "eyes" that independently move to capture the light from individual galaxies. In ideal sky conditions, they enable the instrument to measure the light of 5,000 galaxies in about 20 minutes.