Recycled telescope to solve mystery behind dark energy

Washington: A 45 year- old telescope is being repurposed to create the largest 3D map of the universe and solve the mystery of dark energy, which is believed to drive the accelerating expansion of the cosmos. Tucked inside a 14- story, 500- tonne dome atop a peak in Arizona, the telescope took in the night sky for the first time and recorded its observations in glass photographic plates. The temporary closure sets in motion the largest overhaul in the telescope's history and sets the stage for the installation of the Dark Energy Spectroscopic Instrument ( DESI), which will begin a five- year observing run next year at the US National Science Foundation's Kitt Peak National Observatory ( KPNO), part of the National Optical Astronomy Observatory ( NOAO). This day marks an enormous milestone for us, said Michael Levi DESI Director of the US Department of Energy's Lawrence Berkeley National Laboratory ( Berkeley Lab). Now we remove the old equipment and start the yearlong process of putting the new stuff on, said Levi. More than 465 researchers from about 71 institutions are participating in the DESI collaboration. The entire top end of the telescope, its secondary mirror and a large digital camera, will be removed and replaced with DESI instruments. A large crane will lift the telescope's top end through the observing slit in its dome. Besides providing new insights about the universe's expansion and large- scale structure, DESI will also help set limits on theories related to gravity and the formative stages of the universe.— PTI