The Dark Energy Spectroscopic Instrument (DESI)

The Dark Energy Spectroscopic Instrument (DESI) will measure the effect of dark energy on the expansion of the universe.  It will obtain optical spectra for tens of millions of galaxies and quasars, constructing a 3-dimensional map spanning the nearby universe to 10 billion light years.

DESI will be conducted on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018.  DESI is supported by the Department of Energy Office of Science to perform this Stage IV dark energy measurement using baryon acoustic oscillations and other techniques that rely on spectroscopic measurements.
 The Dark Energy Spectroscopic Instrument (DESI) is scheduled to see ‘first light’ in September.

 Crews at the Mayall Telescope near Tucson, Arizona, lift and install the top-end components for the Dark Energy Spectroscopic Instrument, or DESI. The components, which include a stack of six lenses and other structures or positioning and support, weigh about 12 tons. DESI, scheduled to begin its sky survey next year, is designed to produce the largest 3-D map of the universe and produce new clues about the nature of dark energy. Credit: David Sprayberry, NOAO/AURA
"The survey will reconstruct 11 billion years of cosmic history. It could answer the first and most basic question about dark energy: is it a uniform force across space and time, or has its strength evolved over eons?

It will track cosmic expansion by measuring features of the early Universe, known as baryon acoustic oscillations (BAOs).

These oscillations are ripples in the density of matter that left a spherical imprint in space around which galaxies clustered. The distribution of galaxies is highest in the centre of the imprint, a region called a supercluster, and around its edges — with giant voids between these areas." thanks

Cecile G. Tamura