DESI sits at an elevation of 6,880 feet (2,100 m), where it has been retrofitted onto the Mayall Telescope on top of Kitt Peak in the Sonoran Desert, which is located 55 miles (89 km) from Tucson, Arizona, US.

The data from DESI will be used to create three-dimensional maps of the distribution of matter covering an unprecedented volume of the universe with unparalleled detail.

This will provide insight into the nature of dark energy and establish whether cosmic acceleration is due to a cosmic-scale modification of General Relativity.

DESI will measure the expansion history of the universe using the baryon acoustic oscillations (BAO) imprinted in the clustering of galaxies, quasars, and the intergalactic medium.

It relies only on very large-scale structure and it does so in a manner that enables scientists to separate the acoustic peak of the BAO signature from uncertainties in most systematic errors in the data.

[12] The new optical corrector design creates a very large, 8.0 square degree field of view on the sky, which combined with the new focal plane instrumentation weighs approximately 10 tonnes.

The DESI project scope included construction, installation, and commissioning of the new wide-field corrector and corrector support structure for the telescope, the focal plane assembly with 5,000 robotic fiber positioners and ten guide/focus/alignment sensors, a 40-meter optical fiber cabling system that brings light from the focal plane to the spectrographs, ten 3-arm spectrographs, an instrument control system, and a data analysis pipeline.

The instrument fabrication was managed by the Lawrence Berkeley National Laboratory and oversees operation of the experiment including a 600-person international scientific collaboration.

Cost of construction was $56M from the US Department of Energy's Office of Science plus an additional $19M from other non-federal sources including contributions in-kind.

U.S. Congressional approval for the start of DESI as a new Major Item of Equipment was provided in the Fiscal Year 2015 Energy & Water appropriations legislation.

Congressional authorization was provided in 2015, and the US Department of Energy's Office of Science approved the start of physical construction in June 2016.

Individuals with accounts at the National Energy Research Scientific Computing Center (NERSC) can access the entire public portion of the DESI data.

[29] From this precise data, DESI Director Michael Levi stated:We’re also seeing some potentially interesting differences that could indicate that dark energy is evolving over time.