Dario Gil and Kathy Yelick visit DESI at Kitt Peak

Left to right: Nathalie Palanque-Delabrouille, David Schlegel, Jean Toal Eisen, Dario Gil, Carmala Garzione, Kathy Yelick, Michelle Edwards, and Arjun Dey on the tour of Kitt Peak. (Credit: Marilyn Sargent, Berkeley Lab)

November 11, 2026 — Marsha Fenner

Berkeley Lab Physics Division News

DOE Under Secretary for Science Dario Gil and Berkeley Lab Director Kathy Yelick visited DESI at Kitt Peak in Arizona on November 2.

On November 2, DOE Under Secretary for Science Dario Gil visited the Kitt Peak National Observatory in Arizona, home of the Mayall 4-meter Telescope, which currently hosts the Dark Energy Spectroscopic Instrument (DESI), an international, Berkeley Lab-led experiment that has produced the largest 3D map of the universe to date. Researchers use the map to explore dark energy, which makes up about 70% of our universe and drives its accelerating expansion.

Berkeley Lab Physics Division Director Nathalie Palanque-Delabrouille and DESI Senior Scientist David Schlegel were joined by new Lab Director Kathy Yelick, on her first visit to Kitt Peak.

“It was a great pleasure to introduce DESI and its groundbreaking science to Dario Gil,” said Palanque-Delabrouille. “The visit offered a unique opportunity to showcase the Lab’s ability to manage a complex project from initial construction through to successful operations.”

Kathy Yelick and Dario Gil in the control room, discussing the intriguing results of DESI on dark energy. (Credit: Marilyn Sargent, Berkeley Lab)

The highlight of the tour was the experimental instrument itself, which uses 5,000 robotic positioners that precisely align optical fibers with the location where the light from distant galaxies reaches the focal plane, to an accuracy within 10 microns (or less than the width of a human hair). This novel approach has enabled DESI to map the universe much faster than all prior surveys. Topics of discussion included the role of artificial intelligence (AI) in data analysis and how DESI is developing innovative AI-driven approaches at all stages of the DESI data lifecycle.

“The DESI spectrographs give us the data to place each galaxy on a three-dimensional map,” said David Schlegel, Senior Scientist in Berkeley Lab’s Physics Division. “Our maps are now so large that simulating universes with enough volume and fidelity to interpret them has been one of our biggest challenges. AI-enabled approaches will let us do that.”

David Schlegel (right) and Nathalie Palanque-Delabrouille (left) explain to Dario Gil (center) the functionality of the DESI spectrographs, which disperse the light from distant objects using volume-phase holographic gratings and measure the resulting spectra on CCD detectors. (Credit: Marilyn Sargent, Berkeley Lab)

Concluding the tour, Palanque-Delabrouille and Schlegel presented some of the ways DESI is moving into the future, including the DESI Run 2 survey currently in development, and proposals for what a next-generation instrument could look like.

“DESI continues to map the universe at an incredible pace. In a good month, we measure as many spectra of distant galaxies as all prior surveys over two decades,” continued Palanque-Delabrouille. “ It was a privilege to discuss the intriguing insights we are uncovering about dark energy through this unprecedented 3D cosmological map.”

To close the day’s visit, the group enjoyed observations of the sunset using Kitt Peak’s McMath-Pierce Solar Telescope, the world’s largest solar telescope, followed by observations of Neptune, Saturn, and various nebulae and globular clusters at the 0.6-meter Shreve Telescope.

Dario Gil looks up at the DESI instrument, its six-lens corrector, and fiber-equipped focal plane. (Credit: Marilyn Sargent, Berkeley Lab)

Left Photo: Dario Gil scrutinizes the DESI three-dimensional galaxy map on the screens in the DESI control room. Right Photo: Left to right, Nathalie Palanque-Delabrouille, David Schlegel, Dario Gil, Arjun Dey, and Kathy Yelick in the dome of the Mayall telescope. (Credit: Marilyn Sargent, Berkeley Lab)

Sarah Logsdon (Associate Scientist at NSF NOIRLab), Jean Toal Eisen (Executive Vice President for Corporate Strategy at the Association of Universities for Research in Astronomy (AURA)), Arjun Dey (DESI astronomer at NSF NOIRLab), Carmala Garzione (Dean of the University of Arizona’s College of Science), Dario Gil, Kathy Yelick, Nathalie Palanque-Delabrouille, Kristen Ellis (Associate Principal Deputy Under Secretary for the Office of the Under Secretary for Science, DOE), David Schlegel, and Michelle Edwards (Associate Director of Kitt Peak National Observatory) on the tour of the Kitt Peak facility. (Credit: Marilyn Sargent, Berkeley Lab)

DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science national user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.

The DESI collaboration is honored to be permitted to conduct scientific research on I’oligam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.