UW’s Myers Plays Integral Role in DESI’s 3D Mapping of the Universe

The Dark Energy Spectroscopic Instrument (DESI) has completed its originally planned five-year mission, mapping more than 47 million galaxies and quasars, and creating the largest high-resolution 3D map of the universe to date.

 

Last night, the 5,000 fiber-optic eyes of DESI swiveled onto a patch of sky near the Little Dipper. Roughly every 20 minutes, the fiber-optic eyes locked on to distant pinpricks of light, gathering photons that had traveled toward Earth for billions of years. When the sun rose, collaborators marked completion of a major milestone: successfully surveying all of the area in DESI’s originally planned map of the universe.

 

Adam Myers, a University of Wyoming professor of physics and astronomy, developed the detailed plan for that final sequence of observations, along with the plans for the hundreds of nights of observations that came before it.

 

As the joint level 2 manager for survey operations, Myers is responsible for overseeing how the end-to-end survey is executed. This includes writing the code that takes large imaging surveys of the sky and determines which of the millions of objects in those 2D images DESI will observe. The team of scientists working on DESI developed methods for selecting those objects, which will provide the best 3D information about the universe. After each night of observations, the new data are analyzed. Then, Myers’ programs determine the targets for the next night and the sequence of observations that DESI will undertake.

 

To manage the process where spectra of those targets are taken on a given night, scientists determine what those objects are the next day; use that information to inform what should be observed the following night; and then plan those observations. Spectra are the spread-out light, or electromagnetic radiation, from celestial objects that are organized by wavelength or color, and act as a cosmic barcode.

 

“I find it remarkable that, every day, we process detailed observations of tens of thousands to hundreds of thousands of objects in the sky and use them to plan another set of observations for the subsequent night within a few hours of receiving the data from the telescope,” Myers says.

 

DESI’s quest to understand dark energy is a global endeavor. The international experiment brings together the expertise of more than 900 researchers, including 300 Ph.D. students, from more than 70 institutions. The project is managed by the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory. The instrument was constructed and is operated with funding from the DOE Office of Science.

 

DESI is mounted on the National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a program of the National Science Foundation’s NOIRLab, in southern Arizona. DESI’s 5,000 independently operated swiveling robots can measure the light from thousands of galaxies simultaneously.

 

DESI’s five-year survey -- finished ahead of schedule and with vastly more data than expected -- has produced the largest high-resolution 3D map of the universe ever made. Researchers use that map to explore dark energy, the fundamental ingredient that makes up about 70 percent of the universe and is driving its accelerating expansion. 

 

By comparing how galaxies clustered in the past with their distribution today, researchers have traced dark energy’s influence over 11 billion years of cosmic history. Surprising results using DESI’s first three years of data hinted that dark energy, once thought to be a “cosmological constant,” might be evolving over time. With the full five-year set of data, researchers will have significantly more information to test whether that hint disappears or grows. If confirmed, it will mark a major shift in how we think about our universe and its potential fate, which hinges on the balance between matter and dark energy.

 

“This is my first major experiment where I’ve had a major management role rather than focusing on a narrow scientific avenue. As such, I’ve had a wider view of more aspects of the project,” Myers says. “This has let me see why DESI is such a phenom. Across the entire collaboration, people have found little, clever ways to make the survey a little faster.”

 

Myers credits everyone -- from engineers at the observatory, to observers at the telescope, to instrument-builders, to survey planners, to the people who write software to reduce and calibrate that data, to people responsible for producing the code to run cosmological analyses, to managers themselves -- for finding ways to eke out small improvements. All of these improvements have added up to 1 percent to 3 percent gains in efficiency, he says.

 

“So, we have this bleeding-edge, world-class instrument. But really, it’s the people who join together to run that instrument who make it outstanding. This has really changed my view of how a big project works,” Myers says. “Sure, the technology is amazing. But this technology somewhat obfuscates that, really, it’s the dedicated team that makes the project amazing. It’s been pretty meaningful for me to have a somewhat prominent role in that dedicated team. I’m very proud to be a member of the DESI collaboration because of the wonderful people who comprise it.”

 

“DESI’s five-year survey has been spectacularly successful,” says Michael Levi, DESI director and a scientist at the Berkeley Lab. “The instrument performed better than anticipated. The results have been incredibly exciting. And the size and scope of the map, and how quickly we’ve been able to execute, is phenomenal. We’re going to celebrate completion of the original survey and then get started on the work of churning through the data, because we’re all curious about what new surprises are waiting for us.”

 

DESI has now measured cosmological data for six times as many galaxies and quasars as all previous measurements combined. The collaboration will immediately begin processing the completed dataset, with the first dark energy results from DESI’s full five-year survey expected in 2027. In the meantime, DESI scientists continue to analyze the survey’s first three years of data, refining dark energy measurements and producing additional results on the structure and evolution of the universe, with several papers planned later this year.

 

“The Dark Energy Spectroscopic Instrument has truly exceeded all expectations, delivering an unprecedented 3D map of the universe that will revolutionize our understanding of dark energy,” says Kathy Turner, program manager for the Cosmic Frontier in the Office of High Energy Physics at the DOE. “From its inception, we envisioned a project that would push the boundaries of cosmology. And to see it come to such a spectacularly successful completion for its initial survey, ahead of schedule and with such rich data, is incredibly rewarding. The dedication and ingenuity of the entire DESI collaboration have made this world-leading science a reality, and I am immensely proud of the groundbreaking results we are already seeing and the discoveries yet to come as we continue to explore the mysteries of our cosmos.”

 

Before constructing the 3D map, physicists’ best estimate of the way the universe accelerates, sometimes called “dark energy,” was likely smooth, continuous and constant, says Myers, whose main concern was that the DESI experiment would confirm that, just at higher precision.

 

“To my astonishment, the map from only the first year of DESI data, when combined with other datasets such as supernova observations, strongly suggested that this dark energy is dynamic and is evolving through time,” Myers says. “This was a completely new discovery in basic physics. It’s rare that somebody gets to be a part of something like this.”

 

Because of the instrument’s excellent performance and hints that dark energy might evolve, DESI will continue observations into 2028 and further expand the map. And Myers says he will continue in his role.

 

“The experiment is entering a new phase. In addition to expanding the map even further, we’ll be looking at a new set of galaxies that will help constrain dark energy at an interesting time in cosmic history,” Myers says. “We’ll also study streams of stars in our own Milky Way galaxy to see if their motions can tell us more about the nature of dark matter. Finally, as DESI has proven to be a real workhorse instrument, we’ll be starting to plan for future surveys beyond even 2028.”

 

Support for the Dark Energy Spectroscopic Instrument

 

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; the Secretariat of Science, Humanities Technology and Innovation of Mexico; the Ministry of Science and Innovation of Spain; and 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.

 

For a video of DESI building up its map of observations over five years, go to https://www.youtube.com/watch?v=cZZJNF4jqNI.

 

To read the Berkeley Lab press release, go to https://newscenter.lbl.gov/2026/04/15/desi-completes-planned-3d-map-of-the-universe-and-continues-exploring/.