The Dark Energy Spectroscopic Instrument completed its five-year mission to build the largest 3D map of the universe ever constructed, finishing ahead of schedule on April 14, 2026.
DESI, mounted on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona, used 5,000 fiber optic eyes to observe more than 47 million galaxies and quasars and over 20 million nearby stars, far exceeding the original goal of 34 million galaxies and quasars.
This represents a sixfold increase on previous observations of galaxies and quasars, according to Klaus Honscheid, lead scientist of DESI instrument operations and a professor at The University of Ohio.
The collaboration will immediately begin processing the completed dataset, with the first dark energy results from the full five-year survey expected in 2027.
In the meantime, 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 for later this year.
DESI has now measured cosmological data for six times as many galaxies and quasars as all previous measurements combined.
The project’s success is even more impressive in light of several challenges, including interrupted final tests in 2020 due to the COVID-19 pandemic and the Contreras Fire sweeping over Kitt Peak in 2022, which did not damage the telescope but slowed recovery efforts due to monsoons and mudslides.
“DESI has exceeded expectations. It is a big deal because the DESI team was able to complete a heavily ambitious survey program on schedule and on budget,” Honscheid told Space.com.
“Our ability to complete the survey in five years was challenged more than once. Everyone on the operations team worked incredibly hard to keep the survey progressing with high efficiency. And I reckon rightly so, we are all very proud that we actually achieved this goal.”
Kathy Turner, Program Manager for the Cosmic Frontier in the Office of High Energy Physics at the Department of Energy, said the instrument has “truly exceeded all expectations, delivering an unprecedented 3D map of the universe that will revolutionize our understanding of dark energy.”
She added that seeing the project come to such a “spectacularly successful completion for its initial survey, ahead of schedule and with such rich data, is incredibly rewarding.”
Dark energy accounts for around 70% of the universe’s matter and energy budget, but scientists have no idea what it actually is, only that it drives the accelerating expansion of the universe.
Using just year one observations, researchers already saw tantalizing evidence that dark energy is even stranger than predicted, suggesting we may need to revise the standard model of cosmology.
What is dark energy and why does it matter?
Dark energy is the mysterious force driving the accelerating expansion of the universe, making up about 70% of its matter and energy budget, though its true nature remains unknown.
When will the first results from DESI’s full five-year survey be released?
The first dark energy results from DESI’s completed five-year dataset are expected in 2027, after immediate processing begins.
How did DESI overcome challenges during its mission?
Despite pandemic-related delays in 2020 and the Contreras Fire in 2022 that slowed recovery due to monsoons and mudslides, DESI continued operations without damage to the telescope and completed its survey ahead of schedule.