After fire and monsoon, DESI resumes cataloging the universe


In the early hours of June 17, flames engulfed the main observatory site, causing the white domes to glow red as the firelight reflected.

Fire and smoke wrapped around the summit and continued north, igniting a total of about 30,000 acres before being contained. At the observatory, four supporting buildings were burnt down, but all scientific equipment and telescopes remained.

The road to recovery

Telescope on top of a mountain with a helicopter carrying a power pole nearby.

On September 27, crews installed a new power pole atop the Kit. Miles of fire-damaged power poles will need repair or replacement. (credit: Bob Stupak)

It took several weeks to secure the site and restore essential functions such as power and water. The fire damaged the observatory’s access road, burning all the firewalls and miles of electricity poles. The monsoons followed closely, causing mudslides. With charred vegetation unable to stabilize the soil, a boulder the size of a car fell onto the road. The crew that arrives at the site to assess the damage and start cleaning traveled together in a daily convoy to reduce disruptions in road repairs.

“The amount of work required to recover from something like this is always surprising,” said Stupak. “This facility is pretty much a small town here. We are very secluded. Everything from drinking water to data is a huge effort by a lot of people.”

DESI collaborators took a systematic approach, starting and checking one system at a time. Experts looked for any damage from smoke, changed air filters, cleaned optical components with a special carbon dioxide scrubber. They examined 5,000 robotic GPS devices that rotate and lock on galaxies, and placed spectrometers (instruments that measure the wavelength of light) under vacuum, removing all the air over the course of several days. The final step was to turn on sensitive image sensors known as CCDs, which convert light into data and operate in extreme cold. Everything works. When the monsoons finally disappeared, DESI resumed cataloging the universe.

Automatically controlled fiber optic backlit with blue light.

The dark energy spectroscopy instrument contains many state-of-the-art components, including a unique GPS. The 5,000 robotically controlled optical fibers collect spectral data from celestial bodies, some of which are billions of light years away. (credit: DESI collaboration)

The sky survey uses the distance and velocity of distant galaxies, and collects data known as “redshift”. During the first year of observations leading up to the fire, the researchers were already well ahead of schedule, collecting 14 million redshifts for a galaxy and a quasar — ​​which is 30% of the total they plan to collect during the device’s five-year run. The collaboration does not anticipate any long-term impact from the fire and is working on a big data release in early 2023.

In the coming months, crews will continue to repair the larger site and improve the device, and perform additional cleaning on the optics to return it to its pre-fire condition.

“It feels really great to be back in Heaven again,” said Bobbitt, who has worked at DESI for more than a decade. “The fact that the telescope and instrument are still there is all we need – and it just needs a little tuning to be as good as before.”

DESI, including Mayall Telescope operations, is supported by the Department of Energy’s Office of Science and the National Center for Scientific Computing for Energy Research, a user facility of the Department of Energy’s Office of Science. Additional support for DESI is provided by the US National Science Foundation, the UK Science and Technology Facilities Council, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, the French Commission for Alternative and Atomic Energy (CEA), the National Science and Technology Council of Mexico, the Ministry of Spanish Economy, DESI member institutions.

Kitt Peak National Observatory (KPNO) is a program of the National Science Foundation NOIRLab.

DESI Collaboration has the honor to allow him to conduct scientific research on Mount Iolkam Du’ag (Kitt Peak), a mountain of particular interest to the nation of Tohono O’odham.

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Founded in 1931 on the belief that the best scientific challenges faced by teams, Lawrence Berkeley National Laboratory and its scientists have been awarded 16 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable environmental and energy solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter and the universe. Scientists from all over the world rely on the laboratory’s facilities for their discovery science. Berkeley Lab is a multi-program national laboratory, operated by the University of California to the US Department of Energy’s Office of Science.

The US Department of Energy’s Office of Science is the largest supporter of basic research in the physical sciences in the United States, working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.


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