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After fire and monsoons, DESI resumes cataloguing the cosmos

November 9, 2022

After fire and monsoons, DESI resumes cataloguing the cosmos

Honscheid

A recent article in Symmetry Magazine (a joint Fermilab/SLAC publication) featured a story that Prof. Klaus Honscheid has been involved with: On June 11, lightning struck a remote ridge in the Baboquivari Mountain range outside of Tucson, Arizona. Within days, the Contreras Fire had traveled 8 miles and climbed Kitt Peak, a 6,800-foot mountain dotted with white telescope domes. Within one was the Dark Energy Spectroscopic Instrument, the heart of a next-generation sky survey that is creating the largest 3D map of the universe.

Researchers use DESI to study dark energy, the mysterious force accelerating the expansion of our universe. It’s a clue into the fundamental workings of nature, how the universe evolved, and how it may end.

Collaborators who had spent years designing, building and running the instrument watched the flames sweep over the observatory’s southern ridge on webcams—until the power went out. They switched to watching the curlicue paths of planes dropping fire retardant.

When the smoke had cleared, teams returned to find something astounding: All of the scientific equipment was intact. For several weeks, they carefully cleaned components and turned DESI’s systems on one by one. On Sept. 10, DESI began imaging the night sky once again.

“We’re relieved to return to our science with equipment that is performing almost as well as it was before the fire,” says Michael Levi, director of the international DESI collaboration and a scientist at the Department of Energy’s Lawrence Berkeley National Laboratory, which manages the project. “I’m eternally grateful to the firefighters and the crews who secured the site, and their patience and ingenuity getting things running again.”

It’s not entirely business as usual yet, since the fire knocked out power lines and the high-speed network normally used to transmit data. The telescope is temporarily powered by a generator, and the information recorded each night has to take a more circuitous route to researchers around the globe. Each day, the data (roughly 80 gigabytes worth on a clear night, capturing about 150,000 celestial objects) is loaded onto an external hard drive and driven down the winding mountain road, past the recently charred mesquite and rebounding wild grasses, for processing in Tucson.

DESI owes much of the successful restart to quick actions by crews on the mountain who secured the precious equipment.

“We’ve performed tests during the restart and found little loss in performance despite the terrible conditions that the mountain experienced,” says  Claire Poppett, one of DESI’s lead observers and a physicist at UC Berkeley’s Space Sciences Laboratory. “The work that the crew did to protect the instrument was phenomenal, and we wouldn’t be in the good shape we are in without it.” 

By Lauren Biron

Read More: https://www.symmetrymagazine.org/article/after-fire-and-monsoons-desi-resumes-cataloguing-the-cosmos