just after seven For months, a huge team of scientists using the Dark Energy Spectrometer has mapped the universe larger than all other 3D surveys combined. And since their five-year mission is only 10% complete, there’s more to be done.
DESI, pronounced like the name Desi Arnaz, has revealed a spectacular cosmic web of more than 7.5 million galaxies that will scan up to 40 million galaxies. Funded by the U.S. Department of Energy, the instrument was installed on the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson, Arizona. It measures the precise distances of galaxies from Earth and the light they emit over a range of wavelengths, both quantity and quality. It will eventually cover about 8,000 square degrees, or about 20 percent of the sky. The science from parsing the data is yet to come, but it will especially help astrophysicists study how the universe is expanding.
“It’s been a fantastic adventure. We were able to keep going despite the pandemic. We had to shut down for a few months before we got used to it,” said Julien Guy, DESI project scientist at Lawrence Berkeley National Laboratory, the lead agency for the collaboration. Observations and data processing are now mostly automated; each morning, scientists collect data on as many as 100,000 galaxies overnight, he said.
“It’s amazing how well this instrument works and how well it’s designed to go out and get distances to these galaxies. It’s a very efficient machine, in a way that would have made it impossible to even 20 years ago. Incredible ways to harvest them. Early universe.
DESI actually consists of several devices housed within the telescope’s 14-story dome. The circular focal plane is located near the top and consists of 10 wedge-shaped petals, each with 500 microrobots. They enable the instrument’s galactic mapping: These 5,000 pencil-sized robotic motors locate optical fibers that must be placed precisely within 10 micrometers—less than the thickness of a human hair. This enables the instrument to collect precise data on 5,000 galaxies at a time. The telescope then points to another area of the night sky and begins work on the next 5,000. In contrast, in one of DESI’s predecessors, Sloan Digital Sky Survey, at a telescope in southern New Mexico, scientists had to manually drill holes in a circular aluminum plate at the telescope’s focal point to make each set of measurements and insert small optical fibers for each galaxy they wanted to observe.