Berkeley Lab researchers create world’s best telescope to map distant galaxies

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This summer, Lawrence Berkeley National Laboratory researchers will complete the development of the world’s best telescope for mapping distant galaxies.

The telescope has been dubbed the Dark Energy Spectroscopic Instrument, or DESI. Development of the telescope is mostly complete, according to project scientist David Schlegel, who was one of the founders of the DESI project. DESI’s last attachments will be added this summer — at which point research can be conducted.
“This first test was very successful so it is an important milestone,” said Gaston Gutierrez, lead scientist for the mechanical structure of DESI, in an email. “There are no science results yet since DESI will not start taking science quality data until the end of this year, after 5,000 robotic actuated fibers and 10 spectrographs are completely installed and tested.”

The DESI project was proposed in 2009, but actual construction of the telescope did not begin until 2013. Development required six of the largest telescope lenses in the world, each of which took four years to make, Schlegel said.

As its name implies, the main function of the DESI is to learn more about dark energy, Gutierrez said in the email. He added that dark energy makes up a majority of the universe and yet, scientists know even less about it than they do about dark matter.

“We don’t understand 70 percent of what the universe is made of,” Gutierrez said.

According to Gutierrez, dark energy is responsible for the acceleration of the continuous expansion of the 13.8 billion-year-old universe. During the first half of its lifetime, the universe’s expansion was slowing down, but expansion later accelerated because of dark energy.

Dark matter will also be more easily studied using DESI. Schlegel described dark matter as made up of particles that scientists are unfamiliar with, despite there being five times more dark matter than baryonic matter — the matter made of protons, neutrons and electrons. Schlegel added that researchers can learn about dark matter using DESI by better examining the effects of its gravitational pulls.

DESI is 10 times better than any existing telescope for mapping galaxies, according to Schlegel. He added that it can observe an area 40 times larger than that of the full moon — the Hubble telescope could only see a tiny fraction of that — in addition to mapping galaxies much faster than previous telescopes.

Prior to DESI’s development, a telescope in New Mexico had been used since 1998 to make maps of galaxies, according to Schlegel. He added that more work can be done in the first year of using DESI than the New Mexico telescope did in the last 20 years.

“You could take the 20 biggest telescopes in the world, and together, they wouldn’t be as fast as this one,” Schlegel said. “They are great at doing other things, but in the task of making large-scale maps, they’re not as good as this one.”

Yao Huang is the lead research and ideas reporter. Contact him at [email protected] and follow him on Twitter at @Yhoneplus.