WASHINGTON — A 45-year-old telescope in the United States is set to create the largest three-dimensional map of the universe, which could help to solve the mystery of dark energy that is believed to drive the accelerating expansion of the universe.
The four-meter Nicholas U. Mayall Telescope, put inside a 14-story, 500-ton dome atop a mile-high peak, closed on Monday to have its largest-ever overhaul and set the stage for installing the Dark Energy Spectroscopic Instrument (DESI).
The new instrument will begin a five-year observing run at Kitt Peak National Observatory after its installation next year.
Besides finding evidences about the universe’s expansion, DESI will also help to set limits on theories related to gravity and the formative stages of the universe.
It could even provide new mass measurements for a variety of elusive yet abundant neutrinos, a kind of subatomic particles.
“One of the primary ways that we learn about the unseen universe is by its subtle effects on the clustering of galaxies,” said DESI Collaboration co-spokesperson Daniel Eisenstein of Harvard University. “The new maps from DESI will provide an exquisite new level of sensitivity in our study of cosmology.”
The expansion of the telescope’s field-of-view will allow DESI to map out about one-third of the sky.
Brenna Flaugher, a DESI project scientist who leads the Astrophysics Department at Fermi National Accelerator Laboratory, said: “Instead of one at a time we can measure the velocities of 5,000 galaxies at a time, we will measure more than 30 million of them in our five-year survey.”
DESI’s observations will provide a deep look into the early universe, up to about 11 billion years ago.
All of DESI’s six lenses, each about a meter in diameter, are complete.
DESI will use an array of 5,000 swiveling robots, each carefully choreographed to point a fiber-optic cable at a preprogrammed sequence of deep-space objects, including millions of galaxies and quasars, which are galaxies that harbor massive, actively feeding black holes.
The cylindrical, fiber-toting robots, which will be embedded in a rounded metal unit called a focal plane, will reposition to capture a new exposure of the sky roughly every 20 minutes.
The fiber-optic cables will carry the light from these objects to 10 spectrographs, tools that will measure the properties of this light and help to pinpoint the objects’ distance and the rate at which they are moving away from us.
Installation of DESI’s components is expected to begin soon and to wrap up in April 2019, with first science observations planned in September 2019.