Mayall Telescope
The overhauled Nicholas U. Mayall Telescope is expected to help astronomers solve mysteries surrounding dark energy.P. Marenfeld and NOAO/AURA/NSF

An unknown form of energy, which is believed to permeate all of space, has been baffling astronomers for decades. Dubbed the dark energy, this mysterious phenomenon is said to account for roughly 68 percent of the universe while continuously driving the accelerating expansion of the cosmos.

But, the so-called dark energy continues to be a hypothesis even today. To help astronomers reveal the secrets surrounding dark energy, a 45-year-old telescope in the US has now been tasked to create the largest 3D map of the universe, which is expected to demystify this unexplained form of energy.

The 4-meter Nicholas U. Mayall Telescope, tucked inside a 14-story, 500-ton dome atop a mile-high peak in Arizona, was closed on Monday to prepare it for the newly assigned role. The temporary closure was mainly for the installation of the Dark Energy Spectroscopic Instrument (DESI), which will observe the universe for five years, starting 2019, at the National Science Foundation's Kitt Peak National Observatory (KPNO).

The make-over

As part of the overhaul, the top end of the telescope that houses its secondary mirror and a large digital camera will be replaced with DESI instruments.

According to scientists, DESI will not only provide new insights into the universe's expansion but will also help them better understand the variety of elusive yet abundant neutrinos out there is in the universe.

"One of the primary ways that we learn about the unseen universe is by its subtle effects on the clustering of galaxies," DESI Collaboration co-spokesperson Daniel Eisenstein of Harvard University said in a statement. "The new maps from DESI would provide an exquisite new level of sensitivity in our study of cosmology."

Mapping the sky

DESI will expand the Mayall telescope's field-of-view in a way that it will be able to map nearly one-third of the sky.

"The telescope was designed to carry a person at the top who aimed and steered it, but with DESI it's all automated," 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."

Using an array of 5,000 rotating robots, DESI's observations will provide a deep look into the early universe, up to about 11 billion years ago. These cylindrical, fibre-toting robots will reposition to capture a new exposure of the sky in every 20 minutes.

"We can see about a billion galaxies in the survey images, which is quite a bit of fun to explore," David Schlegel, a DESI project scientist, said. "The DESI instrument will precisely measure millions of those galaxies to see the effects of dark energy."

According to scientists, installation of DESI's components is expected to complete in April 2019 while the first science observations likely to take place in September 2019.