Plans to transform Kitt Peak’s largest telescope into an instrument capable of mapping the universe in an effort to understand dark energy were boosted Tuesday with a $2.1 million grant from the Gordon and Betty Moore Foundation.

While not exactly chump change, the award is a small part of the cost of widening the field of view of the 4-meter Mayall Telescope and equipping it with the world’s largest spectrograph.

The resulting BigBOSS instrument will be used to create a 3-D map of the universe, precisely plotting the location of 24 million galaxies and 2 million quasars over five years.

The grant is “sort of our seed money for this project,” said Arjun Dey, astronomer with Tucson-based National Optical Astronomy Observatory, which has joined with Lawrence Berkeley National Laboratory to propose the project to the U.S. Department of Energy and the National Science Foundation.

The grant will be used to build one of ten spectrograph units that will be fed light from 5,000 optical fibers — part of a “proof of concept” for the instrument.

The estimated $100 million cost of the project will come partly from its international collaborators, but also seeks 75 percent of the total from the two federal agencies.

“We are hoping that DOE and NSF can come together and make this project happen on Kitt Peak,” said Dey.

The potential transition for Mayall comes as the NSF seeks to defund the telescopes it supports on Kitt Peak, site of the first national observatory telescopes.

The foundation grant was given to the Berkeley Center for Cosmological Physics, whose executive director, Saul Perlmutter, headed one of two teams that won the 2011 Nobel Prize in physics for the discovery that the expansion of the universe is accelerating.

That discovery led to formulation of an unknown force known as dark energy, needed to explain why the universe’s mass is not slowing down from gravitational force.

“After we won the Nobel Prize, the question we all heard most was, ‘Now that you’ve discovered dark energy, what comes next?’” said Perlmutter, in a statement issued by the Lawrence Berkeley National Lab.

“The answer is pretty clear: we have to find out what dark energy is. There’s no end of theories. To know which are possible, what we need most is the kind of accurate observational evidence that only BigBOSS and other advanced experiments can give us.”