U.S. researchers say a new instrument will be a "time machine" to allow scientists to study the universe's earliest galaxies that could never be studied before.

Built by researchers at UCLA, the MOSFIRE instrument -- or Multi-Object Spectrometer for Infra-Red Exploration -- has been installed in the Keck I Telescope at the W.M. Keck Observatory atop Mauna Kea in Hawaii.

The instrument will gather light in infrared wavelengths invisible to the human eye to penetrate cosmic dust and see distant objects whose light has been stretched or "red shifted" to the infrared by the expansion of the universe, a UCLA release said Wednesday.

"The instrument was designed to study the most distant, faintest galaxies," project leader Ian S. McLean, a UCLA physics and astronomy professor, said.

"When we look at the most distant galaxies, we see them not as they are now but as they were when the light left them that is just now arriving here. Some of the galaxies that we are studying were formed some 10 billion years ago -- only a few billion years after the Big Bang."

Light collected by the Keck I Telescope was fed into MOSFIRE for the first time on April 4, the UCLA release said.

"We are looking back in time to the era of the formation of some of the very first galaxies, which are small and very faint," McLean said.

"That is an era that we need to study if we are going to understand the large-scale structure of the universe."